Exhaust

things Lewis Collard likes, by Lewis Collard

This was my Rover P5's engine.

You'll notice that it's not in the Rover P5.

So, the workshop build was completed, giving me a much nicer space to work in. The Mazda 323 GTX was fully someone else's problem while the engine is (still) being rebuilt. And some time ago I made some major life changes to give me more time and motivation; it worked! Which meant I could finally get back to the Rover P5, for which there are thousands of pounds worth of parts in storage to fit, and a list of jobs that'll keep me out of trouble for the foreseeable future. And I found myself procrastinating, again. Why?

Someone wise once told me that when I find myself procrastinating, I need to look for the fear. I think one of those fears is that I have seen some really nicely-done Rover P5s, and I doubt I will ever be able to do one as well as those. There's a fear of being judged by all the people that build all those perfect P5s. Half of that doesn't matter (it doesn't need to be perfect) and the other half is mostly something I made up (there so so very few judgy people in the classic car world and I'm actually thick-skinned faced with actual criticism rather than imaginary criticism anyway).

What I also found out was: When finished, I just wouldn't find the P5 fun to drive.

It's a beautiful car, maybe one of the most beautiful cars ever made. This one in particular, in this colour, is so beautiful that I was forced to impulse-purchase it. And yet, it has an engine designed shortly after World War II, a carburettor, a distributor with points, and 115 horsepower. The horsepower number sounds OK, but it is in a car weighing 1700 kilograms. It is substantially slower than my totally-standard 1.4 litre Ford Fiesta from 2004, even if you forget the fact that my Fiesta can corner and a P5 can't. Or that my Fiesta has actually worked every day, where a car with a carb and a distributor with points is a lottery.

A 3-litre Rover P5 is not fun to me, and I live my life one fun at a time, or something.

Anyone sensible would have sold the car at that admission-to-self. Actually, anybody sensible would not have bought impulse-purchased a non-working car for £3500 unseen over the Internet, so wouldn't reach this point in the first place. Because I'm not sensible, I decided to start a new plan: make a Rover P5 fun to drive.

I actually had several ideas. One was to develop fuel injection & electronically-controlled ignition for the IOE engine, to at least make it reliable and probably get a few more horsepowers out of it. That would open up more options, like shoving a massive turbo onto it for the lolz, and well, if that idea sounds insane that's why I didn't do it.

So, what else? Rover V8? 2JZ? K20???

They all have their merits. And yet, those are all petrol engines. Any discussion of drivetrain swaps in classic cars must eventually face the spectre of electrification.

Electric means 100% torque at zero RPM, fewer moving parts, near-silent; it's, like, the future, man. And though some consider it sacrilege to electrify a classic car, it can be argued that changing an old, unreliable, underpowered petrol engine to a modern, reliable, much more powerful one is changing the character of a car every bit as much as electrifying a car is. And nobody but the dullest of rivet-counters objects much to all the mad engine swaps out there; why object, then, to electrification?

But there's more. We all know that petrol engines pollute. Some would argue that, whatever the historic value of these old cars, an internal combustion engine in a classic car in The Current Year is like painting an historic house with lead paint, heating it with trees felled from old-growth forests, and emptying a chamber pot from its windows onto the street. Such a thing may have been a grim necessary in the past; doing it today when we have clearly better and cleaner options is entirely irresponsible. And, honestly, it's very hard to argue with that.

And that is why I bought

a Corvette engine, because fuck 'em.

This is the Chevrolet LS1, a 5.7 litre V8 petrol engine with about 350 horsepower and over 350 lbs/ft of torque, and an aftermarket that will take them to arbitrarily large power numbers. And it makes cool V8 noises! Now we're talking!!

This is not another dumb impulse purchase (he said with a straight face) but the product of a lot of thinking. I wanted reliable power in a compact package that had some hope of fitting in the P5.

I needed something well-documented; "LS1 into a Rover P5" might not have been done before, but "LS engine into something that shouldn't have an LS engine" has been done probably thousands of times. And anything you are thinking of doing with an LS1, the fine folks over at the LS1Tech.com forums have probably already done it five times and found out which of those five ways works best and which four don't.

I needed something somewhat modern; no LS engine has a distributor, and they definitely do not have a carb, which would allow me to preserve my unbroken 41-year streak of not dealing with carbs. (Yes, I would rather re-engineer a car entirely rather than ever deal with bloody carbs and this is literally what is happening here.)

It is a simple engine, compared to other modern engines with the same power figures. I reckon I could hold one in my head. Simplicity means less to go wrong, and simplicity means that if it does go wrong it's straightforward to fix. Simplicity also means that they could build them cheaper, and make up the difference with displacement.

It's kind of cheap. There are no scrapyard LS engines in England; this cost me nearly £4000 and it had to be shipped from Ireland. But if you price it against any other 350 horsepower engine it's not that bad. Sure, everyone's getting 350+ out of their K20s these days - but you won't get a K20 pushing out that kind of power reliably for £4k. Or maybe I could probably pick up one of the German V8s for that money - but then that would be a monstrously complicated engine with no substantial after-market. Or I could pick up a JZ - for substantially more money, and complexity, and that still wouldn't push 350 horsepower without modification. (This was actually my original plan. My brother talked me out of it. I am glad he did, and not just because that means losing the next several years of my life to this is not at all my fault.)

I used to hate the saying there's no replacement for displacement. You probably won't find me using it again after this very paragraph, in fact. But I have to admit there's something to it. For reliable power at a given price point, sometimes it's best to throw a bunch of unsophisticated cubic centimeters at the problem. "Quantity has a quality all its own", as Stalin once said while trying to find positive things to say about my welding. Or, "when in doubt, use brute force".

And that is how Lewis convinced himself that buying a 5.7 litre V8 was a good idea! So...

Does it fit?!

As if I'd ask that sort of question before spending all of my money on an engine! But I had a hunch that it would. Its 5.7 litre displacement seems ludicrous to anyone whose patriotism includes no eagles, but it's actually a remarkably compact engine. It's substantially smaller in most dimensions than a Rover V8, and we know a Rover V8 fits in a Rover P5. But measurements can lie; I wouldn't know for a fact that it fits until I shoved it in the engine bay and saw what it collided with.

What I didn't feel like doing, though, was lifting 215 kilos in and out more than once, because setting up the engine crane every time would be effort. Which is why I bought another LS engine!

The eagle-eyed among you will notice that this isn't really an LS engine. It's the wrong colour! This is, instead, a mockup engine, or as I like to call it, a stunt engine. It replicates all of the critical dimensions and mounting points of a real LS engine. My one even has fake cylinder heads! And it weighs like 8kg, or 15kg with the "heads", which is a weight nobody minds lifting in and out of a car. You can get one at Speedway Motors in the US. (Their website plain doesn't work with non-US delivery addresses and telephone numbers though; you'll have to give them a phone call if you're outside the US, and brace yourself for the shipping cost.)

So, I dropped the stunt engine into the P5's engine bay, in about the same place that the original IOE engine sat.

Let's talk first about what "fits" means. What that really means is that it doesn't hit anything that I want it to clear. There are some things that are non-negotiable. It can't interfere with any part of the steering. I don't want to chop out the front crossmember. I don't want to cut into the bulkhead. I don't want to redesign the suspension. I don't want to have a bulge in the bonnet, because that would look silly. Anything else - especially adding metal to the car - is up for grabs.

As you can see, there's miles of vertical space there, and no clearance problems around the heads. Let's look at the air conditioning pump.

Acres of room there, because I threw the air-con pump onto the scrap pile (not gonna need it, and saves 8kg), so there's nothing to clear. Woohoo!!

Let's look at the other side.

The big mount on the right-hand side is one of my old engine mounting points; that's going to get chopped off. The small brackets at the front are for the radiator or something, I forgot. Don't worry about those. They're in the way, but they can be anywhere on that front crossmember, and anyway nobody said that the radiator must be at the front of the car.

:)

Still, there's a possibility that the alternator will not clear the front crossmember. It's going to be tight. Even if it fits, it might be a pain to get in and out. It might necessitate a more compact alternator, and if that doesn't work I can mount the alternator at the top right of the engine as the LS-engined trucks have it. There's some possible solution for it out there even if I don't know what that is yet, so let's call that OK.

It's a bit tight around the steering box and somewhat less tight on the steering relay on the other side. Tight, but some design of engine mounting won't conflict. I can fabricate around this - run mounting rails from the rear to the front - in a way that'll allow me to get the steering components in and out.

And there's enough room at the back that I'll be able to unbolt the engine from the box with less hassle than the original engine! But while we're looking at the back...

No possible design of sump is going to clear that rear crossmember. This crossmember is negotiable though; it needs to be more or less there, but it doesn't have to look like this. It can plausibly be dropped lower and I'll pretend that this isn't going to result in any ground clearance issues.

My brother has a way of asking the obvious questions that I did not think of, such as...

And well, yes, I can.

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So, an LS engine fits in a Rover P5, for some value of "LS engine" and "fits". With that point proved, I could drop the front subframe.

This was easier than expected. The six bolts that held it in actually came undone, perhaps because of plenty of penetrant applied in the days before. The only other things in the way were the old over-complicated handbrake mechanism (which is going to be replaced by something much simpler when that comes around), an earth strap, and a brake line, all of which were swiftly defeated by an angle grinder.

With the subframe on the floor, I could take a look at the original engine mounts. I said "Corvette engine" earlier because it is, but it was also fitted in many other cars, and I think these are Pontiac GTO mounts (which obviously implies this engine came from a GTO, and not a Corvette). With those bolted to the stunt engine, I could see that re-using them is somewhat plausible.

But that is without the engine at the correct height relative to the subframe; they're both sitting on the ground.

What is the correct height and location of the engine, though? I actually decided on this early on, before the old engine came out. It was to copy the forwardmost point and the crank centreline of the P5's engine. The engine is exactly central in the subframe. The very front of the vertical centre of the front pulley is 160mm from the deepest point of the dip of the front crossmember, with the front face of it sitting exactly in the fore-aft centre of that crossmember. The engine tilts back at an angle of 3 degrees. That, I decided, will be the position of the new engine; it is as good as any.

But to get the stunt engine in position on the subframe, how am I going to measure those dimensions relative to the front face and centreline of the front pulley, when my stunt engine does not have a front pulley? The answer, obviously, is to fit a front pulley to it. Here's what that looks like.

The eagle-eyed among you will notice that this isn't really an LS1 front pulley. It's the wrong colour! This is, instead, a mockup pulley, or as I like to call it, a stunt pulley. I don't actually need a whole front pulley; I need something to mark out the centreline of the crank and the stick-out of the real pulley. So I welded some shit together and came up with this. The centre of the rectangular cut-out on the front of the stunt engine corresponds with the crank centreline of the LS. After I positioned it as precisely as I reasonably could, I marked some sharp lines with a paint pen on the stunt pulley. When all four of these markings are lined up with the edges of the rectangular cut-out, like this...

...I know that the stunt pulley is exactly where it needs to be. This saves a lot of tedious measuring (it took 15 minutes to line this up perfectly to make the markings) and it's easy to validate with an eyeball that it hasn't shifted anywhere.

Anyway, let's get the fake pulley onto the fake engine, put it on the subframe and see how it goes.

To do this, I bought these cheap adjustable caravan stands to hold the subframe up to a working height...

...and lifted the stunt engine up to the correct height with this jack designed for gearboxes (which means it has a perfectly linear upwards lift unlike a conventional jack)...

...and with everything in more-or-less the right place....

...bolt the steering box and relay into the subframe and see what fouls what.

It turned out I can't use those GTO engine mounts, because they foul on the steering arms - even if they could bolt to mid-air there would be no clearance there.

Shame, because I liked them, and didn't really want to make my own, but needs must. I made an initial version of my mounts out of cardboard.

Which was fine, except there was no space to get a bolt into the engine block, so I came up with a second one...

...which I could fit to the stunt engine block using a bolt. Which meant I could turn that into steel, and to talk about turning it into steel we shall have a brief diversion about tools.

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Tools! I like them! Tools help you make things! And yet I am prone as anyone to thinking that just one more tool is going to solve all my problems. What I actually needed to do instead of buying more tools was to use the ones I have.

Some of those tools are three 115mm angle grinders. They all perform exactly the same. I like having one with a cutting disc, one with a flappy wheel disc, and one with a grinding disc. It saves having to change discs, which I don't like doing because life is short.

The other one is a cheap MIG welder. It's a Clarke 151EN which my brother gave me for free (thanks Alex), which he bought for about £200 in 2013 and didn't use much.

I've converted it to use a Euro torch, to make it easier to find consumables. I also ripped out the gas feed from the welder to use it solely with flux-core (gasless) wire. A lot of people don't like flux-core welding. I kinda like it; I get nearly the same results and I don't need to worry about running out of gas. It's easy to get flux core wire from Amazon; it's more effort to get a gas bottle refilled. And I want to prove a point, and only to myself: that tooling is not what is coming between me and getting actual stuff done.

It's a cheap welder so I might burn it out before I've finished the subframe. Or I'll end up converting it to gas! But for now this will do.

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Anyway, with the cheap welder and a selection of angle grinders I turned my cardboard engine mount into 3mm steel...

...and then remade it again with a 6mm main plate chopped off a generic LS engine mount, and 3mm steel for the rest...

...which almost solved the problems I had from the first round. (I'll still need to fettle it in the press a bit to get rid of some heat distortion from welding, and tidy up the welds; that can be done later.)

Those with some the mounting rubbers clear the steering arms with room to spare.

Nice! And I'll need that room to spare, because I need to fabricate some rails for these mounts to sit on. And that starts with these:

These took three revisions across three days to make. Someone who is good at this would have done it in a fraction of the time; I don't know what I'm doing, so it takes longer. That's part of the fun of this. I've never done an engine swap (if you don't count putting a slightly larger-displacement version of the same engine into a car), let alone an LS swap into something that never had an LS. I can chop up metal with an angle grinder and do an ugly job of sticking it together with a gasless MIG I got for free; those are my "skills". And this rules! If I only did what I know I'd still be soiling myself and crying for food. Just give it a go; what's the worst that can happen?

Anyway, the idea behind these sections of rail is that I can bolt them to the engine mount. Then I can get the subframe exactly level, and then get the stunt engine in exactly the right position relative to the subframe (rather than the crude approximation I did to check my steering clearances). This took three hours! And it required continued adjustment over the course of the day as the temperature changed and when I accidentally kicked the caravan stands. From there, you can fabricate outwards from the stub rails towards the front corners of the subframe. This is how a partly-completed rail looks:

And getting the engine in the right position gets a lot easier after the first quarter of these rails is in place! Here is how it extends backwards:

The box to which it extends rearwards (right in the pic above) is not strong enough for these purposes. It is a fairly-thin reinforcer between the suspension arm mounting points and the rear crossmember, which are strong enough for this job. I'll reinforce this box later.

Anyway, spend nine days straight on doing all of those things and you get something that looks like this:

That's close enough to done for the moment; it holds the engine in the correct place and at the correct angles for us to move on for a while. Let's take a look at that alternator clearance again.

That nearly fits. Nearly fitting means "doesn't fit". But "nearly" also implies a couple of solutions that aren't top-mounting the alternator (which I don't want to do because this will merely move the clearance problem somewhere else rather than solve it). One of those would be to simply notch the new subframe rails a little. But I think it would be better to solve this by fitting a modern, more compact alternator. That's the obvious solution to me, because I want to replace my alternator anyway; it and all the other ancillaries on the engine came without no guarantee that they work.

Let's talk about the sump for a second. It's abundantly clear to me that the original front-sump would never clear the steering gear. So I bought this Camaro rear-ish sump instead...

...which still won't clear the steering gear at the front! But it's a better starting point because it has the oil filter at the rear. That means it can be modified to fit. What I knew all along was that the rear of any LS sump won't clear the centre crossmember. There was a little clearance on a sump-less stunt engine - in fact, millimetres from clearing the centre crossmember with the rear sump. But modifying the sump at the rear is not a solution. The sump on the LS engines are structural; the bellhousing bolts to it. So there's a hard limit on how shallow you can make a sump at the rear, and I think the Camaro sump is as shallow as it can be in the areas that interfere with the crossmember.

Instead, that means that we have to brace the chassis with some angle iron, cut the centre crossmember out...

...and remake it, but about an inch or two lower. To do this, I took an oversized length piece of 25x50x3mm box section steel, and clamped that to some temporary angle iron pointing downwards from the outside of the chassis rail, spending as long as I needed to get it in exactly the right position.

From there, I could add some steel plate to hold it in place...

...and then add a whole load more steel and miles of flux core welding wire to make it into a centre crossmember, and by the way there goes another three days.

At which point I started to wonder how much of the weight savings from fitting an LS1 are being negated by the sheer volume of steel I'm putting into this!

After that, I knew that there was going to be some clearance problems around the starter motor. So I cut out some of the steel I just added, chopped a slice of 100mm steel pipe, and shoved that in the hole I made (it's just right of the rear of the engine below).

As promised earlier, I reinforced the box between the suspension arm mounts and the stub of the old rear crossmember by adding even more 3mm steel.

And with all that done, I could spend a day and a half going around fixing up my bad welds, cleaning up a little,...and add a little zinc-rich primer as a temporary to stop everything from rusting faster than a British car leaving the factory. While Chip Foose is not going to start hammering my inbox trying to hire me for my beautiful fabrication skills, it looks pretty OK for someone who has absolutely no clue what he is doing.

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So that's where I am now: an LS engine (or stunt version thereof), sitting in a Rover P5 subframe, with most of the things clearing the things they need to clear. Some things need fettling, and some things might still need to be welded to it; this is not its final form. But this is done enough that I can call it done for now.

And that, is the easy part out of the way. :) See you next time.

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Part numbers from this post:

• Stunt engine: Speedway Motors SoloSwap 12640748
• Transmission jack: Draper 09021
• Welder: Clarke 151EN
• Sump: General Motors 12640748
• Die grinder: Sealey SA671
• Zinc primer: U-POL WELD/AL
• Cardboard: Amazon single-skin envelopes (from my deliveries), Felix cat food boxes
• Steel supplied by Thomas B. Bonnett

A fully-dressed LS1 V8 engine weighs exactly 215 kilos. That is 474 Freedoms if you are from the United States of America. I put it in the title of this post to save the world a click.

This includes everything that is normally directly attached to the engine - power steering & air con pump, alternator, inlet & exhaust manifolds, flywheel, engine mounts, fuel rail, engine side of the wiring loom, etc. There's plenty of numbers out there on the Internet that involve the words "about" and "I think", and I didn't like that, so I lifted one with a £35 crane scale from Amazon to find out for sure.

You're welcome!

I know what you're thinking. It's "how would you know what I'm thinking?". But for the sake of the narrative I'll say that what you're actually thinking is "Lewis, why on earth would you be weighing a Corvette engine?"

That's a good question! And well, things just escalated, a little...

I now have a workshop.

Which is to say I've been busy.

Inside that workshop, lives the 2.5-metre-long home-made mother of all steel workbenches.

And on that 2.5-metre-long home-made mother of all steel workbenches that lives inside the workshop are these angle grinder brackets.

I use angle grinders all the time, often enough that I always want one immediately to hand. But I don't like them being on workbenches permanently taking up space, because that space could be better used for things I am working on. What I really needed was some neat solution to hang them on a wall, or in this case the steel upstand of the 2.5-metre-long home-made mother of all steel workbenches.

I could have bought some brackets for a few quid from Amazon, but I had some 1mm galvanised steel. which was free because it was being thrown away.

I also had angle grinders to make it with, obviously, because that is what I wanted to hang on the brackets. Stuff I already had was even cheaper than a few quid. But, more importantly, making it myself meant I could have it that day, rather than at 6pm the next.

Anyway, that means I've worked out the dimensions so you don't have to! Which brings me to the point of this post. If you need one yourself, or two, or four of these crude angle grinder brackets for yourself, you can use my handy instructions below and make some of your own. You can click through to the larger image if you want to print it out.

It is optimised for being made in a hurry by someone sloppy (that's me); there are generous tolerances in several places to allow for errors.

I chose 55mm for the height, because the galvanised steel strips that were kicking around at the moment I had the idea were 110mm in width, and that meant I could fit two onto a single strip. You can modify the design to make them taller if you like, but with 1mm steel I wouldn't make them much shallower.

Enjoy!

This was my rocker cover.

I picked it up from my engine builder when I delivered the turbo.

I shouldn't really file it under the "Rationalising" series. My rocker cover needed a new gasket and then would have continued to last forever, because they don't wear out. There was nothing to rationalise; it was neither badly modified nor badly designed. What it also was not, as even the indifferent will notice, was pretty.

Here is one that is pretty:

That's not mine; it is one beautifully restored by 80s Hero. I could have done exactly the same thing with mine, but the one above is perfect. Because it has been done perfectly, I can't do better than it, so instead I would have to do something completely different. I had an idea which I did not know would work or not, but if it worked as well as it did in my head it would be awesome.

But before I could do any of that, I had to remove nearly four decades of corrosion, flaky paint, and overcooked oil from it. Half a gallon of old petrol, some oven cleaner and a pressure washer got it back to this...

...then paint stripper, wire brushes, Brillo pads, and arms got it to bare metal.

I could have had this vapour blasted instead of cleaning it myself, manually. I didn't mostly because I started this a few days before Christmas when everything was closed, and partly because I started this a few days before Christmas and needed something to keep me out of trouble in my time off. But I happen to like that this preserves some of the "texture" of the aluminium. Other people have done the ultra-shiny mirror-finish engine bay to perfection; again, because I can't beat that, I have to do something different instead.

After all that, the underside didn't look quite so toxic either.

Back to the plan that was in my head! That plan was to mask off everything but the raised parts, spray those black, then unmask it and clear-coat both the painted and unpainted parts. For the fine bits of masking, I tested with 4mm and 5mm Hobby 2000 tape, which is designed for scale modellers. I figured they really like sharp lines in that world, but to be sure that it would work with the paint I was using I did a test on a sheet of clean brand-new steel plate I had kicking around.

Nice; that's sharp enough that the texture of the rocker cover is my limitation. And with that giving me confidence in the plan, I masked it up...

...then gave it a couple of coats of Jenolite matt BBQ paint, as previously seen on my heat shield. I didn't use this paint for its temperature-resistant properties; if it ever got close to 650 C at the rocker cover I would have bigger things to worry about than my paint coming off, such as my engine being violently on fire. Rather, that was the matt black paint which I had kicking around, so I used it.

That required baking (in the big BBQ this time round) to make it cure, and then I lacquered it with Jenolite clear coat. Which I'm not going to show you yet!

Originally, as you can on 80s Hero's beautiful rocker cover, the lettering would be red. I actually did this on the first iteration of the rocker cover (never believe that I get stuff right the first time), and I didn't like it. Instead, I decided on something more subtle, which was to paint in the letters in a slightly different black to make it recede a little.

It is subtle! So subtle that I'm not sure it actually made any difference other than in photos with a light carefully angled to show the difference - let alone from the 10 feet or so away that anyone but me will ever see this. But I know it is there!

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One of my HT lead separator thingies was broken. It's on the right of the original picture above. You probably won't see it, because it was broken.

Fortunately, these are identical to the ones fitted to the early 1.6 MX5s. That means I can buy reproductions of them. I could probably find genuine ones if I was more patient, but these were available immediately. I think they are 3D printed. They are not as strong as the originals; I broke one while mishandling the rocker cover.

Also, I couldn't leave my throttle cable bracket looking like this:

So I didn't. It got attacked with a wire brush and then sprayed with Jenolite satin black paint. (I love Jenolite paints! I mention them often enough that you'd think they sponsor me; I use enough of their paint that I wish they would.)

It bothered me that I used the wrong bolts in this pic. I thought allen heads would look neater, then after I had torqued them down didn't like how they sat. I replaced them with M6x16mm flanged bolts almost immediately after I took the photo.

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Meanwhile, this was my oil filler cap.

There was nothing wrong with it. If there was, these are one of the parts shared with the MX-5; I can buy as many of those as I want! And that would look better than most of the aftermarket ones. They're too blingy and branded, which is not at all the look I wanted for my engine bay, because I'm not obsessive about minor details while simultaneously having a blindspot for the big important things at all.

I almost liked the Hoonigan-by-Mishimoto filler cap.

Which is blingy and branded! But it has a nice shape, which meant I could do something with it. So I bought it, and had the red anodising blasted off it by my local powder coaters. And then, to match the rocker cover, I masked off everything but the top face and the 45 degree chamfer on the corner, painted that black with the same Jenolite matt black BBQ paint, baked it...

View original image

...and clear-coated it. After which it looked rather more like I wanted it to look!

That took much of a day by itself even if you don't count the time I spent over-thinking this!

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And after all that, I have the best rocker cover.

Or at least, I have one that doesn't look like anybody else's, and one that turned out exactly the way it did in my head when I first had the idea. And minus the silly overkill oil cap all of this probably would have cost me about 50 quid even if I wasn't using materials which I already had.

Next!

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Part numbers from this post

• 4mm masking tape: Hobby 2000 H2K80007
• Green masking tape: Frog Tape 155874
• Black high-temperature paint: Jenolite 89096
• Clear coat: Jenolite 88987
• Satin black paint: Jenolite 89510
• Oil filler cap: Mishimoto MMOFC-MAZ-HOONRD
• HT lead separator thingies: Mazda B660-10-241 (unavailable)

All of my neighbors are all up in arms
About something they saw on TV
Some politician got busted for something
That won't make much difference to me
Now I'm sure it's all true and I'm tired of this too
But I can't pray for some guy to fall
I say let all these people do what all these people do
I'm just happy to be here at all

This was my turbo.

It is an IHI VJ9, and it is also ancient worn-out junk that cannot be fixed.

The VJ9 is a tiny turbocharger built on the IHI RHB5 frame. Despite its size, it is ridiculously laggy compared to a modern turbo of the same size. I came to love that in the few months I had it on the road; a mildly-lively 16v engine that transforms violently into a howling turbocharged rally car engine at about 3500 RPM is hilarious.

This is actually the second turbo that has been fitted to this car. Back when my brother owned my 323 GTX, the original turbo was so worn out that the car spewed enough white smoke to be an actual danger to other road users, so he used his superpower of finding car parts that do not exist to acquire a "good" spare.

"Good" is in quotes, because it was still worn out; there was slack in the shaft, just not a quarter-inch of it like the old one, and the car did not spew smoke after the turbo was swapped. It was sure to be another failure in the near future, and re-fitting this to a freshly-rebuilt engine seemed insane to me.

As I found out, replacing or rebuilding this turbo has some pitfalls: there are no replacement VJ9s, there are no spare parts, and nobody will work on them.

1. There are no replacement IHI VJ9s.

They're gone; as far as I know they were only fitted to the Mazda 323 GTX, and only outside of the US. US models of the GTX had a slightly different VJ14 on the same RHB5 frame; the US models of the GTX made somewhat less power, so I shall assume the US turbo is worse. Occasionally one spots a used VJ14 out there, but that might well be a worse turbo than the VJ9 and there's no guarantee that it would have been a straight fit anyway.

The obvious answer is to have my current turbo rebuilt, which brings us to...

2. There are no spare parts.

I shipped my turbo to who I consider the best turbo company in the country - for turbos that are not obscure ones fitted to extremely obscure cars, anyway. The report back was that the turbo was actually completely shagged:

The bearing housing has damaged ring lands and the actual internal sleeve has separated – not reusable.

Turbine shaft has heavy journal wear – not reusable.

Seal plate has excessive ring land damage – not reusable.

Turbine housing has multiple cracks around the wastegate seat and volute – will go again with some processing.

Compressor housing has rub damage – will go again with some processing.

...and as I soon found out, none of the parts required exist anywhere; there was a multi-month delay getting my turbo back while aforementioned best-in-the-country turbo company scoured all their sources for some stash of parts that we all hoped existed, and did not exist.

3. Nobody will work on them

I know; I've tried. Any company in this country whose website claims they will rebuild a VJ9 will not actually rebuild a VJ9, and I know this because I have called all of them. Most likely some SEO geniuses thought that generating a page saying "we can rebuild X!" for each X of every possible turbo in the world would generate business for companies, rather than generate a small amount of wasted time for all concerned.

A rebuild was not going to happen, then. The only other option while maintaining a bottom-mount setup would have been to get a hybrid turbo. That, to simplify a lot, means preserving some part of the outer shell of an existing turbo and shoving completely different internals inside it. Nobody is willing to do this in this country, either; the few people who actually got back to me told me that it outright was not possible to do this with a VJ9.

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What, then, of options that didn't maintain the bottom-mount setup? Turbo manifolds are available for the early 1.6 litre MX5s. I like the Walton Motorsport one, but cheaper options are available if you like playing "will it disintegrate" roulette. One of those turbo manifolds would bolt right up to the B6T's cylinder head; the B6ZE in the early MX5s is almost a B6T with the turbo removed. But I don't like this for a few reasons:

• It would mean re-routing the exhaust and intake. Doable, but that would have to wait for the car to be in my possession again.
• These manifolds are designed for the MX5; they work with the clearances and constraints of the MX5 engine bay, which mounts 90 degrees out from how the B6T fits in to the. Though the exhaust manifold might bolt up, there is no guarantee at all that that I would actually have space for it with any given turbo attached.
• Mazda might have gone with a bottom-mount setup for a good reason. I don't know for a fact that they did, because I cannot give you any of those reasons, but I also don't know that they did not. I default to assuming that any major manufacturer knew what they were doing given the technology available at the time, and do differently if I know better.

Any of those things could have added months and unknown expenses to the project. But there are no bottom-mount turbos. Now what?

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You may have noticed that I qualified an earlier paragraph about hybrid turbos with "in this country". Fortunately, nobody has told Bryan Nickell from BNR Supercars that it is not possible to build a VJ9 hybrid, because he has been doing this for years. Actually, he's been doing this with the US-market VJ14s, but the VJ9 is similar enough in the bits that matter to make it possible to do the same conversion.

You strip the turbo down to this...

...post it to Alabama, then some time and about a grand later it comes back as this monster:

So, backtracking. The first pic is the turbine housing, and just the turbine housing. This bolts up to your exhaust manifold on one end, and bolts up to your downpipe on the other. Preserving this means that fitting this turbo does not require any modifications to the exhaust system; it stays as a bottom-mount turbo, bolting up to your original exhaust manifold and exhaust.

The rest of the turbo is thrown in the bin (don't actually do this, you'll need at least the compressor housing later as a reference for building pipework), and in its place you get a Garrett GT2860 CHRA with 360° thrust bearing, a much bigger compressor housing, an upgraded wastegate actuator, and a ported wastegate to avoid boost creep. Or, in other words, most of a modern Garrett GT2860 shoved inside half of an IHI VJ9!

All of that is balanced meticulously, turning a worn-out turbo that was never very good even when new into a modern, reliable turbo good for about 330 horsepower (which is about 130 more than I care to have, but I like having the option). This completely rules!! And it allows me to keep the bottom mount setup, with the same exhaust manifold & downpipe, and the same water and oil feeds. So all that was left was to just bolt it all together, and

JUST KIDDING THAT NEVER HAPPENS

Of course I knew that it was not going to be that simple. The cold-side intake of the new turbo being substantially larger than the VJ9 rather guaranteed that. So let's start with this intake pipe.

I can't modify this pipe, because it is made of plastic. Well, I could; that wouldn't be that much worse than at least one of the modifications I have seen in this engine bay (clue: it is in the photo above). But half of the rationalisation project is to remove bad modifications, and I do not want to add another.

Finding someone who could fabricate a new intake pipe for turned out to be harder than it sounds (and this resulted in another multi-month delay), so I decided I might as well try and make it myself out of steel. And that starts with this:

(Richard Brunning voice) This may look like some pieces of wood screwed into a piece of wood. But what it actually is, is a jig for the intake pipe.

It marks out the rough locations of the inlet and outlet of the pipe, and it has some exhaust studs screwed into the wood which mark the location of the bolt holes. Some more pieces of wood mark the inlet and outlet of the pipe. All of this allows me to line up a piece of pipe (I happened to have an offcut of exhaust tubing which was exactly the right diameter for the job), and make some mounting points out of cardboard:

Those get made into 1.2mm steel with an angle grinder and welded on, and with a 90 degree silicone hose bend attached and a bit of Jenolite satin black paint...

...I have an intake pipe! And yes, I know those mounting points look like they are not fitted straight; I sacrificed this to get the mounting angle perfect. You'll live.

You may have noted the nice bead on the end of that pipe. I made that with a £70 hand-cranked bead roller. That was not a bad investment. It's easy to use; even I got it more-or-less right on my second attempt.

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Meanwhile, the water feed pipe for the turbo used to have a bracket that bolted on to a mounting point on the turbo.

That mounting point does not exist on the new hybrid turbo. This bracket might have been overkill and I considered doing away with it altogether, but again I just assumed Mazda knew what they were doing when they did this, so made a prototype adapter bracket to go onto a mounting point on the compressor housing:

But after giving it some thought, I realised this would put the water pipe in the wrong orientation; it would feed from the correct side, but it would feed water up into the turbo, rather than down. That would be fighting gravity, which isn't such a big deal, but because it was fed from a completely different place, further modifications would be required on the engine side of all of this to make it work. I didn't want that, so I rethought it, chopped off the bracket from the water pipe, and welded on this crude prototype bracket made out of some 1mm scrap (also, see if you can spot where I forgot to turn on the MIG welder's gas)...

...before committing to it and making a preliminary version out of 2mm steel.

But then I realised that with a small modification to my original wastegate actuator heatshield...

...I could incorporate that into the assembly, by making another 2mm steel bracket to bolt on to it via some M6 captive bolts welded on to the water pipe bracket.

Which, when refined a little with a flappy wheel and painted in more satin black Jenolite paint, actually looks quite neat.

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Meanwhile, here was my "boost controller".

I put "boost controller" in quotes. My brother doesn't like it when I call it a boost controller; he insists that this is merely a bleed valve, and so I call it a boost controller to annoy him. It bleeds off air pressure to the wastegate, which means that the wastegate opens at a higher boost pressure. This is a very cheap way to run more boost in a turbo car. This did the job; it meant the 323 GTX was running about 13 psi, which with some calculations I completely made up would make it run about 200 horsepower.

Still, I didn't like this boost controller, which is why I put it in quotes. It dangled around the engine bay not attached to anything but its hoses; thus, it was a bad modification. So I spent a few quid on a new Turbosmart Boost-Tee manual boost controller, which probably does the same thing, but looks much better.

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This controller came with a bracket to attach it somewhere, and I was not entirely sure where when I bought it. Most people would just shove it into the bodywork with self tappers or cable tie it somewhere; if I did that, it would be another bad modification. Instead, after looking at my nice new intake pipe I figured attaching it there might be a good idea. So I did!

I took a 5mm-ish-thick section of angle iron, chopped it into smaller bits of steel, drilled and tapped some M4 threads into it...

...and welded them on to my intake pipe to became the mounting points for both the pipe clamps and the boost controller.

But, it bugged me that the boost controller bracket and the pipe clamps were shiny stainless steel, so I fixed that too, not that I am obsessed about tiny details or anything.

And then I modified the wastegate actuator heat shield bracket to add a routing guide for the pipe, which is to say, I drilled a hole in a piece of steel and welded that on to it.

You may notice that the water pipe is uncomfortably close to the intake pipe. You'd be wrong, because it's actually touching, which is more than uncomfortably close. We'll fix this later!

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Back to our intake pipe. Here is a photo of it, in case you forgot what it looks like.

The mounting point on the right hand side on this photo bolts onto the engine somewhere. The one on the left used to bolt on to the turbo, on a mounting point that no longer exists. Which is OK, because we can add another bracket to our combined water pipe & wastegate actuator heat shield bracket to make a three way bracket!11

That means making a rough template out of a previously-unseen proprietary composite material (Frogtape-reinforced cardboard)...

...then copying that on to 2mm steel...

...then fine-tuning with a flappy wheel and other abrasive tools until it is a BRACKET.

If you didn't notice (and also if you did), the holes here are slotted on opposite axes (and doing this burned out my Ryobi multi-tool; lesson learned). This is because I am working blind, without the car; while I have taken as much care as I can to get this intake pipe dimensionally compatible with the original, I still don't know anything for a fact. With the combination of these slots, the flexible 90 degree bend, and the flex in the mounting points (the reason I made them out of 1.2mm steel!), this should have enough adjustment to fit on the car even if I got it completely wrong, which I don't think I did.

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And now, some odds and ends, which happened at various points and didn't really fit into the narrative.

The downpipe and exhaust manifold were ceramic coated by my local powder coaters. This is an extremely high-temperature coating that should keep the heat in the exhaust system and out of the engine bay; as said previously, I am quite serious about heat management this time round.

This could be great, or it'll lock the heat into the cast iron and cause it to fail spectacularly. We will see!

Talking of the exhaust manifold, several of the studs did not come out cleanly. I cut these off, and re-drilled them. But I made two huge mistakes. One of them I re-drilled ever so slightly away from where it should have been - maybe three quarters of a millimetre, which took it out of tolerance and meant that the turbo did not fit on it. With another of these, the hole clearly needed helicoiling, and I made the mistake of not using a drill press when drilling it out for the helicoil. I figured the existing hole would guide me well-enough to be able to do it with a hand drill, and no it did not guide me well-enough; the hole for the helicoil was not made straight, and this meant the stud did not go in straight.

I thought this would be a write-off for the manifold, because nobody wants to fix 36 year old cast iron. Except Matt from Fusion Fabrications! Who drilled all but one of the holes out to 12mm, forced in some cast iron bungs, then meticulously re-drilled all the holes at the correct spacing.

Back to that water feed pipe from earlier. This only needed a tiny modification to get it to clear the much-larger intake pipe; I heated it up with the oxy-propane torch, and bent it in the other direction using two long sockets either side of the original bend.

The oil drain should have been a straight bolt-on fit. The Garrett CHRA was drilled to have them as two M6 holes spaced 38mm centre-to-centre. This is the correct spacing for every RHB5 turbo. But the drain from my VJ9 was spaced at 40mm for no reason, because why wouldn't you randomly have one turbocharger in a range of turbochargers with a subtly different oil drain?? Which means, it does not fit. So, the holes on the original oil drain had to be slotted 1mm inwards (thanks Maurice).

And finally, the water drain pipe was not long enough to clear the much bigger turbine housing. So that was remade using the original banjo fitting.

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And so, thirteen months later, it is Done; all that is left is to drive it and all the other new bits over to my engine builder tomorrow.

The turbo itself is a massive upgrade. The ceramic coatings & improved heat shielding should also be a substantial upgrade, and the new boost controller is not a bad modification like the old one was. And it looks a whole lot less ugly, though it is likely that nobody but me and my engine builder are ever going to see any of this.

More than anything, though, this has been a massive confidence boost for me. After having so many supplier delays (accounting for about nine of the thirteen months when you factor in people who gave me radio silence), I figured I'd take a punt at doing as much as I could of the work myself, such as the brackets & pipework & boost controller mounting. In one case doing it myself didn't work out; I should not have taken such a cavalier approach to the exhaust manifold studs, and I am thankful for Matt for fixing my mess. But sometimes it actually worked out fine! The pipework & brackets work well enough, and that was mostly just me and an angle grinder and a worn-out MIG welder.

So, back to that Rover P5...

I originally planned to fold this into the upcoming "turbo" part of the rationalisation series, but there are parts of that which are still not complete, and are entirely out of my hands at the moment. Also, the heat shield turned into a multi-weekend mini-project in which I learned some things, so maybe you can too.

This was my heat shield.

Actually, it's my heat shield bolted to a scabby, worn-out, nearly-four-decades-old turbo. The heat shield is made of two sections. In the photo above, it's the piece of metal with white scribbles on it, and the piece of metal bolted to that. It is supposed to protect things in your engine bay from the turbo's extremely hot turbine housing.

Mine was not in very good shape. It had started to rot, and when I unbolted it with the impact wrench, a bolt came undone, with a chunk of both sections of the heat shield attached to it.

As I had other things to do, and no clear plan for what to do with my turbo (if I had proceeded with a completely different turbo I wouldn't be able to re-use any part of the heat shield), I filed it under "I'll deal with that later", and stopped thinking about it for several months.

When I returned to the heat shield, I planned to make a new one, because I thought the larger section of the heat shield would be impossible to repair. It is not a solid sheet of metal; it is a sandwich made of two sheets of 0.4mm-thick steel - far too thin for me to weld. In between those sheets is a fibrous heat-resistant material. Because I have probably inhaled quite a bit of it I shall pretend that material is fibreglass, and is definitely not some other fibrous material that was rather too popular for its heat-resistant properties in decades gone by.

I did not enjoy the idea of making a new heat shield, because the correct material for making heat shields is about £150 for a 30x25cm sheet - and the chances that I'd get it right the first time weren't very high, so I could count on buying a couple of sheets. That would be a rather small expense in the unending stream of expenses that the 323 GTX has given me; one sheet costs a little less than one-sixth of a turbo, or one-twenty-secondth of an engine rebuild. On a whim, though, I figured that I may as well try to fix it despite being sure I would not be able to; I wouldn't have really lost anything by trying other than some offcuts of steel, some consumables, and a little time. So I made a very loose plan for some repair sections out of some cardboard...

...then I chopped up some bits of steel, and tried to stick it all together with a MIG welder.

It worked! That is the kind of welding that would fill a YouTube comments section with horror, and I'm OK with that. The excuse is that the metal was paper-thin and that I'm using a worn-out 20-year-old MIG welder which doesn't work at any wire feed speed other than "full send". The full truth is the previous sentence plus the fact I do not weld often enough to be good at it. Still, it's out of sight so it doesn't matter how ugly it is, and these crude welds are strong enough for these non-structural purposes. I went back over some of the areas the next weekend because I wasn't happy with it; it didn't look much better than this after the second round.

Anyway, that was a small success; I did a minor modification with an angle grinder to accommodate the new CHRA, de-rusted the rest of the heat shield with Jenolite rust eater...

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...and I could have left it there. Having an unpainted steel heat shield was better than what I had, which was a disintegrating unpainted heat shield. But I wanted to paint it. That would mostly be to make it look nice, but that would also give it a better chance of lasting another 36 years.

And that's why I had a BBQ!

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The temperatures near the turbine area of a turbocharger can be quite extreme, hence the need for a heat shield. For paint to survive in this area for any time, it needs to be special high-temperature paint, and all paints of this type require curing in a hot environment, usually in the region of 150°C (300°F). I previously attempted this by improvising a solar oven, but with no sunshine to be seen in England for the next six months I decided to liberate an old BBQ and use that for generating a lot of heat.

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I tried to time all this so as soon as the BBQ was uncomfortably hot, the heat shield would be painted and ready to go in the "oven". Some time later, after curing and cooling, the result...

...was a total failure. The paint came off in my hands while handling it, as if I had thrown flour onto the part and expected it to stick. I don't know why this did not work. The surface was impeccably clean when I sprayed it, it was sprayed under relatively-controlled conditions, and the BBQ was definitely hot enough to cure the paint. Maybe the lesson here is not to buy no-brand-in-particular VHT paint. That probably means I need to revisit some earlier stuff since I have pipework painted with the same silver VHT paint.

Anyway, I wiped off what was left of the VHT paint and tried something else! Something I already had, which was this stuff:

It is Jenolite black BBQ paint. It is good for 650°C. That is as hot as I'd ever want it to be at the heat shield; if it got much hotter than that I'd have some other problem like the car being on fire (though later I will mitigate that too). It is less blingy than the silver VHT, but that is probably better, because it won't look like garbage once it inevitably gets dirty.

The instructions on the can say nothing about using heat to cure, but product descriptions online seem to hint at it. And, if it's going to burn off to some extent on its first heating I would rather that happen in controlled conditions, like on my BBQ, rather than on my car, where it would probably result in a scramble to work out what was causing all the smoke.

Dinner time!

After cooling, nothing came off in my hands, and after spraying with electrical contact cleaner and wiping it more thoroughly only a small amount of black came off. That is as obviously attributable to the soot from the BBQ as it was from the paint, so I called that a win.

And, I could have left it there! But the black paint is just cosmetic. Inspired by this post, I decided to give the heat shield some heat barrier properties as well. I experimented with a couple of self-adhesive materials here. I believe their rated temperature ranges; I wanted to know what their failure modes were when I exceed those temperatures. If I have a thermal problem down there I do not want anything to combust.

That is why I spent some time on a quiet Sunday afternoon setting things on fire with an oxypropane torch.

An oxypropane torch burns at about 2000°C (3600°F). That is about the same temperature that a UFO must endure while entering Earth's atmosphere; i.e. far beyond anything I am likely to see at my turbine housing, and far beyond anything these heat barrier materials are designed to withstand. I subjected it to these temperatures for two reasons. One, because it is very fun. Two, because extreme beyond-design-basis temperatures will illustrate the failure mode of the material.

The heat barrier pictured above caught fire at these temperatures. I'm not naming the material because I don't want to "name and shame" when I am subjecting it to temperatures far beyond anything it is designed for. This material may well yet be useful in future; I tested this material inside my BBQ as well while curing paint and it held up very well. I may well use the remainder of it to modify my BBQ to retain even more heat for future paint-curing exercises, and if it surprises you to read the words "modify my BBQ" here you might not know me very well.

The winner was Thermo-Tec Aluminized Heat Barrier (which was also used in the post linked above). It is self-adhesive, bonded to fibreglass (violating a promise to myself to never work with fibreglass again; I was itching for days), bonded to a thin aluminised layer. It is rated to 1093°C (2000°F), which is somewhat hotter than the worst-case scenario temperatures near my turbine housing. More interesting (and more fun) than any of that, when it failed at the oxy-propane torch the adhesive and the fibreglass substrate hardened (rather than caught on fire) and the aluminised coating fell off. That is a graceful failure.

I found it easier to apply the heat barrier in multiple sections. The smaller part of my heat shield required three, the larger part needed two. It's fine for the sections to overlap at the edges; you are not sufficiently space-constrained for a tiny bit of extra thickness in places to be an issue, and a little overlap is better than leaving a small gap. I also found it very useful to make cardboard templates first; it has about the same flexibility as the heat shield material, but rather less awkward to work with, and it's free to make mistakes. Thermo-Tec very thoughtfully included some cardboard for this purpose, with their packaging.

And if you're wondering, yes I made the obvious mistake when tracing around the cardboard out the material the first time. I won't tell you what that is; you will make the same mistake exactly once, and you won't feel bad about it because you know I did it too.

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And with all that done, it looks pretty sweet, bad welding notwithstanding.

As always, with the car some distance away undergoing an engine rebuild I am doing all of this blind. I won't know it'll work until I run the car up to temperature for a sustained period of time, which is some time away. I must trust that the paint and the heat barrier are going to work at their rated temperatures, that my turbo isn't going to run vastly hotter than any turbo normally does. Other than a single hole to drill where the two sections overlap (which I cannot do until the exhaust manifold is back to allow me to bolt everything together, and its current absence is yet another story for later), I shall call that finished.

Onwards!

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Part numbers mentioned in this post:

• Rust converter: Jenolite #89023
• Black BBQ paint: Jenolite #89096
• Self-adhesive heat shield: Thermo-Tec #13500

I had an overheating episode in 2020. It was not fun. It lacked so much fun that as part of the 323 GTX rationalisation subproject I wanted to give the 323 GTX some bonnet vents. Actually, I don't think bonnet vents would have saved me in that situation, because it dramatically overheated at low speed, but still, that scared me into doing as much as I could to keep it cool in every situation.

Putting vents into a bonnet requires making holes in the bonnet. Fortunately, I had a spare bonnet for this car. Actually, it's the original bonnet for the car; the reason for my original bonnet being off the car is too long to go into here. The one currently fitted to the car was fucked by an idiot, and that is also something I won't go into here, so the original bonnet was intended to go back on at some point.

Anyway, I am lucky to have a spare bonnet for this. It is probably the only bonnet in the country which is not fitted to a car. It might seem like a strange act of sacrilege to make holes in it, like sticking a sunroof on an E-type but more so. Oh well; originality went out the window a long time ago, and it's not like there's any other owners around to criticise me anyway! :D

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So, vents. You're spoilt for choice these days, as old people are obliged to say. Given my insatiable urge to over-solve every problem, I decided to set myself some arbitrary criteria. Otherwise I would just be able to buy whatever vents, make a hole in the bonnet, and glue them in. That would be too easy!

Of course, I wanted something functional; that requires a rear-facing vent and not a scoop. But also, I wanted something that did not look out of place on a 1980s car. The generic vents that you can buy on eBay for a few quid function as well as anything does. But they are all designed for modern cars; often they are copies of vents fitted from the factory to modern cars. They would look strange on the boxy little 323. I also wanted subtle. The 323 GTX is a very subtle car. There are very few giveaways on the exterior that it is a mental turbocharged rally car at heart and not Grandad's shopping hatch, and I wanted to keep it that way.

Instead of subtle, I ended up impulse-purchasing a pair of Ford Sierra RS500 Cosworth vents instead! Woohoo!

Don't worry, these are not genuine RS500 vents! Because I am not insane. There were a couple of genuine ones on eBay with a £300 starting bid. I didn't really want to pay that for something I was not sure would actually work, nor did I want to deprive someone's RS500 or Sierra Cosworth project of its proper vents. My vents are fibreglass copies from this seller on eBay that cost about £65 shipped. Mine have a lip on them to allow them to be fitted easily to not-RS500 bonnets like mine; otherwise, they are very close to the originals.

I liked them. They would not look completely wrong on the 323 GTX, because both the GTX and the RS500 were race cars at heart, born from homologation necessities in the same era.

Anyway, I ordered them, they showed up a few days later and oh no, they are quite big.

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They're so big that it wasn't clear they would actually fit anywhere. This is the sort of thing I should have figured out before buying them, like by finding an RS500 and measuring the vents, or asking the seller, but that's not how I work. If I was better at thinking through the consequences before impulse-purchasing stuff I would not own two project cars.

Here's a picture of the inside of the bonnet. Danger zones are annotated in red, potential locations are annotated in green:

Location A was OK, because it only required cutting out the brace at danger zone 2. However, any location for it would require that it would overlap the styling line (small indentation running the length of the bonnet) at 3, which would look weird. Moving it outboard to avoid this line would put it in danger zone 1, and that would be cutting a lot of strength out of the bonnet.

Location B might have been OK, but it had the same problem of either overlapping styling line 3 or going outboard into danger zone 1, and would have meant cutting into danger zone 4, and it would have been a lot of work to translate the strength cut out here somewhere else.

For styling purposes location C might have been fine, but it meant cutting most of the brace in danger zone 4 too. It also overlapped the line of the bonnet bulge at danger zone 6.

Location D is...a strange one. It would have required cutting out multiple bits of bracing in danger zone 5, but this strength would have been easier to translate elsewhere. I thought it might look a bit weird, so I flipped the bonnet over, plopped the vent on top..

..and decided that yes, this definitely looks weird and I don't like it. It might have worked fine with a vent of some other shape, but this parallelogram shape so close to and overlapping the centre line of the bonnet just doesn't work.

E might have actually been optimal if the bracing was designed differently; it is location C moved far enough back that the bonnet bulge is no longer an issue. But that would have meant cutting the brace in danger zone 4 and the smaller part of 5; again, this strength would be hard to translate elsewhere.

So, after a full day thinking about it, I realised the vent just won't work on this bonnet. At this point anyone else would have just bought a different, smaller vent that'll actually fit. But I'm not the kind to give up, so I decided to look at some photos of cool cars. When doing that, I noticed from this pic of the Sierra Sapphire RS Cosworth...

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...that it's actually OK to have a vent being intersected by a styling line. Nobody complained about it on the Sapphire RS Cosworth as far as I know, or even noticed. Thus, location A will probably work fine! Yay!

I did a little prayer for courage, cut out some bracing...

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...made a hole...

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...and did a dry run of the vent to see if I liked it.

As the kids would say these days, sick fam, and innit. That is to say, I liked it, which is just as well, because that hole is never going to be un-made.

Note it is now the vent. My brother came up with the idea of using a single vent, because that would look cool, and also make it look less like it was trying to be an RS500. I agreed - quite enthusiastically, because as well as looking cool this only meant making one big hole in the bonnet rather than two. That would halve the work, and I like putting in less effort if I can get away with it.

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Back to the vents themselves, then. Unlike the ABS vents you can buy for about 30 quid, fibreglass never comes out of a mould perfect. These vents were not perfect, and I did not expect them to be.

I could have left this problem to whoever does the bodywork on my car when it comes back from the engine builder. I did this myself instead.

The process is this:

• apply a very thin skim of knifing putty to any low spots
• sand them back
• apply filler primer
• sand back the filler primer
• find progressively smaller low spots and go back to the first step
• enjoy your beautiful vent!

It took forever until I was happy skipping to the last step. Actually it felt like I was making no progress until I put it side-by-side with a fresh-from-the-mould one...

...and realised that at some point I had to stop chasing increasingly small perfections, that I had to consider it good enough, and that I had probably reached that at least one iteration ago. It is Done!

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Actually, not done.

So, my vent will turn one big hole into four, smaller, better-looking holes with rather better aerodynamic qualities. Those four holes allow air out of the engine bay, which is good, but also allow things into the engine bay, which is not desirable. Of course, an engine bay is not a sealed environment; I won't bother to make plugs for the vents to prevent water ingress, because if your engine explodes on water ingress it will do so one day whether you have bonnet vents or not. But, it seemed wise to put something in place to stop ingestion of larger particles, such as sparrows.

Also, vent mesh looks nice. So let's do it!

This is steel mesh. It costs about £10 for an A5-sized sheet. I like mild steel because it's easier to work than stainless steel and it survives being bent repeatedly in different directions rather better than aluminium does. The latter is a good characteristic for this application, given that I did not really know what I was doing and might have to un-bend and re-bend the material quite often.

The first one took about two and a half hours, from memory. The others took somewhat less because I almost knew what I was doing at that point.

I painted these immediately after forming them to shape. If it seems like a strange decision to paint them now, bear in mind it may be many months until this vent gets its final coat of paint; I did not want it to gain corrosion in storage. And it is much easier to ensure that it has a thorough coat of paint now than it would be after it was glued in.

I glued these in with two part epoxy. I learned - maybe re-learned - two things. One is that two-part epoxy is horrifically messy. Another is that I shouldn't be using it on a boiling-hot summer day, because it sets basically instantly. These two things combined are hilarious.

At some point I had the idea, and I do not know where it came from, that I should add fibreglass strips to ensure that the mesh was held on firmly.

It was a terrible idea. First because epoxy - even far less epoxy than I used - would have sufficed to hold them in place, and it was completely unnecessary. Second, because there wasn't really anything for the strips to grip to (because the mesh has holes, duh), so when it was dry it peeled right off. So this just left me a mess to tidy up afterwards (which took another day). On the upside it reminded me to never work with fibreglass fabric! It itches like buggery.

Anyway, with that all done, and the mesh glued in, and a final coat of grey primer...

...I'd say it looks AWESOME. And that is even more striking compared to a vent that came straight from the mould.

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And that, is making a short story long, and is also how I lost about seven weekends.

The next part should have been easy. I wanted to get the rest of the bonnet prepped for paint as well. In the earlier pictures the eagle-eyed among you may have noticed an area on the front lip of the bonnet which was coated in red oxide primer. I was aware of this as an area that needed some tidy-ups; the red oxide was applied eons ago to stop rust from progressing. And so I poked around this area with various tools...

...and if this was a YouTube video or my internal monologue, there would be a scream sound effect playing about now. It turned out that much of the front lip of the bonnet was rotten and that the rot had gone all the way through to the outer skin. So as always, things escalated...

...and the rest has become another sub-sub project. As always happens with shit old cars, every job you do generates at least one more job to do. Onwards!