August 7, 2017 10:39 pm - Published by

In the years I’ve had my car, I’ve always planned to go turbocharged. To me as an engine nut, it’s the ultimate in performance tuning: the efficiency in using exhaust gases to boost the intake charge, the noises, the power delivery and intelligent mapping possibilities…

A couple of years back, while I was working in engine mapping, I bought a Megasquirt ECU and fitted it to the bone stock 1.6 to apply what I’d learned and ensure that any issues with the install on the car were ironed out before starting the process of changing EVERYTHING. After that I went back to Uni, and back to the days of being a poor as hell student, so the turbo build got put on hold for a while. I did, however, have enough left over to buy some parts for a homebrew ITB install that most of you will have seen by now! The logic behind this was having already had the ECU, plenty of time and no money, it was the perfect thing to keep me interested and have some fun with the tuning. Since then I’ve absolutely fallen back in love with N/A style! I’ve run this setup over the last year, slowly ironing out the little issues and having a whale of a time ragging the car to the absolute limit trying to make up for the lack of power! It’s been a lot of fun, but there must always be evolution.

After 3 and a bit years of drift days, I’m starting to reach the point where I want to be doing more, and doing the kind of things that it’s just not possible to do with such low power. N/A is great fun for throwing it in hard and holding steady, but it’s not really possible to do things like big power-overs, high speed runs, line changes and easy close twinning with much more powerful cars. Plus, I still want the challenge of building a turbo engine and all the joy that comes with it!

So with the intro over, now we hit the next steps. A few years back a friend of ours crashed his lovely low-mileage import (60k or so I believe?) and Matt decided it’d be the perfect engine to build up for boost. Low miles, well looked after and long-nose 1.6.
He was right! Problem was, he never actually did it.
The head came off, and some basic strip-down happened, and then it just sat in his garage gathering dust.
So when his last engine started to get beyond repair we struck a deal. He would buy a good replacement to drop straight in his car, and I would pay for it, in return for the old forgotten engine.

Having just started my full time job as an Engine Designer with Judd Power, there was no better time to get cracking. Matt brought the old engine over and I began a solid week of tearing it down, deep cleaning, inspecting parts, taking LOTS of pictures. Some parts I also took into work to clean properly, and to borrow some tasty equipment. I’ve even gone as far as to create a complete spec list, writing down every part, including nuts and bolts, with reference to their position in the engine and build order. Everything you would ever need to create a complete MX-5 engine from a box of parts.

So here’s what we got! The engine itself has ended up a tad rusty in the bores from being sat for so long, but nothing deep, it’ll clean up well with a re-hone.


With the sump off, the good news starts! The crank journals and all the bottom end is beautiful condition.


Just look at those bearings! I’ve seen worse go back into race engines! Talking to the builders at work, these bearings are going back into the engine completely as is. They explained that in condition like this, it’s actually better to put these bearings, which have run into the crank and rods but are in perfect condition, back into the engine than it is to put brand new ones in… so that’s exactly what will happen!

It is very important when building an engine to keep track of exactly where everything came from. It’s all been worn in where it sits, and run there happily, and should be put back in the exact position it came from! So all the bearing caps, bearings and bolts have been numbered up in position. (O for oil filter side, N for ‘non’ oil filter side)

With everything stripped down, it was time to head into work for the final teardown of the head and a quick cleanup. This valve press makes removing the cotters INCREDIBLY easy! I also made up a little valve board from some packing card and a perfectly sized box to store the valves and avoid getting them mixed up.

The valves have had a clean up too, taking off all the years of grime and soot to reveal some nice clean metal beneath


The chambers and ports were fully cleaned out, taking care not to touch the seats too aggressively, and the result is a head that looks nearly factory fresh again

And with the ports clean, we get a chance to look at the first major bit of work: porting. It can be seen just how much room for improvement there is with the casting flash and uneven surfaces being very apparently. The stock exhaust side in particular is known for being very restrictive, and there’s a bunch of material there that can be hogged out for better flow, as well as things like knife-edging the ports (bringing the wall between the two valves down to a sharp point to aid flow) and straightening out the channels.

As with everything I do, there’s an ethos to this build to keep it interesting: Maximum spool and drivability
Do MX-5 engines need building up to boost? No.
Do they need a lot of work to make power? No.
Can you just turn up the boost to make up for a bad setup? Yep.
Will I? No.
The plan for this engine is to put in the effort (not the money) to build something that boosts WELL. I am not aiming for crazy numbers (though the internals should be capable of it), but rather a quick-spooling, well-breathing setup. To that end the head will be ported out, the chambers smoothed, the turbo matched properly, the manifold of a good design and the intercooler piping kept short and well-flowing.

Stay tuned for part 2!

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