This is one of those jobs that should be simple and routine.

Instead it was one where nothing wanted to come apart, and none of the new parts would fit!

The main problem was the ABS unit being in the way of the new tubular manifold. With the manifold in position it was actually touching the ABS unit, and that doesn’t allow for the extra 40-50mm of space you need to install it with a turbo hanging off the bottom! Most S13s don’t have ABS so this problem is fairly rare.

I was able to move the ABS gear across and back by modifying its bracket, and ended up with a good 15mm or so of clearance between the manifold and the ABS bracket. It will have a heat shield added to protect it from radiated heat.

One part that needs modification in this upgrade (replacing the S13’s original T25G turbo with a T28 from an S14/15) is the turbo’s intake pipe.

The mounting bolts are at a different angle, so if you don’t get the later model intake pipe you have to modify the old one or make a new one.

I made an adaptor plate using a standard 2″ exhaust flange with a couple of M8 bolts welded to the sides at the right angle. It ends up being quite neat and the factory rubber hose connects up as normal.

Other parts needing modification are the turbo’s oil and coolant lines, and the oil drain to the sump.

The T28’s core sits at a different angle to the T25G, so none of the lines will fit directly.

You can rotate the housings to line it up, but in this case they wouldn’t come loose so I had to leave the core at its original angle.

The oil drain needed some modification, but fortunately this car was getting a set of braided turbo lines, which is much easier and nicer than trying to bend the factory steel ones to fit!

The last part of the job was to add an exhaust bracket, since the factory one was missing.

The front pipe (goes from the dump pipe off the turbo to the cat converter) had a bracket on it but it didn’t line up with anything on the car!
I modified it a bit, and made a new plate from the gearbox mount with a small rubber shock mount between the two.

This car is running a 2L turbo Cosworth engine, and the old exhaust had proven to be a bit too restrictive for the desired power output.

I made up a 3″ stainless pipe and a custom 3″ straight through muffler. The casing is 0.6mm thick stainless steel so save weight (most mufflers are 1.6mm or so) and it’s a lot longer than a normal muffler, to keep the noise levels down.

The front end cap is riveted on, so it can be removed to repack the muffler with new insulation material if necessary in future.

I’ve done a few airboxes for people with exposed “pod” filters - for legality reasons as well as keeping the hot engine bay air out of the engine’s intake.

This one was a bit different because the MX-5’s engine bay is much tighter for space - especially when it has a turbo conversion and a big strut brace across the middle!

I started making up the usual sheet aluminium box, but found that there is not enough width between the headlight motor and the strut tower to fit the filter.

I’ve seen long thin air filters that would do the job, but was unable to source one, so started looking at other options.

The end result was an all stainless steel conical casing that clips on over a base plate, with a 3″ inlet pipe welded in the top. I think it turned out pretty neat, and it matches the rest of the engine bay pretty well.

It’s also easy to service which is nice

Mazda MX5 turbos have a rubber pipe connecting the intercooler outlet to the throttle body.

It’s normally fine, but if you increase the boost it has a habit of blowing up like a balloon and / or splitting the rubber.

Unfortunately there are two other pipes and an air temp sensor mounted on this rubber section - and it changes in diameter from 50mm at the inlet to 65mm at the outlet!

I used a 2.5″ (65mm) 90° mandrel bend, and cut slots in one end so I could reduce it down to 50mm and weld it up again.

Fortunately each of the pipes and the sensor on the original pipe were joined using steel fittings, so I was able to weld those into the new metal elbow and have it all plug in as normal.

The only extra bit needed was some rubber hose to connect between the new pipe and the throttle body.

It ended up looking very factory I think

One common issue with aftermarket exhaust systems is that they don’t tend to be as flexible as the factory ones (a side effect of larger diameter pipes) so they are more prone to cracking - especially if they hang lower than standard and hit the occasional driveway or speedbump.

This one had cracked most of the way around the separate wastegate pipe, and partly around the main pipe. I gave the cracked area a good clean up, welded it back together, and added a bit of reinforcing on the outside - which will hopefully stop it cracking again for a while

My turbocharger based home built jet engine has been running with a combustion chamber way oversized for the turbo.

A while back I bought a couple of large turbos from some sort of earth moving equipment. Apparently the original engine had four of them!

I plasma cut a flange to bolt onto the turbo, and welded a short piece of 100mm exhaust pipe between that and the outlet of the combustion chamber.

A new air pipe was made up using 75mm aluminium intercooler pipe and a CNC cut flange, which should give really good air flow from the turbo to the combustor.

The oil plumbing needed a couple of minor changes, and the whole setup was bolted onto the test frame.

I’ve found that the usual leaf blower starting setup won’t work with this turbo, so I’ll need to sort out a better leaf blower or mechanical starter.

This thing should make some serious power (noise!) when it’s up and running

Years ago I built a jet engine as a bit of an experiment, using mainly scrap metal and various leftover car parts.

Every now and then I drag it out and try some new parts or modifications.

It’s based on a small turbocharger from a Mitsubishi Starion, and currently has a combustion chamber from a Rolls Royce Dart turboprop engine.

Last week I took it along to an event called Dorkbot (http://dorkbot.org/dorkbotsyd/), which is a monthly gathering of people interested in electronic / mechanical / scientific art performances, displays, and experiments.

I fired up the jet engine, made a lot of noise - then gave a bit of a talk on how it works, how it was built, and what I have planned for it in future.

The second presenter on the night showed information and video from an installation artwork / experiment he did in California, where an earthquake simulator was set up in the middle of earthquake territory and was used to display amplified real time seismic activity from the whole state!

The event was a lot of fun, and definitely worth going to if you’re interested in all manner of crazy experimental things!

I just hope I didn’t offend the neighbours too much with the jet, and they’ll have me back to show some of my less noisy projects

For anyone interested in home built jet engines, have a look at this video: http://www.youtube.com/watch?v=4pTUeuEv8Uc

Also check out this very serious backyard jet: http://www.youtube.com/watch?v=VX5U8DlBzzk

This car had the usual blown turbo gasket problem, and the owner figured it was a good time to upgrade the turbo to a newer T28 ball bearing one from a Japanese spec S15 Silvia.

The leaking gaskets are usually caused by the exhaust hitting the ground, or not being properly supported when the factory exhaust is swapped for an aftermaket one.

In this case there was a broken stud in the head, causing the manifold gasket to leak, as well as the normal leak between the manifold and turbo.

Removing the stud involved drilling a hole into the part still stuck in the engine, then using an extractor tool to unscrew it. A new stud was then installed.

Upon inspection, the new T28 turbo proved to have substantial damage, having obviously been in a crashed car. The compressor housing had been broken and pushed back into the blades, damaging them beyond repair.

Fortunately the original T25G turbo checked out fine, so it was reinstalled - after removing a broken bolt from the turbine housing!

Today I replaced a bunch of turbo gaskets, installed braided flexible coolant and oil lines, fixed up some vacuum plumbing and installed a boost controller in a Nissan 200SX (Silvia).

The turbo gasket had blown, which often happens when people run an aftermarket exhaust which isn’t supported properly. The extra weight and missing bracket in the middle puts a lot of stress on the turbo mounting bolts and they tend to loosen off.

This starts the gasket leaking, and eventually it burns through and leaves the turbo hanging loose, dropping performance and making a loud exhaust leak sound.

While the turbo is loose and able to move around the metal coolant and oil pipes are constantly flexing, and they eventually crack and you have a coolant leak as well as an exhaust leak!

So, a new set of gaskets, replacing some damaged manifold studs (and retapping the thread in the engine!), a set of braided lines, and it was good as new

Another problem this car had was that the boost control solenoid was hooked up to the wrong vacuum line, which meant the boost control system didn’t work properly, causing overboosting.

That was fixed up and a new boost controller installed, allowing in cabin adjustment.

Unfortunately I didn’t get a chance to take some photos!