JC050's 91 Charade G102 - Road & Track


I am away at the moment on a month long work trip - but December I will be going hard with getting something done.



Been slow progress but, finally starting on the ITB’s.

This is an old Detomaso manifold that is being sacrificed for the greater good.


Look like a really nice and rigid universal mill you have there. I am really looking forward to see this merged with the Gixer ITBs.


Made a bit of progress today on the ITB’s…

I had to machine the old intake face at 5 degrees for the tubes to clear the fuel pressure regular. I am keeping the TB’s on the original GSXR spacing of 80mm, so the runners have to angle slightly to suit the H-Series bore spacing of 85mm.

I will be using the original GSXR rubbers mounted to a plate to hold the TB’s in place - I figured Suzuki knew what they were doing.

Next I need to take this to someone who can fabricate aluminium…


Made a bit more progress, the ITB manifold is all welded up and smoothed out, and I have grafted a throttle linkage from an old Dai throttle body onto the GSXR setup. A mate cut me a Teflon gasket on a cnc router he made using an Arduino control system - it turned out pretty well.

Next on the to do list is to sort my trumpets and filter setup.


Awesome work mate, can’t wait to see it finished.


that looks awesome! great job. curious how its going to look and sound when its done.


Did a trial fit yesterday, it is a tight fit, and I will have to make a change to the brake booster tap point. Throttle worked well, and I can run the factory cable.

Next I will be getting some some curved pipe (did a cardboard mock up), the trumpets and an ITG filter.


I have made many ram pipes/trumpets/bell mouths and all based on extensive theoretical research and a little dyno time. While only my opinion, if your cardboard cut outs are the profile of your trumpets then there are a couple of issues. The end look to big. If laid out as a straight pipe the diameter change should never be more than 7deg in wall tapper. All turns or bends should be gradual or else the air flow will not be laminar. I would also consider a plenum with a cold air feed. The diff with and without on the last individual application I made one for was a 4% hp gain nearly right across the board. I’d start with straight pipes and get a base line. Great work so far on your - can’t wait to hear how it goes.


Thanks Mr Gormsby, I always appreciate your well thought out feedback.

The cardboard cutouts are just a mock up of some curved pipe I can get my hands on quite easily. They simulate a 135 degree bend 1-3/4 pipe on a centre line radius of 44mm - which is quite tight, but I don’t have much room. The bell mouth would go on the end if these, and I did have plans to run a sausage type filter.

From what I have read I should be aiming for tuned length of somewhere around 350 to 375mm (bell mouth to the back if the intake valve) for a 3rd harmonic at around 6.5 to 7k rpm.

The curved pipe idea came from a BMW M3 V8 setup. Without curving the pipes and the space available the most I can get is a tuned length of around 250mm.

Below is the BMW setup:


Mr Gormsby - some pics from CAD (or 3d fairyland as my old boss used to call it) might help:

And the 7 degree thing, I remember hearing the same info from a guy who used to build expansion chambers for 2 stroke bikes - and I have so far avoided any angles greater than 7 degrees.


That CAD drawing looks fantastic. I would expect what is in the image to work well. I get the space problem. I have to make some new ones for my friends’ Datsun. Not enough room in the engine bay and we need to go a bit longer and larger in main diameter. Basically I will end up with four diff, albeit slight, curves (almost straight, 3deg, 6deg and 9deg on centre lines) because of the strut tower. Hoping to do the internal mold using the 3d printer at work with support material which will be broken down once vacuum formed. Looking forward to hearing how well this goes. This is one of my top three things to follow here - exciting stuff.


That looks very nice! Im still trying to learn 2D cad, I have alot of respect for people who can throw together designs like this on CAD. Im looking forward to seeing it finished, should be the goods :smiley:


Have you changed the fuel pump to a higher flow/pressure unit, or is it still std? I’m going to be doing a build of a Detomatso and will use those MX5 injectors and was wondering if the std fuel pump would cope .


I am running the stock 1.3 fuel pump - has been fine


Still working on the ITBs, been trying to find an economic way to get the curved trumpets made, local 3d printing was too expensive, so eventually got this one made at Shapeways for just over $70. Not too bad - a straight one was going to cost at least $50 anyhow. Just got one for now, to check it over, the other 3 will be on order soon.

Also got my ITG filter sorted.


Wow. Damn nice. What was the print material?


Shapeways call it “Strong and Flexible” - it’s a nylon 12 printed with a Selective Laser Sintering (SLS) process. I wanted nylon for its fuel resistance, I had tried PLA and ABS, they turn to mush if you soak them in fuel.

This print is very slightly porous, but it doesn’t matter for this application.


Hey mate, I’ve got automotive/aircraft grade print material (Ultem 9085 to be exact), if you need anything done :slight_smile:


Did some more trial fits with the trumpet and the ITG filter - all looks good.

Now I can order the remaining trumpets and filter base plate.

Tuned length will be around 425mm (trumpet face to the back of the intake valve)