SEAT Ibiza - rwd turbo
Discussion
The exhaust manifold is conventional 4-1 stainless affair really, as it was designed for when the car was going to have to run with a compressor inlet restrictor (and hence have limited mass flow). As such it is aimed at maximising pulse recovery from low speed rather than being absolutely low restriction/high flow. It's one of the things i would change if i get the time tbh:
The tank has been re-certed don't panic! (because it isn't a bag tank, the re-cert just consists of an internal / external inspection for damage etc)
The tank has been re-certed don't panic! (because it isn't a bag tank, the re-cert just consists of an internal / external inspection for damage etc)
Just for you then Tom, here's some engine pics!
Block built up with custom crank, after internal and external machining to loose mass, remove any flashing and stress raising sharp radii etc:
Bed plate and billet main bearing caps:
CNC'd "sump" (it's only 20mm deep) fitted over to further re-enforce bottom end:
Dry sump pump(later upgraded to extra scaveneg stage just for the turbo, due to low mounting height)
Custom super long T&K Precision head studs for uniform head/block clamp loading:
On with his head: ;-)
Mock up block/head installed to sort out carbon plenum, throttle system, and general plumbing etc:
[URL=http://s135.photobucket.com/user/max_torque_2006/media/SEAT%20Ibiza%20rally%20car/run4_zps25a45198.jpg.html]
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hmm, which sized turbo shall i use?
Yup, big one it is........ ;-)
You can get an idea for how far back the engine is fitted in the chassis from this pic:
Built engine waiting fitting:
Block built up with custom crank, after internal and external machining to loose mass, remove any flashing and stress raising sharp radii etc:
Bed plate and billet main bearing caps:
CNC'd "sump" (it's only 20mm deep) fitted over to further re-enforce bottom end:
Dry sump pump(later upgraded to extra scaveneg stage just for the turbo, due to low mounting height)
Custom super long T&K Precision head studs for uniform head/block clamp loading:
On with his head: ;-)
Mock up block/head installed to sort out carbon plenum, throttle system, and general plumbing etc:
[URL=http://s135.photobucket.com/user/max_torque_2006/media/SEAT%20Ibiza%20rally%20car/run4_zps25a45198.jpg.html]
[/URL]
hmm, which sized turbo shall i use?
Yup, big one it is........ ;-)
You can get an idea for how far back the engine is fitted in the chassis from this pic:
Built engine waiting fitting:
Amazing stuff, which nicely illustrates the gulf between the home enthusiast and and experienced professional when it comes to doing stuff with cars. Normally I look at a build thread and think "I could do that if I had the same budget" but this is way beyond anything I could attempt. Two questions, if I may:
You say you measure the manifold pressure only on the intake stroke - what benefit does this give?
Also, how do you go about insuring something like this? I know it's not road legal but I have heard stories of project cars being stolen from garages etc.
Anyway, thanks for taking the time to walk us all through it and putting all these pictures online!
You say you measure the manifold pressure only on the intake stroke - what benefit does this give?
Also, how do you go about insuring something like this? I know it's not road legal but I have heard stories of project cars being stolen from garages etc.
Anyway, thanks for taking the time to walk us all through it and putting all these pictures online!
aww999 said:
Amazing stuff, which nicely illustrates the gulf between the home enthusiast and and experienced professional when it comes to doing stuff with cars. Normally I look at a build thread and think "I could do that if I had the same budget" but this is way beyond anything I could attempt. Two questions, if I may:
You say you measure the manifold pressure only on the intake stroke - what benefit does this give?
Also, how do you go about insuring something like this? I know it's not road legal but I have heard stories of project cars being stolen from garages etc.
Anyway, thanks for taking the time to walk us all through it and putting all these pictures online!
If you run with port throttles, you don't have the volume of the intake manifold to "average" out the intake pressure pulses. With a conventional single throttle into a large manifold volume and the into the individual runners, as the intake valve opens and the piston pulls air into chamber, the volume of the manifold damps out most of the fast pressure fluctuations, and the throttle ends up flowing a fairly constant mass flow rate. This means you can use Manifold Absolute Pressure (MAP) as engine load determination.You say you measure the manifold pressure only on the intake stroke - what benefit does this give?
Also, how do you go about insuring something like this? I know it's not road legal but I have heard stories of project cars being stolen from garages etc.
Anyway, thanks for taking the time to walk us all through it and putting all these pictures online!
However, what REALLY matters is the air charge density (or the amount of air) trapped in the cylinder when the intake valve closes, because this affects how much fuel you must add, and when you start that charge burning (ignition angle)
If you fit individual throttle plates to your engine (1 per cylinder/runner), there is not enough volume between those plates and the intake valve to damp the pressure fluctuations. Remember, that an intake stroke only occurs every 180degCA, so for the other ~3/4 of the time, the intake valve is shut, and the air in the runner stagnates.
At this point, most people move to using throttle angle as their load arbitor, but although this gives good response, it is poor in terms of absolute accuracy and repeatability, as tiny changes in pressures, air density, throttle angles and flow characteristics make big changes in the actual charge density at IVC (Inlet Valve Closure). And with a turbo car, where intake density and temperature, and crucially pre-turbine exhaust pressure can vary enormously, it's even harder to make it work properly.
To get round this, i developed a system that has a high bandwidth (able to respond very fast) MAP sensor fitted to each intake runner downstream of the individual throttle plates. By using the engine position sensors (Cam/crank sensor etc) my system can then sample each of those MAP sensors in the correct order, and only during the time the intake valve is open. As this "ignores" the pressure in the runners for the rest of the time, the signal to noise ratio is excellent, and the system reports a highly accurate charge density value per runner. This means you get a good, stable load determination, with excellent noise rejection and repeat ability.
Insurance is not an issue, plenty of companies are used to insuring unique classic and motorsport cars ;-)
Edited by anonymous-user on Sunday 27th October 11:49
aww999 said:
Amazing stuff, which nicely illustrates the gulf between the home enthusiast and and experienced professional when it comes to doing stuff with cars. Normally I look at a build thread and think "I could do that if I had the same budget" but this is way beyond anything I could attempt.
Anyway, thanks for taking the time to walk us all through it and putting all these pictures online!
Totally agree, and it is also threads like this that make you start to understand why race cars are soo exspensive! It's only when you start to see the amount of work that goes into them that you can realise the costs involved.Anyway, thanks for taking the time to walk us all through it and putting all these pictures online!
Keep the pics and info coming Max!
It also goes someway to explaining the detail in your other posts and the general fact I seem to agree with a lot of what you write! Bookmarked 
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