924Board.org

[musicalannette]

Hi, just reading a bit further.

If you supercharger is pulling air in through the compressor of the turbo you might have some restriction due to the inlet size of the compressor on the turbo. You can always fit a slightly compressor to the turbo or indded a bigger turbo completley as small increase in area will merit large gains in flow restriction.

If it were the other way round a roots type super charger (by its nature being sealed so as to pump air) would create a near impass for air enterning the system if it were stationary or not turning fast enough to supply the required air, and would need a bypass or secondary air inlet to the turbo to allow the flow required at higher rpm's. You could have the supercharger with variable gearing, so it can turn faster at higher engine rpm's. This really would (i am guessing now) make the car pull like a train as revs increased as both the supercharger and turbo would be non linear, not so sure about drivability though!

While i'm talking about turbo airflow restrictions. I must point out that it is possible (if you really find it necessery) to split a turbocharger up and mate different compressors with turbines if you have some machining facilities and suitable "spares", so much so that a friend has built 3 minature gas turbines from various turbochargers from the scapyard. He melted the odd bearing on the turbine side aswell, but the combustion chambers take a bit of sorting out to keep the flame from getting through to turbine and getting the cooling air ratio correct in an engine that is compact enough to fly in a model.

Just as an aside, you might want to look in to compounding for a bit of fun, here are a couple of links;
http://www.modified.com/editors/0705_sccp_comprex_compressor_supercharger/index.html
http://en.wikipedia.org/wiki/Pressure_wave_supercharger

Cosworth looked into it with their ford 1.5 litre turbo F1 engine.

It's a pre war theory, unfortunately, the youth of today seem to insist that 2 or 3 stage forced induction is compounding!


ahh well.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[leadfoot]

Just some update pics, completed the engine bay installation and auxillary pieces but have to fix up a little bit of engine bay wiring that one of the fury locals decide to dine on one night...









Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

[moone924]

Amazing! I'm so envious of people like you that actually get things accomplished.
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Ryan Moone

Always shopping for a nice s2 931 to baby.
New philosophy : one car project at a time.

[morghen]

[Cedric]

Great work, extra cred for using black connection hoses instead of the standard fugly blue!!
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1980 924 Turbo
www.instagram.com/garagecedric/

[leadfoot]

thankguys,
Morghen, not sure I'll have an issue, as the WUR will provide the boost enrichment as per airflow requirements, well that's the plan, and the CIS tends to be rich in lower to mid rpms at any rate...
I also have the 5th injector driver that can be set to rpm and has adjustable duty cycle too, it's a microtech MF-1 for reference.
http://microtechefi.com/index.php?route=cms/category&path=4

[morghen]

You're right, CIS will probably provide enough fuel.
Oh how i wish i could get a ride in that car
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https://www.the924.com

[musicalannette]

Looks good, i'm sure you dont need encoragement, but I genually hope it's worth it.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[Arvidw]

It's wonderfull, nice work !
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[flosho]

So you were able to twin charge your 924 in like 4 days meanwhile it takes me 2 years to single-charge it.
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[This Space For Rent]

[leadfoot]

4 days .... not likely.....
but it helps when I have previously sc'd a car... was able to use the bracket/manifold designs I'd previously made and improve on them slightly, I knew all the gotcha points and clearance issues I had last time, (rails, oil pan and swaybar/sterring rack) and had a spare block to take some extra measurements and do my bracket welding on.
also best thing I've ever done was to teach myself to weld, countless hours and dollars saved doing this... although I sacrified a little weight saving by using stainless steel for a pipes etc, aluminium would have better heat dispersion and weight. But tigs in this are really expensive... my mate actually prefers oxy of aluminum on smaller parts than his mig, he has been doing it for a while though so he knows the limitations... i.e melt the whole part....
my background in soldering helps with the tigging, and from when I first started it's also come along way. The welders a 10A inverter and cost around $220 + $150 for a really good auto darkening helmet. I chewed through my first bottle of gas and electrodes in a week. Think I managed to do about everything and the new crossover pipe off one bottle nearly this time, broke up the monotony by doing a bit on the bodywork.

All in all I'm really happy with how things have come together, it seemed really complicated at the start, but the more I worked on it the easier it became. As a financial thing, some costs were,

Pulley, already had- so nil
machining of said pulley, $50
sc - $250
SC tensioner $35
manifolds and piping - just materials and argon gas
brackets - materials and machining (I got these water jet cut as I could draw them up in CAD)
Injector controller I had already (think there around $100-$150 2nd hand??)
Wideband & O2 sensor - $100?? forget what this cost
SC clutch controller kit - you have to solder up but for extra they can build + test -$30 + electrical connections (wire + injector) + consumables
extra CSV injector $5-10
Silicon hoses were not cheap, you want to minimise these joins as much as possible - $100 + hose clamps which are also $$$ if you get good ones
conversion of pullies to 4pk/5pk (alt and water pump)- $ prices may vary on material used and whether you have the help of RC and his lathe or someone just as awesome...
P.S this was probably the time consuming part as my clearances for the alternator from my intake manifold were tiny... getting all my measurements for pulley alignment was a real PITA...
Intercooler -$will vary but $180-200 is a good start

looking at getting it on the road this weekend if I can get this t stat back, my mate has 2 small kids so I have to work around him... he also works for home brew!
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

[McGyver]

Is that some broken pipe on this photo?

Amazing project
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931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car
www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)

[leadfoot]

If your refering to the thin one in the upper centre of the pic then no, it's the old vent line to the pcv valve, the outer sheath is worn pretty bad but the integrity of the inner tube is fine, just haven't got around to replacing it yet,
cheers
Stu.
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

[leadfoot]

just an update,
Using a summit rpm window switch as the supercharger clutch controller
http://www.summitracing.com/parts/sum-830452-1
It's a pretty cool little unit, can be triggered off the distributor directly, but will require a relay if drawing more than 3 amps,
the operation details were a little vauge but the "on" rpm will activate above and deactivate below as well, there is also an upper deactivate rpm setting so within the lower and upper you can set up something to trigger.
The clutch has now been modified for a smaller 105mm pulley, a new inner bushing was made and the original cluch centre drive was also kept and shimmed out to the right distance for engagement.

a pic of the 5th injector mounting under the final section of pipe

It als took a bit of time to get the alternator alignment right, the new crank pulley has the alt belt located at the back, so in converting to 4pk alt pulley I also had to mount it as far back as possible, there's about 5mm clearance between the plenum and the mounting point has been modified and contains firm poly bushes to control the deflection when tightening the belt.

Have to get the trans sorted now and I'm also going to install a regulator for the wastegate top port. This will probably be a January project as I'm getting a new garage built soon,
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

[GeorgeV]

This project is amazing. Well done!

What is the material you put in the header panel vents? Where do you get it from? Does it stop insects/leaves getting in the rad?
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1981 932 with mods:
http://www.924board.org/viewtopic.php?t=37921