Clemson Sports Car Club

Josh is definitely a 930 911 turbo guy.

(06-08-2010 11:51 PM)VR4Drive92 Wrote: [ -> ]I prefer low static compression and high boost.

Those engines always have higher hp potential when shoving air down its throat. But I'm a power guy.

A friend of mine has an 1980-something mitsubishi starion. It's got a 2.6L I4 with a 7.00:1 compression ratio. The thing is an absolute turd before the turbo spools (below ~3500rpm).

^^ i want one of those, i've always thought they were so cool.

(06-08-2010 08:38 PM)93redfox Wrote: [ -> ]fastest vehicle i've ridden in was sam corke's evo, a few versions ago. i believe it was the first iteration of the gt35 setup, and while it moved out pretty fast, i know there are faster cars out there. didn't seem laggy, it just had a higher-end powerband, but so did the stock car.

it all comes down to uses/goals though. huge power, higher boost, more time to spool vs. moderate power, lower boost, and quick spool.

1 question: how much different is the cylinder pressure/stress on the motor between the two setups(high compression, low to moderate boost vs. low compression, higher or much higher boost)??

Car back then was making 456 wheel horsepower and 385 wheel torque, works out to about 540 hp/470 tq at the motor. Car made full boost at 4400-3600 depending on what gear I was in, considering it rev'd to 8500 i'd say 4k+ rpm of full boost availability made for a nice power-band.

Back then it was on a T3 .86 hotside and as you recalled it was a GT35 turbocharger, not super big nor tiny, good for about 700whp max. Granted my car is/was stroked to a 2.3 liter it helped in the spool department.

It was at a 9.0:1 compression ratio at 23 PSI fwiw.

Stephan, it's not really all that different because at the end of the day the rod/crank/conrod doesn't know if it's seeing cylinder pressure increases from boost or compression ratio. The difference is when increasing cylinder pressure via boost is that you are usually increasing temperature too, this is why Josh likes bigger turbos, because they are more efficient at compressing air without increasing heat. The less heat you introduce into the charge air the more power you produce, the less likely the car is to detonation, etc etc.

If you know what sort of octane the car is going to be running and don't need it to run on say 87/89 or 91 a slight raise in compression ratio will help for sure, but if your going to be adding power via boost there is no reason to get crazy with compression ratio unless your using some rocket fuel.

For reference Stephan here is the sheet from when you rode in it at 23 psi vs the new setup at 21-22



Scorke

(06-09-2010 12:06 PM)evilevo11 Wrote: [ -> ]Stefan, it's not really all that different because at the end of the day the rod/crank/conrod doesn't know if it's seeing cylinder pressure increases from boost or compression ratio. The difference is when increasing cylinder pressure via boost is that you are usually increasing temperature too, this is why Josh likes bigger turbos, because they are more efficient at compressing air without increasing heat. The less heat you introduce into the charge air the more power you produce, the less likely the car is to detonation, etc etc.

If you know what sort of octane the car is going to be running and don't need it to run on say 87/89 or 91 a slight raise in compression ratio will help for sure, but if your going to be adding power via boost there is no reason to get crazy with compression ratio unless your using some rocket fuel.

Scorke

Thanks man! that is what I was thinking, but I wanted to make sure. Glad the evo's runnin good!

(06-09-2010 10:41 AM)humjaba Wrote: [ -> ]

(06-08-2010 11:51 PM)VR4Drive92 Wrote: [ -> ]I prefer low static compression and high boost.

Those engines always have higher hp potential when shoving air down its throat. But I'm a power guy.

A friend of mine has an 1980-something mitsubishi starion. It's got a 2.6L I4 with a 7.00:1 compression ratio. The thing is an absolute turd before the turbo spools (below ~3500rpm).

exactly... when in racing or spirited driving situations you are never operating low in the rev range.

As long as I have full boost by 5,000 rpm Im fine... (thats where my revs drop to when I shift mostly)

If you need off idle power... buy a Ford GT or a Z06 or ZR1

(06-09-2010 05:01 PM)VR4Drive92 Wrote: [ -> ]

(06-09-2010 10:41 AM)humjaba Wrote: [ -> ]

(06-08-2010 11:51 PM)VR4Drive92 Wrote: [ -> ]I prefer low static compression and high boost.

Those engines always have higher hp potential when shoving air down its throat. But I'm a power guy.

A friend of mine has an 1980-something mitsubishi starion. It's got a 2.6L I4 with a 7.00:1 compression ratio. The thing is an absolute turd before the turbo spools (below ~3500rpm).

exactly... when in racing or spirited driving situations you are never operating low in the rev range.

As long as I have full boost by 5,000 rpm Im fine... (thats where my revs drop to when I shift mostly)

If you need off idle power... buy a Ford GT or a Z06 or ZR1

Did someone say Ford GT?
http://www.youtube.com/watch?v=Uk9vMQRIp1E

Weak sauce...


Yellow> White

http://www.youtube.com/watch?v=ksxEwo7ySm4



Yes Zach... I love the 930. me likey 993's too

(06-09-2010 10:49 PM)VR4Drive92 Wrote: [ -> ]Weak sauce...


Yellow> White

http://www.youtube.com/watch?v=ksxEwo7ySm4



Yes Zach... I love the 930. me likey 993's too

he's driving so fast it's not even touching the ground anymore! hahahaha

On this particular car it's basically instant spool. Typical 50 trim. Even granny shifting when I was test driving it, it would spool ridiculously quick.