Boost effects on low compression engines vs high compression engines

[IPD]

Part of the problem in this thread is that most people in the 3s community have not ever written a timing map. A 9:1, and 8:1 engine can run the same boost, but the 9:1 engine will need less ignition timing, and the room for error between mbt, and detonation will be much smaller. The new BMW turbo's run 10.2:1 compression, and can make plenty of power.

"plenty" as in limited to 12psi max?

[familyMAN]

^have you not seen any "chipped" Beemer results? They do well.

I wouldn't run high compression turbo for pump gas only, but I wouldn't run any turbo car, pump gas only E85 is allowing 1000+whp 10:1 supra's and 600++, 10:1+ evo's.

[donniekak]

"plenty" as in limited to 12psi max?

Last I checked, they were making 700hp on the stock engine.
There are also some evo, and Dsm guys making huge power on the new wiseco high compression pistons, 10.5:1.

[IPD]

^have you not seen any "chipped" Beemer results? They do well.

I wouldn't run high compression turbo for pump gas only, but I wouldn't run any turbo car, pump has only E85 is allowing 1000whp 10:1 supra's and 600+, 10:1+ evo's.

until e85 is the standard (99% of gas stations carry it) i wouldn't count it. what good is having a car where you are on a leash or risk blowing up the engine?

[donniekak]

until e85 is the standard (99% of gas stations carry it) i wouldn't count it. what good is having a car where you are on a leash or risk blowing up the engine?

Ive seen the beemers hit almost 600whp on pump gas.
I know it's hard to believe in 3s land, where hardly anyone actually knows how to tune a car, but writing a good timing map goes a long way with high compression turbo cars.

[IPD]

Ive seen the beemers hit almost 600whp on pump gas.
I know it's hard to believe in 3s land, where hardly anyone actually knows how to tune a car, but writing a good timing map goes a long way with high compression turbo cars.

well then be my guest and volunteer to be the guinea pig who hits 600whp on 10:1 with pump gas on a 6g72.

[DrGonzo]

"plenty" as in limited to 12psi max?

Uhh... Whats limited to 12psi? Surely not a stock block 6g72 - 10:1. I run 14psi on the street and 16psi on the track. That was only with an SAFC2.

well then be my guest and volunteer to be the guinea pig who hits 600whp on 10:1 with pump gas on a 6g72.

I just got a Emanage blue so I can play more with the timing and see what I can push out of it. I also just got finished rebuilding my 450's which will be dropped into the car here soon also. Couple weeks and I should have a decent tune back on it. Surely it won't be anywhere close to 600. Probably around 400+ on my stock 9b's. Then again I don't really know of anyone on a TT motor running 600whp on pump gas.

[IPD]

i was referring to 12psi on a 10.5:1--pure pump. i can't see how you could push it further without hitting knock every time (no meth, no power adders).

and you're right, i don't know of anyone at 600whp on pure 93 octane with a 3.0L 6g72. easy with meth, but that's not pure. i am going to try it with 3.5L though.

[donniekak]

i was referring to 12psi on a 10.5:1--pure pump. i can't see how you could push it further without hitting knock every time (no meth, no power .

Less timing advance, and a very good combustion chamber design. Have you never seen the Honda guys running 20+ psi with the higher compression engines they use? It does however come to a point where the amount of timing you have to pull cancels any increase in power you get from more boost. You also drive the egts up running such low timing.
Even though it's not on a high compression engine, there are Dsm guys making 600-700 horsepower on pump gas. http://www.dsmtuners.com/forums/dyno...&do=Pump%20Gas

If I recall, Chris hill was trapping 140 in the 1/4 with a fwd 10:1 setup to.
What it comes down to is tuning ability. The area between running great, and blowing up gets smaller the higher the compression is.

[NickS VR4]

Just as the chart showed earlier. If you change the compression, and the boost levels stay the same, the internal cylinder pressure will go up. Pressure and Heat create knock. Unless you are able to change the heat, the increased pressure will, IMO, generate knock.