stonebreaker said:
Speaking of boost levels, how much does intake charge temp affect how much boost you can run?
A great deal!
All I can be is anecdotal.
On my engine which is a 1.8 liter with a CR of 10:1 , I can run up to 12 psi on 91 octane with a 3"x9"x19" air to air bar and plate inter cooler.
Guys with no intercooler can run up 5 or 6 psi on my same motor.
The funny thing is, is that as the air gets cooler, it also gets denser. 5psi of not intercooled air is not the same volume as 5 psi with IC, given the same turbo on the same motor.
Getting the intake temps as cool as possible makes the efficiency go way up.
I think that when it was 90degrees out side, my intake temps are at 120 degrees , but with out the IC, they would be 180+, or something like that.Maybe even more.
Bradyb mention Meth/water injection. It not only cools the air, but raises the octane. It is the best way to cool the air w/o an intercooler.
I am set up to run water/alcy injection on my car even though i am intercooled. I have run up to 1 bar on my car with it. (14.7psi).
The cooler the air means that when you go to tune, you can pull less timing , therefor making more power. My current set up keeps the stock timing curves, I pull none out. On really hot days, my knock sensor will pull it out if I push it hard. (which i dont really do).
A lot of guys with my motor say that you should run 8psi and no more than 10 psi on 91 octane. Yet I run a richer A/f mixture and have a bigger IC than they do. Cooler air temps cant be over estimated IMO.
Elevation also affects boost and air density on my car. I live at 3k elevation. When I go to the beach, I can feel the power increase at the same level.