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      06-09-2011, 11:45 AM   #52
Lieutenant Colonel

Drives: 2011 135i
Join Date: Oct 2007
Location: Portland, OR

iTrader: (1)

Originally Posted by nachob View Post
Guys, I'm not an M3 guys can tell that I am doing everything possible to get a 1M over an M3 BUT I am a car guy and actually have worked a few years in an IMSA GTP Dyno and test department and I can tell you with absolute certainty that heat DOES affect peformance. That is why there are big intercoolers on these cars to cool the intake charge. If the outside air is hot, the intercoolers cannot cool the charge. It is a very simple concept. So as an impartial guy, just thought I would mention it before you start a war over something so basic. The interesting thing is that hot air will also affect NA cars. The one advantage turbos have is that hot air is less dense which is why NA cars lose a little power. Turbos can compensate a bit because thinner air gives less resistance to the turbo impeller so it can spin faster and make up for some of the loss of volume, hence making up for the loss of density. As long as the engine can keep from detonating by cooling the air charge with extra fuel, theoretically, the turbo car should do a little better. Once detonation begins due to the heated air charge, the timing will retard and you will lose power. Anyway, just thought I would throw that out there.
All cars loose power at 95* as opposed to 55 or 65*...that's just physics and there's no way around it.

Turbocharged engines have very conservative engine management systems to keep them running safe under all operating conditions. The car will feel slower in hot weather just due to the ECU listening for knock and pulling timing advance accordingly. That's done on purpose to keep the engine from grenading, but it will make the car feel much slower and less sharp than in temps 30-40* cooler.

On a hot track day dumping a 5 gallon drum of 100 oct unleaded would go a long way towards getting the power back. That tends to make the ECU more comfortable to dish out the timing advance again.