"..To increase filling ratio, the inlet cooling can be optimized. Cooler air
results in more dense air and that leads to more pony's. Nowak does that to
the E39 M5 and that yields an extra 20-25 ponys. Another restriction to the
E39 M5 is that it uses the exhaust manifolds of the 4.4 ltr. Nowak and Hartge have develloped their own exhaust manifolds and that leads to an extra 50hp."
This was posted in response to an inquiry from an E34 owner about modifications. The poster, Raymond W., lives in Europe. I thought the exhaust manifold information was interesting.
I seriously doubt those figures, as if there was THAT much additional performance to be gained, BMW and the tuners (Dinan, Hennessey, ACS, Hartge, Hamann) would all be doing it (selling freer-flowing headers), and CAI kits would already be available from more places.
Developing new manifolds or headers would take a bit of time and money to develop. Also, any U.S. tuner has to deal with any emissions regulations that would apply. I am sure those mods are not cheap.
Remember, the car has been out quite a bit longer in Europe. The tuners have had longer to work on them.
I read that too Greg but all that equates to a 100hp increase. I am not sure a header would give you 50hp but it might on an engine with that kind of power output if you re-programmed the engine mangement system. However, I am sure it would "technically" illegal in California.
Bottom line, they port and polish the head, bigger cams, header, exhaust, and intake. Kinda sounds like a hot rod doesn't it?
Awhile back, Steve Dinan showed me the M5 he was using as the guinea pig for his new header system. The power train was out and lying on a bench where he was designing the new intake and exhaust plumbing for it. Very impressive work he was doing; venturis, etc. With these mods and others, he's claiming another 65-75 HP normally aspirated.
Interesting Perf. Info
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