Quote:
Originally Posted by 42pilot
Ideal for power is 18:1. Any richer and you'll increase EGT's and probably trip the CEL quickly. On the other hand, at cruise, it is possible to see 40:1 because of diesel's energy properties.
You probably already know that BMW has sensors in the engine compartment that can sense air flow (bow-pressure). I read an article by Steve Dinan who proved to a Car and Driver author by blowing air with a Home Depot fan at the front of his M5 and it produced +300-ish horsepower. He then started up his new $250,000 focused fan, and pointed it at the front of the car. The dyno then showed +400-ish horsepower. The AF ratio went from 9.5:1 up to something like 12:1. Nothing else was changed except air speed at the front of the car. In addition, to be the most fuel efficient, BMW also senses the speed of the vehicle to contrast it against the fueling table. If the speed sensor says 100 mph (on the rollers) but only senses 25 mph air through the front of the car, it will increase AF to keep the engine cool (gas motor) and reduce horsepower. When I tune rear-engine Porsche's on dyno's, I use a shop that has a Mustang dyno (that can load the engine) and 5 fans (I forget the cu ft/min rate) - three for the engine compartment and two upfront to feed the radiators (oil or water).
Anyway, that's how complex these cars are and why sticking a chip that simply increases fuel pressure and timing could be risky.
|
Thanks for the FYI, you can ask me a lot about suspension dynamics and brakes, but I'm not too familiar with engine tuning. (Probably because there wasn't much to tune on my s52 e36 and sohc civic)
Keep it coming, I may contact you before my dyno day to be go over last minute details and suggestions.
I also contacted the tuner who I will be dynoing my car and he stated he has a OBDII parameter reader and can probably get some basic info such as engine temp, coolant temp and maybe fuel readings, but he is unsure about EGT.
EDIT: found the article you are referring to:
http://m.caranddriver.com/features/i...nt-fans-page-2
Also, my RC has shipped and should arrive over the weekend.