Quote:
Originally Posted by Opplock1
This will be dynoed on all 4 wheels with a dynapack at my local tuner, Church Automotive Testing. You are correct I need to find the right gear that is closest to a 1:1 ratio(6th gear)
As to what I am expecting from the results, I'm fully aware and not expecting the base line to be anywhere near the stated paper values( I'm guessing after the tune I will end up meeting the values stated lol).
Good point as to calling Racechip and getting them involved in my dyno session. I will definitely do so.
I'm also very curious about the stock A/F ratio and how each step of the tune will effect it. With that data I can hopefully fine tune the fuel pressure and timing better.
Any idea what is the "ideal" A/F ratio for Diesel engines?
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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.