So I'm not happy with the update rate on the Torque app for measuring HP/Torque numbers. And the Bavarian Technic ECM reported torque #'s appear to be based on calculations of other engine parameters (and it's update rate is pretty slow as well).
So, I broke out my old GTech Pro. However I was unable to lock-on to an rpm signal when connected to the power outlets due to BMW doing such a good job filtering the noise. So I cludged together a way to power the GTech from the battery and got a crystal clear rpm signal.
Then I found a local car whose owner has a BT and a JBD that is modified for in-cab adjustability.
Last night was near perfect conditions. 70F and no wind. Said vehicle had just completed a DPF regen and had a full tank of fuel. The D is supposed to weight ~3804 lbs according to insideline (http://www.insideline.com/bmw/3-seri...full-test.html
) and with the driver and some items in the trunk it would be total ~4000 lbs.
The runs below are with the JBD at 0, 1 switch thrown (~65%), both switches thrown (~85%).
Procedure was over the same stretch of flat road (interstate), gently accelerating in 1st to 2nd then getting into 3rd gear before giving it the fuel, then letting up at ~80mph so I didn't run the risk of loosing my license if . . .
The numbers include not only loss of the tranny and tires
, like a rolling dyno, but also the loss due to wind resistance. Looks like the Cd and A for the e90 is 0.26 and 2.17m^2. Using this (http://www.gtechprosupport.com/support/AeroDragCalc.php
) says that at 80mph there's roughly 21 hp lost due to wind.
I'll post some of the BT data later of some runs that has some interesting data. Unfortunately it was trying to record too much data and the time steps between readings is larger than I'd like. But things like EGT's, DPF pressures, injection timing, etc are there.