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12-09-2009, 06:28 AM | #1 |
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This is a new mechanism I thought of for measuring engine power. The BMW ECU has a parameter called "Current Torque", which outputs the engine's current torque in Newton Meters. Using a tool like the Bavarian Technic Diagnostic Tool (http://www.bavariantechnic.com/) you can log this value in conjunction with engine speed from the ECU to give you a reasonably cheap and accurate crank horsepower calculator.
Exactly how the Current Torque value is calculated I'm not sure - my guess is that it is calculated based upon a number of other sensor readings in the engine. I'm very confident however this figure will be very accurate, given it is a parameter logged by the BMW ECU. The main point of this thread is to establish a baseline of my car in stock trim, and compare the effect of a number of bolt-on modifications which will include in likely order of testing: - Envy Charge Pipe - AFE/BMC Air Filter - AFE Air Scoops - AA Crank Pulley - Powerchip Stage III Software (claimed +40WHP) - Turner Primary Cat Delete All results will be normalized using SAE J1349 to provide comparative readings as each power measurement is taken. Three runs are taken each time and the best run posted - note that the results from run to run are very similar so far... Note I've posted an historical dyno plot for results captured a few months back when my car was not stock - I didn't have any measurements for SAE correction so I've presented the results uncorrected... Historical Dyno: Powerchip Software, AA Crank Pulley, AFE Filter and AFE Scoops Dyno #1: Stock Results Interesting results - looks pretty much as advertised until the engine hits 7000RPM - past here a fairly uniform decline in torque causes power to peak well short of the claimed 414HP @ 8300RPM figures. My car had the very latest software applied one week ago. Last edited by mixja; 12-09-2009 at 06:56 AM.. |
12-09-2009, 10:39 AM | #3 |
4th down; 4th quarter? Renegade.
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I used a similar value, and VAGCOM, on my old Audi 2.7T to generate a "virtual" dyno and it was pretty accurate as well. Good idea.
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12-09-2009, 10:41 AM | #4 |
4th down; 4th quarter? Renegade.
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What gear were you doing the virtual dyno in? I would assume that could affect the results. I'm sure it will be pretty hard to dyno in 4th gear on the road ; )
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12-09-2009, 12:26 PM | #5 | |
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12-09-2009, 12:31 PM | #6 | |
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Note I didn't have TC off for the Dyno #1 run above and the surface wasn't exactly flat (kind of dipped a bit then climbed a bit)... For DCT it should probably be in S6 as well (Dyno #1 above was in S5, M Dynamic Mode).. |
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12-09-2009, 01:26 PM | #7 |
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Wow, very cool. This might be in the car in part for working with DCT. Looking forward to seeing some logged data. Curious as to how BMW does this. Could be some strain based sensor or could be extracted from some combustion/cylinder monitoring.
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12-09-2009, 05:21 PM | #9 | |
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I think this idea is genius. Definitely going to pick up the tool for a xmas present to myself.
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12-09-2009, 05:27 PM | #10 | |
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12-09-2009, 06:20 PM | #11 | |
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12-09-2009, 11:46 PM | #12 |
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One issue I have at the moment is the BT scan tool is not displaying the correct values for many variables - for example torque is multiplied by 10 (easily fixed), but the pressure/temperature readings are not so easily corrected (not sure as yet how to convert them correctly, I have support calls in with BT about this)...
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12-10-2009, 06:41 PM | #13 |
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This sounds pretty interesting - I dont have a BT Tool, but I have a PLX Kiwi Wifi - will have to see if I can collect the same data somehow.
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