2009 Q7 TDI Baseline Dyno
10-18-2010, 06:43 AM
#1
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2009 Q7 TDI Baseline Dyno
well, i decided to put the beast on a dyno to see what this beast was producing. again, this is a stock TDI. they had to limit the measurement to 3800 rpm since it was shifting to a higher gear around 4000. surprisingly, the Q seems to be underrated. AWE claims 28% loss from crank to wheels. with this calculation, my Q is at 262.4 HP and 460.8 lb ft. of torque at the crank. i am very very happy!!
Last edited by 2PUTT; 10-18-2010 at 07:57 AM.
10-18-2010, 07:55 PM
#3
28% seems about right for AWD Automatic. For a 2WD car, manual transmission, the losses are about 12 to 15%. For a 2WD Automatic car, it is higher, maybe 20%.
There are additional losses on AWD cars beacuse of the additional driveline gear, ie. transfer case.
There are additional losses on AWD cars beacuse of the additional driveline gear, ie. transfer case.
10-19-2010, 05:22 PM
#5
Here is a write up about flywheel (some call crank) hp vs rear wheel hp. It explains the various factors that contribute to driveline losses. It does not have a reduction factor for AWD cars, but folks over on Subaru forums use a 25% loss factor. So, 28% is in the ballpark.
http://www.sdsefi.com/techdyno.htm
You have to remember that dyno testing is not absolute. There are many variables between test conditions and the dynos. But these differences are not of great orders of magnitude. So I personally "trust" dyno number accuracy to the nearest 10 hp.
..and a great article about converting between dyno and crank hp:
http://www.modified.com/tech/modp-10...oss/index.html
http://www.sdsefi.com/techdyno.htm
You have to remember that dyno testing is not absolute. There are many variables between test conditions and the dynos. But these differences are not of great orders of magnitude. So I personally "trust" dyno number accuracy to the nearest 10 hp.
..and a great article about converting between dyno and crank hp:
http://www.modified.com/tech/modp-10...oss/index.html
Last edited by Aggie88; 10-19-2010 at 05:29 PM.
10-19-2010, 08:17 PM
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great articles, but i still do not not understand your rationalization of 28%. Sorry- not trying to be a smart-a$$- just trying to understand how you logically conclude that number. But, that's ok.
Most importantly, the whp is the only real number you can bank on, and the deltas of that number due to mods or issues. Even if one were nuts enough to pull an engine and run it on an engine dyno to actually try to compare the crank and wheel, one still wouldn't know the variables used by the manufacturer to achieve those figures.
This is how i look at it:
Mfr Crank HP: Marketing (underestimate: "speak softly and carry a big stick;" exact, or as close as you can be: " we're not pulling any punches...it is what it is;" overestimate: "can't walk the talk...")
Whp- what matters. Don't even try to convert to crank.
Most importantly, the whp is the only real number you can bank on, and the deltas of that number due to mods or issues. Even if one were nuts enough to pull an engine and run it on an engine dyno to actually try to compare the crank and wheel, one still wouldn't know the variables used by the manufacturer to achieve those figures.
This is how i look at it:
Mfr Crank HP: Marketing (underestimate: "speak softly and carry a big stick;" exact, or as close as you can be: " we're not pulling any punches...it is what it is;" overestimate: "can't walk the talk...")
Whp- what matters. Don't even try to convert to crank.
10-20-2010, 04:50 AM
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The one article is talking about 15% loss. Even if we had just 15% loss with the TQ coming in at 360, 2putt's is still putting out more than Audi's claim of 406 at the crank. While the Quattro is a great drive train, with all the viscous clutches and extra differentials there is significant frictional losses.
Yes horsepower at the wheel is what is important. But with the amount that the TDI is putting to the ground it tells us that the 3.0 TDi is much stronger than Audi's claims. For the 3.0 TDI to be making what Audi's numbers are the Q7 drivetrain would only have a 11.5% loss. And that is impossible.
My experience through the years of building engines, having them dyno'd and then having them put in the car and dyno'd again tells me that 20% is the minimum for a 2wd car. With newer cars we may be at 15% for 2wd but 4wd or AWD is much more.
Yes horsepower at the wheel is what is important. But with the amount that the TDI is putting to the ground it tells us that the 3.0 TDi is much stronger than Audi's claims. For the 3.0 TDI to be making what Audi's numbers are the Q7 drivetrain would only have a 11.5% loss. And that is impossible.
My experience through the years of building engines, having them dyno'd and then having them put in the car and dyno'd again tells me that 20% is the minimum for a 2wd car. With newer cars we may be at 15% for 2wd but 4wd or AWD is much more.
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10-20-2010, 05:47 PM
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