325i engine underrated????

[donutchow]

i was checking out the acura tsx board and this is what i saw, someone had a dyno graph:
__________________________________________________ __-
Well the peak numbers are all essentially the same.

-----2.5L six-----------2.4L four
HP---170.1------------169.9
TQ---156.3@3500---152.4@2800
Both HP numbers come essentially at redline.

If you do some calculation using a driveline loss of about 14% for both cars (pretty standard), you get at the flywheel:

-----2.5L six---2.4L four
HP---197.8----197.6
TQ---181.7----177.2

Which tells us that BMW's HP number was underrated (which I expected), and that the TSXs torque number was underrated (which we knew from the TOV review). So, the TSX has just under FOUR less lb-ft of torque, but it comes on at 700 RPM EARLIER (i.e. more low-end torque). It looks like the TSX torque curve is flatter, but that's due to the differing scales on these two charts. They're both about the same degree of "flatness".

[MrM3]

do you have the actual charts? i'm suprised the tsx would have a flatter tq curve than a 325

[L337E46]

Isn't the TSX FWD?

in my limited knowledge of dyno testing, mostly from reading AA's website, standard drivetrain loss for bmw's at least, is 16-17%. Ive found a dyno for a E36 325, with 189hp stock. 189hp * .84 = 158.76 RWHP , which is remarkably close to what AA got for "base" run. The new E46 325 has what? 184hp? Loosing only 14hp from flywheel to rear wheels is insane. Even if it was underrated, which it is not, why would BMW use such a low number? Im not saying it cant happen, i just dont believe your sources are accurate. There is no way that 2.4cyl achieves its torque that low, lower then a I6. Like MrM3 said, i would have to see the charts before i made any final conclusions. Just from reading the topics here, ive gone from knowing hardly anything, to finding out ALOT, thanks guys!

o, by the way, here was the link from AA: http://www.aatuning.com/dyno/94_325i_vs_94...upercharged.asp

[woobiee]

from numerous sources, i have read that BMW do underrate their engines and that BMW is excellent at transfering power to the wheels with minimal horsepower loss