Funkweasel

drivetrain at the equivalent power the motor just did, it can't. That's all I'm saying. I specifically said I didn't want to argue the merits of fixed losses versus percentage losses. That's all.

I think its best if we just report the whp #s for a stock car on a particular dyno and the whp #s of a modified car and call it a day. The crank back-calculation is bs for the most part anyway, in fact the SAE has stated just that. Its no big deal, why don't we just stick to whp?

ie What'd Josh's car throw down in whp, and what did a stock car do? That's all that matters. ;-)

frank

tire coF, gearoil friction are all dependent of the load,
but you don't want to debate that

fair enough, I have 3 dyno pulls from a B6 A4 1.8T

2 runs are identical for WHP and crank HP

the 3rd, has like 36 WHP LESS that the other
(3 runs in 25 minutes)

while crank HP, dropped only 16 HP
(so drag went up)


I assert that WHP is BS, without drag #'s

and if the SAE just stated that backwards calculation is BS

do you have a link to that white paper?

Yippers®

here is the quote again ..
" 9. Shortley before max. RPM is reached disengage the clutch and release the gas pedal
10. After a successful measurement the engine power, wheel power, drag power and torque are displayed. (if an RPM signal is available)"

It looks to me like MaHa's dyno operator instructions tell the operator to disengage the clutch for coast down measurement. The problem with coast down measurement is they ignore the losses incurred for power input which is a percent loss.

Yippers®

Because it isn't a fixed loss. A portion of the losses are percents.

frank

you are asserting that the direction the load comes from

engine back or Wheel forward changes the percentage loss incured

work is work, whether it goes engine -->clutch--> drivetrain

or eddy brake--> wheel-->drivetrain is a non-issue or a negligable amount


how much do you or the SAE assert is being "unmeasured"?

my suspision is that the SAE finding you are refering to
is a very specific situation,
that shouldn't or can't be directly appiled to this case

frank

MBZ.BMW, Porsche and VW/Audi all rely and reccomend this exact dyno

so all the mechanical enginners working for these companies are wrong?


is it any wonder, I'm not swayed by this arguement

especially when I have seen WHP vary by 20% in a 25 minute time span?

Innovator

You know how to disagree without getting insulting. Your not curt, and you try to back up your facts. Kudos!

frank

you and Quigley are both guilty of that
and you lose many debates that way


I notice Todd doesn't

Innovator

I mean, define loss?

Todd has to walk a fine line, as tuning is his life and his income.

Marc and I are cowboys and speak from the heart without worrying about the consequences as much
:-)

frank

that OCT car did have a cone intake
BUT, the fan speed simulated 70MPH

there still "may" have been an installation issue,
but I don't think that covers a 60HP defict