Dyno Testing

[Greyn57]

Our Melbourne VW club organised a day to run our VW's on a local VW specialist's Dyno for a day. (Sat the 30th here in Aus). Moment of truth for a few and put a few stories (BS) to rest heh heh.

My 2.4MFI measured 104HP at the wheels and 640 ft pounds of torque at 6000rpm.

From stock I beleive the 2.4MFI T motor has 160HP at the flywheel (I assume its at the flywheel) I was happy with the test results on a fairly well used motor. But it seems to be down a bit or loosing a lot thru the drive line. What do you all think?

[air-cool-me]

and 640 ft pounds of torque at 6000rpm.

[Greyn57]

Is that number look out?? I am not a dyno expert.
Looked at the printout. Its 627 T.lbs. Hmmm.

[ssetek]

ooh a dyno dynamics dyno verry nice

[2.7RACER]

Horsepower is derived from torque at a specific rpm.
The formula for HP is torque times rpm divided by 5252.
The numbers for torque at 6000 rpm are impossible for that size engine. Even in OZ. Further more that engine likely develops it's highest torque in the 4000 rpm range. And max HP around 5000-5500. At the wheels I would expect at best 120 HP from a stock higher mileage 2.4 motor.
May I suggest you contact the dyno shop and have them explain the numbers or post a copy here and perhaps we can decipher it. Hang in there we'll get this figured out.

[HardDrive]

627 torque?!?!?! How many beers did the dyno operator have that morning?

[randywebb]

Do the Aussies use ft-lbs. for torque?? That may be what's going on...

[Greyn57]

Thanks for the comments so far guys. The torque thing is a puzzle. I will have a chat to the Dyno guy and see what the lbs line means.

Here is a pic of the print out.
Two power runs.
1st one we discovered that the throttle pedal set up is no good as its only getting a little over 3/4 opening.

2nd one was manually opening the throttle wide by hand at the engine. Made more power and noise.

[Mr Beau]

Something doesn't seem to be setup right. What gear did you do the runs in? Maybe the torque would be correct if divided by the gear ratios, but this would be strange. Did they have an RPM reading connected to the engine, or was it just taken from the wheel sensors?

[Greyn57]

Runs were done in 3rd gear. This Karmann has a single side plate VW gear box. Runs are done in as close to 1 to 1 ratio as possible.

Its was only off the wheel sensors (rollers?) No RPM reading. There were over a dozen cars to get thru so set up time was limited

[zzwhm]

[QUOTE]Originally posted by 2.7RACER
[B]At the wheels I would expect at best 120 HP from a stock higher mileage 2.4 motor.

For comparison, my freshly rebuilt stock 2.4 is getting 130hp at the rear wheels and 131 ft./lb.
Bill

[Mr Beau]

Even if the gearbox is 1:1, the final drive ratio and the diameter of the tires affects the "torque" at the wheels. If you work out the ratio between the engine and the wheels, you can convert the lower axis to RPM. The HP numbers will still be "accurate", but not the torque because the engine RPM wasn't known at the time.