dyno stuff

[don.broadus at exeloncorp.com]

The Chassis Dyno measures torque the same way an engine dyno does.
 A chassis dyno is calibrated with weights on a torque arm.
The rollers are locked and calibrated weights are hung on the torque arm
usually 1 foot long (hence Ft. Lbs.) I would guess that perhaps the dyno was
calibrated
in Newton meters instead of foot lbs. Check your calibration weights and
checking arm
if they are metric, the conversion is   newton meters X .73756 = foot lbs.
The roller diameter , checking arm , dyno constant all are factored in to
select the calibration
weights. The chassis dyno doesn't care about the differential ratio, it only
cares about the roller 
RPM and twisting force applied to the roller.              Don

 

> -----Original Message-----
> From:	Programmer [SMTP:nwester at eidnet.org]
> Sent:	Wednesday, May 02, 2001 9:32 AM
> To:	gmecm at diy-efi.org
> Subject:	dyno stuff
> 
> Thought I'd run this past the collective,
> 
> Here's the story:
> We've got a Maha Chassis dyno, built by the boys in Germany--totally
> digital
> machine. My torque numbers always seem so high compared to my HP
> numbers--but maybe this is why. I can't get anything close to what a
> DynoJet
> or Mustang, etc...shows for torque.
> 
> Let's say the engine outputs 200 ftlbs torque at the crankshaft at a given
> RPM. Why would you see a similar number at the wheels when the
> "differential" multiplies the torque ? You shouldn't right ?? I've had
> numbers as high as 1774 ft/lbs on a low 11 sec car, but HP numbers around
> 420. How did they do their calcs ? At this point, I'm the only one in
> Canada
> with this dyno...and nobody can give me answers.
> 
> Lyndon
> 
> 
> 
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