Torque measurement

[Greg Hermann]

>A dyno works the same way. The rotor of the dyno is coupled to the engine
>under test. The dyno case is supported by trunion bearings. water is
>circulated between the rotor and case. The rotor tries to turn the case, and
>a load cell on the case reads out torque.  In an engine, the crank is the
>rotor and the block is the case, a load cell on the block would read out
>torque just like a dyno does. If you want to measure off of the drive shaft
>an in line load cell would be needed. The cost of an in line is over $3K a
>tension compression load cell is around $500.
>                                                            Don

I did NOT want to read off the driveshaft--I simply suggested CALIBRATING
off of it! The torque reaction at the motor mounts is most definitely the
torque reaction of the engine/transmission ASSEMBLY, the reaction to the
output torque in the driveshaft, and therefore will vary with what gear the
tranny is in as well as with the engine's output torque.

Regards, Greg
>
>> -----Original Message-----
>> From:	bearbvd at sni.net [SMTP:bearbvd at sni.net]
>> Sent:	Friday, April 09, 1999 9:07 AM
>> To:	diy_efi at efi332.eng.ohio-state.edu
>> Subject:	Re: Torque measurement
>>
>> >-----Original Message-----
>> >From: Greg Hermann <bearbvd at sni.net>
>> >To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>> >Date: Thursday, April 08, 1999 10:30 PM
>> >Subject: RE: Torque measurement
>> >
>> >
>> ><SNIP>
>> >
>> >>
>> >>Well--you would be measuring the torque output of the TRANSMISSION, not
>> the
>> >>engine--so you would need to calibrate the thing a fair amount higher
>> for
>> >>the low gears. Look at the engine-tranny package as a black box to
>> >>visualize why this is so. And calibrating with a bar stuck through the
>> >>output yoke, with the tranny in gear, might be a lot easier approach.
>> >>
>> >>Greg
>> >
>> >
>> >Hmmmm(n).  I uderstand what you are saying, but if the transmission is in
>> >neutral, and I open the throttle, the engine rotates oposite to the crank
>> >direction.  There is no output from the transmission... Is this just the
>> >energy that is being stored in the flywheel causing this oposite
>> reaction,
>> >or am I more lost than I think?
>> >
>> >Ord
>>
>> Yep--in the situation you describe, it is the reaction to the rotational
>> inertia of the ratating assembly that makes the engine rock.
>>
>> Greg
>>