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Re: Dyno in shop

Subject: Re: Dyno in shop
From: Brian Kelley <>
Date: Fri, 12 Jan 1996 10:11:47 EST
John Ross writes:

> They look like a hydraulic pump with a small
> oil tank and some gagues.  I've been thinking it might be possible to rig up
> a pump with a drive system and mesashure the preshure and calculate the tork.
> It's then easy to calculate the Hp from tork and RPM. Does any one with
> experience with fluid dynamics have any ideas on how you can develop a tork
> to preshure formula for a hydraulic pump?  

I believe things would get ugly very quickly with a pressure/volume
based torque calculation.  I don't think that approach could ever be

A much better approach is to measure the rotational torque on the
pump housing.  Strain gauges are pretty inexpensive.

The hydraulic pump approach is intriguing.  I wonder how much pump
you'd need to soak up 500 ft/lbs?  You have to be able to take
everything WOT has to give at a specific RPM (and hopefully hold it
there for accuracy).  I also wonder what the rpm limits are for the
pumps.  The load could be increased by increasing the pump back
pressure, but by how much before something fails?

If the engine development program doesn't work out, I'll bet a pump
that large could also be rigged up to do double duty as a car crusher ;-)



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