"Rick" wrote in message
ink.net...

"Jerry Martes" wrote in message
news:5lS_c.4605$vI2.1373@trnddc02...

"Ned Simmons" wrote in message
...
In article gIw_c.2426$j62.422@trnddc04,
says...



I've got a little pump-dyno here where I mounted the pump so it is
free to
rotate. Then, when the flow is restricted, the pump tries to
rotate.
When I measure the torque imposed on the pump and the shaft RPM, I
assume I
can calculate HP with Excel. But, the idea of several GPM at a
thousnd
+
PSI scares me enough that I dont want to test it in the garage. I
might
get courage to test it on a fractional HP motor. All the other
dyno
loads
I've tried get too hot when loaded for even a few minutes. Water
spray
helps extend the test run time, but even the water makes a little
mess.

Jerry

If the hydraulics are done properly I wouldn't be too
concerned. I've got the schematics here for a 100 HP test
stand I designed and built for one of the big hydraulics
mfrs. for testing high speed hydraulic pumps and motors. As
well as testing both pumps and motors, it checked
volumetric efficiency and went thru an automated sequence
while logging data, so I'm sure it's much more elaborate
than what you've got, but if you're interested in the
schematics let me know.

Ned Simmons

Ned

My problems are associated with a poor decission I made in the design
of
this little dyno. I wanted the drag on the load's rotation to be
minimal.
So, I made the lines into and out of the pump as flexible as possible.
I
thought the output hose could be "light weight" because it is such low
pressiure. My brother-in-law spent his life designing hydraulics for
Northrop. He told me storries about high pressure liquids punching
small
holes in outlet hoses due to some caracteristic of high pressure pumps.
I
thought -- Oh Sh*t. Since I have other things to occupy my time, I
dropped
that dyno for a while.

I appreciate your offer to share your dyno information with me. I
wish
I
could get involved with a project that uses a big dyno.

What kind of instruments do you use to log the data. I got a Lab Jack
but
get confused about how to use it.

Jerry.


The go kart guys have all sorts of unique "dynos". Your eddy current one
sounds pretty cute though.

Rick

I didnt do much research on dynos before I began building mine. I did try
to understand the "Inertia Dyno" that is used for Kart engine testing. I
would think the inertia Dyno would be hard to beat for Kart engines.
I suspect there much better versions of the eddy current dyno that the one
I built. The only good thing I have to say about this spinning aluminum
disc it "it is easy to build and operate at home". Don Foreman actually
suggestedthis concept to me (spinning aluminum disc). It was too simple to
ignore. It is really easy to control so the data is quite repeatable. The
disc brake loads I *was* building are very difficult to make smooth. They
tend to skew the data due to pulsating effects from any small imperfections
in the disc and/or caliper.
I doubt that anything I know about eddy current dynos would be interesting
to anyone in the Kart business. I just sold my Kart this week.

Jerry