DIY_EFI Digest V1 #241

[Robert Van Zant]

>The biggest problem with almost any dyno is getting rid of the heat 
>generated. For a 200HP engine, that's more than 500,000 BTU/hr.
>That's enough to boil off 523lbs of water per hour, or 65 gallons.

     Sorry to be dense.  I'm not exactly clear how one would (on
a home budget) convert 200hp to boiling water, but I do know that 65
gallons isn't that much.  I could live with 1/2 dozen 55 gallon drums
full of water next to my garage.  I'm swimming pool impaired, so 
Einar's excellent suggestion isn't an option.  Also, do we really plan
to generate 200hp for a full hour?  I know we're talking about average
output over some period, but assuming the calculation is linear (400hp
@30min, etc), I could easily live with the 200hp/hr figure.

> The frame of this "hub coupled" device should probably carry the weight
> of the car rear end by the hubs to avoid large angles at the axle joints.
> A modular approach with the dyno part hooking into a test frame should make
> it possible to share the more expensive parts between several users on a
> time-share basis. Then the test frame can be anything from rollers to a
> simple engine test stand.

    Now we're getting somewhere, and good point about the u-joint angles,
btw.  If I had so much as a modicum of artistic talent (ascii or otherwise),
I'd draw the completely-portable, pins-together, axle-driven dyno now 
rolling around in my head.  I don't, so use your imagination.  Differentials
attempt to rotate under load, hence the need for traction bars, perhaps some
means of measuring this action could be converted to HP.

> Someone seems to be doubtful whether this has something to do with DIY-EFI.
> It seems pretty clear to me that dialling in an EFI by the seat of your pants
> requires a well calibrated bum. (I)  So..you need a DYI-dyno!

     Absolutely agreed, but I hope you meant do-it-yourself, not 
do-yourself-in.

bob