Engine dyno for EFI project

[Ed Lansinger]

Dave Morrill wrote:

>Does anyone have any tips or plans on how to build an engine dyno? 
>...
>I initially began thinking about using a disc brake for a load...

Of course, that's what early dynamometers were, a brake, giving rise to terms
such as "brake horsepower".

I'm not saying you can't do it, but I was part of a quick experiment once
to do just such a thing.  I would recommend against it unless you are willing
to put in some serious engineering analysis and development.  For that effort
and expense you'd be better off buying a water brake dyno as Anthony suggested.

>But then I though about a cast iron disc spinning at >7000 RPM and did not feel 
>like this was very safe, heat and wear would be significant probs as well,

Yes to all of the above.

>The numbers would not be
>exact but at least I would be able to see relative improvements as I made
>changes to the efi system.

If you are willing to live with that level of inaccuracy, then it seems to
me that in-vehicle tests will give you what you are looking for (I assume
this is for a vehicle of some sort).

>I guess the industry uses a water pump for a load, I'm not sure how to do the 
>calculations, do you use water pressure as a measurement, flow rate of
>liquid?  What method could be used to calibrate?

Measure the mass flow rate and the temperature rise across the water brake.

Just how much horsepower are you talking about?

There are machine shops that will rent dyno time.  That is probably the best
way to go in terms of safety and low capital investment.

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Ed Lansinger
General Motors Powertrain
Powertrain Control Center
Premium V Software & Calibration Group
Milford Proving Ground, Milford, MI
elansi01 at mpg.gmpt.gmeds.com  8-341-3049  (810) 684-3049
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