Engine dyno for EFI reqs 450-500hp

[Lawrence E. Piekarski]

>
>> Can anyone recommend some reading for dyno testing strategies (I'm not familiar
>> with the motoring technique that Robert Dingli mentioned)?  Books, SAE papers,
>> articles, etc...  So far I've been unable to find any significant text on this
>> topic, I will be contacting the dyno mfgs that Jeff and Anthony Tsakiris
>> mentioned ASAP.
>
>Motoring is when the dyno actually forces the engine to turn over.  It is
>used for simulating the inertial effects of a car when the throttle is
>released and the car is coasting with the engine acting as a brake.
>
>You won't have to worry about this for your application.

When I was at GMI, I used an electric dyno that as of the motoring type. It
was 4000 rpm max and I had a quad-4 attached to it. The way it worked was 
simple. The engine was mounted to a rigid plate and had all the connections
wired remotely to a separate room. The crankshaft was bolted to a big 
electric motor. The motor case was mounted in bearing so that it could 
spin freely and there was an arm mounted to the side of the motor case that
was attached to a load cell. The motor was an industrial variable phase
locked motor (or something like that). You dialed in the rpm and the motor
just spun at the rpm and could not be sped up or slowed down.

Now, you could play with the engine. Lets say you had the throttle wide
open, but no spark for fuel (ignition off). The dyno registered a negative
horsepower. This is the parasitic loss of the internals of the motor (windage,
oil pump, friction). At some point, you could get the engine to product 0hp. 
This would be equivalent to idle. As you went to wide open throttle, the
dyno registered positive horsepower. 

The design was simple. Finding an electric motor in the 7000-8000 rpm range
could be a problem. Also, I don't know how much electronics were required
to control the motor.

The ability to motor the engine was very useful, IMHO. Especially on a drag
engine, you are looking for the extra hp. Of course, this is a EFI group
and there is not much you can do electrically when the system is off...

-- 
(* Larry Piekarski, Lead Software Engineer *)
(*      Luxury Car HVAC Display Heads      *)
(*      c1ilep at kocrsv01.delcoelect.com     *)
(*      Delco Electronics, Kokomo, IN      *)