Engine dyno for EFI reqs 450-500hp

[Craig Pugsley]

> All,
> 	Great comments on engine dyno's, much thanks! 
> Many asked what our requirements are.
> 
> -Target HP for the engine we are building is 400HP (turbo, Efi ~114 oct gas, 
> 	ESC.)
> -Engine is for a drag car, however, typically we are only able to get
> 	3-4 passes in before racing starts, this does not provide as much
> 	of an opportunity for tuning the engine as I'm sure we will initially 
> 	need as we bring an EFI system online from the ground up.  
> -Would like to be able to do static RPM as well as transient testing.
> -From your comments it seems a water brake may be the best way to go, however
>         the transmission torque converter idea seems interesting as well???  
>         Can they absorb the power/heat reliably?

I thought a dyno with a big disc brake on the output of the engine
(either via an automatic transmission or with a brake master cylinder
hydraulically/mechanically feeding back to keep the load constant), with
a water spray on the brake to cool it. Perhaps a truck differential and
brake assembly (ignore the fact that this would weigh serveral hundred
kilos).

Alternatively, how about a hacked automatic transmission with a varying
amount of fluid in the convertor (no fluid=no load, full of fluid~=
lockup). To implement this I thought you could drill some outlet holes
on the outside periphery of the torque convertor to provide drainage,
and the flow rate of fluid into the convertor varied to provide the
level of fluid. Obviously this might need some fancy control to get it
to work due to the drainage rate being faster at higher speeds. Also, if
the drainage rate is not even the whole assembly could be out of balance
(not nice at 7000 RPM :-(

Or, how about driving another engine set up as a water pump
(eg remove the valves or play with the cam timing so you don't try to
compress the water, and have the water so it alternates between
cylinders, with a water tap that is variable to control the load.)

With any home brew type arrangement (especially when you're testing the
400hp sort of stuff mentioned above), I'd suggest something solid around
the load device (eg 1/4" plate steel scatter shield), and the testing
be done remotely (ie brick wall between you and the test rig.).

Cheers,
Craig.