OT: dyno for my RC model car

Hi all, apologies in advance for the blatant nature of this off topic post!

I have a nitro fuel powered 4.6cc piston engined model car. The engine has a claimed power output of 2.7kw @ 33,000rpm.
I am able to tune the engine to the environmental conditions on the day and thought it would be pretty cool to set the thing up on a dyno.
Problem is i dont have much of an idea on what components to use to generate the load? I have 3d modelling software, a mill, lathe and access to odds and ends. I have some spare parts at hand. A couple of 12vdc high power hobby electric motors, a siemens s7 1200 (i can use wincc runtime to act as the front end with logging and trends). But thats about it.
Would anyone would care to share some ideas or suggestions on getting this little project up and going?

What RPM are you going to run it at then
gear reduction -> tire RPM -> tire peripheral speed (inches per second etc) -> torque at tire periphery.

THe simplest would be a line in the same plane as the vehicle thru a turning block to an overhead block and then hoisting a load.

Load weight X speed would give you HP ie HP = 550 foot lb / second.

But things sound a bit fast for that.
Dan Bentler

I think they can be built from pumps, or generators, then measure amps/load the generator/batteries.

I read Car Craft all the time, but never really looked close an an automotive dyno.

My overall ratio is 15.257:1 in 2nd (top) gear.
The claimed max engine rpm is 41000rpm.
The tyre diameter is 140mm.
This gives me a top speed of 71km/h.
I calculate the torque @ 33000rpm (2.7kw) to be 0.781nm at the engine output shaft.

So at the wheels i have a max velocity of 1182m/min @ 41000rpm and a reflected torque of 11.916nm @ 33000rpm

Just doing a bit more reading it looks like an inertia dyno might work. Basically sit the car on a lump of round bar and run it. Very similar to conventional drive on dyno's except my rc car is 4wd.

I have a programmable sick encoder i can use with the s71200 to find the average angular velocity between samples. Im thinking a 5 second run with a 1000 samples should be a good start. Now, how the heck do i work this backwards to find the right piece of roundbar (2 of them for the front and rear) to act as the flywheel.

OkiePC said:

I think they can be built from pumps, or generators, then measure amps/load the generator/batteries.

I read Car Craft all the time, but never really looked close an an automotive dyno.

Click to expand...

Lol http://www.youtube.com/watch?v=xCwrZp9b7xE

The car wheel and the dyno wheel must be 100% coupled (ideally) thus the peripheral speed of both must be same.

You know car wheel RPM and speed ie distance per time. Now pick an RPM of dyno wheel and divide into speed. That will give you diameter.

Dan Bentler