Does a dynojet measure torque or horsepower?

If for instance, it wasn't measureing rpm's correctly, which figure would be off? torque or hp?

The last time i got my car dyno'd it wasn't measuring rpms correctly (i think he had it set for 90 degree rotation of the crank shaft every time a plug fired and i didn't see a choice for 120 degrees -- isn't that what the deal is since we have 3 rotor faces?)
The tachometer is a measure of crankshaft/driveshaft speed right?

I would think it would measure torque, but i guess i don't really know- thats why i'm asking.

 

What color is your FD?? I was just wondering if I know you or not since we're in the same town.

Zach

 

The dyno measures torque. HP is calculated using the recorded values for torque and rpm.

The rotary turns 180 degrees per spark.. or 360, depending on which lead you're looking at of course.

 

Since HP=RPM*Torque/5252, you can re-calculate the HP based on a known 'correct' RPM.

I may be confused, but wouldn't 90 degrees be the correct setting IF the dyno were monitoring one of the leading plugs? My logic is that in the 13B-REW a single rotor fires once each 180 degrees of shaft rotation, the second rotor timing is fixed at 90 degrees offset to the first, and since the leading plugs fire together, there would be one pulse each 90 degrees of shaft rotation. Am I missing something?