We tested our Rototest for calibration after it had been in service for a long period of time. No shift. It was a lot more precise than the rollers, but it had some quirks when used for sweep testing (aping an inertial dyno).
You could also lock the car into a specific load and leave it running there for hours, something you can't do with an eddy brake or the big friction brake on a Dynojet. That was really useful for us, but pointless for most shops.
Picture how much harder the gears in the tranny and diff are forced into each other with the 1000hp than with the 200hp. The wiping motion across each other equals way different amounts of frictional losses.
WOW Really Paul? wrote: Jerry, what dyno type was that?
I wasn't sure until I watched the video I posted on Facebook. I can see part of a Dynojet sign on the right side. (I tried to embed the video here but it kept disappearing)
Fun note: the 1990 Miata and the 2005 Miata are very, very similar although power ratings went from 116 hp to 178. That's a 50% increase. Guess how much the drivetrain losses changed when comparing wheel hp to SAE hp?
They didn't. The 1990s lost about 25-28 hp. The 2005 turbo cars lost about 25-28 hp.
sesto elemento wrote: Picture how much harder the gears in the tranny and diff are forced into each other with the 1000hp than with the 200hp. The wiping motion across each other equals way different amounts of frictional losses.
Best practice is to dyno a car in the 1:1 gear ratio (often 4th on a 6-speed or 5th on a 6-speed), which in most RWD transmissions involves directly coupling the input and output shafts together. That results in no power being transmitted through the gears.
The differential, yes.
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