Sport Compact Car, Aug 04 edition.

Article called, What's wrong with your dyno.

Pg 202, the graph.

Test vehicle on 7 different dynos.
174 on a Dynojet at HKS
132 on a Dyno Dynamics.

167, 165 of 2 other Dynojets.

At that rate, on a alledged 522 reading as a high, 396 could be expected as a low.

While they're OK, for back to back testing, and noting trends, once you get past that, and start bench racing numbers, it can quickly become meaningless trivia, rather than being meaningful.

BTW, strapped Doc to a dyno, once, and he allegedly made, .298547 HP.
But he had just finished two pepsis.
Sleepy tired, but slipped and fell off the roller.

 

I remember reading one of those mags a few months ago. They had a special section all about how dyno's lie and how people misinterpert the data. Then they turned right around in an article in the same mag that claimed a 4 hp increase with a cold air kit based on a 6 hp spike in the dyno curve. The spike didn't even last for more than 50 rpm's, it was obvious it was a hickup during the run. I read up on the competition from time to time and I'm still not scared. Even the 50 grand supra's are pretty much useless any where but on the dyno.

 

Yeah the only dyno I'd trust (for Hp measurement) is an engine dyno (or an AC or DC powered chassis dyno)
The only real measure is on the strip, or track or wherever you want.
I'd never try to back calculate some engine horsepower from a chassis dyno, and I'd never compare dynojets to mustangs to dynapacks.
If you're making changes and want to see a number with the improvement, go to the same dyno that it was baselined with.
The main use of a dyno for me is just a controlled substitute for a road for calibrating and algorithm development.