I did some searching around and found the following write up posted on multiple forums. Any opinions?
Interesting Dyno Factoids (Dyno Dynamics, Mustang, Dynojet) - The Unofficial BMW M5 Messageboard (m5board.com)
\\Interesting Dyno Factoids (Dyno Dynamics, Mustang, Dynojet)
I got these from the shop that is about to dyno my M Coupe. It is consistent with what I have been told elsewhere but certainly an interesting read:
20) My car makes 300 hp but your dyno says it makes 215. What is up? Our dyno is the most accurate measurement of torque at the wheels. More accurate than most. No "interpolation" or "estimation" or "inertia factors" are applied like they are on other competitors' lesser machines. What this means is that this is the actual torque being applied at the tire. Typically, a 300hp all wheel drive car will measure in around 210-215 on our dyno. This is normal.
21) I went to a Mustang dyno and they said theirs reads low, but you say yours reads low. Is this just some trick used by tuners? The Dyno Dynamics is known throughout the industry as being the "heartbreaker" dyno - because it breaks the heart of every man that thinks he has 500 hp when he really has 350. The Dyno Dynamics reads lower than the Mustang. It reads WAY lower than a Dynojet. It reads WAY lower than a Dynapack (which actually reads too high on tip-in). The closest in numbers (at low HP) is the mustang, but using the above example, the same 300hp car was dyno'd back to back on a Dyno Dynamics 450 LowBoy (what we have) and a Mustang AWD500E (what some other guys have), and that 300hp rated car consistently read 223 on the Dyno Dynam ics and 249 on the Mustang. One hour apart, exact same car, same town, same altitude, etc.
22) Why dont you just make your numbers look high to be the same as some others? Dyno correction is not a fixed amount. In other words, adding 30% at xx RPM and xx power does not translate. i.e. Using the above example, a car that makes 225 is about 1.3 to get 300. A 900hp car on this dyno is NOT making 1200hp ! Dyno numbers should be used for relative back to back comparison, and nothing else.
23) How do I compare my dyno results to others with similar setups? For Subaru owners, there are enough internet resources to compare, but essentially, Dyno Dynamics and Dynapack are the only 'consistent' numbers, and Dynapack reads very high, Dyno Dynamics very low. We can help you seek out other similar results. A great resource listing a slew of Dyno Dynamics HP baselines is available in the Gallery section at the KTR Performance Dyno Gallery Web Site. It should be noted that KTR uses atmospheric correction, which we do not use on our dyno plots.
24) How do I compare my pulls to Mustang Dyno, or a Dynojet, or a Dynapack? Every dyno is different. If you want dynojet or mustang-ish #s you have to multiply by 1.18 or so, 1.25+ for DynaPack. But remember, this is just ballpark, as it is not linear.
The way these are numbered, I am led to believe that they are an excerpt from some list, but I haven't been able to find the original source list yet.