Chassis Dyno

[MandarinaRacing]

Are they all the same, is there a right way or a wrong way of measuring horpower on these things, are they accurate???.....I've heard on other boards that you can cheat a chassis dyno (don't know how) to get more or less horsepower figures (read magazine type tests).
Also do you accelerate your car in 1st gear or do you go through the gears, with it be the same....hm?????

Lotta questions, neeed more caffeine.....

Alex

 

[StrangeRanger]

Chassis dynos are less accurate than engine dynos. The vehicle drivetrain intrduces a bunch of variables some of which can be manipulated by the operator to skew the results a bit. Most operators have figured out how to get the sort of optimistic numbers that their customers want to see. Imagine that. :roll:

They are VERY useful for tuning and evaluating mods. A 10 HP gain is still a 10 HP gain. The dyno may say you've gained from 290 to 300 when in reality you've gained from 270 to 280. It's still 10 HP.

 

[Anonymous]

Don't forget that dyno's can't really compare to one another anyway. A water brake vs eddy current vs inertia, etc doesn't work. Even from one SuperFlow to another SuperFlow you're going to get inconsistencies.

To give an example: An import mag a year or two ago took the same car and went to like 10 different dynos, all in Cali. From the highest to lowest was about 30hp difference, and we're talking a 150hp 4cyl here. (No, not on the same days, but that was after correction, which some people insist on comparing).


-=Whittey=-

 

[Anonymous]

Alex, I watched them doing chassis dyno pulls at the Runoffs last September, and they were doing the pulls in 4th gear, or whichever gear has a 1:1 ratio. The explanation being that a 1:1 ratio gives the least distorted numbers.