I've read that the most accurate way to measure the effect of a mod is to dyno, then install mod, then redyno the same day on same dynamometer; but with header install, for instance, which can require 8 hours of install time, making two dynos on the same day can be difficult. What if i redyno the next day?
Just how reliable is the typical dynamometer from one day to the next if sae corrections are made each time?

 

you should probably go when all weather conditions are the same or very similar to the day of your original dyno.

 

any other opinions?

 

matt ... with your luck on the dynos I would be worried about 10 minutes .... your car just doesnt like to show gains. I suggest only using the dyno to make sure your a/f is cool ... just ignore the numbers as long as the car feels faster ...

 

Does it matter? It seems that this way is just to "cheat" the actual horsepower numbers... We all know when you install a mod when you i.e. an intake system you can def feel the changes. But what happens 1 week 2 weeks later? The car feels the same again. What I am trying to say is that it shouldn't matter what your DYNO numbers really say because 2-3 even 4 weeks from now your car will have the horsepower it has and their is no changing that. Am I making sense?

Some people say that the ECU needs to adjust, say you install the intake system. DYNO THE CAR RIGHT AWAY, and get 240whp say in 1 week later you dyno the car again and you lose horsepower, and are now at 235whp. Sure, you can brag and say I got 240whp but reality is that you are now handicapped 5whp and probably don't even know it. So its cool to say that you dyno your car 1 month later that day and see your power and you can proudly say I have xxx HP. But maybe doing back to back runs from just a fresh install maybe inaccurate, unless ecu tuning is involved.

 

to ensure consistency on a roller intertia dyno make sure that they properly center you car before strapping. For consistent results this is a must and lots of people have no idea what im even talkin about.

Park the car on the rollers and just put wheel chocks in. Then you turn off the E-Brake and turn off the dyno brake and spin the rollers with your foot until the car is done centering itself. This is a must with RWD cars otherwise the chances of you strapping thec ar at a slight angle are high and that angle increase tread resistence and reduces HP.

 

interesting; i've never noticed that being done, but maybe i wasn't paying attn.

 

z

 

On the AWD Mustang dyno, they did something similar to let the car align itself. Needless to say, it didn't matter. The d@mn Supra (Greg @ Injected Performance) merely lost traction (centered) and dynoed over 500whp. It was crazy . . . bits of rubber flying everywhere when dynoing *LOL* Hate to see if he actually was able to get a grip