Gernby

A roller type dyno is calculating the engine torque by comparing the engine's RPM to the roller's RPM over time as the engine goes through its whole RPM range. Having lower gearing just means that for every rotation of the roller, the engine is going to have to rotate the drivetrain components that much more.

Increasing mechanical advantage will improve acceleration, but the dyno will factor out the mechanical advantage to estimate the torque. In all cases I can think of, increasing mechanical advantage increases loss.

455guy

So if the dyno can tell the difference between 4.44's and 4.10's then why should hp change when you change gears? Once again let my state that when I Dyno car that I work on, there is only about a 2% difference. Once again gears don't make hp.

Gernby

[QUOTE]Originally posted by 455guy
[B]So if the dyno can tell the difference between 4.44's and 4.10's then why should hp change when you

Yellow Streak

I just spoke with Mustang Dynamometer - I called and spoke to their tech department. He told me 2 things:

1. Get the June issue of Chevy High Performance magazine as it explains all about dyno technology and the differences between the various types of dynamometers.

2. He said that all dynos measure HP by looking at the acceleration of the rollers. He said that if the car is able to accelerate the speed of the rollers quicker because of a gear change, the dyno will have a higher HP reading. He said it would likely not be significant, in the area of 1%. He went on to say that if *everything* else is equal, there is no way that taller gears can produce lower HP numbers on a Mustang dyno.

-YS

Gernby

Honestly, I don't know anything about Mustang dynos, but it is easy for you to do your own test. Do a few runs in each gear, and see which gear provides the biggest WHP numbers. Assuming you keep all other things equal, and monitor the coolant temps, I bet you will get the highest HP numbers from 5th gear, since it is closest to a 1:1 ratio, and the lowest from 1st gear.