View Single Post
fredmeister fredmeister is offline
Smart quod bastardus
fredmeister's Avatar
Join Date: Oct 2002
Location: Baltimore, MD, USA
Posts: 2,235
Originally Posted by WinRice View Post
Because gear ratio can increase or decrease output torque by a factor of the gear ratio, not accounting for friction losses.

From Wikipedia:
A gear train can be analyzed using the principle of virtual work to show that its torque ratio, which is the ratio of its output torque to its input torque, is equal to the gear ratio, or speed ratio, of the gear train.

This means that the input torque TA applied to the input gear GA and the output torque TB" on the output gear GB are related by the ratio

where R is the gear ratio of the gear train.
Got it now i feel stupid for overlooking this. I was thinking wheel horsepower and mistakenly thought gear ratio has no effect but you are right sir. So I guess the dyno does a conversion based upon the gear ratio you enter and then converts to RWHP. The of course you can back calculate HP at the crank using a good suitable tranny loss number which most people accept 12-15% for the 911.

1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 06-15-2013, 04:41 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #23 (permalink)