Spy RSX-S said:
i know that changing the gearing and wheel size would created higher or lower numbers on the dyno for TQ but would they affect the HP numbers at all?
HP = (TQ*RPM)/5252
Originally posted by compdoc777
Only thing that will effect HP/TQ numbers on the dyno is the wheel weight rotational mass. Bigger heavier wheels will slow it down and lighter will speed it up. Changing the gear ratio will only effect how long you can stay in gear but not power.
Tire diameter will certainly affect numbers if it's not calculated for. If you use a smaller diameter tire, it raises your gearing & you put more torque to the ground. If the dyno doesn't know this & assumes a stock tire size, the numbers will be off.
Dyno software allows you to input the tire diameter you're using (unless it's something like a dynapack which measures directly from the hub). So it's a matter of making sure the technician inputs the correct tire diameter & doesn't just use the stock settings.