How Gearing Effects HP from 1-3rd in 727's

273 said
Hp at the wheels will be the same.

Torque doesn't move your car it's hp.

Say you make 300 lbs-ft at 2600 rpm which is 149.5 hp.

So say you got a 1st gear of 2.45 and 4.10 in the back with a 24 inch tires (24 inch tire gives you a 1 foot radius so it don't increase or decrease torque to the ground).

So 1st gear with 4.10 at about 18 mph would rev about 2600 rpm and 4.10 in 3rd will rev 2600 rpm at about 45 mph.

Now let's see how much hp at the tire both situation give.

4.10 in 1st give you about 10.05 overall gear ratio. So 10.05 x 300 lbs-ft = 3015 lbs-ft to the tires and 1507.5 lbs-ft to each.
2600 rpm at the engine will be 259 rpm at the wheel so let's put it in the hp formula 259 x 1507.5 = 390572
390572 ÷ 5252 = 74.25 hp per tire or 149.5 hp overall.

4.10 in 3rd will be 4.10 x 300 lbs-ft will give you 1230 lbs-ft to the tires or 615 lbs-ft per tire. And 2600 rpm at the engine will be 635 rpm at the tires. And let calculate the hp at the tires. 635 x 615 = 390572
390572 ÷ 5252 = 74.25 per tire or again 149.5 hp overall.

I will have to research this deeper because it is critical to have realistic numbers. The Dyno says it was an increase of 35% after putting my proto on than before with nothing else changing. I am not sure of the tire size, I need to measure them. I have the gear ratios and know it is a 727 trans. Other than that, I don't see why anything would change if I used the exact same set up in both tests... But I will try to get more answers on my next run sometime hopefully next week and post the data sheet in a pic.

Thanks,
Bob