i have a 11 v6. I put in 3:73 gears.
the guy at the dyno place told me that though the gears will give me more launch, they actually cause about a 10hp drop to the rear wheels.
Is this true?

 

I havent done my gears yet, but from what I've read you will lose a bit of HP and torque. 10 HP seems a bit on the high side though.

 

Yes and no. The power read will actually go down because of the torque amplification of your gears. Essentially, it takes less of your engines power to turn that dyno with those gears. If it takes LESS power, the dyno is going to read like your engine is putting out less power.

So in reality, you're not actually losing any power. Your car will just require less of it to do the same job as before.

Think of people using pulleys to move weight. If you lift 200 pounds straight up, and then lift 200 pounds up using a pulley system, have you actually gotten weaker, or has the workload just gotten easier?

Get what I mean?

 

Provided you went from a higher gear (lower numerically) then yes, it will cause a drop. 10 is a little on the high side.

 

What a great analogy...and correct.

 

this is the best explaination that i have come up with to explain the hp loss from smaller gears:

this is how the dyno figures hp/tq
wheel HP = (wheel rpm x wheel tq) / 5252

when changing gears in that equation, the wheel tq and the number 5252 will stay the same, but the wheel rpm will be lower (since you change from for instance 3.55 to 4.10), since you will lose a slight top speed with the gear change.
now since that top speed is slightly less, it will equate to less hp on the dyno.
your engine hp is the same, only the way the dyno figures hp to the wheels will be less.
but your car will go faster.

 

Thanks for the info. It makes me feel better cause the car seems to kick A$$.