What's the Differance?

[prariepunk]

Hi..... again, I was wondering, is the differance between Horsepower and HP @ rear wheels dependant on gears? Does High # gears=more HP @ rear wheels?

[dingus]

you can measure HP either at the wheels or at the crank... what really matters is what you put down at the wheels but if you're tuning your engine taking a reading from the crank is a better idea.

the lower your gear ratios the more torque you'll be able to put down at the wheels, like a 4.10 gear is a lower gear ratio than 3.07.

[Bounty__Hunter]

I always thought rear-wheel HP takes into account the parasitic drag of the tranny, transfer case, and differentials, regardless of the gear ratio in any of them.

	Transfer Case Mounted behind and driven by the vehicle transmission, the transfer case transmits power to the front and rear driveshafts in 4WD Jeep vehicles and offers high and low range.

[TwistedCopper]

I always understood it that rear wheel horsepower is measured at the wheels instead of the crankshaft... that's all. That being the case then gearing, parasitic drag of all the drivetrain components, and even tire size/weight are all a factor. If you changed the gears, tire size, tranny, whatever you'll get different results because it is a true end result at the wheels.

Saying how much horsepower an engine has is a result from measuring it at the crank. Saying how much horsepower your Jeep has is a result of measuring it at the wheels.

[shevyluv69]

Horse power is a callculated figure based apon tourqe curve and lots of other varieables.

I always thought rear-wheel HP takes into account the parasitic drag of the tranny, transfer case, and differentials, regardless of the gear ratio in any of them.

I also belive this to be true so at flywheel will always be more than at wheel. Just my 2 cents

[Snitty]

Horsepower should be nearly consistant with a change in gears. Horsepower is a measure of torque over time. A higher gear (lower numeric) will give you lower torque, but will apply that torque over many more revolutions. A lower gear (higher numeric) will give you higher torque, but it will be applied over less revolutions. It should about even out, give or take for mechanical drag

[88Wrangles]

Ya, Snitty is right. It should always be about the same...no matter what your gear ratios are.

The gear ratios will change how exactly that torque is used, but it will always be the same torque #'s no matter what gears you have.