I have heard people say that changing your gear ratio will have no affect on dyno torque ratings?

How can this be?

I can see that gear ratio's have no affect on HP and TQ ratings at the flywheel. Obviously

And I can see that gear ratio's would have no affect of Rear wheel HP.

But how is it possible that lower gears do not give me more torque at the tires on the pavement?

It seems to me that it does.

Or maybe I have just misunderstood some that said that it dosen't give more torque at the wheels.

Just wanted to get your attention Thump cause I seem to remember you in the conversation a while back.....several months ago at least...

 

The only thing it changes is TQ versus road speed. Think about it. The lower the ratio (higher the number) with the same tire size the lower the speed the torque curve is at in each gear.

A torque curve is constant. You have a certain TQ value at any given engine RPM. The only way to change a torque curve is with tuning or mods such as intake, exhaust, cams, efans, underdrive pulleys, etc. I suppose you can change the TQ value at the rear wheels with tranny mods.

 

so your telling me that i wont pick up any acceleration or tq when i put 4.88 gears in my truck and reprogram my computer with my superchips to the new gears and tires

 

I'm not sure what your saying. Also keep in mind that I have never gotten anything dyno'ed so I'm a bit clueless about that.

As I understand, when a vehicle gets' dyno tested.....Calculations are made for drivetrain loss, etc, so that the dyno sheet is supposed to represent the HP and TQ numbers that the motor creates at the flywheel. Is this correct?

But if I have a 1 HP motor geared really high....won't I have very low torque at the wheel vs. a 1HP motor geared really low....won't it have higher torque at the wheel?

If you try to hold a 10 speed tire still while I pedal in 10th gear you may be able to hold it.

But if I have it in 1st gear you won't be able to because I will be able to put more torque on the tire.

The same should apply if I re-gear a axle. All of a sudden 1st gear is much lower than 1st gear used to be so I should be able to gain more torque with the same motor.

 

Let's work on the spelling first, then we will move on to Physics.

 

I've been waiting for that. I just figured it would be from a different new moderator.

My brain can comprehend physics better than spelling.:o

Well I think it does......untill someone completly shoots me down on my above logic..

 

you get more torque per "bite" from your tire. your engine isn't producing more torque.

make sense ?

Same amount of torque, being used over a smaller distance. The bite is harder and more forceful, but your truck is making the same amount of it.

 

I typed fast so I could beat him!

 

You will get more torque from the avialable HP, but the curve will remain the same.

 

No I know the engine dosen't change at all.

But sometimes don't manufactuers talk about HP and TQ at the pavement?

An vehicle can produce 300 hp at the flywheel and only have 230 or whatever on the ground due to drivetrain loss. Just like an engine can produce 300 Foot LBS of torque at the flywheel and only put 230 on the ground. Lets say this vehicle has 3:73 gears

Can it be assumed that re-gearing from 3:73's to 4:88's could make the vehicle still produce 300 foot lbs at the flywheel but now produce 280 ft lbs(made up number) on the ground?

 

.i edited my response it didnt make sense lmao

 

Ok that's what I was getting at..........thank you......

 

I know what u mean but I think this is the kind of statement that made me start this thread.

The truck is producing more torque. But the motor isn't.

 

You got it bud. That last staement says it all. your truck's motor is not producing more torque. Same amount. When it gets to your dif, it is now being multiplied by a different number, (high number) allowing more of it (torque), which translate to more torque hitting the pavement. Your tires have more "bite" with the gearing.

Take a Samurai for instance. Something like 50 ft lbs of torque (stock at the motor). yet through all the gearing we do to them, they can break your neck, and pull tractors around in the field. With out gearing, you can BARELY move it on 33" tires. Granted, we can now only go about 25 mph MAX, but you don't need any more speed then that !

 

hey MT, how big of gears can you stuff in those sami's