do gears actually increase HP?

[Darth Menace]

Hey I read on a write-up on this site how different . Can anyone explain how this works if it does actually increase it? I thought it just gets the rpm's higher in a short time.

 

[2002_red_gts]

Gears are used as a torque multiplier. You don't gain any power you are just using energy that is all ready there and redirecting it to where you want. IE lower gears take top in energy and apply it down low. Your just stealing from peter to feed Paul

 

[Jeffsss]

short sweet answer. no

 

[GTS-R 001]

Higher gears = less dyno horsepower but a faster feeling more torqey feeling car

 

[Allan]

It feels like it.........but it's just an illusion.....

 

[viper k]

it gets you better 1/4 miles times if you don't go crazy!

 

[Jack B]

It feels like it.........but it's just an illusion.....

Please give me an explanation of why it is an illusion, disprove the following:

1 We change from 3.07's to to 3.55's.

2. If you establish a table of rpm versus acceleration for each gear, the torque and hence the acceleration is better for the 3.55's in every cell then it is with the 3.07's.

3. The 3.55's will take you to approx 135 mph (26" tire) in fourth gear at the drag strip, that allows most NA cars to finish the quarter in fourth.

4. If both cars have equal traction, the car with the 3.55's has to be faster in the quarter.

My point is, most cars are gauged for power by their drag strip performance. Maybe I am missing something, I am all ears.

 

[Allan]

Well, the illusion is, that the car accelerates quicker, so the perception is that somehow there's more power, but there isn't more power. The power is the same, right? We're using mechanical advantage of being able to turn the tire easier by changing the gear ratio. So it FEELS like the car is faster, and it is, but with the same power as before the gear swap. Hence the 'illusion'. Remember, Some people call it the "poor man's supercharger".

 

[mattdillon]

I know JonB has always said by the seat of the pants power, its like adding 60-70 extra hp. On some previous threads on here (about this subject), I think some of the guys said it Does NOT improve your time in the quarter mile. To me, it seems like it would have to but thats what some were saying. Maybe some of the guys that know for sure (that have done it) will get back on here & chime in. jmo

 

[BlackSnake99]

So does downshifting my bicycle make my legs stronger?

 

[dave6666]

HP is generated by the engine and the engine only. The transmission and final drive convert the power generated by the engine into something that the car can use; controllable forward motion. That is all they do.

Therefore...

NOTHING YOU DO TO YOUR CAR WITH THE EXCEPTION OF INCREASING THE ENGINE'S OUTPUT CHANGES YOUR HORSEPOWER!

Anything else is basic mechanical understanding fail. Now for those of you that will say I changed my gears and my dyno is different, all you did was change the curve; the relationships of torque and power and how they are consumed and delivered by the drive line.

 

[Dan Cragin]

Changing the gears does increase the applied torque to the wheels, torque gets you down the road. The first Cummings truck Dodge put out made 150hp but 400torque. Lower gears do not help unless you can get traction, so consider a better posi when you do a gear change.

 

[heliguy25]

This thread makes me lol

 

[Darth Menace]

I'm not asking to sound stupid, but i thought somewhere on this site there was a writeup about changing gears and the HP gains. some mathematical thing. I guess i was wrong

 

[dave6666]

I'm not asking to sound stupid, but i thought somewhere on this site there was a writeup about changing gears and the HP gains. some mathematical thing. I guess i was wrong

You do not gain or lose hp by changing gears. You only change how much power is lost in the drive line, and how it is applied at the wheels where most people measure it.

 

[slitherv10]

Not sure about the technical aspects of gear changing but, I do know the guys at the track must be doing something right or know something about racing and A To B times as it seems to me they all have higher gears in thier 1/4 miles cars. I have never personaly seen a quarter mile car with 283 gears in the back. 373,410,411 and obviuosly higher. Must be some truth to that no?....Chime in guys and respond or add to this. Liek I said I am not an expert but, I do see that in most drag cars. I would say that would differ on track cars. But there, you need HP moer than torque right. So I think like DC said earlier post that you do get the torque working for you in the higher gears which is what gets you to the other side faster.

 

[heliguy25]

Not sure about the technical aspects of gear changing but, I do know the guys at the track must be doing something right or know something about racing and A To B times as it seems to me they all have higher gears in thier 1/4 miles cars. I have never personaly seen a quarter mile car with 283 gears in the back. 373,410,411 and obviuosly higher. Must be some truth to that no?....Chime in guys and respond or add to this. Liek I said I am not an expert but, I do see that in most drag cars. I would say that would differ on track cars. But there, you need HP moer than torque right. So I think like DC said earlier post that you do get the torque working for you in the higher gears which is what gets you to the other side faster.

torque and hp are relative to each other as they both use similar inputs to figure them out mathematically. Just shortens the power band due to changing the gear ratios.

 

[dave6666]

If you change gears - and gears only - and improve your lap time or 1/4 mile times, what you have done is to better map the physics of the car and it's surroundings (like the track surface etc.) to the intended use and desired result. Your horespower is still the same. Given a final drive gear ratio change, there could be slight variations in the hp measured by a dyno as the measurement concept used by the dyno may interpret the faster drum acceleration as power, but these would be relatively slight in comparison to something like heads / cam / blower and so on.

All you are doing when you change gears is moving the curve of desired utilization closer to what you are wanting results wise. It feels like horsepower and gets called horsepower when you do gear changes, but it is not an increase in power.

 

[GTS-R 001]

I think what happens on a Dyno is that by running the higher gearing your peak Torque number is registered at a lower RPM than it would have been and then when you run the calculator to determine HP since you are using a lower # the HP number ends up being lower. All teh grpahs I have seen where someone changes to higher gears and then re-dynos, they dyno less, not by much but less, even though teh car is faster and feels more powerfull

 

[Allan]

I think that a supercharger, turbo, nos, pcm tuning, cam, head work, exhaust/intake upgrades, are things that will actually increase HP.......nuff said......

 

[dave6666]

I think that a supercharger, turbo, nos, pcm tuning, cam, head work, exhaust/intake upgrades, are things that will actually increase HP.......nuff said......

Because those things... attach to the engine where the power is made.

Nuff said + more. Sorry.

 

[Mopar Boy]

The first Cummings truck Dodge put out made 150hp but 400torque. .

Your killin me here! The first gens had a hard enough time looking powerful on the HP scale!

160hp.....




Carry on.