How does more HP make you go faster?
 

Ok this might be the dumbest question in the whole world but I am a relative noob and theres always something I've been trying to figure out. I would think that more HP your engine outputs makes you able to accelerate faster which I believe just means that your wheels can accelerate faster and you can run through the RPM gauge quicker.


But then again, so wouldn't that mean the more I upgrade my car the faster my RPM's will shoot up when I floor it? Of course I don't mean to spin out, I mean with complete traction and all.


So wouldn't changing the rear gears to something very steep substitute for more hp??


lol,
Brandon

Mostly, Power to weight ratio is the big variable of how fast a car is but gearing, transmission, tires, weight distribution/transfer, and other things also play a part. Power to weight is what your thinking of with the hp thing. More hp doesn't equal quicker revving, more hp equals more hp made through the same rpms as before. Quicker revving is usually from less drivetrain weight or a more free flowing exhaust.

Yes, upgrading to steeper gears helps a lot with the 1/4 as long as the gears you use don't make you go/shift into fifth or close to fifth when racing.

Thanks for the reply. When you said that a more powerful/upgraded car just makes more HP over the same RPM, thats what I am confused about.

Unless the wheels spin at different speeds, I don't see how it makes your car able to go faster?

The other way of making your car faster is to reduce it's weight.. try figuring that one out :D

Figure out a way of removing 500 lbs of weight & the car will accelerate a LOT faster even though it will still have the same horsepower.

Yeah well thats what I don't understand because sometimes when I have passengers in the car and I floor it, I will run through the RPM gauge slower. So I had to think in opposite, a car with more horsepower will just run through the RPM's faster. So wouldn't steep gears substitute for more HP

I thiink what you are looking for is more.....leverage. Steeper gears will get you off the line faster, but you loose that advantage on the top end when, the motor has to scream to turn those gears.

Also, a little torque helps in the pulling dept....more cubes!

Acceleration involves a number of items.

This helps to expalin the key elements.
http://www.howstuffworks.com/horsepower.htm
http://www.asknumbers.com/WhatisTorque.aspx

Mass (Weight)
Torque (the ability to turn something)
HP (The abiilty to do work over time)

Those are very simplified. In a car there are a ton of other things to consider, gearing, drivetrain loss, drag, etc.

Changing the rear differential gears will net you more TQ (torque) not more HP (Horsepower). Pinion gears are what are called TQ multipliers meaning they take the TQ introduced from your driveshaft and multiply it by whatever the gear ratio is. (3.27, 3.73, etc) Again, it's over simplified but you get the point.

Take my info and Mustang Joes, in that order and you begin to see how complex making your car faster can be when you start to pick it apart.

Cool thanks for the replies. I never knew changing the rear gears get you more torque. I thought it does nothing to the numbers.

A good example of how gear ratios affect performance can be found in your garage,, your bicycle :D

Ride around in a very low gear & you can take off from a dead start very quickly, possibly even able to "burn rubber" a little bit. But you have no top speed at all.
Ride around in top gear and the bike is a dog from dead start, but top speed is great.

Cars work pretty much the same way. Swapping in lower gears makes the car a lot "quicker" but you lose top speed so the car is "slower"

Look at it like this. The more you lift weights the stronger you get, the more you can lift. In your final gear, your car will only go as fast as your engine's HP will allow it. More torque will make your car accelerate faster. After you've reached your peak torque, its your HP to weight ratio along with your final drive ratio that determines your speed.

I just made it up, sounds logical though.