I'm not much of a mechanic and I have always wondered what exactly is the differance between horsepower and torque ?
What benefits do horsepower give you ?
What benefits does torque give you ?
I hear people talk about when you are out of the torque band and into the horsepower band, what does that mean ?

In what ways can you change the torque or horsepower that a gasoline engine puts out ?

Thanks for any input

 

Torque is the amount of work that can be done, and horsepower is how quickly work can be done. Think of a 6-cylinder diesel dumptruck. It takes forever for one to get up to 60-mph, but it can perform a lot of work (such as 15-tons of gravel). Now, think of an Indy race car. Lots of horsepower and very little torque -- it can get up to 60-mph or even faster, in a quicker amount of time but can't handle much of a load.

For a gas engine, torque management is performed via the cam, rods, and the transmission. With the newer computer controlled transmissions, up to 20 ft/lbs of torque can be unlocked by simple reprogramming, because EVERY SINGLE VEHICLE off of the assembly line is built for the *average* driver, not for a specific task. Now, get into beefing up the transmission with a heavy duty torque converter, and your gasser can haul more. Then, you need to look into the next section -- THE BRAKES!

 

horsepower is a derivitave of torque. The only two ways to increase horsepower is to either increase rpms, or increase torque, or both. The longer the stroke of your crank the more torque you'll produce, the smaller your crank the less torque your'll produce but the more rpms you have the more horsepower you have. Rods have nothing to do with horsepower or torque. Also the higher your valve duration is the more horsepower you'll have but the less torque you'll have. the less duration you ave on your cam the more torque you have, but the less horsepower you'll have, less rpms. This is were variable valve timing comes into play like vtech.
horsepower is the ability to move so many pounds so far in one second...i forget the exact numbers....

 

If you run a longer or shorter stroke (rods), then yes, they can affect torque vs. horsepower.

 

Im still a little confused, I have owned 3 cummins diesels they have great pulling power in the low rpms say 1500 - 2000. I am using a V10 now and it doesn't have much power untill you get to 2500 - 3000 rpm. In that range it has more pulling power than the cummins diesels.
I think the torque in the cummins are rated alot higher but the horsepower in the V10 is rated higher. Why and how is that possible?
I was considering putting some 1.7 rocker arms on the V10 after reading your post I assume that will lower the torque and raise horsepower ? I use my truck exclusively for pulling what effect would that modification have on it ?
Also I have a manual transmission so I assume the post about changing the torque converter via computer controls doesn't apply to a manual .

 

you already have 1.7 rocker arms in the V10

 

I think stock ison the V10 is 1.6?

 

I'm pretty sure it's 1.7, there wsa debate about this a while ago when some guys were talking about using dodge viper rockers as a cheap upgrade. the geometry from the viper to ram conversion isn't quite right, but in the process I think a few V10 owners discovered the stock rockers were 1.7's

If you do a search for viper rockers on the 2nd gen forum I'm sure you'll find it. Could save you the money of buying 20 rocker arms for your engine. On the flip side, you'll see an improvement in going with roller rockers over the stock rocker arms

 

actually horsepower doesnt exist. Horsepower is a mathamatical equasion using the physical mesuruement of power that a motor produces, that physical mesurement is torque ( torque*rpm (rpm that that particular torque number is found)/5252=hp) This is why diesels make very low hp, because even though they make twice the torque of the gas motor (for arguments sake) it makes it at less than half of the rpm, so the math works out to less hp. As far as what it really means in life, Torque is what you feel. Torque is the fun, its the seat of the pants. Now just because hp doesnt actually exist doesnt mean its worthless. Obviously theres a mathamatical equasion for a reason. The hp is every bit as real as torque is (atleast in racing terms). Torque gets you going, and Hp keeps you moving. Basicly its because of where the torque is located relitive to the rpms that your spinning. Now, my truck is worthless in the high rpms, because even though it makes most of its horsepower by 4800 it makes all of its torque by about 3500 or so. Having low end torque helps for starting off (if you dont spin) but it makes for a dog up top. Mid range power gives you a decent compromise, and high end power gives you a crappy low end usuially. Theres always exceptions or ways to tweek it, but the best ways to change top end power is the flow characteristics of the motor. shorter intake runners, a "hotter" cam, longtube headers and a free flowing exhaust, along with modificiation to allow you to rev the motor higher is basicly what you want if your talking straight line. If you want a beefey daily driver just throw on all the bolt ons and get a smile on your face.

the basic reason why diesels are awesome for towing is BECAUSE their torque is down low, your making a majority if not all of your torque arround 1000-1500 rpm, which makes the power 100% useable for towing, because when your towing your turning the motor at right about that rpm, especially from a stop. Now in a gas motor that makesan equal ammount oftorque at say at 3500, youd have to be spinning the motor to 3500 to be able to take advantage of that, but below your torque band (where the motor starts/stops to make signifigant power) your not going to be able to pull jack. Which is why when guys chain up the diesel almost always wins, because to be able to out pull the diesel the guy with the gas motor has to be spinning his motor faster, and the motor wont spin faster unless the wheels spin faster, but the wheels arent going anywhere, so they burnout, and the day is lost.

or manual runner controls like the IMRC setups on gen 1 4v 4.6 ford motors(92-98) which shuts off half the flow of the valves essentially making it a 2 valve motor for part of the rpm range (almost the same idea as vtec but less sophisticated)

 

rods do not affect stroke. The only thing that affects stroke is your crank. Rods affect piston to rod angularity and compression ratio. You can have a 4.5 inch stroke crank and run a 3 inchrod or a 3.5 inch rod and you'll still only have 4.5 inches of stroke. Rods do not affect stroke or cubic inches

sorry had to fix my post