I know that horsepower isn't the only thing needed and that torque is what gets your vehicle of the line. Right? So does this mean more torque is better acceleration? As in... going down the road and you punch it, the more torque you have the faster you accelerate? or not?


someone just explain it for me..

 

Well look at a diesel, they have monstrous amounts of torque, but up until a few years ago, they didn't have very much top end. So they weren't very fast, but thats not what they are made for. Torque gets you going, horsepower keeps you going. They are both equally important. It is also important as to when the torque curve starts (lower is better for trucks) and how long it lasts, also, how flat it is helps too...

 

ok. made some sense. i mean, i understand the curves and how they work too...but im looking at something... 95 f150 with the i6. and its got torque out the pooper, but not lots of hp. so i guess maybe i should just ask how great those are....

 

so D. ever messed with an old I6?

 

The 4.9 liter is a great motor, most say bullet proof. No top end on it, but my buddy has put his thru hell and back, and she still runs like a champ @ 200,000.

 

It's the longer stroke that gives more torque, due to increased M.A. of the crank throw.

For reference:

http://www.circletrack.com/techartic...ogy/index.html

 

im getting the 95 f150 itch...... must resist. stick to 5.0 swap in the ranger....

 

I'm having convulsions over peoples lack of understanding about "horsepower" & "torque". ak ak ak...

What horsepower means is this: In Watt's judgement, one horse can do 33,000 foot-pounds of work every minute. So, imagine a horse raising coal out of a coal mine as shown above. A horse exerting 1 horsepower can raise 330 pounds of coal 100 feet in a minute, or 33 pounds of coal 1,000 feet in one minute, or 1,000 pounds 33 feet in one minute. You can make up whatever combination of feet and pounds you like. As long as the product is 33,000 foot-pounds in one minute, you have a horsepower.

There is only torque. Period. End of discussion. And no matter what a fellers understanding of "HP" might be. There is no such thing as horsepower in a "car".

When it comes to accelerating a car you have pretty much 3 variables that effect a cars ability to accelerate.

1) Torque curve & gearing. (engine twist, tranny ratios, rear end ratio, and tire diameter)

2) Weight (power to weight ratio)

3) Traction (the ability to maximize the torque produced)


People only confuse themselves when you try to throw "HP" into it.
The term "horsepower" is simply a "cow path".
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Illustration:
Many years ago when cows ranged freely a cow walked a daily circut looking for food. This "path" got beaten down and became a routine. People moved into the area and found that path easiest to travel. As time goes on they developed this path and it became a street. Then in modern times you have a city with winding roads that don't make much sense as to why they go where they go. It's all because a long since passed away cow made a path in a field! Yet everyday thousands of people travel this "cow path" and never take the time to question why. Some will even defend the path/street as making sence because that's the path thier father took. Thier grandfather, ect...
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Now.. that's a lame analogy to make my point. Horsepower is not a real thing. It's a "perception" that our forefathers came up with to help people at the time comprend the work a engine could do. You can't measure it. And actually it only complicates an already complex subject for folks that don't understand what torque is.

Accelerating a car from 0mph as quickly as is possible comes down to the torque curve of the motor -vs- the gear ratio (tire,tranny,diff) -vs- the traction available -vs- the power to weight ratio.

Rich

 

So is that where the term "off the beaten path" came from? LOL...

 

That's a whole study in of itself! Who knows.. maybe?

 

Rich, you contradicted yourself twice! based on what you are thinking, there is no such thing as power to weight ratio, it should be torque to weight ratio!!

 

From you own link!

"What is Torque?

We’ve been through this before, but to refresh your memory, torque is the result of a force being applied on an object at some distance from its axis of rotation. If we allow torque to act during a period of time, we observe horsepower. Crankshafts make torque. Cylinder pressure causes torque to be made. In the case of engines, for the most part, how much torque is made depends upon cylinder pressure and the distance from crankshaft axis of rotation to the point of applied force—cylinder pressure acting on a piston/rod assembly. Crankshaft “stroke” plays a part in this factor. In other words, the longer the stroke, the greater the distance from the axis of crank rotation, and the more the torque produced. Long-stroke engines make more torque at lower rpm than shorter stroke ones, right?"

I'd make only one correction to this text. You can't observe horsepower. Rather you can calculate it.

So called "horsepower" has becomed so in-grained in the gear heads way of thinking that it makes guys like me shake my head and smile.

Rich

 

"Power" is indeed a relative term. That one I'll give you. It too is a calulated "thing".

Smarty pants..

 

the reason a diesel deosnt seem fast even though it makes 800ft lbs is because it only revs to 3k rpms, the torque curve is very short, and more often then not diesel's are heavy . BUT if you used a CVT trans ( which is a transmission that doesnt shift, rather it Constantly Varies the gear ratios hense "CVT") to keep it right at peak torque you would find that that slow powerfull stump pulling Diesel now is much faster..

this is the same reason why a flat broad torque curve is so desireable. if you make 400ftlbs from 2k rpms to 6k rpms that is going to pull nonstop and accelorate much faster then a car with 500ftlbs from 5krpms to 6500 rpms but only 250-300ftlbs everywhere eles

JOSH