HP vs TQ

HP is only an equation based of a torque at a specific RPM.

(Tq x RPM) / 5250 = HP

I would rather have both as one is based off the other .

What he said ^

A 302 is a 302 and typically will make a maximum of 350 - 375 ft-lb of torque N/A using pump gas, using the best of parts (H/C/I). As said before, HP is a function of torque and engine speed (RPM), so the higher you can make this torque in the engine speed range, the more HP you'll produce. So really, build an engine that has good breathing qualities so it can spin right up to 6500-7500 RPM without choking and you'll make good power. A good example is an Indy car engine, which makes 700 HP, but they spin at 10300 RPM, so really their little 3.5L V-8 is only making 356.8 ft-lb at that engine speed (assuming peak HP comes at 10300 PRM), a torque that a well built 302 can make easily.

That being said, there are several ways you can make more torque (assuming you've reached the limits of H/C/I): power adders (blower/turbo/nitrous) or bumping up the compression ratio. Aside from these, torque is really displacement-reliant, so if you want more of it, you could always go the stroker or 351ci -up (460ci *laughs deviously* > ) engine swap.

Everyone that's posted so far is correct.

HP and TQ are related by the equation posted by 25th.

Ever wonder why on every dyno chart the HP and TQ lines ALWAYS meet at 5250 RPM? It because of that equation. 5250 is a constant that converts TQ (lb-ft) X RPM (Rev/Min) to HP.

Suppose your engine makes 300 lb-ft of TQ at 3500 RPM. Using the HP equation, that is 200 HP at 3500 RPM. Now the same engine is still reving higher, the torque will peak and start to fall off again. So, say at 5500 RPM, the TQ is also 300 lb-ft. This would make 314 HP at 5500 RPM.

Torque is twisting force. HP is the speed at which the twisting force is produced. In the example above, twisting force is the same at both 3500 and 5500 RPM, but HP output is higher due the same twisting force being achieved at a faster engine speed. See the difference.

Instead of asking: Do I want TQ or HP? A better question is where do I want my TQ? At lower RPM's or higher in the engine range.

It's kinda hard in a 302 but ALWAYS build a motor for torque, and HP will follow.

Simple definition:

Torque is what gets you off the starting line as quickly as traction permits.
HP is what increases your speed as you go down the track.

Gearing can multiply torque at the cost of increased RPM's and decreased top speed.

For racing, I would be looking at the highest average horsepower in my shifting range.

jrichker said:

Simple definition:

Torque is what gets you off the starting line as quickly as traction permits.
HP is what increases your speed as you go down the track.

Gearing can multiply torque at the cost of increased RPM's and decreased top speed.

Click to expand...

Ahhhh, your reply is debatable. Torque is for much more then off the line power.
When your doing 65mph on a highway and wanna pass someone, the speed at which you pass him will depend upon how much torque you have.

Great help here guys (except GTO, ) as I always wonderd why dyno charts always crossed at 5250

When I sold cars my sales manager always said torque is what people drive and HP is what they buy, stupid but made sense

5spd GT said:

For racing, I would be looking at the highest average horsepower in my shifting range.

Click to expand...

Why I shift my stock cam car at 5500...

25thmustang said:

Why I shift my stock cam car at 5500...

Click to expand...

...and your point is?

I have always liked the thought of torque gets you moving, and horsepower keeps you moving and accelerating.

The curve between torque and horsepower overlap

GTOReturns - Look at the RPM that they are passing the car at.

Launch at 2k, cruise at 2k, pass at 2k.

Without horsepower, diesel trucks would win races and without torque, jet-powered cars would win all the races

The broadest torque curve (which is proportional to HP) is what should be looked at.

It really is all in how you define it. This is why this topic is so popular...

5spd GT said:

...and your point is?

I have always liked the thought of torque gets you moving, and horsepower keeps you moving and accelerating.

The curve between torque and horsepower overlap

GTOReturns - Look at the RPM that they are passing the car at.

Launch at 2k, cruise at 2k, pass at 2k.

Without horsepower, diesel trucks would win races and without torque, jet-powered cars would win all the races

The broadest torque curve (which is proportional to HP) is what should be looked at.

It really is all in how you define it. This is why this topic is so popular...

Click to expand...

No sht sherlock. They go hand in hand. The original question was in not so many words, which do you like better. More torque then HP is usually a good thing!

Gotcha Brian

I am getting out of here before this turns into a flame fest. I don't feel like it right now

HP is how much work can be done at a certain engine rpm.

say you have an engine that makes 500 HP at 5000rpm. if you were to hold this engine at 5000 rpm for 1 minute, and could measure it, the engine would do 500 HP worth of work.

torque is the actual twisting force an engine produces. its what you feel when you take off, when you get on it and the car pushes you into the seat, this is torque

more torque doesnt have to turn as fast to make a given HP number. on the other side of that, a smaller engine producing less torque, will have to turn faster to achieve the same HP.

for example, take a diesel engine, their engines make LOTS of torque. but why arent they fast if torque is so important. due to the MASS and weight of their rotating assemblies. they are limited to RPM, most diesel engines dont rev past 3000 rpm. so their HP number is lower. but in their operating range, they can pull anything. they are just so heavy etc etc they arent going to perform at the drag strip.

if you were to make a diesel engine capable of revving up really high, they would make AWESOME horsepower. and there are some. some of the racing diesels like the gale banks stuff. they are working their diesels and are revving them in upwards of 6500 RPM. now they are making SERIOUS horsepower. they are making gobs of torque and turning it fast to get alot of work done (horsepower)

on the other side. take a little f1 race car, they have little 3.0L v10 or at least some of them do. super tiny engines. they make a lower torque figure. at stated above a simple street 5.0 can make the same torque figure an f1 race car can, but why does the f1 car move so FAST. well since their rotating assemblies are so small and LIGHT they can rev the piss out of the engine. some of them rev up to 20,000 RPM!!!! this is how their get their horsepower figure, just turning the engine FASTER to get more work done.

torque is what you feel. a simple way to look at it, if you have more torque, you can make a given HP number at a lower RPM. the less torque you have, your going to have rev the engine up higher to get the HP number.

another simple scenario, in a perfect world... take an engine that makes 100ft lbs of torque and 100 HP @ 5000 rpm

now take an engine that makes 50 ftlbs ( half the torque of the above engine)
and this engine ALSO makes 100 HP, what is different about this engine.

its TURNING FASTER, how much, in theory its turning twice the RPM so 10000 rpm
its making half the torque, so it needs to turn twice as fast to do the same amount of work (HP) as the other engine.

HP is DIRECTLY proportional to how fast a car can go. your mph trap speed in the 1/4 mile is a good indicator of horsepower

given a long enough road, the engine with MORE HP will always win a race/cover more ground in an alotted time, assuming the cars/weight are identical.

but people always say torque is king, it does make a difference on the street, stoplight to stoplight racing. take identical cars. the once with more torque can easily win a short race with an identical car making less torque but more HP, the engine with more torque just has enough twisting force to get out of the hole faster. the lower torque engine wont have the physical twisting force to get moving quite as fast but once its starts revving up and make more HP than the other engine it will catch up.

take the same race where the torquey engine pulls away from a stop light. extend this race to a LONG road, if the other engine, regardless of torque figure...( in this case less) is making more HP the car will eventually pull ahead of the other car.

so in theory we want as much torque as possible. and the ability to keep the torque there all the time and turn the engine very fast. so we want as much torque producing as much horsepower as possibly. but were very limited with engine size and the physical limits of metal and other parts. we cant just turn an engine an infinite rpm

this is how i understand it. but i'm no expert so anyone with more info etc can chime in