CoedNaked

I've heard/seen several arguments on here about torque versus horsepower.
And there are lots of theories and even scientific points of view that try to explain what horsepower and torque is, but I offer you what I think is the laypersons point of view with regard to horsepower and torque and apply it to the 3vze 3.0 V6.

This engine has very good torque down low as per dyno graphs I have seen and it kind of dies up top at it's horsepower peak which probably is related to relatively small stock exhaust pipes (but an 1/8" to a 1/4" I'd say, or at least add mandrel bending to the stock size to help flow). Many feel the 3vze stock is best between 3000 - 4000 RPM's. Many feel that is when the 3vze starts to really pull and I feel the same way. But it's not because that's when the 3vze gets it's torque. It's because that is where the 3vze gets it's horsepower (or at least more of it, with the most torque present). Torque is something you can't really feel. What torque is to me is the apparent "twisting" action of the driveshaft, crankshaft, & gears in turning the rear wheels. But Horsepower is how the engine uses it's torque. That is why if you've ever driven a naturally aspirated diesel engine, you will notice it doesn't accelerate worth a crap - say one with like 130-150 HP and say 250-300 foot pounds of torque - but when you load 'er up and tow with it, it doesn't bog down at all, or as much, as say a gas engine would. I think I can honestly say the same (to a similar but lesser degree) for the 3vze. While it doesn't accelerate like a sports car, I've noticed it takes a lot to really bog the engine down to the point it looses speed because it has torque. Torque being the twisting action - and this twisting action resisting the mass it pushes. As you climb in the RPM's, you pick up horsepower which starts to work with this torque and make the truck pull/accelerate better.

My opinion of course.

InternetRoadkill

Horsepower is the rate at which the engine produces torque.

Chrisnxl185

thats makes sense to me. This is why i can cruise in 5th gear at 30 miles per hour.

tc

HP essentially equals torque * RPM. Note that power is energy and is conserved. That is why if you reduce the RPM with gearing the torque increases.

Here's an article that explains it better than I ever could
http://www.vettenet.org/torquehp.html

elripster

In metric units, power (watts) equals torque (Nm) * revs/second. It's a little less straight forward in English units but all you need to remember is that it's not torque Vs. RPM, as much as it is torque times RPM to get power, or the rate and engine converts energy from chemical to kinematic or energy of motion.

You'll find, it's typically easier to tune and engine to rev higher to get more power than it is to increase the torque. If you tune it to rev and gear lower, you will get a faster vehicle.

Torque, however, is exactly what you feel when you are driving. You can feel acceleration but not velocity. Sure the engine's power output is going up as its rpms increase but it's the torque you are feeling accelerate the truck.

Frank

bwhyit

HP is merely a calculation. Torque x RPM / 5252. You'll notice on any dyno output the torque and HP curve always cross at 5252 RPM.

elripster

Here is a great site. You can calculate horsepower in a number of different ways.

http://www.ajdesigner.com/phphorsepo...horsepower.php

Frank

Targetnut

actually it is torque that you feel. horsepower is the measure of work that the torque is doing.

generally speaking torque gives you acceleration and horsepower gives you speed.

stormin94

Coed Naked was right with his first post: There are endless explanations for the relationship of horsepower and torque. I've heard from several muscle car mechanics that your engine is essentially an air pump. the more air you can get through it, the more horsepower you are gonna get. So in other words, horsepower is affected more by airflow. They also say that torque is affected most by compression ratio, and displacement. This may not apply to newer cars though.

But when this method is applied to a Honda S2000 2.2 liter 4 cylender, the engine makes 240 horsepower@ around 7,200RPM, and around 170ft-lb of torque. Compression ratio is around 10.5:1 or so. Smaller motor, higher compression, High HP( for the size) and decent torque(for a 2.2 liter gas motor). The rotary engine makes 235 Horsepower, and somewhere near 140-150 torque. Lower compression of a rotary(around 8.5:1 compression ratio)

Where as a larger displacement 5.7 liter chevy V8 makes around 340 horsepower, and around 360 torque. I'm not sure of exact numbers for current models, though. I believe compression is around 9.0:1 or so. So the bigger motor is gonna pump more air through(obviously, it's holes are bigger, and there are more of them, so it's gonna pump more) and it is a larger displacement, so it makes more torque.

I've noticed that for the most part, with a fairly average compression ratio (we'll say 9.0:1 for now) and running off of unleaded gasoline, there seems to be a point to where as the displacement increases, the torque gradually becomes more than the horsepower rating does. For example, the Honda S2000 has 240HP, and 170lb-ft of torque @2.2 liters, the Toyota 4.0 liter v6( as found in the newer tacomas) has around 240 horsepower, and 270torque. I think the displacement where HP generally tends to match torque the closest is between 2.9 liters and 3.2 liters. This of course is based on the completely unlikely scenario that the engines all have the same compression ratio, the same intake valves as the others, the same exhaust size as the others, and the same fuel as every others.

This has probably not been tested yet but it would be interesting to see the results if it ever did. I hope this didn't confuse anyone, becaue I'm gonna have to try really hard to explain this if I lost someone along the way.

nate V

Sounds good to me
excellent explanation you have here makes perfect sense to me.
awesome thread

davenjai

TQ is for weight HP for speed. Best example I know of is motorcycle engines. In line 4 cyl develop a lot of HP and no TQ. Generally twice the HP as TQ. vtwin 2 cyl motors produce more equal levels of both. The fast bikes are light and high HP. The touring style are heavier, carry more gear and have bigger engines with more TQ. Pick the right tool for the job comes to mind. I would want HP for mud/sand and TQ for crawling/rocks.

FredTJ

As with anything regarding TQ and HP, they are directly related, absolutely, 100%. The formula has already been posted. Dyno's don't even measure HP. They measure torque and the HP is computed (using the already given formula).
You can't increase torque without increasing HP.
Those "smaller" bikes with the 4cyls, like the 600cc's produce all of their HP simply through RPM's.
Those engines really don't produce much power at all, but "work" because of their revs. Most of those 600's run around 12K RPM's.




Fred

Targetnut

Torque is the force that the engine creates. Horsepower is the calculated work that the torque can do.

faubrunner64

put some bigger tires on without re-gearing and that will change drasticaly. even with only 32's on i felt a change. ive never felt that way about my 3.0 i sure wish it was tho

toy power

torque represents the amount of work an engine can do. horsepower represents the speed at which it is able to complete the said amount of work.

tc

Everyone please read this again.

An interesting point is that if the wheel doesn't move, you can apply 1,000,000 ft-lb of torque, and still have 0 Horsepower.

Belize Off Road Team

i couldn't agree more! since i have removed the Cat. and muffler and for the most part, straightend out my exhaust, i have more power at lower RPM's and it takes hills and heavy loads ALOT better than with the previous stock size pipes. i have even IMPROVED my MPGs from 400kms(to one tank in the city) to 480kms(to one tank in the city). for example, i loaded my Surf with 30 boxes of 2'x2' floor tiles(not the light ones either!!) and with my PP 1" lift progressive coils the back end was sagging like that of a 90 years olds behind. hit one of the speed bumps and i would hit my rear bumpstops. BUT the engine drove like it was empty! a little trouble on hills, but it's only a 3.0L 6cyl, not a 4.7L 8cyl. i now feel my 3VZ-E has more power between 1500-4000RPM with my new exhaust. but you can't stop me on hills, not even slow me down(unless with a load)! but i suppose it helps to have a engine that is running like NEW and a unrestricted exhaust system right? i'm still to take my numbers to a track against another vehicle, but i really damn confindent it will show MAJOR improvments!

and any way, if i can FEEL a big difference in power, it must be signifigant(maybe getting close to the 150hp at the wheels)

Dirt Driver

This isn't related to displacement; it is dictated by the engine design and what rpm the torque and power peaks occur at.

For example, a stock '87-93 Ford 5.0 high output came with 225bhp and 300lb-ft. Peak power came in around 4800rpm. Build that same engine to make 450bhp at 6500 rpm and the power will be higher than torque with no change in displacement.

yotasavg

this is an excellent thread.

FredTJ

You really need to pay more for your rope.....

There is no way in hell that you got a 20% INCREASE in fuel mileage and a ton more power by simply removing the cat (which provides almost no restriction at all) and straightening out the exhaust.
If you did then something else was really pooched, such as a totally blocked cat, major crimped (bent) exhaust pipe or whatever.



Fred