Thread: Torque curve ?

This is apparantly the old Torque vs Power arguement that plently of people have. I was curious so I was reading this:
http://vettenet.org/torquehp.html

which explains the matter reasonably well, using drag racing as an example.

yeah Ok I like that except for the "it is better to make torque at high RPM than low RPM"


Pfhaffple.


If your engine is not making torque down low you cant use it period.

heres an example.....

MY 1968 petrol IIa rover (kermit) lets say 60 hp max has won a tug of war against a 300+hp WRX driven by a wog. How and why?

Simple its all about the torque curve.

the 2.25 rover engine is a long stroke engine the longer the stroke the bigger the swing of the crank the bigger the swing of the crank the more torque you make. (but you loose out on high speed stuff as your engine will shake itself to pieces) The WRX engine is a short stroke engine that needs to be doing about 3000 Rpm to be making peak torque. At lower RPMs for a variety of reasons its got nuthin.

so when MR (best xmas caroling voice here singing 12 days of xmas)I have a 300 HP engine, brass button clutch, 5 speed gearbox, all wheel drive, great big ego and a partridge in a pear tree was trying to get a launch with an additional 1.7t of landrover holding him back He couldnt get to 3000 Rpm without spinning the wheels and as we know with the wheels spinning you have no grip so no drive. similarly when he tried a gentler launch he had sooo much grip and such a heavy clutch that since he wasnt making enough power he stalled.

However, Kermit with his long throw crank, heavy clutch 4wd and low down torque could get moving simpley because of the fact that all the torque was down low, closer to 0 rpm which is what speed the wheels and gears are doing when you're stopped.

EDIT

which reminds me....

If high rpm toeque is so damn good why is it that mos trucks dont have engines that do 10000000000000000000000000 rpm but nearer to a paltry 2400 rpm tops and in most cases peak power is over and done with by 14-1800 RPM? Ditto those little baby diesels you get in ships and the like that make max rpms of 160 or so? (have a look in the V8 vs diesels thread theres a link to a small engine in there)

ENDEDIT

Originally Posted by Blknight.aus

MY 1968 petrol IIa rover (kermit) lets say 60 hp max has won a tug of war against a 300+hp WRX driven by a wog. How and why?

Simple its all about the torque curve.

As usual, Dave, you're talking crap!

It's all about the driver.

Now if the WRX had been driven by an Aussie........






Ron

Originally Posted by Blknight.aus

yeah Ok I like that except for the "it is better to make torque at high RPM than low RPM"

MY 1968 petrol IIa rover (kermit) lets say 60 hp max has won a tug of war against a 300+hp WRX driven by a wog. How and why?

Simple its all about the torque curve.

ENDEDIT

He would have been one very p*ssed off Wog

Reminds me of the 54 Customline we had years ago. That old side valve could pull away in top gear at 1000rpm without a shudder

Originally Posted by Blknight.aus

If high rpm toeque is so damn good why is it that mos trucks dont have engines that do 10000000000000000000000000 rpm but nearer to a paltry 2400 rpm tops and in most cases peak power is over and done with by 14-1800 RPM? Ditto those little baby diesels you get in ships and the like that make max rpms of 160 or so? (have a look in the V8 vs diesels thread theres a link to a small engine in there)

ENDEDIT

Good illustration!

Torque is capacity to do work. Horsepower has time as a factor. Horsepower is work done in time taken. Put simply, a heavy truck that has high torque and low horsepower will have good startability and gradability, but wont pull three trailers up the dotted line at 110 k's. This is one of the reasons that American power trains took over the heavy truck market in Oz. The Europeans, particularly the Brits, could not understand the necessity for (then) 100kph cruising speeds.

Originally Posted by RonMcGr

He would have been one very p*ssed off Wog

Reminds me of the 54 Customline we had years ago. That old side valve could pull away in top gear at 1000rpm without a shudder

I was returning from Da's place the other week and as I approached the 'burbs (I'm on the fringes) lazy me thought ah I'll see how far I can go in 4th. It was late & I didn't catch any red lights but yes I did manage that final 6km or so all the way to my driveway. Love the V8, such a lazy engine.

Brian is right. Torque (and gearing provides a similar effect) determines your tractive effort, so how much you can pull and such like.

Whereas power (and it doesn't matter what rpm it is developed at the gear just has to match) it the rate at which you do work. So the faster you want to climb a hill you the more power you need. So the wrx would beat the 2a hands down climbing (a bitumen) hill.

Anyway i am just saying the same as everyone else but hopefully in a way that makes it clearer.

This is the idea of an engine with a flat torque curve. The torque is available over a wide range, in each gear, making the vehicle more driveable.

Another examble is the difference between the 2a and suzuki sierra. The 2a is better at rock hopping because of the gearing and wide torque spread of the engine allows the engine develop the torque to climb the rocks. The sierra on the other hand is a bit higher geared and the engine isn't as torquey so when it comes against a rock the force required can exceed that available and it will stall(unless the clutch is slipped bring it back on torque or momentum is on your side.)

Does that make sense?

WR.