Wisconsin S2k

This is for all the push-rod heads out there who say honda's have no torque. I asked a family friend of mine who is retired in Florida about torque. He worked for GM in detroit as an engineer and mechanic designer or something like that for 40 years. I basically asked him that if honda's have no torque, then why is it they go so fast off the line..... here goes as best I can remember.

Basically it works like this. let's say you want to spin a gear that has 10 teeth and weighs 10 pounds. (remember this is just for example). Let's say it takes 100ft-lbs of torque to get it spinning at X rpm. Now you want to take a gear that is 20 teeth and 20 pounds and also get it spinning at X rpm. That would take maybe 160 ft-lbs of torque to get that gear up to the same rpm in the same amount of time as the first gear. With me so far?

Now, apply gears, gear weight, ratio, etc. to our cars. A honda, as he explained it, has smaller lighter gears because of the HIGH rpm's that our cars go, as well as a different ratio, different transmission, etc. So.... 153ft-lbs of torque on a small gear is for example, equal to a bigger gear with 300ft-lbs of torque. So basically because our gears dont require as much torque, we can have less torque than a "grand am" or "mustang". So basically he said that theoretically our cars have just as much, or more torque than many other cars out there.

rocketman

I get the reasoning, but I would still like the torque. The way I would look at it is that the smaller, lighter car can go as fast or faster than the heavier, higher torque car using less torque.

If we had the same 300 ft-lbs of torque, we could kick the holy sh*t out of the other car

cmnsnse

Heh, yeah with taller gears too!!

I suppose that the smaller gears could be part of it, but usually the gears are built with the power requirements in mind rather than before the engine. The most significant part is the ratio, if the muscle cars used our ratios theyd go through the gears pretty quick and peeter out around 100mph, but they'd also put down buttloads of torque . . .

FCGuy

I can feel a "1" rating coming

Can't say I really followed it. But there are a lot of ways of looking at this. Here's the way I see it (and it is physically sound)...

If you have 150 lb-ft of torque on an input shaft (crank) going into a set of gears with overall 10:1 ratio, you get 1500 lb-ft on the output shaft (wheel). The output shaft rpm is 1/10th the input shaft and the power (=torque*rpm) is the same. [Note: I'm ignoring losses which are a second-order effect]

If you have 300 lb-ft of crank torque going into an overall ratio of 5:1, you also get 1500 lb-ft at the wheel.

If it's the same size wheel, you'll get the same force to the road. If the same vehicle (mass, Cd, etc) you'll get the same accel.

What is different? The 150 lb-ft engine is spinning twice as fast. To maintain the same 2:1 mechanical advantage, it needs to have a redline 2x that of the other engine. Otherwise, you'll have to shift at a lower (road) speed and lose the mechanical advantage. And thus have lower output torque and thus lower acceleration.

That's basically what is happening with the S2000. It makes less torque, but more rpm. So at a given road speed, you use a higher gear ratio thus making back some (if not all) of that torque at the wheel.

But do note that if you are going the same rpm, at the same road speed (say you are in 3rd whereas you might be in 2nd in the torque-monster), you have lost that advantage and will be slower (again, hp=torque*rpm). You'll have to downshift to get that advantage back. Which you can do if you are "loafing" at 5000 rpm since the S2K spins up to 8900.

It can be shown that it is really the same as indicated by hp, but I'll leave that for another day.

Stand alone, peak hp gives you a better indication of a car's accel than a peak torque figure. Tell me a car weighs 3000 lbs and has a 200 hp engine and I'll get you closer to the 0-60 than if you just told me it made 200 lb-ft of torque with unknown hp. But to be precise, you'll need to know the full hp (or torque) vs rpm curve, the gearing, weight, Cd*A, losses, balance, tires...