06-07-2011, 05:51 PM
Join Date: Jan 2009
Location: Columbus, OH
Total Cats: 177
Crank torque doesn't mean jack ****.
The only form of torque that actually matters is the torque applied between the rubber and the road.
As long as the torque curve is relatively flat, it doesn't matter if the engine is spinning at 2rpm or 100,000rpm - HP is all that matters.
Put a different way: The horsepower number that actually matters is what is measured at the crankshaft - the engine creates horsepower. The torque number that actually matters is what is measured after the post-final drive ratio - real torque is derived from gearing.
So - engines have one single simple job - create horsepower - nothing else matters. It is the job of gearing to give you torque. I can have two engines, one of them spins at 1 RPM, and has a flat torque curve of 500FT LB from a dead stop, all the way to its redline. The second engine spins to 10,000 rpm, and has a flat torque curve of 200FT LB.
Which one are you going to put in your car?
The 500Ft. Lb. engine produces 0.095 horsepower
The high revving 200Ft. Lb. engine produces 381 horsepower.
Despite having only 40% of the available torque, the rev happy engine develops more than 4,000 times as much horsepower.
This is an extreme example, but if you think about it critically, instead of thinking what people have told you to think over the years, you'll understand that crank torque really is a useless number for measuring performance potential. The 500 ft. lb. engine is absolutely useless in this example, while the 200ft. lb. engine could easily find its way into a compact sports car.
Here is your single bye: By using two engines, side by side, with identical horsepower ratings, the engine that develops horsepower through torque will be required to overcome less rotational inertia than the rev happy engine simply because it doesn't have to accelerate through as great an RPM range as the higher rpm, lower torque engine - but that (and only that) is the one benefit of a torquey engine over a revvy engine, given the same power output. It is worth noting, however, that the torquey engine is likely to have larger components (pistons/rods/crank/etc) than the revvy engine because it is developing its power through torque, and that the disadvantage of size and weight of these larger / heavier components may possibly outweigh the revvy engine's disadvantage of a wider RPM range.
I have yet to hear an intelligent argument on the benefits of crank developed torque, so I hope you have such an argument, because I would like to learn more. All of the counter-arguments I have ever recieved in response to my argument have all been in the form of whiny, bitchy, childish "it is because I said it is", as opposed to providing examples of where my information is incorrect, or providing thoughts on subjects that I had previously not considered.
My argument doesn't come from listening to other people's arguments. My opinions on this matter have been formed through my own critical thought while using a very basic understanding of the principles of physics.