[ZDan]

Originally Posted by Suberman

Anybody noticed that the Honda engine doesn't produce significantly more torque than the Subaru?

The F20C makes *less* torque than the FA20. The difference is that it continues to make torque at higher rpm. POWER.

Acceleration is a function of torque to weight ratios. Power to weight ratios are just shorthand for torque. Only torque accelerates.

Power to weight is indeed the more important metric. Engine torque/weight is by itself meaningless, it doesn't give enough information to determine performance.
Torque at higher rpm is BETTER than torque at lower rpm, because at higher rpm it is making more POWER. This is why the heavier S2000 is quicker than the FR-S/BRZ despite making less engine torque.

Power is the ability to apply torque *at the rear wheels*, where it matters, at a given speed. Torque at higher rpm puts more torque *at the rear wheels* than torque at lower rpm, because at higher rpm it is getting more torque multiplication through gearing.

Power is the rate of doing work. It is force multiplied by velocity, or torque multiplied by rotational speed. This is what *accelerates* things.
Torque moves things, but it doesn't tell you how FAST you can move them.

With engine torque, you have to multiply by the gear ratios to get rear wheel torque and then thrust at the rear wheels (what pushes the car forward) from that.
Engine power, on the other hand, is directly related to thrust at the rear wheels.

Power is force * velocity. Engine power is rear wheel thrust multiplied by road speed. You can easily calculate thrust at the rear tires in pounds from engine rwhp and road speed without knowing gear ratios or tire diameters.
1 horsepower = 550 lb * ft/sec
Thrust = 550*rwhp / road speed in ft/s.

This is why supercharged engines punch so far above their weight if power to weight ratios are used.

Evidence? If you plot the 1/4-mile trap speeds of cars (preferably those that make either much lower or much higher numerical values for hp than lb-ft) versus power/weight and torque/weight, you'll find strong correlation for power/weight, not so much for torque/weight. Whether or they get their power and torque naturally aspirated, turboed or supercharged.

Rpm makes more power for any given torque at that rom but generally speaking moves the torque curve up the rpm range.

Of course if you tune for higher-rpm torque, you will generally sacrifice lower-rpm torque somewhere in the rev range, even with variable valve timing.

Since volumetric efficiency for emission certified street engines is getting pretty uniform these days this is no surprise.
Bmep is the holy grail. Can you get high bmep at low rpm and at high rpm! Hello variable valve timing.

BMEP (torque) at higher rpm is more important than at lower rpm for making power. Variable valve timing is fine, but to REALLY be able to breathe at elevated rpm, you need greater valve lift and duration (which VTEC provided for the S2000).