What matters; HP or TQ?

[Bo White]

Originally Posted by jessrayo

It does if you have the engine below 5252 rpm for most of the race. If you race a bike that revs over 9000rpm, the one with the most horsepower wins.

Actually the one with the most torque wins.
The more TQ at a given rpm the more HP you will have.

Look at the equation for HP like was posted earlier.
HP=TQxRPM/5252
Say you have an engine making 300TQ at 6000rpm, that means the engine is making 342HP at the same RPM.
Say you have an engine making 600TQ at 6000rpm, that means the engine is making 685HP at the same RPM.
Another engine making 300TQ at 7000rpm, its making 399HP at 7000rpm.
An engine making 600TQ at 7000rpm so it will at that same RPM make 799HP.
Its all in how much torque you can make for as far as you can carry it, even in bikes/Formula1/NASCAR/NHRA.....

[ayousef]

oh my god I cant believe this discussion is still going on!!!

The one with the most Torque and the most RPM (assuming you can make decent torque at that RPM wins) so in other words the one with the most average horsepower across his rpm range wins.

You can make 90lbs torque at 20,000 and you will beat the car that makes 900lbs at 1500rpms, assuming both are geared for equal speeds in every gear.

[ClawSS]

From a different VVT thread...look at this torque curve after the cam swap! It should feel very nice pushing the go pedal in this one.

"Some engines [that] have a power curve that looks like a tabletop [instead of] a mountain range in profile are pure pleasures to drive." Comp Cams' Scooter Brothers adds, "If it's a Comp Eliminator, Pro Stock, or Winston Cup car, maybe peak power is the answer," because these engines operate in a relatively narrow rpm band. "But for the dual-purpose car, torque must be flat for an extended period of time."

[1985airborne]

Hell this is great! After analyzing my boost level and dynograph Im guessing that I should run 10.4-10.9 in the qtr mile...what you guys thinks?

[Bo White]

Originally Posted by ClawSS

From a different VVT thread...look at this torque curve after the cam swap! It should feel very nice pushing the go pedal in this one.

Correct, look at what happened when you carried the torque further up in rpm.

[matt55]

What matters; HP or TQ?

BOTH /thread

[dreksnot]

Horse torque. Torque power. Horse torque power.

[jessrayo]

Originally Posted by Bo White

Correct, look at what happened when you carried the torque further up in rpm.

See I guess you could say the torque is carried farther up but I would say the cam changed the motor from torque bias motor to horsepower biased.

In first graph max torque is more than max horsepower. If you add horsepower and torque together at every single point along the graph the highest total value will be around 4700 rpm, it was a torque biased motor. After the cam change peak horsepower is increased by 76 and peak torque only increased by about 11. This mod helped horsepower much more than torque. I'm typing in the reply box and I'm too lazy to open another window and look at actual numbers so don't flame me too bad if these numbers are not exact... Anyway, after this cam change the motor now has more peak horsepower than torque. The biggest gains in the graph are all above 5252, the peak sum of torque and hp readings at any point along the graph now occurs around 5700. This motor will now pull better above 5252 rpm.

Because torque and horsepower are directly related with the only variable being rpm, you cannot add one without adding the other. The only thing you can do is influence where the gains are most significant. If you want them on the bottom of the power band then you are looking for torque, if you want them at the top then you need horsepower.

The horsepower/ torque relationship is fixed mathematically. If I add 1 horsepower at every place on the power band it will alter torque exactly the same.

1 HP at 1000 rpm will increase torque by 5.25 ft/lbs
1 HP at 2000 rpm will increase torque by 2.62 ft/lbs
1 HP at 3000 rpm will increase torque by 1.75 ft/lbs
1 HP at 4000 rpm will increase torque by 1.31 ft/lbs
1 HP at 5000 rpm will increase torque by 1.05 ft/lbs
1 HP at 6000 rpm will increase torque by 0.87 ft/lbs
1 HP at 7000 rpm will increase torque by 0.75 ft/lbs

This can be figured inversely for torque;

1 ft/lb at 1000 rpm will increase HP by 0.19
1 ft/lb at 2000 rpm will increase HP by 0.38
1 ft/lb at 3000 rpm will increase HP by 0.57
1 ft/lb at 4000 rpm will increase HP by 0.76
1 ft/lb at 5000 rpm will increase HP by 0.95
1 ft/lb at 6000 rpm will increase HP by 1.14
1 ft/lb at 7000 rpm will increase HP by 1.33
1 ft/lb at 8000 rpm will increase HP by 1.52

I still feel if you want the motor to perform better below 5252 rpm, torque is the more important. If you add torque above 5252 you are adding MORE horsepower. You can call it torque above 5252 but there is mathematically more horsepower gain than torque.

[Bo White]

Anytime you can carry good torque past 5252 you will have more peak HP than peak torque.
Like I've been saying to have good HP you have to have good torque.