Enticer
Veteran
If the RX1 has more torque at 9800 - 10,000 why wouldn't we clutch down to 9500, let the motor pull harder and then finish off at 10,200 or 10,400, whatever you feel best with. On any dyno charts that I've seen I don't see the hot spot at 9500 to 10,000 as far as big torque numbers. Help me out on this. Thanks, Enticer
welterracer
TY 4 Stroke God
The motor pulls harder at 9800 than at 9500..
You want to stay in peak torque as long as you can... then let the HP take over!!
You want to stay in peak torque as long as you can... then let the HP take over!!
LazyBastard
TY 4 Stroke God
Engine torque values are misleading. When you gear down 2:1, you get double the torque, which means double the rate of acceleration. To get the optimal torque at any particular vehicle speed, you need a gear ratio that puts the engine into its point of maximum POWER, in this case 10400 rpm.
There is exactly ONE place on any vehicle where actual torque value matters... on the final drive. Front drive axyl. You get the maximum torque there by running 10400 rpm and maximizing clutch efficiency.
Think about it like this... when you ride a pedal bike with multiple gear ratios... you put it in HARD (fast) gear and try riding up a 45 degree slope. You are generating LOTS of torque against the shaft, but you are SLOWING DOWN because the resistance torque is GREATER. Shift it into EASY (slow) gear, and pushing the pedals becomes EFFORTLESS (and you can go faster with less torque!), *BUT* you can't go very fast before you throw a connecting rod (leg)... So as you accelerate going up the hill, you raise the gear ratio to keep your RPMs down where you make best POWER.
There is exactly ONE place on any vehicle where actual torque value matters... on the final drive. Front drive axyl. You get the maximum torque there by running 10400 rpm and maximizing clutch efficiency.
Think about it like this... when you ride a pedal bike with multiple gear ratios... you put it in HARD (fast) gear and try riding up a 45 degree slope. You are generating LOTS of torque against the shaft, but you are SLOWING DOWN because the resistance torque is GREATER. Shift it into EASY (slow) gear, and pushing the pedals becomes EFFORTLESS (and you can go faster with less torque!), *BUT* you can't go very fast before you throw a connecting rod (leg)... So as you accelerate going up the hill, you raise the gear ratio to keep your RPMs down where you make best POWER.
LazyBastard
TY 4 Stroke God
welterracer said:
WRONG!
welterracer
TY 4 Stroke God
LazyBastard said:
This is what ive always been told about the rx-1!!! You want the rpms to stay about 9800 out of the hole to about 600 feet then pull to about 10,200 (stock rx)
LazyBastard
TY 4 Stroke God
Some people get confused by the WORD "torque". Ever heard the phrase, "bullsh** baffels brains"?
Taken from an actual Dyno chart for RX1 (CPR), max torque is listed as 79.0 at 8600 rpm with 129.3 hp. Max power is listed as 142.1 at 10300 rpm with torque 72.5.
Assuming a final drive speed of, just for the sake of argument, 1500 rpm.
The formula relating horsepower and torque is this: (power * 5250)/rpm = torque, or (torque * rpm)/5250 = power.
Please note that 5250/rpm is constant since we are using a baseline rpm of 1500, which equates torque to power as torque = k(power), where k is a constant, in this case, 3.5 (which is 5250/1500).
Now, assuming a perfectly efficient transmission (granted, its not, but percentage lost is the same);
Final shaft torque for 8600 rpm = (129.3 * 5250)/1500 = 452.55 ft-lb.
Final shaft torque for 10300 rpm = (142.1 * 5250)/1500 = 497.35 ft-lb.
(497.35 - 452.55) / 452.55 * 100 = 9.90% <-- IMPORTANT!!!
By running at the point of peak POWER instead of peak engine TORQUE, you are generating nearly 10% more torque on the driveshaft! That means that with clutching pulling peak RPMs, you get 10% more acceleration than with clutching pulling peak torque!
CAUTION: If you try clutching like this, you need to be considerate of TWO THINGS;
1) clutch efficiency... If you spin it faster by making it slip, you are worse off.
2) TRACTION! By adding more power to the track, you may be forcing your track to BREAK FREE, which will allow your sled to just sit there spinning (net acceleration lower than otherwise). For a proper comparison between clutching for torque and clutching for power, you need to have either PERFECT traction on both, or 10% better traction on the one clutched for POWER.
Taken from an actual Dyno chart for RX1 (CPR), max torque is listed as 79.0 at 8600 rpm with 129.3 hp. Max power is listed as 142.1 at 10300 rpm with torque 72.5.
Assuming a final drive speed of, just for the sake of argument, 1500 rpm.
The formula relating horsepower and torque is this: (power * 5250)/rpm = torque, or (torque * rpm)/5250 = power.
Please note that 5250/rpm is constant since we are using a baseline rpm of 1500, which equates torque to power as torque = k(power), where k is a constant, in this case, 3.5 (which is 5250/1500).
Now, assuming a perfectly efficient transmission (granted, its not, but percentage lost is the same);
Final shaft torque for 8600 rpm = (129.3 * 5250)/1500 = 452.55 ft-lb.
Final shaft torque for 10300 rpm = (142.1 * 5250)/1500 = 497.35 ft-lb.
(497.35 - 452.55) / 452.55 * 100 = 9.90% <-- IMPORTANT!!!
By running at the point of peak POWER instead of peak engine TORQUE, you are generating nearly 10% more torque on the driveshaft! That means that with clutching pulling peak RPMs, you get 10% more acceleration than with clutching pulling peak torque!
CAUTION: If you try clutching like this, you need to be considerate of TWO THINGS;
1) clutch efficiency... If you spin it faster by making it slip, you are worse off.
2) TRACTION! By adding more power to the track, you may be forcing your track to BREAK FREE, which will allow your sled to just sit there spinning (net acceleration lower than otherwise). For a proper comparison between clutching for torque and clutching for power, you need to have either PERFECT traction on both, or 10% better traction on the one clutched for POWER.
