Pheonix

After simulating the stock drivetrain.
1-2 6950rpm
2-3 6950rpm
3-4 6950rpm
4-5 6950rpm
5-6 6880rpm
For maximum accelleration, you really want to shift as high as possible when working on the stock rpm limits on the stock engine.

Maximum accelleration is achived by the maximum average horsepower output.

onsknht

OK I got the other post too, so responding to both here...

The practical point that I was making was that the ONLY thing you feel in your *** when you hit the accellerator is TORQUE... Once you go past 4700rpm, torque is decreasing even though HP may still be going up. To say torque is a static measurement couldn't be farther from the truth... There isn't a dynometer made that will measure HP, they all measure torque and then HP is calculated off the torque value... HP merely states how much work can be done in a period of time 33,000 lbs lifted in one minute is the same as (i believe) 1lb spinning at 5252 rpm. Remember that...

HP = ((torque * RMP) / 5252)

So why is HP important?

Because it's better to make torque at high rpm than low rpm because you can take advantage of gearing. You could make gobs of torque at low RPM but the ability to do work over a certain amount of time is limited because of the RPM, so it is said to have less HP... Therefore HP is directly related to RPM, but at the expense of torque, especially when peak HP is higher than peak torque.

The rationale therefore in your example is that a car with a higher RPM/Torque drop-off can pull a gear longer and is therefore faster, even though a car with identicle torque and less HP jumps off the line just as quickly... This is true, but seriously, how many of us are drag racing street cars?

Do this... Using your calculator (hopefully it will give you ETs), take the values of the ES and bump up the HP/RPM value and leave everything else constant... Now compare the speed trap values to runs where the HP/Torque values are more realistic and tell me why the High HP/Low Torque model is slower than the High HP/High Torque model.

Now tell me torque doesn't matter?

Basically, IMO cruising around town on the highway, watever... You're acclleration while slightly faster at peak HP/Torque will not feel any faster than if you were to shift at just peak torque... By the time the values converge, you've lost some torque.... Plain and simply put, Torque gets you there, and HP is what keeps you there.

Another example... Take a normally aspirated car and take it to peak torque in 1st gear, now slam it... Next do the same but take it to the 'power peak' (HP/torque converge) and tell me which "feels" stronger. I guarantee the puch you feel at peak torque is a lot stronger than the puch felt at the power peak.

In the end, I think we're both right on this, just getting at two different cases and not everything will be the same as a result of gearing, etc. Trucks for example are commonly rated as having more torque than HP whereas cars are commonly rated as having more HP than torque.... IMO - HP isn't jack without Torque, but it's an easier value for the marketing ***** to deal with, I ignore it almost completely and look at how hard it's going to get there.