Originally Posted by HybridSS
your missing some info and have a few things crossed up. Saying that a car with 100 hp and 100 ft lbs makes max power at 5252 isnt right. How in the world can you make that inference? Now if you say the car makes 100 hp AND 100 ft lbs at the exact same time and both are peaks..then yes...it will be at 5252 rpm. Not many cars will make both peak HP AND peak Tq at the cross point of 5252. As a matter of fact I have never seen one. Usually peak Tq is made substantially lower in rpm than peak HP. In other words...just saying the cars HP peaks at 100 and the Tq peaks at 100 is pretty useless to make any prediction on how the car may accelerate. You really need to know what the entire Tq curve (and HP curve) through the RPMs looks like.
Even if we look at yout theoretical engine where we say it makes those peak #s at THE SAME TIME...you still cannot tell which one would be faster. Maybe the one that makes 100ft/lbs at 5252 rpm also makes 95 ft/lbs all the way out to 7500 rpm....and then is geared accordingly. And the other engine drops off drastically just after 2700 rpms. Looking at peak #s alone will never tell you anything. Do yourself a favor and go read the link posted.
No, the engines HAVE to exist that way, its not theorhetical. Its:
RPM=(HP*5252)/RPM.
You say "what if it also makes 95ft-lbs all the way to 7500? Then:
HP=(TQ*RPM)/5252
Hp=(95*7500)/5252; HP=~136
You see? Then its PEAK HP is no longer 100! It no longer fits the example. It changed, all Im doing is using the exact variables you gave me to do some calculations. The big problem here is you guys are trying to boil it down to HP vs TQ. This really cant be done, the formula to FIND HP, includes RPM.
Ghost, my good buddy. Put that Cam on there and prove my point. Run a dyno before AND after, not only will you gain tq.. you will also gain power. Its so obvious it figuratively kicking you in the face:
HP=(TQ*RPM)/5252
Ok your drag engine that you build gets 100hp/100ft-lbs tq at 5252 rpm.
Now we put in your cam and gain 10ft-lbs tq.
HP=(TQ*RPM)/5252
HP=(110*5252)/5252; HP=110
OMG you gained power to! That must be how you moved down the track faster!
Torque is a FORCE, applying a force to something means nothing. Go outside and push on your house. Your applying a FORCE to it but doing NO work. As soon as that FORCE moves something then it is doing WORK (which horsepower measures).
You also CANNOT leave RPM out of the equation, trying to boil it down to HP vs TQ sounds nice but you can't do that and expect truely understand whats happening, all three variables are dependant on eachother.
Btw, I have read that article before and IMO reading an arguement between a few members isnt the best way to learn. Obviously one of them has got to be wrong and when their arguements are as long and somewhat convoluted as theirs were it gets very confusing.