umm, no, actually i am quite 100% correct in my statement.

max acceleration at any speed is ALWAYS at the power peak, not the torque peak.

it's not the torque the engine produces that moves the car. it's the torque the TIRE produces on the ROAD via gearing that moves the car. and at the power peak, that torque is greatest.

why?
because at the torque peak at any given speed you'd be in a higher gear than at the power peak and you'd have less mechanical advantage from the lower gear ratio.

torque @ axle = torque @ flywheel x overall gear ratio. if you are going 60mph at your torque peak the overall gear ratio would be lower.. and the difference in gear ratio will be bigger than the difference in engine torque at the power peak. if you want to pm me (or if anyone posts a request) i can explain this in MUCH, MUCH greater detail. with hypothetical numerical examples.

 

OOH ooh I get to correct the engine builder!

F = TQ at the drive wheel / radius of the drive wheel. Come on now, watch the units. Tq is in ft-lbs. Force is lbs.....

 

I'll save you the trouble...

F (at the wheel) = M (of car) * A (of car)

If the mass stays the same (if it doesn't you're in trouble), then the max Acceleration happens at max wheel Force.

If wheel Force = wheel Torque / wheel radius, and the wheel radius is constant, then max Force happens at max wheel Torque.

Max wheel Torque happens at max engine torque with the most mechanical advantage, ie. lowest gear (highest gear ratio).

So max acceleration happens at max engine torque in 1st gear. Of course this assumes that the acceleration is in the forward direction....

 

Exactly, I am right and shadow is wrong, and as an engineer I know how to cancel my units.

I didn't bother going into the details of cancelling out all the units for the TR folk, I am just pointing out that torque directly relates to acceleration through the gearing and wheels.

The torque is only being used for force transmision anyways since your pistons and car are not rolling down the road.

 

yup. except that first gear is the anamoly here. after that you will get better mechanical advantage by remaining near the POWER peak because you stay in the lower gear.

this is why i say peak acceleration at ANY GIVEN SPEED is at the power peak.

in first gear at peak torque you are going to slow to be at your power peak because you don't have a numerically higher gear ratio available.

yeah you could artificially put your engine at power peak by slipping the clutch, but much the extra energy is spent producing heat (burning up the clutch) rather than moving the car.


a car with a CVT holding the engine at the POWER peak will produce the most possible overall acceleration out of any engine.


i could go REALLY mathematical by going into the calculus describing it all, but i'll spare the people who don't understand differentiation and integration


F = m*a is a GROSS, GROSS oversimplification of it because F and hence a are CONSTANTLY changing. you need to start delving into integral and differential calculus to REALLY explain why peak acceleration occurs at the power peak.

but i'd practically prepare you people for an A in a college classical mechanics course with calculus to explain this to you all.

 

no, because you apparently did not read my statement.

i said at ANY GIVEN SPEED peak acceleration occurs at PEAK power. trust me, i am not wrong on this.

you may be an engineer but physics is my favorite subject. and judging by the As i have gotten in classical physics and most other schools of science, trust me, i understand what is going on. on top of it i figure out stuff like this and calculate things like this FOR FUN. if you wanna discuss further, please, by all means PM or IM me.

 

Most cars don't have CVTs and can not take advantage of staying in the sweet spot of torque multiplication and power.

Real cars with clutches and gears experience their greatest acceleration in each gear at peak TQ, as has already been proven.

Your brain is stuck in power and work mode which is not what is being discussed here, max acceleration is.

 

well, your brain is stuck in one-gear mode and peak acceleration is at the torque peak IN A GIVEN GEAR. if you DROP ONE GEAR and move to the power peak you will have MORE acceleration than at the torque peak in the higher gear. you seem to fail to realise this.

and if you wanna pull out the CVT argument, chew on this:
most speeds you won't have a gear available that puts you at either the torque OR the power peak. how do you answer that? this is how:
take any given speed. find the rpm you will be in ALL gears at that speed. the gear that has the highest POWER at the rpm the engine will be in when that gear is selected, is the gear that will have the highest acceleration. net result: maximize average POWER between gearshifts and you will cover x distance in the least amount of time possible. you're an engineer. surely you understand the math. work it out

besides the original intent of the thread is to see who understands the difference between torque and power

it is OBVIOUSLY apparent that both of us do. the rest here is arguing semantics.

 

Heh, I was just having a little fun with ya, 0HP.

All other engineers should check in and swing your dick around. This is fun.

 

it's all good. tony & i have known each other a couple years now (we met when his 0HP930 actually had hp--sometime before my TR join date )

there is some mutual respect between us. or at least i should hope so