[Durbrain]

Originally Posted by Garrett

That has nothing to do with your original statement.



Any car... no matter who makes it or builds it will accelerate at the rate appropraite to it torque curve.. and you bloody link explains that.

That statement isn't correct. It should be "Any car...no matter who makes it or builds it will accelerate at the rate appropriate to its torque curve within any one gear "

But you can't ignore gearing. Absolute torque at the wheels is determined by engine torque X multiplication provided by gearing (minus losses within the drivetrain).

Comparing two cars with exactly equivalent gearing, one having low torque high HP (a diesel) and the other high torque & low HP. Sure, the former will likely outaccelerate the latter in 1st gear up to around 4000 rpm. But then the former car will have to shift into second gear which has less torque multiplcation whilst the latter car can remain in 1st gear up 'till around 7K rpm. So whilst the former car may have had an advantage initially, it quickly loses steam once it has to shift.

If you maximise the use of gears in any car, it will be HP that determines outright acceleration. Yes - in any single gear the torque curve will exactly mirror the rate of acceleration, but outright acceleration doesnt happen in one gear. There is no point in having a car with a peak torque of 700 Nm if it peaks at 1000rpm, and redlines at 2000 rpm.

The only reason high-torque at low RPM type cars feel fast in 'everyday' driving is because normally we only drive in the 1500-3000 rpm range. If we limit our driving to <3000 rpm, then high-torque, low-HP cars such as diesels feel like rockets. But this is an unfair comparison to petrol engines - in order to make the most of a high-hp, low-torque petrol engine, you must take advantage of torque multiplication of low gearing and this can only occur if they are revved to high-RPMS.

In summary, the rate of acceleration you feel is the torque at the wheels , not the torque at the engine. Torque at the wheels is a function of the engine torque X multiplied by the gearing factor. High-hp, low-torque carcan take advantage of this by remaining in lower gears and thus providing an overall torque at the wheels curve that will on average be greater than that of a low-hp, high-torque car.