Mr.Clutch?

Sep 20, 2008 292 Replies

It proves that power is the cause of acceleration, which is the product of torque and rpm. You've already been given the formulae some time ago, but clearly you don't seem to have learnt anything if your best reply is "Eh?".

There are no red herrings apart from those you introduce.

I asked you ages ago how BHP (an imperial unit) was calculated, and it was very obvious you didn't know.

So much for one who claims to understand basic mechanics. It's rather obvious you don't understand them at all - but merely find things on Google.

Pray tell how that example proves it to you, Fred? Or you might ask Peter how it does too.

What it does say is two identical cars with the same torque *at the driven wheels* will accelerate the same.

But thanks for confirming your total lack of understanding.

These days the definition of a Horsepower is 746W. There was an old definition of horse power that involved just bore size leading to undersquare engines.

The inch is similarly defined, apologies if I gave you the impression I didn't know.

Any link I use is to explain things to you in a simple effective way such that most people would understand. I generally use websites like wikipedia as a reference.

I have used a number of equations and referenced them to wikipedia. Unfortunately they were way beyond you ability to comprehend, and you snipped the bits as you always do to anything that is too difficult for you.

You wouldn't understand, so it's a pointless exercise.

It proves that claims regarding engine torque without quoting the gear ratio are worthless. No one quotes wheel torque. Powertrain engineers work with traction force curves, which takes the installed wheel size into account.

Whereas bhp at engine arrives at the wheels, only affected by the efficiency of the transmission. Most cars suffer very similar transmission losses.

And the reason they have the same torque at the wheels is because they have the same power.

Irrespective of its torque no gearing could save the ass of a lower power car. Eg 180Nm @ 4000rpm or 200Nm @ 3600rpm v's 100Nm @ 8000 rpm. Even though they have 80% and 100% more torque, the 180Nm/200Nm cars are losers, 75Kw < 83Kw. This is contrary to all claims regarding torques ability to win races.

I asked about BHP, Fred. I take it you don't know the difference.

It was not a definition of horsepower, Fred. It was a formula used to calculate taxation classes. Nothing more.

IIUC, it's not knowing what it is, but how it's calculated to understanding the various relationships.

Racing engines are a very special design. Generally with the peak torque and peak BHP very close together, RPM wise. Making it near impossible to determine where the peak acceleration in a single gear occurs.

But this discussion didn't start out about specialist engines.

Quite. Odd that one who claims such an in depth knowledge of Newton mechanics (or any other fancy name he can find) doesn't seem to get that.

FWIW if you measure any electric motor at 746 watts, if won't be generating 1 HP.

All units of power are work done / time. Is that what you are alluding to?

You might be confusing power in and power out, they are usually very different.

The excuse you need to know engine power in BHP rather than kW in order to solve a simple question is just that, an excuse for why they don't know the answer.

You could just divide the power in kW by 0.746 yourself if you feel it is any help, or is that beyond you too.

Correct, it was a very, very simple question you are unable to answer.

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