In article ,
Roger Mills wrote:
On 10/04/2016 00:35, Dave Plowman (News) wrote:
In ,
Roger wrote:
Because you've singled out power to weight as some sort of benchmark.
And it would be easy enough to find a small capacity high revving bike
engine with the same sort of peak BHP as a lazy V8. Put them in
vehicles so the power to weight ratio is the same, and see which one
accelerates faster. It will be the one with the flatter torque curve.

It's not a practical thing to do - and you'd *have* to do it to prove
whether or not your statement is true.

Actually, quite easy to do.

I think you might have some difficulty trying to install a bile engine
in a car!

Really? There are several around. Although more what you'd call sports
cars.

But are you then saying power to weight isn't the be all and end all of
acceleration?


I'm saying that it's the most significant factor. I would expect a
diesel car to perform similarly to a petrol car with the same power to
weight ratio - as indicated by the figures which someone quoted to other
day.

They may have a similar 0-60 time or whatever, but how they perform in a
single gear is likely very different. The very point I was making about
torque versus power.

But when you start comparing apples with pears by speculating about
putting a bike engine in a car, you are shifting the goalposts more than
somewhat. Your hypothetical bike engine probably wouldn't do so well
because you wouldn't to able to deliver near maximum power - and I
stress the word *power* - to the wheels for as large a proportion of the
time.

I was merely commenting on power to weight ratio. That may be a reasonable
guide to performance where the engines are similar. But doesn't take into
account how the vehicle will perform in a single gear if the engine type
varies wildly. For that, you need to know about the torque output of the
engine.

--
*Could it be that "I do " is the longest sentence? *

Dave Plowman London SW
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