You forgot about the difference in displacement.
It's a 1200 cc difference between Honda and
BMW (and 2 pistons). There's no substitute for
cubic inches, unless you have a turbocharger
or supercharger.
The S2000 is 87x84 mm bore & stroke = 1997 cc.
The Z3 M is (used to be) 86.4x91 mm bore & stroke
= 3201 cc. They are both high rpm. engines even if
the S2000 is extreme. Long stroke = more friction
(and heat) and short stroke = higher piston speed
(not piston stroke) at the same rpm. Both are critical
factors in engine design. The BMW M engine have max.
piston speed almost the same as Formula 1 engines.
Here's another one. Shorter connecting rods gives
more low rpm torque but higher friction (and heat).
Longer rods gives less low rpm torque but more power
and less friction at high rpm.
Thomas
Peter Long wrote:
> Came across this today and found it interesting - sums up very well the
> trap we all fall into when discussing engine output....the 'I've got
> bigger numbers than you' syndrome. Why Nissan engines *feel* better
> than Honda engines....torque, baby, torque!
>
> "A long (er) stroke engine tends to produce more torque, (torque is what
> directly affects the rate of acceleration), and over a larger RPM range.
> What this means to you is the car will be easier to drive.
> A good example of the difference torque makes is the current Honda S2000
> vs. a 98-00 BMW Z3 //M Roadster/Coupe. Both the S2000 and the //M
> Roadster/Coupes generate 240 hp and are within 200 lbs. of each other in
> total weight. However, the S2000 produces about 150-160 ft-lbs. of
> torque, while the BMW's have nearly 240 ft-lbs. The 0-60 times and 1/4
> mile times are fairly close, with the BMW's taking the lead. Yes, the
> S2000 will go 0-60 in less than 6 seconds (5.9), but you have to rev the
> engine to nearly 9000-rpm and drop the clutch. A more reasonable (daily
> driven, real world) launch at say 4000 rpm will put 0-60 in the high 6
> to low 7 second range. Now, the BMW's can be coaxed to near 5.0 seconds
> 0-60 by using a high-rev launch, but the average person can almost
> always produce a sub 6-second time with the same 4000 rpm launch . It's
> a function of the extra torque, and that it's available lower in the
> powerband. The rate of acceleration is greater. These are two extreme
> examples to show you that 240 hp is not equal to 240 hp.... peak
> horsepower ratings sell magazines, torque wins races."
>
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