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Comparison of two engines of the same displacement

by anhtho
Tags: comparison, displacement, engines
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Dec14-12, 01:43 AM
P: 5
Hi all,

I have this question, and hope you could help me to solve.

There are two engines with the same displacement (say 250cc). One with smaller piston and the other bigger. Of course the first one will move longer.
If everything else is the same or similar, generally, which engine is the stronger ?

Thanks for any input.
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Dec14-12, 02:32 AM
P: 777
With a larger piston you can have crank/ rod geometry which favors higher rpm (because the piston acceleration is lower). Which means you can get more power.

I believe the longer stroke of the smaller piston favors higher low-end torque, which makes this the "stronger" engine (stronger, but less powerful).

I'm sure there is more to it than that, so someone else please chime in...
Dec14-12, 02:44 AM
P: 31
With a short stroke a problem arises with clearance for the valves makers of high performance engines tend to favour an equal bore and stroke a so called square design

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