pining,twin plugging,etc...

[Gary Derian]

A bigger bore is more sensitive to detonation.  Thats why really big engines
are always diesel.  The bigger the bore, the more leakage past the rings.
Also engines are smaller and lighter when they have a smaller bore and
longer stroke for a given displacement.  The European BMW M3 engine (which
by the way is 1/2 of the McLaren F1 V-12) is undersquare and delivers 321 hp
from 3.2 liters.

In theory, undersquare allows higher revs, bigger valves and more power per
liter which is good only for racing classes regulated by engine
displacement.  Everywhere else power per weight, specific fuel consumption,
and cost are the main constraints.  Near square engines have a better
balance.

Gary Derian <gderian at cybergate.net>

>---------------SNIP------------------
>
>> Certain Chrysler engineers believe that pistons over 4" dia. waste fuel.
>> Too much ends up collecting around the sides of the piston.  They were
more
>> interested in complete burn for emissions, hence the V10.  Ford has
tagged
>> along and released a V10 of their own, around 420 ci, I think.  Have you
ever
>> noticed anything like this?  Maybe as more power for a given fuel
consumption?
>
>
>What's the story on this one--I've heard that a bigger bore is more
>efficient and the opposite side that more, smaller cylinders is better?
>I got into a discussion about "thumpers" in a motorcycle mail list one
>time and nothing was every really resolved.
>