pining,twin plugging,etc...

[Max]

> 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 

How can you put bigger valves into a circle that is a small diameter?  The
larger the bore the larger the maximum valve sizes are, think about it. 
Intake valve area is limited to roughly 34% of the bore size on a 4 valve
race engine.  A smaller bore would limit the size of the valve.  FWIW, F1
engines are around 100 mm bore for a 3 litre engine with 8 cylinders and it
is estimated that the3 litre V10's are running around 92-94 mm bores.  This
means that they are highly oversquare engines.  The only advantage for a
small bore on a street car is the smaller crevice volume which lowers HC
emissions.  This is also why the piston to wall clearance has gotten much
tighter lately and why the top ring is moving up the piston.  Some engines
are down to .002" piston to wall clearance stock on a 86mm bore.

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.
> 
> >---------------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.
> >
> 
>