pining,twin plugging,etc...

[Gary Derian]

Sorry guys, my turn for the cone shaped hat.  I wrote "undersquare allows
higher revs..." when I meant oversquare.  By the way, how many angels can
fit on the point of a cone shaped hat?

The McLaren F1 I referred to was the $1 million road car with a 6.2 liter
BMW V-12 not the Formula 1 racing car with the 3 liter Ilmor V-10.

In my opinion, longer stroke engines make better road car engines whan all
is taken into account.  A 377 Chevy (3.75 inch stroke) is a lot better in a
Camaro than a 302 (3 inch stroke).  It has more power, more torque, is more
flexible, weighs the same, costs nearly the same.

Gary Derian <gderian at cybergate.net>

>> 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.
>> >
>>
>>