pining,twin plugging,etc...

Matthew B. Watts mwatts at facility.cs.utah.edu
Wed Mar 11 12:45:32 GMT 1998


-----Original Message-----
From: Shannen Durphey <shannen at mcn.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Tuesday, March 10, 1998 8:39 AM
Subject: Re: pining,twin plugging,etc...


---------------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.

My gut instinct is that there is some practical limit of size due to
simple mass of the piston trying to change directions all the time,
plus burn rate of the fuel mixture.  A rule of thumb that I heard was
around 600cc per cylinder; anything more and your outside of the
"workable" range.

I'm still amazed after building Ford FE big block motors for a couple
of years that a little 125cc dirt bike engine can produce so much
power for its size and weight.  Someone needs to nail this matter
down for future reference...

Matt








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