Wow,
Lots of good letters have just been written on this subject.
( Chip Old, Roger Garnett, William Woodruff )
Randy Wilson, I think you misunderstood me. I was making a simplified piston-
cylinder model based on a flattop, two-valve setup like that commonly found
on older English cars, hence the math was setup for a Triumph 2-litre six.
What you say about combustion chambers being below the deck is certainly
applicable to modern cars. The flat-head Jag 12 was somewhat of a singularity,
and the H.E. was a much better design than the flat-head. The H.E. cylinder
head design, however, relies on a swirling effect that derives from intense
turbulent fluid mechanics research. I haven't taken the time to investigate
the H.E. head from a fluid mechanics perspective, but I imagine it could get
pretty gnarly quickly.
I guess I wasn't too clear on the 'compromise' resulting from milling the
head. Torque is calculated from Pressure*Volume, and while milling the head
increases the Pressure, it decreases the volume. Hence the compromise.
Boring out the cylinder increases Volume and Pressure. As I said in my first
post, the compromise in milling the head works, (for older English cars!!)
Happy calculating !
Greg Meboe MEBOE@wsuvm1.csc.wsu.edu
Dept of Mechanical and Materials Engineering
Washington State University Pullman, Wash.
'67 Spit-6 (Daily) '74 TR-6 (In Progress)
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