Not sure if this went ..
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From: Ronak, TP (Timothy)
Sent: Sunday, January 22, 2006 10:36 PM
To: 'sosnaenergyconsulting@cox.net'
Cc: Tiger News Group List
Subject: Compression
David,
The dynamics of the internal compression engine are complex and I have
trouble sometimes trying to run the what ifs in my head. I have run
several high compression engines with the highest being a 14:1 engine we
ran on a mixture of Methanol and C-114 racing fuel. The dynamics
camshaft technology have led to the increasing compression ratios as
people try to extract higher HP out of engines. To get more HP you need
more RPM and sometimes it results in very low torque (Think of the high
revving 1969 Chevy 302) or a very peaky combination. The best view is to
look for an operating range the engine will be used in and then try to
maximize torque and HP as an average value over that entire range. My
Brother-in-law was a master at this playing with the Jericho gears and
rear axle ratios until we had the best combination that ensured the
engine spent all of its time in the are under the HP curve that gave us
the highest average HP value (usable HP 620 HP peak with average at 525
as I recall out of 350 ci Chevy). I still stick by the 195 lbs cylinder
pressure as it was for pump gas (old premium fuel) as there is only so
much energy density in the fuel and as I understand all that is needed
to fully burn this is enough compression, a decent spark and good flame
travel and it will completely burn everything that got into the chamber.
Any additional pressure and the energy used to compress the charge more
is wasted HP as it is not necessary and it has the down side of
significantly increasing engine temp due to this extra cylinder
pressure. The dynamics of sucking the richest charge into the cylinder
are separate from this ... but connected to Intake runner volume, Valve
shrouding, cam and valve timing events as Theo described can
significantly affect performance far more than compression alone. A
stock cam with a 12:1 motor in my opinion will result in an engine that
even with 104 octane fuel will result in an engine that once warm will
be exceedingly hard to crank, is likely to run on due to pre-ignition
and will have a tendency to overheat due to the extra cylinder pressures
you will be dealing with. I used to run octane boost and never really
had any luck with the stuff as it seemed to always come out of
suspension as I still had pre-ignition. If you really want to do this
regardless then try to retard the cam to close the intake as late as
possible and permit less pressure build up on the cranking pressure
stroke. It will raise the RPM band of the engine significantly. This
kind of goes with what Tom's friend who builds Shelby engines indicated
that to increase HP you need to raise RPM with all other things constant
and optimized. What I can say is that if you are truly looking to raise
output through compression the clear ways to do it are to avoid a dome
and try to obtain a smaller chamber head. The super stock route is flat
piston, Small Chamber angle milled heads and 11.0:1.
For what it is worth.
Best Regards,
Tim Ronak
Business Development Manager
Akzo Nobel Coatings
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