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If I got my APS stuff right, the only really bad
thing about a higher CR is that your engine will last even less long if you
mismanage it. However, it seems that if you are rigorously keeping
your peak pressures way beyond TDC (e.g. 16 or more degrees) then high CR isn't
going to hurt you. The pressure difference between correctly
manage high CR and correctly managed standard CR should be at most (high CR/low
CR) or 20%. But the (peak) pressure difference between 50 df
LOP and 25 df ROP is 100% or more?
Colyn
----- Original Message -----
Sent: Thursday, May 12, 2005 8:24
AM
Subject: [LML] Re: Plasma III on Hi
Compression Engines
"I put those two
pieces of information together and reach the conclusion that if there are ways
to operate the engine at high power but minimize the peak torsionals,
then that method ought to be used. I’m not sure I
answered your question. If not, let me try again. Regards,
George"
Yes you did answer my
question...thanks. One more. How much of a tight rope are we
walking with the TSIO550 trying to balance peak pressure and TIT? Well,
two questions. I have discussed with some the advisability of raising
the compression ratio on the TSIO550 and I advised against it. The quest for
efficiency is outweighed by the quest for durability. What do you think?
A similar question. Would you advise retarding the timing if Scot's
engine was stock CR? Retard 2 to 3 deg's more at 9 to 1 and 5 to 7
deg's more at 10 to 1??? If this is so, then stock CR is the way to
go. Finally let me say I believe there are lots of variables that affect
engine durability like oil type and viscosity, engine component balance and
prop balance to name a few. So this is not a discussion on whether or not
Scott or someone else should run a given CR. I'm trying to isolate and
understand a given engine calibration feature and I'm most interested in the
TSIO550.
Craig
Berland
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