Shane writes---
"IMHO, 9.5:1 is a very conservative figure, and is a good number for
people who are not careful about ignition timing, or live in Colorado,
or cruise in the mountains frequently.
If you are careful about timing, and do not live in the mountains, then
I would advocate that 10:1 is safe."
*******
Shane---You are correct in that a higher CR than 9.5 can be run with the
TR engine, but using support equipment such as MSD accessories, Octane
boosters, and such is what I consider "gadgets". (I have used many of
these, and they do work!)
Shane writes further---"If you are fanatical about timing, and have a
great ignition system (i.e., MSD or Jacobs), and are prepared to carry
octane booster for your trips into the mountains, then I would say that
10.5:1 is at the edge. If you have a high-tech multi-port fuel-injection
and engine management system, I would guess that even 11:1 would be safe
with stock TR6 pistons.
*******
Engines running in the higher mountain elevations can actually support
higher CR's.. This phenomenia occurs as atmospheric pressure drops about
3% for every 1,000 ft. of elevation., which would mean that a 10:1 CR
would be the equivalent of 8.5:1 in Denver. This might be the reason
that concludes Shane's last paragraph:
"I ran 10:1 on my Pantera, and ran it regularly (and hard) at 5,000',
with no detonation. Other Mates were running 10:1 and 10.5:1 with
absolutely no pinging."
That9s my belief, and I'm putting money and my motor on 10.5:1.
[Don9t ask me for stock market picks] YMMV.
Shane Ingate in Maryland
******
Dick Taylor
L.A.
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