Doug,
This is a question that is more complicated than it appears on the surface.
Generally cars with higher compression ratios (even the UK TR6) have other
engine caracteristics optimised to the higher compression. For instance, my
TR6 has 10:1 CR. However it also has a different camshaft, a modified
distributor curve, triple webers, and a header. The modified camshaft allows
me to run 10:1 CR without problems - indeed, with that particular camshaft
you need to run higher compression to gain the whole benefit. I must use
premium fuel, but rarely have any pinging. Merely raising your compression
without changing cam or ignition timing can give you negligable power
benefits along with a tendency toward knocking or pinging. For a good
synopsis of this, go to: http://www.elgincams.com/campaper.html (its
primarily about camshafts, but touches on compression ratio and other
factors)
Hope this helps,
Hugh Barber
Hollister, CA
'73 TR6
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net]On
Behalf Of dirtbeard
Sent: Sunday, July 13, 2003 6:27 PM
To: 6pack@autox.team.net
Subject: cutting down cyl head for '74 TR6, octane, etc.
Hi List,
When I rebuilt my cylinder head for my '74 TR6
last summer, I was uncertain regarding the pending
California changes exempting 20 year-old cars from
smog check, so I did not mill the head.
Now it appears that the 20 year exemption is in
place, and it should be safe to up the compression
a bit.
I would appreciate very much hearing your
experiences with milling the head and octane
requirements, ping, detonation, etc. I am not
racing the car, but would like to make it more
efficient. It would be fine if it would need
premium gas, but I do not want to get exotic here.
I know I will need to get shorter push rods, but
before I do something I will regret, I would like
to hear your personal experiences before "making
the cut."
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