90-98 ron
Joined: Jul 2000
Posts: 6,522
Likes: 92
From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Re: 90-98 ron
An 85 LG4 has lower compression than the 85 L69 which was around 9.5:1 compression.
I've had both engines.
Either runs fine on RON+MON)/2 rated 87 octane at sea level, 85 at 8000ft above sea.
I've even run a tank of 85 down at lower altitudes without issue.
Or you can bump timing a bit and run 89 - 93 as desired.
98 RON will be more than high enough and allow a little extra base timing. With stock timing, an engine in good tune with clean combustion chambers, 90 would probably run fine.
I've had both engines.
Either runs fine on RON+MON)/2 rated 87 octane at sea level, 85 at 8000ft above sea.
I've even run a tank of 85 down at lower altitudes without issue.
Or you can bump timing a bit and run 89 - 93 as desired.
98 RON will be more than high enough and allow a little extra base timing. With stock timing, an engine in good tune with clean combustion chambers, 90 would probably run fine.
Last edited by jmd; Oct 19, 2011 at 12:18 PM.
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Cruzin Kaz
Third Gen Association of Ontario
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Dec 22, 2002 11:31 PM
