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Old 10-05-2006, 12:56 AM
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curtis73 curtis73 is offline
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If it were an automatic I'd say run it with a very conservative timing. Since its a manual you'll probably run into trouble. There are several head gasket thicknesses available, try running a thicker head gasket. Another expensive option would be to run a high-end EFI setup that retained the knock sensors. Stock LT1s run as high as 11:1 on 87 octane. My iron-head LT1 runs 10.5:1 with a 191/196 cam making low RPM cylinder pressures super high and I never hear detonation on 87 octane.

Two things going for you are the modern combustion chamber helps quench and swirl which (on those heads) helps allow it to run another .5 compression or so. Then the aluminum helps with another .4 -.5. The knock sensors, MPFI, and very sophisticated spark map take care of the rest. But when comparing an LT1 to a typical old school V8, count on a buffer of at least .8 more compression for a given octane. Whereas it used to be a max of 10:1 on old school iron heads and 95 octane, consider 10.5 or 10.8 a little more realistic on an LT1. You might be fine with just a careful timing curve.

There are other options. Retard the cam a little, run water injection, run a bit cooler plug (which you can get away with at that compression anyway) use a 160 thermostat (which I don't recommend ANY other time except on LT1s since they are reverse cooling), and jet it up just enough to make it a tiny bit rich. I think you'll be fine if you use all or some of these techniques.
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