INTERNAL ENGINE MODIFICATIONS Valvetrain |Heads | Strokers | Design | Assembly

11.5:1 compression

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Old Jul 9, 2006 | 04:00 PM
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Default 11.5:1 compression

would 11.5:1 compression be to much to have if i was putting in 93 octane pump gas?
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Old Jul 9, 2006 | 04:11 PM
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Iron heads, definately. Aluminum heads, depends on your tune and what weather conditions you drive in. I have seen people get away with it, and some that havent... Also depends on what size cam you are running, if it has a good bit of duration it will help bleed some cylinder pressure and might make it possible.
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Old Jul 9, 2006 | 05:31 PM
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Originally Posted by jblack6527
Iron heads, definately. Aluminum heads, depends on your tune and what weather conditions you drive in. I have seen people get away with it, and some that havent... Also depends on what size cam you are running, if it has a good bit of duration it will help bleed some cylinder pressure and might make it possible.
Agreed. 10.5:1 with iron heads it about all you can do on the street with 93. Many variables there though.
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Old Jul 9, 2006 | 09:08 PM
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with aluminum heads you can run upwards of 12:1 on 93... I personally wouldn't though. I'm at 11.5:1 right now with the heads I just bought and put on, 93 is fine. Is this going to be happening with your carburated motor?
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Old Jul 9, 2006 | 11:44 PM
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I ran 93 octane with 11.4:1 on one engine and it ran well, but I wouldn't drag race it on 93 with my timing setup and didn't want to lessen the timing due to performance loss. The trick is usually in the tune, but do your best to make sure there's no knock regardless with that fuel, or your engine may suffer a short life. Personally, I wouldn't want that much timing with iron heads using 93 or lower octane fuel.
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Old Jul 12, 2006 | 09:03 PM
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yeah its going on my carbes motor, im gonna do an 11.5:1 comp. motor with AFR 195cc heads and a comp cams XE286H cam.
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Old Jul 12, 2006 | 09:07 PM
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Originally Posted by ProStreet83C10
yeah its going on my carbes motor, im gonna do an 11.5:1 comp. motor with AFR 195cc heads and a comp cams XE286H cam.
what ci is the engine? what carb + intake manifold you runnin?
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Old Jul 12, 2006 | 09:11 PM
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its gonna be a 383 with a victor jr intake or a weiand xcelerator intake and a demon 750
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