LT1-LT4 Modifications 1993-97 Gen II Small Block V8

383 compression

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Old May 19, 2009 | 11:13 PM
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Default 383 compression

When buying pistons for my 383 stroker build, summit sent me the wrong pistons. They sent my pistons for a regular 350 that would have been smacking my cylinder heads. I returned them and i got the same ones just for a stroker application. This being my first build and me being a dumbass i didn't double check piston head volume so now i have a nice 12.6:1 compression ratio.

I know i could get some different cylinder heads with some bigger combustion chambers, but what Octane would be ok to use when drivign around on the street? when using 93 i dont hear any pinging but i notice a little difference in power when i use 110.
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Old May 19, 2009 | 11:22 PM
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make sure your running a knock sensor, and if you own or have access to datalogging software/equipment you should be able to check to see if the computer is retarding the timing. How big is your cam? If it has a decent amount of overlap then you should be fine.
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Old May 19, 2009 | 11:26 PM
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Well, I have heard of higher compression on 93, but your cam size matters also.
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Old May 19, 2009 | 11:30 PM
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small cam, Lt4 Hotcam. Knock sensor is working properly, and i hope its retarding my timing. I could get access to a scangauge tool if that would help. But is it gonna hurt it much to be driving around on 93? or how much 110 should i mix with it. 110 is 7.99 a gallon right now
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Old May 20, 2009 | 01:36 AM
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Are you sure you'll have 12.6 CR? How about posting the numbers you used so we can double check your math. Maybe it'll not a concern after-all.

Jake

West Point ROCKS!
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Old May 20, 2009 | 06:15 PM
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Hotcam is too small, I would not run 12:6:1 with that. Try researching dynamic compression ratio (DCR), I think 9:4:1 DCR is about the max for pump gas, there are DCR calculators on the net. In case you are correct about the compression and do not want to switch cams, your last option would be to go with an E85 setup. But considering the research that you already need to do, I would not advise this for the novice.

Last edited by Chevyguy358; May 21, 2009 at 12:37 AM.
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Old May 20, 2009 | 06:37 PM
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Originally Posted by Chevyguy358
Hotcam is too small, I would not run 12:6:1 with that. Try researching dynamic compression ratio (DCR), I think 9:4:1 is about the max for pump gas, there are DCR calculators on the net. In case you are correct about the compression and do not want to switch cams, your last option would be to go with an E85 setup. But considering the research that you already need to do, I would not advise this for the novice.
^^^Agreed. Calculate your DCR to determine your octane requirement. No one can tell you "You're good with pump gas", not knowing anything about your engine, heads, etc.
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