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Compression lt1 383

Old 12-16-2018, 10:28 PM
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Compression lt1 383

Hey,what kinda compression are a lot of you guys running to run on pump gas? I got 2 relief flat tops and with 3.75 stroke and If I run a 58cc or 60cc combustion chamber Iím looking at 12to1or so.i have heard that i mite get away being able to run pump gas if I run like a 256/276 110lsa cam.. but just like to no what some of you are running on pump gas,I want to get compression as high as I can ,but not have run race gas... The higher I can get the compression the more power in guna squeze out of the engine ,with good porting and support mods.
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Old 12-17-2018, 04:08 PM
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Re: Compression lt1 383

I built a 383 with aluminum LT1 heads and a GM hot cam. We aimed at 10:1 CR so we could run pump gas. No, we didn't build it to win trophies at the track, just terrorize at the local traffic lights.
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Old 12-17-2018, 08:51 PM
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Re: Compression lt1 383

Originally Posted by Strick View Post
I built a 383 with aluminum LT1 heads and a GM hot cam. We aimed at 10:1 CR so we could run pump gas. No, we didn't build it to win trophies at the track, just terrorize at the local traffic lights.
That's lower than stock...
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Old 12-17-2018, 08:54 PM
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Re: Compression lt1 383

Originally Posted by Cokesbody View Post
Hey,what kinda compression are a lot of you guys running to run on pump gas? I got 2 relief flat tops and with 3.75 stroke and If I run a 58cc or 60cc combustion chamber Iím looking at 12to1or so.i have heard that i mite get away being able to run pump gas if I run like a 256/276 110lsa cam.. but just like to no what some of you are running on pump gas,I want to get compression as high as I can ,but not have run race gas... The higher I can get the compression the more power in guna squeze out of the engine ,with good porting and support mods.
With the right cam 12:1 not a problem. Plenty of examples in the archives.
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Old 12-18-2018, 05:51 PM
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Re: Compression lt1 383

12to1 that’s more like it.i emailed loyd he said bout 12to1 or little above,with like a 244/254 110lsa cam,he figured you would have to run 92 93 octane.were I live most I’m guna get at pump would be 91,n I could at some 104 booster to it,but I would really like to make shur I’m not guna have a detination problem.i was thinking changing out the pistons to a 4 releif flat top and run the stock heads witch I’m guna have loyd port and run like a .50 head gasket and with deck height should put me around 11.5,but I am open to any suggestions because I want get most out of engine first time around n not wish I did things different after it’s in..
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Old 12-18-2018, 10:37 PM
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Re: Compression lt1 383

you can run a thicker head gasket to lower compression or pull some timing for the 91 octane. 12:xx compression build
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Old 12-19-2018, 09:36 AM
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Re: Compression lt1 383

Originally Posted by Strick View Post
I built a 383 with aluminum LT1 heads and a GM hot cam. We aimed at 10:1 CR so we could run pump gas. No, we didn't build it to win trophies at the track, just terrorize at the local traffic lights.
Why would you lower the CR? Not necessary, unless you're running iron heads.
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Old 12-26-2018, 05:35 PM
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Re: Compression lt1 383

I have a new all forged 383 LT1 with LE3 heads, 847 cam (234/[email protected]/.575/.595" lift) and my cr is 12.5:1 and I'm running 93 pump gas with no problems. However when I got my engine I asked what my timing curve should be for the SCR I'm running and my machine shop told me 14*- 16* initial at idle and slowly ramp it up to 32* - 34* total.
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Old 01-09-2019, 12:34 PM
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Re: Compression lt1 383

Originally Posted by Injuneer View Post


Why would you lower the CR? Not necessary, unless you're running iron heads.
Agree, there is zero reason to run lower than stock compression. Especially with an aftermarket cam as you are most likely lowering the dynamic compression even lower than the 0.4 reduction in static that you are running. 11-12 is not a problem on 93 pump gas if you are running the right cam.
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