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MS3, 12.5 CR, and pump gas?

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Old Mar 19, 2006 | 01:00 AM
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From: Wright Patterson AFB
Default MS3, 12.5 CR, and pump gas?

Is it possible, with a forged 346 to run a CR this high on Pump gas and the ms3?
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Old Mar 19, 2006 | 01:17 AM
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You might be able to with the correct pistons and heads...That will be a pretty stout motor.I think that 93 might be as looooow as you would want to run really with that type of CR.
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Old Mar 19, 2006 | 01:22 AM
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From: Wright Patterson AFB
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Originally Posted by orangeapeel
You might be able to with the correct pistons and heads...That will be a pretty stout motor.I think that 93 might be as looooow as you would want to run really with that type of CR.
THe pistons are Lunati domed top, with a Stock head
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Old Mar 19, 2006 | 01:27 AM
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What was the CR for those pistons? I am guessing if you have stock heads then it must be 12.5:1 .
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Old Mar 19, 2006 | 01:32 AM
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From: Wright Patterson AFB
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Originally Posted by orangeapeel
What was the CR for those pistons? I am guessing if you have stock heads then it must be 12.5:1 .

you got itr
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Old Mar 19, 2006 | 11:40 AM
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DCR would be over 9.0:1. I'd look at a bigger cam.
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Old Mar 19, 2006 | 11:46 AM
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I would not do domed pistons unless absolutely necessary.
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Old Mar 19, 2006 | 12:08 PM
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the reason being for the domed piston is that I found a killer deal on a forged short block, the only bad thing about, is its stout *** CR. Is there away to lower the CR just enough to use the stock heads? like using a thicker head gasket?
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Old Mar 19, 2006 | 12:46 PM
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use the thickest head gasket possible and have the chambers cleaned up to help lower the compression ration maybe.
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Old Mar 19, 2006 | 12:55 PM
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Man,
Domed pistons have specific applications, daily driving is not one of them.
You'll have issues with those.
Killer deal now = more $$$ and huge headache and butt kicking later.
If it is such a killer deal, then buy it, swap pistons for some other ones (flat tops or valve relieved) sell those and recover some money.
If you understood the function of a domed piston, you wouldn't even consider this option.
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Old Mar 19, 2006 | 01:05 PM
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From: Justin, TX
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Originally Posted by PREDATOR-Z
Man,
Domed pistons have specific applications, daily driving is not one of them.
You'll have issues with those.
Killer deal now = more $$$ and huge headache and butt kicking later.
If it is such a killer deal, then buy it, swap pistons for some other ones (flat tops or valve relieved) sell those and recover some money.
If you understood the function of a domed piston, you wouldn't even consider this option.
I am assuming that he was using these because they are forged. They just happened to be domed as a downside. I do know someone who has a solid roller setup and runs domed pistons on the street and it is a pain in the *** for him. I think he has had the heads off 3 times in the last 5000 miles. And that is the mild part of it.
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Old Mar 19, 2006 | 03:33 PM
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you could get the big chamber 6.0 heads and lower it some along with thicker head gasket. but might as well just swap pistons
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Old Mar 19, 2006 | 05:26 PM
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I would not run a thicker head gasket under any circumstances. A loose quench will give you detonation problems at that compression. I believe Lunati rates the 12.5:1 with .053" gaskets anyway, so you can't get much thicker, nor would you want to.

Domes screw with the flame travel and are better suited to quick burning race fuel.
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