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Boost psi vs. displacement

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Old 10-25-2009, 10:51 PM   #1
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Default Boost psi vs. displacement

Is there a calculator or anything that would calculate the boost psi (cam and heads being equal) of changing the cubic inch of an engine. I am debating what size of engine to build with a MP112 blower. It produced 11.5 lbs of boost on a 402 so any estimation what that would change to on a 416 or a 434ci engine? is it better to have a smaller engine and more boost or a bigger engine and less boost?
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Old 10-25-2009, 11:00 PM   #2
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Even though I don't think that this formula is perfect, it would probably give you a decent ballpark idea on what you are looking for. Run the formula for your current setup and for your new setup and look at what the difference in psi is, then subtract that from your actual current psi. Like I said, not perfect, but probably close.

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Old 10-26-2009, 12:26 AM   #3
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Using that formula and doing a bit of guessing on the calculation(doing it backwards from what I know to calculate the MP122 CFM) does it sound right that I should lose 1 pound of boost roughly all things being equal when I increase from 402 ci to 416 ci and another pound of boost if i was to go from the 416 to a 434ci.

Am i better to have a higher amount of boost on a smaller engine (402ci with 11.5lbs) or less boost in a larger engine (434ci with 9lbs)?
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Old 10-26-2009, 02:13 AM   #4
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I would think that 112 is on the verge of being to small for a 402 let alone anything larger.
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Old 10-26-2009, 02:56 AM   #5
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i have a 112 on a 6.0 and it seems to be runnin out of steam

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Old 10-26-2009, 09:58 PM   #6
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I made a mistake-I have a 112 but am replacing it with a over driven 122. Since my motor is toast I am trying to build a motor that will truely maximize the 122 and be able for further expansion. My 112 was pushing the limit on the LS6 346 ci that i had but now that I have bought a bigger supercharger (the LS6 has 2 broken pistons and the block is scored to badly) and want to build the max displacement motor that the supercharger will support-but I dont think the MP122 will keep up with the big displacement motor.
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Old 10-26-2009, 10:35 PM   #7
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Originally Posted by s-cam View Post
Am i better to have a higher amount of boost on a smaller engine (402ci with 11.5lbs) or less boost in a larger engine (434ci with 9lbs)?
All boost really is is a measure of resistance. Just because you you loose a pound or 2 going to a larger motor doesn't mean your flowing any less air. The larger motor will make more power and torque I'm sure.

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