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I Blumpkin Entirely Way Too Much
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i wouldnt boost it, im sure you can boost it, but most blowers react better for lower CR... there are alot of threads about this already if im not mistaken. you might do some searching
 

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for a street car around 8 psi to be safe 10:1 if you want to boost it drop to a 9:1 or 8.5:1 youll make up the compression with the boost!
 

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Discussion Starter #7
what is the stock CR of the pi motors?

i thought that was around 10:1 and they can take more than 8#'s

i am ant 10#'s right now. but i have a forged short block to put in and with the TF 44cc heads it's gonna be around 10:1

o and it will have upgraded p1sc to a d1
 

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Self proclaimed A-hole
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stock is around 9:1, and if you are at 10:1 anything over 10lbs you going to have to start using race gas to prevent detonation. Your risking anything over that without race gas mixed in.
 

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what about 11:1 cr?:(
 

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The issue is the dynamic compression ratio. Alot goes into that number. Your timing, cams and boost all determine the dynamic compression ratio. And that is the only number that matters for pump gas. 9 lbs of boost on a 9:1 car is like 6 lbs of boost on a 11:1 compression car. It all comes down to the final compression ratio.

General knowledge, intercoolers help, race gas helps, methanol injection helps. All of these things can help lower the Compression ratio or raise the detonation limit of the fuel. Special fuel set ups can be installed that only add methanol or race gas at high rpm so you don't have to run 110 octane all day. But the set ups are not cheap.

Also, the higher the static compression ratio the harder it is to tune. It has been proven that a car with 9:1 compression and a car with 11:1 compression with matching final compression numbers make the same power. But the car with higher compression gets to boost quicker, but is SIGNIFICANTLY harder to tune.

MM&FF has an article about boost and static compression ratios. I can try and find it if you like.
 

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please do find this article
 

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9.74cr is stock for 2000-2004.
 

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That is a big problem for most people.
Hopefully it will expand to more service stations throughout the country soon.
 

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Boost gets you laid
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yeah i'd say you can run a lot more than 10psi with 10:1 compression. stock is 9.74 and i was running 10psi on 91 octane, and theres plenty of people around running more than that on stock compression. my new setup is gonna be 9.6:1 and i'm planning on running more than 15psi i'll let you know how it goes.
 

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my stroker is 10:1 and my tuner said to not go past 10 psi and to only use a centrifical supercharger because the boost isnt instant as with a turbo or kenne bell. from 10 to 12 i have to use meth injection.. anything over is race fuel for sure.
 

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I have a friend that gained 12 HP and 22 TQ over race fuel doing the E-85 swap N/A....it was a high CR bolt on car with a Carb.....If they opened an E-85 station next to where I live I would do the swap...

"ED"
 
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