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Discussion Starter #1
whats the best compression to have if i was only planning to run 7psi dailly 10 race day. Could i raise my compression up to 10.5 and still run that psi?
 

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Stock compression is good for that psi....but this sould be in the F/I section. with a big enought intercooler and good tuning you can make it work.
 

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Stock compression sounds about right to me too. You dont want to raise compression insanely if your going F/I, and from what ive heard, about 9:1 compression is premium.
 

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Discussion Starter #4
will 10.5:1 good to run 7
 

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I wouldnt. Too much stress on the stock internals. Stock compression is pretty much the right compression for F/I.
 

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With the right tune, 10.5:1 would be fine... The lower the compression, the more room for error in tuning, aka a little safer.
 

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Discussion Starter #7
well the reason im asking is because i hed my head milled .300 cuz i was going to go NA but i changed my mind. How about a SC arent they better since they dont make taht much psi? i might just get a JRSC would that be better then a turbo with 10.5 CR
 

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Well a turbo or sc svt has that compression and makes wicked power. That compression will be fine as long as you run good fuel and get a good tune. If you dont want more than 10 psi, JRSC is cheaper, but if you get it and need more than youll want turbo. From the boost numbers you gave, the compression will help with power and will not hurt the motor unless you do something stupid. The tune will have to be more spot on though.
 

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correct me if i am mistaken but 10 psi will put out much more TQ than the jrsc. Around 167 compared to close to 200 ft lbs.
 

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zetecfreak said:
Well a turbo or sc svt has that compression and makes wicked power. That compression will be fine as long as you run good fuel and get a good tune. If you dont want more than 10 psi, JRSC is cheaper, but if you get it and need more than youll want turbo. From the boost numbers you gave, the compression will help with power and will not hurt the motor unless you do something stupid. The tune will have to be more spot on though.
The SVT Zetec also has a stronger bottom end; better block with forged connecting rods so its more capable of taking a beating without blowing up. You can probably get away with it but you're pusing it...I'd talk to Tom and see what he has to say.
 

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eh you can run 12psi on stock internals and be fine. just have a really good tune and a J&S safeguard. you shouldn't really worry about the higher compression too much. all the zetec's i've seen fail has been from detonation.
 
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