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i had my head milled because i was going to go NA but now im thinking about getting a supercharger. Will this be a bad idea since my CR is between 10.0-10.5 right now. How much boods does jrsc make? what about with a 2.3 and 2.4 pulley?
 

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that compression should still make good power with a JRSC. I wanted to go higher compression, to see how much power that would make...but Im kind of burned out now. Oscar jackson says that anything that will make power on an NA motor, will make power with a Roots blower. The regular JRSC kit makes like 5-6 psi, BBK makes 8-9 psi, and the 2.3" supercharger pulley or 2.5" sc/ 5.7" crank pulley combo makes 11-12 psi.
 

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i have the bbk so is that the 2.3 pulley? how can i get the 2.5/5.7 combo? and how much is it?also is 11-12psi too much for the blower?
 

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Don't use the 5.7 pulley with a JRSC+BBK, the blower can't handle spinning that fast. I'm not an expert on the subject but maybe someone with more experience can chime in. I just know that is a very bad idea.
 

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the max RPM on the JRSC is around 16500 rpms on the blower itself after that is is just inefficient, and much more than that (over 17k rpms) can damage the rotor. The 5.7 and 2.3 combo will be fine if you shift around 6800 rpms or so. I have a 2.4in pulley and putting on a 5.7 crank pulley and setting my redline at 7000 rpms, that should put me right at 16500 rpms on the blower. There is a formula for determining the blower rpm, that i am looking for right now..

Kharazmatic, its not the boost you have to worry about. When you go with that combo you have 2 worries:
1) the blower is inefficient at such high RPMS
2) you could over spin the blower and cause damage.
 

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No, it can go 16500 without damageing it, but its not efficient at that speed, its just cuts up the air and makes it hotter at that speed.

if it goes over 17k then you will damage the blower itself.
 

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ok so from reading this im guessing the 5.7/2.3 combo actually makes good power. just dont over rev it right? ok so where can i get it? and should i get a dyno tune after?
 

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5.7 pulley is sold by CFM.

the blower pulley you will have to get custom made.

any time you add boost, you want to retune the car.
 

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I wouldnt go with a 2.3/5.7" pulley combo...on my dyno runs with the 2.5/5.7 it made good power up to about 6800 rpm, then it started to actually lose power. So I left my Rev limiter at 6800. It could have been the power band of the Crower Stg 1's that I had in there...but I wouldnt spin the blower more than you have to. There are other things that you can do to the car to make power...dont risk blowing a motor, or the SC itself. TRUST ME!!!. I've spent ALOT of time on the dyno experimenting with some different things.

See how the power starts to even drop a little bit at the end of the run at 6,800 rpm. Its even more noticable at 7,200 rpm. But I dont have a printout of that.


Dont Push too much boost....I know from experience.
 

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Its not the boost that killed your motor.

It was the heat, and from your other thread on FJ, you didnt have it tuned for a while.

Dont be afraid to go higher boost, just do it CORRECTLY.
 

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for the 1,000,000th time. I drove the car with the STANDARD BBK, on the STANDARD BBK tune from Ford for a few thousand miles. Then I added the bigger pulley and had it IMMIDIATELY tuned by FocusSport. I dont know how more "Right" I could have done things.
 

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would the 2.5 standard bbk pulley and a 5.7 pulley be considered too much boost? how much psi and hp do you think you gained?
 

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Thats not really too much boost...its around 12lbs. Its probably a little too much for non-cooled...but if you had a H2o/Meth injection it should be fine. I picked up about 15whp and 10wtq. The problem is, you are starting to make the blower inefficient. So thats why you dont see a HUGE power increase. It is a power increase all across the board, so it feels alot better...but its not a really big peak whp gain.
 
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