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Discussion Starter #1
whats the smallest size pulley the jrsc+bbk can hadle without harming anything? and how much boost would it create? i have the zetec kit. i want more boost but dont want to break anything
 

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I am not sure of the pulley size for your vehicle but be careful, too small a pulley with out an intercooler and you will create too much heat and that will lead to power loss and engine problems.
 

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i wouldnt go any bigger than the regular 2.5" BBK pulley. I was running a BBK and a 5.7" crank pulley, and I was getting about 12lbs of boost. That lasted about 500 miles. the car had been tuned also...but 12psi is too much for the stock motor, non intercooled. If you want to run the bigger pulley, throw on a ported and polished head to lower your "boost" back down. or at least get a water meth injection. Here is what happened to my engine at 12psi.



 

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Keep it under 12PSI.

Take it from someone who knows.
 

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thefrush said:
Keep it under 12PSI.

Take it from someone who knows.
yeah, I just edited my post and put some pics up
 

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ehh, 12 psi is just fine...relocate your IAT to your manifold AFTER the blower rotors, that way the ECU will pull timing if it gets too hot.

Also, get water/meth injection, but DONT rely on it permenately (as in, dont set your tune with it), use it as a fail safe.


the one thing you DONT want to do is overspin the blower, keep the blower under 16500 RPMs. (i think th e5.7 crank pulley and BBK pulley put the blower at around 16rpms at 7k rpms engine speed)


Its not the boost that killed those motors, it was the heat. A simple relocation of your IAT solves this.
 

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I just relocated the IAT sensor to the manifold, once I add water meth injection and a P&P head, I'll go back to the 5.7" pulley.
 

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justinrlamb00 said:
I just relocated the IAT sensor to the manifold, once I add water meth injection and a P&P head, I'll go back to the 5.7" pulley.
So, you going to invest in a J&S Safeguard ?

Also, you forgot to post the pic with the eye.
That's the best one.
 

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VenomRogue said:
Its not the boost that killed those motors, it was the heat.

Yeah, that is the biggest draw back with a roots type blower! They are only about 50% to 60% efficient and produce a LOT of heat. I learned a lot about that type of blower when I had my Grand Prix GTP. I had read where people were trying to run 3" blower pulleys and blowing their engines because they didn't have any kind of intercooling. At any rate, I think you get the gist, too much boost w/o intercooling = too much heat = engine problems.
 

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Discussion Starter #10
thanks for all the input im not going to chance it. can i add anything else to my motor to get more hp? or is that it for the jrsc+bbk?
 

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FR head.

you will lose about 3lbs of boost, but gain 20-25 whp.
 

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VenomRogue said:
FR head.

you will lose about 3lbs of boost, but gain 20-25 whp.
thats only because you increase the flow. Ive also heard a cat delete pipe will "lower" boost again only because it increases the flow.
 

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SVT_BMXer said:
thats only because you increase the flow. Ive also heard a cat delete pipe will "lower" boost again only because it increases the flow.

correct, i didnt mean it to sound like losing boost is a bad thing.

you make it more efficient so it moves more air, so less boost builds up.
 

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VenomRogue..whats your numbers by the way...I've been meening to ask you that since I knew that you had that FR head, but I forgot to ask.
 

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Discussion Starter #15
so since you loose boost and gain power. would you be able to get a different pully to up the boost again? so more power. does adding the fr head lower temps since it lowers boost pressure?
 

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-justin- I have no numbers at the current time, i am putting rods and pistons in at the moment.

I plan on upgrading to a turbo, PW kit, or maybe even a high boost procharger in the future, and I got a good deal on the parts, so I am doing this now, so I can add a 50-100 shot direct port nitrous shot to it in the near future.

According to Oscar Jackson himself, he gained 17 whp on his son's car with the FR head, and that was at 5000 ft above sea level. At sea level I probably picked up 25 or more HP to the wheels.


-khara- Yes, you can change out the pullies to up the boost, but remember, you dont want to go over 16500 rpms on the blower, it will cause damage to the blower. The 5.7 crank pulley and 2.4/2.5 pulley is would be the limit, that would put the blower right at 16000 rpms at 7000 rpm engine speed
 

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VenomRogue are you keeping the FR head on the car if you turbo it?? I want to get rid of my JRSC and get a Roush Turbo...I dont know of anyone out there that is running a turbo with that head, just wondering. Im having all kinds of damn problems with my car now, Im getting kind of burned out with it. Maybe I will just get rid of it.
 

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any forced induction will benefit from teh FR head, so yes, i will be keeping it.

saw the pictures on FJ, just rebuild it, stronger, and relocate that IAT sensor.
 

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Discussion Starter #19
what all comes with the fr head? do i need to buy anything else or is it direct bolt on and drive?
 

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kharazmatik said:
what all comes with the fr head? do i need to buy anything else or is it direct bolt on and drive?
bolt on and drive, basically, except for the cams, it doesnt come with cams.

you do have to remeasure out the buckets for the cams, so it makes a good time to add a set of cams to it.
 
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