okay i have a jackson racing supercharger in my 02 svt and the guy before me had it at 11 and now it running 6 after he gave it to me.....how do i turn it up? i have the computer but i dont think that helps....sorry im new to this im only 17 so dont hate

Superchargers make a set amount of boost based upon the pulley size on their snout. Now, since your boost has decreased by 5psi, that indicates a problem, perhaps. I see you live in the hiiiigh up city of Colorado Springs. Did you pick up the car in a much lower altitude? High altitude prevents a supercharger from making full boost because of how thin the air is. If you got the car IN C Springs and it went down 5psi and you haven't added a bigger exhaust or anything, then you have a problem. ECU tuning doesn't affect how much boost you make, for the most part.

maybe the previous owner had a different pulley on it but removed it prior to selling?

well i bought it from a guy in the springs, and he had a 10lb pully and he didnt take it off....so there is problem?

Well...did you ever actually see his boost gauge go to 10psi or did he tell you it was supposed to? Granted, even at that altitude, it shouldn't drop 4psi. Does the car run rough? Only thing I can think of is something either wrong with your valves or a boost leak at the intake manifold.

How are you driving the car? You will not reach full boost untill 7,000 RPMS which would be around 9-10 PSI for a jackson racing + pulley.

Just driving it around and driving semi hard you will only see an instant 5psi +... your psi will rise the further your RPMs go UP.

bouncing off what they said, the jrsc i have on mine is set up for 6lbs, which i believe is the stock(jrsc) boost level. the 10 is alot for a stock engine. but it sounds like its just the factory pulley

How are you driving the car? You will not reach full boost untill 7,000 RPMS which would be around 9-10 PSI for a jackson racing + pulley.

Just driving it around and driving semi hard you will only see an instant 5psi +... your psi will rise the further your RPMs go UP.
Nope. Roots style blowers are meant to make full boost right off idle. That's why they're called positive displacement...they make your motor "act bigger" all the time. Centrifugal blowers build boost the closer you get to red line, though.

cant you tell the difference in the pullies by the color. arent the bbk pulleys blue. it has been years since i had a jrsc so i dont remember. but i do know you can measure the pulley diameter and that will tell you for sure. also check to see if you have any dust on the pulleys from belt slippage.

Nope. Roots style blowers are meant to make full boost right off idle. That's why they're called positive displacement...they make your motor "act bigger" all the time. Centrifugal blowers build boost the closer you get to red line, though.



yes with the JRSC you do make 5 psi off idle (running hard). But I'm pretty sure with the BBK you will not make 9-10 psi until redline....mine didn't at least

Hey gang, this is my old car ...

Sorry, I am terrible with names and it's been a while - Tyler?

The car was sold with the 10lb pulley / BBK on it. At our altitude you will only see about 7-8psi max boost and that's normal. If you romp on it from a roll mid rpm range, it should instantly nail 5-6psi and slowly build a few more psi as you approach redline. Drive it up Pikes Peak and watch that decline as you approach the summit, lol. When at idle, you should also see it will read vacuum @ around 10 - 15 depending.

5-6psi seems a little low for in-town. How is your vacuum? If both are out of whack, I would check the by-pass valve between the manifold and the blower. And then start checking the vacuum lines for a leak.

The by-pass valves are known to get small holes in them (it happened to me), and they will cause a random vacuum leak/boost loss. The car will idle a little funk, your vacuum will read low and you will loose 1-2psi. Best way to test it is to take a Mighty-Vac and hook it up to the vacuum line on the by-pass and start pumping. You will see the by-pass start to open. If it just kinda wiggles as you pump, you probably have a hole in the diaphram.

As far as turning up the boost - you are pretty much at the blowers safe limits. You can start swapping pulleys and overdriving the blower, but I really wouldn't suggest it. Bad things have happened to others and the Ford tuners in this area are not up to snuff on SVT focus'.

ps - you can always bring it by and I will take a look at it and see if I can figure it out. Cant say I wouldn't mind driving her again .... not to mention I have been wanting to race my old SVT with the new Forester XT, lol.

i would definitly check for a vac leak. but with problems aside the only way to turn up boost on a sc is to change pulleys either your crank or sc pulley

Nope. Roots style blowers are meant to make full boost right off idle. That's why they're called positive displacement...they make your motor "act bigger" all the time. Centrifugal blowers build boost the closer you get to red line, though.

Not true. Mine doesn't and never has. If I nail it, it will hit 6-7psi instantly but won't hit full 10psi till after 6K. Has always been like this, it builds boost as rpm increase.

To the OP, sounds like a vac/boost leak to me.

Meh, I haven't looked into superchargers as much as turbos, since nobody cares about them anyway [:p]

To the OP, sounds like a vac/boost leak to me.

If he doesn't make 7-8psi, yes. Otherwise, it's perfect ... we are at over 6k feet here so he'll never make 10psi on the BBK. He would have to overdrive it ... and we know what happens then.

He would have to overdrive it ... and we know what happens then.

He would make more power? [giddy]

for a little bit, yeah. :D