Hoping someone can help. I have the 6lb. powerdyne setup on my car. I just had my stock exhaust manifolds and y-pipe changed out to the Arizona speed and Marine headers with the Random Tech Y-pipe. Before the change I always would bearly make 5lbs. of boost and from everything I ever read or heard I was told that once you change to headers you will loose boost because of better flow but I have the exact opposite effect. I just took my car for a ride tonight for the 1st time after the install and according to my gauge I am making a solid 6lbs with ease in all gears. I have always kept the BTM at 0 because I never had any issues with knocking and now from 5 to 6 lbs my car is making what kind of sounds like a knock. I forgot to play around with the btm setting because like I said it has never been an issue. Does any of this sound normal to anyone? I am hoping the next time I get a chance to get out and play around with the btm that I will be able to get rid of the knock or whatever that sound is. If anyone has any suggestions or opinions on this I would really like to hear what you think. Thanks guys I hope you can help out with this.

 

I wouldn't expect to see any change in boost from switching to headers. If you had a cam with a lot of valve overlap, you might see a small decrease.

Rich

 

Throw a scan tool on the car and take it for a run. That way you can see if you're getting knock instead of guessing.

 

Headers and the rest of the exhaust shouldn't have an effect with boost, ur intake valves shouldn't be open when the motor is on the exhaust stroke. Depends on the cam ur running.

 

When you say you have a 6lb powerdyne supercharger is that with the 6lb pulley or the 9lb pulley.... ON powerdyne.com they said the 9lb pulley produces 6psi of boost..Just curious because I am thinking of putting a bigger pulley on and don't know how big to go safely.. it has the 4.5lb pulley right now.. thanks, also did you have to reprogram your car or not? thanks,

 

I am with fast350camaro...We NEED to know

 

Finally got the car out again and played around with BTM and knock went away. Thank god. I agree with the responses about exhaust not increasing boost and if I didn't see it for myself I wouldn't beleive it. My gauge may be screwed up for all I know I'm going to make an appointment at the dyno and see where i'm at now for hp and air/fuel, it feels alot stronger so we'll see.

FAST350CAMARO & OVRPWRD,

I have the original 6lb setup. I ordered a costome 6.5 crank pulley which I haven't gotten yet because like I said I figured I would be around 4.5 lbs of boost after the headers and I was only at 5 before. The 6.5 with the 6lb head unit is the same 9lb setup just a little better because your using bigger pulley's, less chance for belt slip. If you have the 4.5 get a 7" crank pulley for the same effect and that is a better setup yet. Powerdyne head unit can only spin up to 43K both set up's I mentioned spin head unit at about 40-41K at 6k RPM. MISLMAN put out a great post with all the calculations for the different setups if you want to do a search. As far as the amount of boost you should make it's alot higher than 6. People post on here that they get 7.5lbs with the 9lb configuration. You shouldn't need a reprogram. I did because I replaced my stock injectors because at max hp I was maxing them out. If you change pulleys just get to a dyno and have your air/fuel checked that's the biggest reason why people blow their motors. 12.5 is a pretty good ratio.

 

Great info. Bill. This may be a really dumb question... but what do you mean when you refer to the 'head unit'. So in short what is the best/safest way to get more boost?

 

When I said "head unit" I was refering to the supercharger itself. As far as the safest setup. I was always told that you shouldn't go any higher than 8lbs with an intercooled charger and any higher than 6lbs without an intercooler. I see alot of posts with people running the 9lb setup and not having any problems, and if you have headers and cam and R.R.'s on the car you probably won't see more than 6.5lbs anyway.(What do you get out of your 4.5 now with your cam and headwork?) Superchargers in general are tough on a motor that doesn't have forged internals but the way I look at it is if you make sure your getting enough fuel and you don't beat the hell out of the car 24/7 it should last a while. Here are a few configurations for the 9lb setup that give you about 2,000 impeller RPM buffer incase you bring the car over 6K which I wouldn't do. Just set up your rev limiter for that so it'll help remind you.

6.0" crank pulley (comes w/charger) 2.70" supercharger pulley=40,667rpm
6.5" crank pulley 2.93" supercharger pulley (size of 6lb pulley)=40,056rpm
7.0" crank pulley 3.12" supercharger pulley (size of 4.5lb pulley)=41,058rpm

I think the best setup is the 3rd because you have bigger pulleys which reduces the chance of belt slip. I will have the 2nd setup on my car only because I have the 6lb setup and didn't want to buy 2 pulleys. Like I said these rpm speeds are at 6k if you go over that you will be getting close to maxing out the SC and probably ruining it. Hope this helped and if you have anymore ?'s I'll try to help you out. Good Luck. Hopefully I'll be able to get to the dyno soon and post my new results but I have a few things to straighten out 1st.

 

This may be a dumb question but where can I get a 7.0 crank pulley for my 4.5 powerdyne set up.. also how hard is it to install and how much boost should this create over the stock 4.5 powerdyne supercharger setup.

 

A company called ASP they will machine any size pulley you want. I think their # is 1-877-928-8678. It's an easy install and people are posting that they get between 6.5 and 7.5 lbs depending on cam, headwork, etc.