For those of you not familar with my set up it is a carbed 454BBC with a P1-SC and I had a couple of thoughts/questions I was looking for your insight into.

1. What's more important psi or flow? Currently I'm running the smallest pully ATI offers for the P1-SC in order to make 10 or 11 psi at 5500 rpm. I am considering going to a larger cam (from a 220/220 .500 115 LSA to a 232/237 .547 114 LSA) and possibly doing some simple head claen up work (gasket matching, etc.). Both of these mods in my mind should have the effect of raising the engine's flow ability which in turn will lower the psi I see at the gage. Am I correct in my assumption that flow is more important than absolute psi? (Assuming the carb isn't the cause of the restriction.) I can order a custum pulley, but I am gettin close to the max rpm of the blower.

2. I am currently running an ATI ProFlow bypass valve. This is the $140 black model. Do you have any idea how much flow am I losing through the valve when it's supposed to be closed? It really doesn't seem to seal up very well in the fully closed position. It is working correctly, but there definately is not a "perfect" seal between the butterfly valve and the body. Is there a better valve out there that doesn't cost a small fortune?

Thanks in advance for your help.

 

PSI means nothing..CFM is what you are after.Do the head work and cam shaft and the power will go up while the PSI you see will go down.Then you can pulley back up the boost,just dont over spin the blower.

I have not seen pics of you setup but I would think good BOV will work for you.any leak is going to cause a loss of boost..it may not be much

 

Here is a pic of the set-up, minus the newly added CAI (excuse the dirt please). It's the ATI Proflo vented to atmosphere. I was just wondering if anyone had a feel for how these rate compared to some others.

 

Your blower is waaay to small for that motor. You will see a huge gain from going to a bigger blower. That P1SC was not even enough for my mild 355 daily driver. You'll pick up CFM and boost. Also there are no bad side effects of going bigger on the blower. If you get a bigger cam gas mileage and driveability goes downhill. Heads will help but good ones will cost big dollars and the return is not as big.

As far as your BOV, That proflow will not leak enough air to be significant. The main difference you'll see between a proflow and mondo is the transition from vacuum to boost will be more controllable and you'll get less wheelspin.

 

Honestly, in fairness ATI warned that I would be near the blower's limit but it should be good to at least 800 hp and 1200 CFM. Also, since I am running pump gas & iron heads without intercooling, 10 to 12 psi is about all the motor is going to want anyway. I'm currently spinning the blower to about 53K rpm with the pully combo that is on it, so a custom 3.15" pully gets me closer to the 62K max. Gas milage is already well into the single digit range so that isn't much of a concern, LOL. The car is a solid 11 second car as it stands with the small cam and as cast heads, so I'm just looking at giving it the nudge it needs to break in the 10's (although I am already over powering the DR's, so full slicks will become a necessity for track days.)

Good info, thanks.

 

Have you thought about chemical intercooling via a methanol injection setup? That will give you another serious kick in the pants.

Prochargers claims of 800hp and 1200cfm are a little inflated. I don't think I've ever heard on anyone making 800hp with a P1SC unless they were spraying a 150 shot. I'm really surprised your able to get 10 psi. Your efficient tubing is helping alot. Also if you go to a pulley that small you will probably get some belt slip.

Nice motor. I love the torque of the big blocks.