[DapperDan]

So going to be adding headers,cam,and probably porting the heads, on the fence about dropping compression ( will be running Ms109 + Meth)
Right now stock with just cat deletes about 12 lbs
Trying to figure how much boost will be lost with the improved flow so I know how far to pulley down to get it back. Do you lose a lb with headers a lb with cam a lb with ported heads , is there any general rule or formula how much boost you lose with each mod.

[KingLT1]

Boost is just a measure of restriction. The supercharger still is going to spin the same rpm. If you pulley down to get the boost back you are likely going to be spinning that P1 well past it's efficiency range. At 12 psi on the SBE it's likely there already.

That being said my guess is you will be around 9 psi.

[GT-ER]

The loss of boost just means the engine is more efficient and will in turn make more power. You'll only need to raise the boost if you want to make even more power, but don't feel like it's needed to take advantage of the mods.

[laynlo15]

We usually see about 1.5 to 2.5 lose of boost with long tubes and no cats. But since you already have no cats I'd say about 1.5 to 2 on the headers, if you lower the compression a little less also. We also see about 1.5 to 2 psi for every 1/4 inch of smaller pulley change and that's about what I've seen on my changes also. With Meth and Ms109 you'll also be able to run more timing. I run about 25 degrees with no issues on my Manley forged motor and it takes less of a fuel system to run VP/Meth compared to E85.

[DapperDan]

Originally Posted by KingLT1

Boost is just a measure of restriction. The supercharger still is going to spin the same rpm. If you pulley down to get the boost back you are likely going to be spinning that P1 well past it's efficiency range. At 12 psi on the SBE it's likely there already.

That being said my guess is you will be around 9 psi.

If I'm doing the math correctly its currently spinning about 55000rpm and the procharger chart says a max of 65000 for the p1x. So I'm thinking I have alittle left to play with or would it be better to step up head units instead of maxing the little one all the way out

[wnta1ss]

Originally Posted by KingLT1

Boost is just a measure of restriction. The supercharger still is going to spin the same rpm.

How fast you spin the blower IS how hard you are pushing the blower. There is no 'get it back' to do, you aren't actually losing anything with the headers, porting, etc, 'boost' is just a number.

[wnta1ss]

Originally Posted by DapperDan

So going to be adding headers,cam,and probably porting the heads, on the fence about dropping compression ( will be running Ms109 + Meth)

Dropping compression means less efficiency for the engine. Whether it's worth it to put up with that is up to the customer. Since you will be using 105PON fuel plus methanol injection, with your P1X blower, my opinion would favor sticking with stock compression (like the Vengeance Racing 'drop in'). This because you'd have to turn the small blower really hard to make up for the low compression. And turning the blower really hard could mean IATs rise significantly. To my point of view, the lowered compression would make more sense if you were doing an F1a or F1a-94 with a much bigger fuel system and going for 1000+ rwhp type of thing. In other words, blowers big enough to move sufficient air while spinning at a rate where they are still efficient. Just something to think about while you plan your rebuild.