Quick question!

[Shocker98GT]

Superchargers don't like high compression but nitrous does am i right? So say someone has a 96-98 block with the pi swap forged internals, and a sc. Then another guy has a 96-98 block with npi heads that are ported and polished forged internals, and a sc. Now they both want to create as much boost as possible with the sc and still be runnin safely. Who is going to be able to run more boost before their engines can't handle anymore? That's kind of what i've been wantin to know. O0

If you're getting forged internals then you're able to choose your piston dish, in which you could achieve the same compression with either head. You don't want to drop below 8.5:1 compression ratio anyway. In the end, PI car makes more power. Or, in general, the car that is capable of the most airflow before adding the supercharger is the one that wins (all else being equal, i.e. camshafts suited to the job, etc.)

 

[IEC Stang]

Thanks for all your info guys it's helped me to understand all this a bit better. I like the idea of being an underdog so when the time comes i am going to port and polish my npi heads so i can run 10psi max boost safely. I just think it will be easier on the engine with my lower compression. Plus i just like the idea of making good use of my existing heads. O0

 

[scarface]

I ran blower cams, I figured if I was going to change cams, might as well get after market.

 

[Jrgunn5150]

Thanks for your input Jrgunn5150. You said that I can even run up to 10psi. with a good tune?

Yes it shouldn't be a problem asuming your bottom end is in good shape.

PI cams would be an improvement, but blower cams would be even better.

 

[bigjohnson4.6gt]

would it be alright to run blower cams without a blower? id assume you could with a good tune, but mostly because i gotta save up for a blower

 

[97stanger]

yes you can, and in the long run it will save you money from buying N/A cams and then swapping them out to blower cams when you get the money. You just won't get the full potential out of them until you get the blower.

 

[bigjohnson4.6gt]

yes you can, and in the long run it will save you money from buying N/A cams and then swapping them out to blower cams when you get the money. You just won't get the full potential out of them until you get the blower.

would i be losing any power/torque with them or is it just gaining over stock PI cams? At this point im thinking of going with VT Stage 3 cams

 

[voidfinger]

ok guys, sorry but i'm thinking of this too. Say if i was to build a 98 short block with the stock cc pistons, what would the cr be with the pi heads? i've heard from 10:1 to 10.7:1 Now, if i was to build a cobra motor with stock compression what would it be at??? Now if you were to put a vortec on it and a meth injection kit, what would be the safest/highest boost for it, if it had forged pistons and rods? thanks dudes.

 

[Jrgunn5150]

Stock everything, NPI block and a PI head = 10.4:1 compression ratio.

Cobra motor compression depends on the year.

Safe boost is a disputable point, but I would say you should be safe to 18 psi or more at that compression with Meth. Basically, with a good tune /good fuel/forged internals, you can run all the boost you want on the street.

 

[voidfinger]

O cool, i didn't know what the numbers where for the cobra's i thought they were all 10:1 in 96-98? i'm not messing with the 99 up ones. lol

I would have the forged pistons/rods, pump 93 oct, and i would probably have a safer than most tune I'm thinking of only going to 14 or 16 psi.

 

[Shocker98GT]

BTW, ported P.I. heads tend to have larger chambers because they grind down the swirl dams and smooth out the chamber. Heads like the D.S.S. full ports have a 50cc chamber, where the non-PI head is 51cc so the difference is negligible. Just have to know who's porting it.

A good tuner is a must as well. Really if you have a good enough tune you could run a supercharger with the raised compression, you just have to make sure you get a guy that knows what he's doing. IMO the best 2V/4V tuner in the industry is Tim Barth of T&J Performance (modularpowerhouse.com, the ones that make the mongoose kits, etc.). He's renowned for his ability to make very safe and powerful tunes, and he doesn't do load tuning like most others do, he sets his timing curves up differently. I haven't heard a single complaint from his products and services, everyone that I've met that dealt with him has been completely satisfied with his work O0

 

[voidfinger]

cool