I have a question for anybody who can answer. why when you put a s/c on a V8 do you only push about 12 psi? i run at least that in my gtp on a bad day in my GTP and its a V6. im just wondering.

Boost is realative to the amount of space in the cylinders if you were running an 871 on 350 vs 383 same heads, cam, and rotating assembly, the 350 would make more boost because it has less space for the forced air to fill, so the manifold pressure is higher on a smaller engine. Boost is also controled by how fast you spin the blower but more boost means more heat on a roots type blower hinceforth the innercooler. On the old hydro I used to crew for we had a PSI blower that made 60lbs of boost on a 572inch alcohol burning hemi.

Damn, thats alot of boost. Someday i will have somthing like that. Of course thats after i have my GN! HEHEHE.

alright, i've got a boost question too. my best friend is looking at that vortech unit for carburetted applications.

he's got an '84 hurst olds w/ 307; 8:1 compression; aftermarket cam (powerband from about 2500-6250 right now), edelbrock performer intake w/ rochester quadrajet. he's thinking of adding a 1" spacer plate to adapt up a holley square bore double pumper and putting that sc onto the 307. how much boost could we run on cast pistons without causing damage, and how much of a power gain (in percentage) would that be? vortech says nearly 18psi, which would be about an 80-85% gain. sound about right?

jason

you may want to tell your friend that the Olds motors aren't very foregiving with cylinder pressure. i wouldn't put no more than 6 or 8 psi into it unless that motor is setup to handle higher pressures..O ringing and H beam rods are a must, i'd also get a nice set of blower pistons.

Edited by Cutlass (Wed Aug 14, 02   4:07 PM)

will do! thanks. we just found a guy in town who can get us a set of custom JE pistons for around $700 set up however we want with rings. any places down there that you know of who can cut us a better deal than that?

going with the low boost to start couldn't hurt. why h beam rods though? wouldnt' a good set of oliver i beams be just as good? from what i've read, i can't recall the difference between the two, but i thought it was that one was strong torsionally (the i beams), and the other was strong vs. significant linear compresison (h beams). did i just answer my own question?

good to hear about your engine!!

jason

thye reason you run an h-beam rod is for strength. they can take the added cylinder pressure and force of a blown or nitrous motor.

accually thats just the coommon myth about h rods....the real trouth is that h rods twist less. and i rods are lighter. but the h rods are better for nitrous and superchargers because force induction tends to twist rods more...but a well built i rod is no less stronger than an h.

That makes sense but can't be sure about the twist thing. If your running a dished nitrous or blower piston I can't see why the force would twist the rod. I know that it can tend to make the piston rock on the clearance of the ringland and scrape your cylinder. But it's true the average h-beam is stronger compared to the average I-beam because of added weight and surface area of braceing.

the twist comes from the flow of air in the cylender. the combustion chamber is kidney shaped...air is swirled from the intake valve compressed ignighted and then the exsplosion is swirled to the exhaust side of the combustion chamber...thus creating the turning effect. naturally in a forced induction ingine the amount of gasses that are swirlng creates a greater twisting effect. thats all i have to say about that...

Pretty impressive! Now I see what your saying.

uHHHHHHH O..brandon somebody's smarter...lol..your gonna dieee!! clown lol ...

the problem with Oliver rods is the $$$$ you'll spend on them, you can get a nice set of H beams and still have a bit of cash left over to use somewhere else.