Ive been reading everything you guys have posted about going blown through.. i understand most of it and gonna try to run a twin setup on my 350 ci small block chevy.. one snag i have seen though is choosing which cam to put in that will be compatible with the setup. i see that most of your guys cams have a LSA (lobe seperation angle) of 114.. most small cams ive been looking at.. are hydraulic roller.. but have a LSA of 110... is it a must with a turbo? i see that valve overlap is a huge part of choosing the cam..basically i wanna know what kind of numbers im lookin at here to buy a hydraulic roller cam for my motor.

 

http://www.forcedinductions.com/help.htm There is a nice cam guide here for choosing a cam. Or you can always call CamMotion and have them spec out a cam for your combination.

 

thanks.. the site was very helpful

 

i have forged pistons and rods.. my 350 sb is bored to .060 though and only a cast crank.. if im lookin to run 10-15 psi of boost then will it be required to have a steel crank? i figure that my motor will top out around 6000 rpm and that it will be fine with the rest of the rotating assemply being forged.. also any chance of cylinder wall damage under boost due to the bore?

 

Don't forget that boost is not indicative of power, but of restriction. Yes if you take two motors that are basicly the same you will consistely make the same power with the same boost, add heads cam and intake that are better designed for the setup to one it will make more power than the other even with the same boost.
I would tend to stray away from a crank that's been cut heavily, but below 600hp I wouldn't be too afraid of something cut .010. For the most part the Grand National guys seem to do pretty well living by that rule. For a 350SB they say the maximum "safe" bore is usually 30, but your milage may vary. If you're looking for 4-500HP I'd just throw together what you've got, gap the rings for forced induction and make sure the compression isn't through the roof and run it.

Just change out the cam unless this is ultra low bucks, it would probably work with a larger sized turbine (lower back pressure) but it will probably end up costing you power in the long run, and a wider LSA will make it more streetable. You don't need to have a ton of overlap to make good power on a streetable turbo setup.

 

ive got all hyrdaulic roller cam, and lifter setup.. a turbo setup cam with a valver overlap of 1, also have a compression of about 9:1 or maybe higher 8:1.. ive been trying to setup the motor as much as possible so that i can run a twin turbo setup as a winter project..forged pistons and rods are pretty much all i need now.. the block at .060 over is the only thing that is really got me wondering if i should just get a new block and put my rotating assembly and stuff on that or try and use my block and see what happens..

 

.060 over is a lot, so if you don't plan to push it, it might be okay, but if you plan to make big power you should just find a block you can go .020 to .030 over.

 

yah seeing i got so much into it now im figuring that with everything properly balanced and with the right twins i can prob get around 10 psi of boost and not blow a motor..hopefully.. i wouldnt wanna push it way over that and try for the 700 rwhp numbers i originally thought i could get.. when i can afford another block though we shall be in buisness