i know forced induction creates compression so with that being said i'm wondering what you guys are running compression wise on twin turbo or blower motors ?
thanks

 

All depends on how much boost you plan to use.

 

say i decide to run 9-1 pistons how much boost could i run if say i'm running twin 50 trims .call it a 350 motor dart heads
is there a stickie on here of building a twin turbo'd small block ?

 

it still depends. your weak points on a (properly tuned) forced induction motor will be the crank, rods, and possibly the pistons (but those will be more temperature sensitive). Stock 350 internals probably wouldnt appreciate much over 9psi - so twin 50 trims really are over doing it. if you want to boost big look into forged internals first

 

alright give me some idea of what internals i'll need to hold 15-20 lbs of boost

 

It really does not matter how many turbos you want to use, what matters is the amount of boost. 15-20 PSI doubles the normal air pressure. Theoretically, all else being the same, that should double the power, but it won't. Inter cooling is almost a must. For the engine to live with that boost it is going to need forged pistons, rods, crankshaft, and 4 bolt mains. Also it would be best to hold the compression ratio to no more than 8:1, in order to control detonation and keep the engine in one piece. The low compression will make the engine soft at the bottom end until the turbos spool up, that is why I prefer superchargers.

 

thanks for the info ,my last car had 8.5 -1 pistons but it was a 4 cylinder . i knew i needed fairly low compression to pull off twin turbos , i will use an intercooler plus a meth injection kit . what do the v8 guys use to tune with ? i was tunning on my last car with a piggy back settup , do they make such a thing for this car ?
.

 

the larger piston bore also requires a lower compression than the 4 cylinder. thats why a large displacement engine will run around 8.5:1 CR to run on 87 octane, but a small bore 4 cylinder can run 10:1 or higher and still run on 87 detonation free.

as far as tuning, what do you plan on running? factory style fuel injection, aftermarket fuel injection, carb?

and as far as the motor itself to handle 15-20 psi, you will need forged pistons, rods, and crank. i also suggest a main cap girdle, valley girdle, and head studs to keep the block from cracking.

now, i was just reading in my camaro performers magazine about a twin turbo first gen. its a 407 sbc, individual throttle body fuel injected running turbonetics 60-1 HIHI P-trim at 10 psi. their compressin is 8.25:1. the shop that built the car was prodigy customs www.prodigycustoms.com i suggest maybe contacting them in reference to the project "Motiv8er" and they could direct you to the engine builder

 

thanks man ,i'm still in the planning stages thats why all the questions .
i'm thinking i'm gonnas go with carbs maybe a tunnel ram an dual 4 barrels with twin 50 trims . i'm planning on getting a 12bolt rear end an using 3.73 gears .i syill want it to be streetable . i'm gonna check out this company you gave me the link to .thanks again .

 

anybody else ??????????????