Chris'stransam

iTrader: (7)

Ok , lets say I am building a 408 with lsa heads and it is built for boost . If i twin turbo it when would i see boost if i use 5862 turbo compared to a 6262 turbo ? Would you do a 370 instead of the 408 and witch turbo would u use ? and when would u be at full boost ? I think I have found out how i am goning to build this , but need help on motor and turbo size . LOL

stevieturbo

More importantly is how much power do you want ? Where in the rpm range are you wanting most power ?

Full boost depends on many factors...first off being how much boost is full for you ?

Auto/manual will play a part, as will overall design, engine size etc

408 implies iron, 370 implies alloy...which do you want ? Size will have little bearing in ultimate power goals.

Chris'stransam

iTrader: (7)

I am looken for 800hp . The car is a 6speed. i will be using a iron block eather way i go . weather i use a 4" stroke or the stock 3.622 . the bore size will be the same 4.030 . 408 or or 376

stevieturbo

Unless you need the extra torque or spool from a larger motor...ie 4" stroke, I wouldnt bother.

For 800hp may as well go with the smaller turbos, again unless you arent fussy about spool, then go for the larger, then you'll have a little room to grow later..
I'm sure either will be making good usable boost well below 4k anyway.
Probably 3k

But it will be dependant on manifolds and camshaft too.

PPI Typhoon

iTrader: (1)

I put a pair of 6266 on my LSX376 aiming for 800-1000

01SSRMS

iTrader: (7)

Also going with 6266s on my 376 twin build based on recommendations from a sponsor. Same goals of 800-1000 with a 6 speed.

jmm98LS1

iTrader: (28)

Same story here, 10:1 370ci and twin 6165's with a 6 speed. Should spool silly fast and make enough power to be useless on the street. Perfect!

Chris'stransam

iTrader: (7)

But y not use the 4" stroke and not lean on the turbo to hard and have the motor as efficient as possible and make good power off boost and crazy power on boost . That would make fun .

slowride

iTrader: (3)

I'm only on my 7 psi gate springs right now (which slows spool over a controller) but I can build a few lbs in the low 2000 rpm range and a full 7 before 3000. My turbos mount right off the manifold so that helps. Engine is my old NA stroker 383 with ported 317 that drop compression to ~10.0:1. Turbos are journal 6265 turbonetics cast wheels and a .82 t3 v band housing. Even with my base tune it can blow off the toyo DR's easy in 2nd, but they are old and it is getting cooler out.

oscs

iTrader: (19)

Have you ever seen a 408 piston side by side with a 370? The 370 has WAY more meat on it. There is also something to be said about keeping stock geometry when building a boost motor. At your desired HP level you can absolutely replace displacement with boost. In turn picking up a little reliability (my opinion) with that said I stuck with a iron block 370CI 9.5:1 twin 66/65's shooting for 1k to the wheels through a 6spd

stevieturbo

There are a few negatives about a 4" stroke, and more in an iron block which has shorter liners.

IMO these outweigh any positives unless you absolutely need that extra torque...ie it was a very heavy vehicle or something

slowride

iTrader: (3)

I know if I didn't have a 4" crank engine already I wouldn't switch to one. Stock iron blocks have the shortest cylinder of them all.