mike907

I am fairly new here, fairly new to modification of the ls type motors. not new to performance stuff.

short run down, i have a 74 3/4 ton cm truck with a 383, and end goal is a turbo/twin turbo 408 with a 4l80/6l80/90.

I have a 2002 lm7 5.3, and most of an lq9 6.0. I am pretty set on doing a twin turbo setup. shooting for 600 rwhp (or more) my plan is to use the 5.3 to use for fabricating the piping etc. if it grenades no big, im going to build the 6.0 block to a fully forged 408. also planning on starting with some ebay turbos till i get the swing of it, then purchasing quality turbos for the 408.

that being said, i have been reading through different threads and posts. I even bought a book to help learn me some stuff(still need to read more). most twin setups seem to be right around a 66-67mm with ive seen anywhere from a .68 ar to like .90 ar.

I was wondering if anyone had suggestions or what you are running for a twin turbo set up? what kind of headers are you guys using ?

do you guys use a standard calculation for figuring turbo size?

also, wrong section for this question i know, but when i tore the 6.0 down all the way, the 2nd from the rear of the engine cam bearing came out with the camshaft, i had to get the bearing over the last journal on the cam to get the cam out, not too worried as i am going to rebuild the motor and am not reusing any of the internals, normal? abnormal? spun cam bearing? was here, thought id ask

forcd ind

iTrader: (7)

Prob you will get asked if you want the turbos sized for the 5.3 or 6.0
A lot of guys mod. the stock manifolds for turbos, a lot based on your fab skills-there are some ready made manifolds also, based on budget
As far as the cam bearing, yes some have experienced them coming out-doesn't seem to be a reason for it, but a good machinist should mic the cam and also place the bearings in the correct place-some pin them in
Is this street or some track-street use you prob want a quicker spool

mike907

Turbos porbably sized for the 6.0, since that is the ultimate goal, and have it just running and going for the 5.3. I have seen the flipped truck manifolds, i am probably going to opt for some some forward facing headers.

On the cam bearings, good to know, i was worried it spun and possibly ruined the block.

The truck will be used for street/summer driving, the nearest track is 350 miles away, so i doubt it will ever make it there

JoeNova

Your goal is 600whp. You could pretty much picky any 60+ mm twins and overshoot that goal without trying. Size them for the 5.3 with compressors capable of making 600 on a 6.0. When you.make the switch, you'll have similar power with much faster spool.

mike907

alright, yeah if it makes more than 600, i will do some sort of happy dance, 600 just seams like a reasonable request see people making tons of power with justa bone stock 5.3, of the 3 cheap fast and reliable, im shooting for reliable and fast but the truck does weigh 6200lbs, so we will see