Driver311

iTrader: (1)

Easy. I have heard from multiple peeps that these headers will drop boost about 2psi. In fact Im running a 3.4 pulley to hit 10psi at 5700.

03sierraslt

iTrader: (22)

Yes, Headers and ORY will drop close to 2lb. On your 4.8 I would guess more around 1-1.5lb. 2 or so on a larger motor.

Driver311

iTrader: (1)

So guys Im gonna be going back to the dyno on tuesday. but a wideband on the truck and the afrs are pretty rich. Its in the 9s from about 2500-4000 then it progressively climbs to 10.5 by 5700rpms where rev limiter is set. So here is what we are gonna do. Gonna lean the bottom end out to around 12.5 then have it progressively get richer as boost climbs to peak where we will have it at 11.8ish. We are also gonna raise rev limiter to 6100-6200 for the street and probably make a few pulls to 6300-6400 to see how it likes it. Im guessing itll continue to make more boost the higher we raise it. Right not it barely taps 10psi at 5700. Im hoping itll make some good gains getting afr dialed and raising the rev limiter. Thinking it might get 11psi by 6200? Whats your guys thoughts? Im hoping the raised limiter and leaning it out till take it to 500whp at 6200. The dyno operator thinks itll see more like 515-520whp based off how aggressive the dyno climbs to 5700 right now. All I know is it pulls really good past 5000 but when it shifts it kind of falls flat then picks back up. Im hoping the extra 500rpm of limiter keeps it more in the powerband. Ill post the graphs before and after tuesday night. Should be interesting.

La Chochita

ull see and feel the difference once u lean out that rich part...and I'm thinking u will gain from 1 to 2 psi from 5700 to 6200. Maybe u will break the 500 hp mark...good luck on it.

beastmode

iTrader: (52)

Anymore updates on this?

Driver311

iTrader: (1)

Havin issues with my tune/tuner not sure whats up. Been to the dyno twice now and the idle is still not right (going lean) and throwin a maf code and o2 sensor code. So isnt quite dialed yet. Getting frustrated to tell you the truth. My maf came apart on the dyno so we glued it back together. The dyno tuner thinks the maf could be issue or the right front o2 sensor may be fouled out. So i bought a 2nd maf but truck dont run right with it. So its gonna need to be redialed. Problem is dyno is 280miles away and made the trip twice now LOL Fack

ltr450ryder

iTrader: (13)

do a sd tune and forget about the maf

Driver311

iTrader: (1)

He wants alot of mulla to do that. Im really thinking about selling the procharger setup the way it is. Custom piping, fmic and all. Then swapping in a 2008+ 6.0 with my bolt ons, add a cam while out and tune. Should net me close to 400whp 400ftlbs and have way more fun factor than the procharger has now. I love it dont get me wrong but I do wish it hit harder down low. Give it more fun factor. Then shortly after just do a simple smaller turbo setup. Still on the bench right now. We will see how it finishes out. Right now when it shifts it just falls to far out of boost for my liking. Needs 4.11s and that will help alot i think vs the 3.73s.

beastmode

iTrader: (52)

I'd invest the money in a good aftermarket converter before I swapped from 3.73s > 4.10s.

Jr. SXT

Do you have a stall? It falls flat after it shifts because the 4.8 lack torque on the lower rpms. a Stall will definatley help.

I had a similar setup in my 2007 NNBS RCSB Sierra 4.8L. I had the same situation, bought a used P1 put in a FMIC and flex fuel injectors and put down
463rwhp bone stock exhaust system cats and all on a maf tune. only other mod was a 6L80 Swap with a 3k stall. I deleted the cats to reduce back pressure and i will tell you the the exhaust pipe would whistle at WOT lol.... look like a damn leaf blower .

I had the same problem that it would fall on its face when it shifted even with the 6l80 and 3k stall. She was a beast on a roll but from a dig she was a pig.

I swapped the 4.8 for a 5.3 i had laying around and did a DOD delete and ls3 cam, head studs, crank pin kit, Pacesetter LTs 3" ORY to 4" at the Y through a 4" Magnaflow all the way out the stock location, Walbro 255, and a True Trac with stock 3.23s. and swapped out the E-38 to a 08 model for SD Tune. She put Down 503rwhp. running out of injector. gained a lot of Torque on low end, just what i needed.

I then put a 2.8 pulley (6Rib), Vic Jr w/ Wilson 102mm Elbow, NW 102 TB Ford 47# injectors, and a 230/228 we had laying around. 569rwhp. She was a beast! only problem, was i was throwing belts like crazy becuse the bypass valve was too small and would shake the unit. had to drive it just right so it wouldnt throw it. The 6L80 started giving me problems and would act stupid and get hung up between shifts at the current power levels, swapped it for another fresh rebuilt 6L80 with red Clutches that held up for a short time period. Only got 2 Passes the one night i decided to take it to RPR and did a PB of 12.5 @ 99mph with shifting issues. I got tired of it and sold the procharger decided to do a turbo setup and go back to a built 4L70

Hang in there with it brother its alot of fun. Wish i would of stuck with it a little longer.

Sorry for the Thread Jack and long read. Good Luck with your build!