brandon6.0

iTrader: (32)

This might be a long read. Kinda hard to explain. I have a customers obs ls swap. We swapped this 5yrs ago with a built 60e, 4.8 btr stg4 truck cam, tbss intake etc. My tuning. Been tuning close to 15 yrs. Truck ran great! Plenty of power pulled to 7k, great power everywhere for a 4.8 couldn't beat it for a simple combo!

this yr we went a diff route. Gen4 6.0 square port heads, tick stg3 sns cam, holley high ram, built 80e etc. Truck is down on alot of power. Revs clean at idle and feels strong but down the rd it's a dog. Weak through out the pull and gets to 5500rpm it noses over hard. I can short shift it and it will start pulling again. Just doesn't run like a well built 6.0 should

Lil more on the combo.
4.10 posi
80e FTI billet 3800
-6 braided fuel lines with aeromotive regulator
longtubes to 2.25 true duals and flow 40s
4" Cai
92mm tb with high ram 36# flex inj.
etc.

I disconnected the Cai and ran it just open tb without any luck. I think it's either blowing through the converter or exhaust restriction. Idc is showing around 80% at wot. I even swing timing to 29* to see with no change from 24*. We do run a lingenfelter 58 to 24 box on this combo. Thoughts?

wlink14

That exhaust is pretty small and with the addition of mufflers I would imagine it is choking your high flowing engine.
Easiest way to troubleshoot would be disconnect the exhaust the the headers and clamp some 1' extensions on there and go for a rip.

brandon6.0

iTrader: (32)

Yea I think thts what imma try tomorrow to see what happens. I think I have some spare exhaust parts laying around

Y2K_Frenzy

Coming way out of left field here, but as far as it being a dog on the road could that partly have to do with the 80e’s gear ratios?

brandon6.0

iTrader: (32)

Imo no. I've built plenty of 80e combos and nothing similar to this one. My stock 06 5.3 crew cab will walk the dog on this truck currently. I've done over 30+ ls swaps diff combos trannies etc. Over the yrs. I actually assembled engine and built the trans myself. I build trannies daily. It puzzles the he'll out of me. This truck had this exhaust on it. I would have had 3" true duals with magnaflows imo. I was working with what he had.

I think it's exhaust tho. Flowmaster are known for comming apart inside. Ls don't like restrictions anyways. I'll try exhaust tom throw something together and see if it picks up some power.

wannafbody

iTrader: (2)

Square port heads will be soft down low compare to cathedrals but should make more power up top.

brandon6.0

iTrader: (32)

Yea I know. But it can't even make it past a 5500rpm pull without nosing over hard. It's got a power loss some where. Troubles like this suck.

Imma try and rig up a fuel pressure tester as well tomorrow.

1988montecarloss

iTrader: (6)

running out of fuel/something choking it if the tune is right

G Atsma

Which fuel pump are you running? As said just above, it might be starving for fuel.

brandon6.0

iTrader: (32)

Pump we installed yrs back. Usually a walbro 255 pump. I gotta order an adapter to read fuel pressure with the braided line stuff. I'll report back finding

Old Buzzard

As mentioned:
"longtubes to 2.25 true duals and flow 40s".
The pipe size and the "blowmasters are where I'd start.

brandon6.0

iTrader: (32)

Well got a fuel pressure gauge on it. Pressure is fallen off bad. Around 40psi at wot. So gonna install a aem340 and go from there. Exhaust is gonna be our next issue I'm sure

DualQuadDave

iTrader: (6)

Those 36# injectors are too small. Figure it this way, GM put 42#'s on the LS3 and 50#'s on the L92 on a stock motor. You have a hiram and a big cam, you need more. Easiest/best solution is the 50#s and have enough fuel pump.

Old Buzzard

What??

G Atsma

From GM, L92's get 30# injectors, NOT 50#. What BS!
LS3 does get 42# injectors.

Keith

L9H gets 54lb/hr, right?

G Atsma

Yes. Possibly flex-fuel, for the huge amounts of fuel they consume when it's ethanol-heavy.

LilJayV10

iTrader: (39)

You are not running out of injector with the 36lbs, that thing isn't making that much power.

If the low fuel pressure is the problem, which it's a good possibility, I would have thought it would have been seen on the WB02. Hell, you probably could see it on the narrowbands too.