LSxSprayed

we checked compression if i remember is around 155-165 in all cylinders. Cam was degree'd

Forcefed86

iTrader: (4)

Flat top 5.3? That’s really low cranking compression wise. For reference I had 190-200 with the isky triple 12 cam about 1 degree advanced. I had 140-150 when it was 8* retarded installed dot to dot. Who degree’d cam? Sure they did it correctly? I picked up 12 mph with no other changes after correcting the cam timing. I’d expect it to be a little lower with the 317 heads, but that seems excessive. ( I ran the 243s and LS9 gaskets) Not saying that’s your problem, but you might want to double check.

Boost leaks would be my next guess? Built a pressure testing rig?

LSxSprayed

its lower compression, used dished pistons and a little thicker gasket. cam is done right we know that for a fact

Forcefed86

iTrader: (4)

So how low is it? Weight?

My 317 headed dished piston 5.3 was 8.6:1. With the small S475 on LS1 intake and 26lbs it went a best of 8.93 @ 153 @ 3050lbs. That was with the LS9 cam.

The BallSS

iTrader: (9)

I went 12.2 @ 123mph with a TC78 and street radials lol.
Something is definitely waaaaaay wrong, I hope you get it sorted out.

LilJohn

cams too big for starters. probably having backpressure issues.

LSxSprayed

The car sounds weird too not like a normal turbo car

LilJohn

for a low compression 5.3 that cam is huge. its basically the same thing as my stage 3.

And just for reference... the stage 3 shelf cam is what is ran in JP Delisi's car Black Jesus.

So you have the same camshaft as whats in a 10:1 408ci stroker motor with LS3 heads and a Hi ram with a GT55 garrett hanging off it.

Id bet a fairly large sum of money that the car would go quicker and faster with a smaller camshaft.

The BallSS

iTrader: (9)

Shouldn't that cam be in the 220 @ .050 range and 115-116 LSA for a 5.3?

LSxSprayed

MEssaged you on fb, ill send the video

newschool72

iTrader: (12)

If I had not read all the posts first I would have suggested the same thing. That cam is huge for a low compression 5.3 ! Cranking compression is right in line for that much cam too. Be way better off with a 2teens at .050 with a 5.3, IMHO.Your last post is on the money, OP! LilJohn will steer you right.

LilJohn

not that wide no. you could be anywhere from 212-220 on the intake side with it.

with it being to the lower end of the spectrum i would for sure take a more moderate approach to the cam timing.

The BallSS

iTrader: (9)

So one of your Stage 1 or 2 cams I'd imagine?

LilJohn

stage 1 or even smaller maybe down into one of the truck cams that serve double duty.

01ssreda4

iTrader: (96)

Can you explain a little further? Was it supposed to be 8 degrees retarded dot to dot or was it cut wrong?

B18B1LS1

iTrader: (12)

Post the whole time slip. Your ET and mph are way off. Curious where it starts to fall off

LSxSprayed

It falls off everywhere lol

ls3fox

whats the weight of this thing and what turbo is on it

Dian

when i used to do turbos i would make provisions to measure bosst before and after cooler, pressure before and after turbine and egt before turbine before attemptig a first pull.

Forcefed86

iTrader: (4)

Sure the cams too big and not optimal for that setup. But you really think that’s the main cause of the car trapping 12-20mph slower than it should? Something seems way off with that combo, other than an overly large cam. Powers gotta be going somewhere. I’d find out what springs are on it and double check push rod length is correct. Are you running aftermarket lifters? Build a simple boost leak check rig. (lots of videos on you tube for this).

Think you could have something collapsed on the hotside? Flex coupling maybe? Rig up a quick back pressure gauge ($4 push to reset tire gauge works great) on the exh system and see where you’re at. Also turn the thing down. Try 15ish then bump a pound at a time watching gains. As soon as they level off, stop adding boost. When you stop seeing gains keep adding boost, things tend to break.

My Cam was cut fine, the key way in my crank was about 8* retarded. So when I installed my cam with the factory timing set it was 8* retarded from where it should have been. Seems a few newer gen4 engines have this issue, most do not. If the cam hit the card and was degree’d properly you should be fine there. If the “Professional engine builder” said they degree’d it and you have doubts, check it.