Turbo-Geist

I figured I would post in here since there are likely more people running an LS7 intake and forced induction than over in the C5 section.

I was doing some 60 to 160+ mph pulls yesterday on a runway and noticed some cracks on almost all of the reinforcing ribs of my LS7 intake where it bolts to the head. Manifold pressure was approximately 18psi. Has anyone seen failures in this area? Any idea what may have happened?

Turbo-Geist

The heads have only had a clean-up mill and the intake was torqued using an inch pound torque wrench and the proper sequence.

irok

did you do the clean-up mill yourself?took too much off or something not straight

Turbo-Geist

WCCH did the heads. I had another stock LS7 intake on previously and no issues.

Unreal

Strange freak failure.

My car this morning alone saw 24-25psi for 20-25 pulls. Not to mention the 1000+ 20+psi pulls without issue. I would throw another on and move on.

realcanuk

Tough one there. Doesn't look like would be caused by boost. I would say over tightening but if you torqued it shouldn't be that.

RecMech

Definitely not where I would expect it to fail.. Looks like bolt stress as others have stated.

My LS7 intake sees 27 psi with no issues yet.

Turbo-Geist

Great. I appreciate all of the input. I bought this one used so not sure what may have happened. I'll pull it off this week and see if maybe it was contacting the valley cover bolts. The plan is to hopefully pick up another used one for a good price and try again.

EX1

I'm with these guys. The failure point makes me think it was something related to installation. I put 23-24psi through mine

Smoove

Looks like more than 89in-lbs on install.

Turbo-Geist

Another LS7 intake showed up this week so I finally got back to it tonight. Prior to unbolting, I set the wrench on 70 inch-lbs and it took a few pulls before the wrench clicked. Clearly the bolts were not overtorqued.

Also no obvious signs that the valley bolts were too tall and causing an issue. No marks or indentations on the bottom of the intake.

I'm not sure what else to check. You could see the plastic being relieved of stress as the bolts were loosened.

Here's a shot showing the valley cover bolts for reference.

stevieturbo

As others suggested, check the intake does sit perfectly in the vee....in case either block deck or heads have not been machined quite correctly and there is a misalignment there.

Or maybe the intake itself had a slight manufacturing defect and was not perfect.

realcanuk

The intake was bought used. Anything could have happened to it previously. I wouldn't spend too much time trying to guess what.

Turbo-Geist

Block was decked by Race Engine Development (RED) in California and then checked by the machine shop prior to assembly. Heads were done by West Coast Cylinder Heads and then also checked prior to assembly. Both of these vendors are highly capable so I'm ruling out those possibilities.

I had a different stock LS7 intake installed prior to this and it didn't have these issues.

Yep. I'm going to pay even closer attention when this latest used one goes back on. I would have bolted it on last night but it was shipped in Styrofoam and not bagged. Small particles got inside the intake, so wash it out today and then install tonight.

Dyno on Friday. Plan is to add boost until it quits making power.

schpenxel

45psi

Turbo-Geist

psia or psig?

schpenxel

I meant psig but was kidding

Turbo-Geist

Turbo-Geist

Following up and closing this one out.

I finished the intake swap Friday morning and went to the dyno. We made 6 pulls in the 18 to 23psi range with zero issues as far as the intake goes. There must have been a pre-existing condition with the other one.

NeedaC6

Glad you got it fixed, Ben. Like others have said, I think the intake just had issues not related to your install.