Summerkruse13

I have new Corvette LS3 exhaust manifold and can use the 2 bolt flange. Wondering if those are good enough for 30+ boost. Or I can get truck manfolds and weld a v band on them? Any thoughts?

tektrans

Idk a ton about FI but it sounds like you are talking about a turbo set up so my question is, wouldn't the 30lbs be after the turbos? In that case what's the difference?

mn_vette

I think we need a few more details on your planned build before suggestions can be made.

Summerkruse13

What do you need to know? Just asking if the 2 bolt flange on the manifold can hold 30 plus P. SI or will at leak, and I'd be better off going to a vband clamp. Seems like a simple question.

old motorhead

You're not going to have 30psi there unless you have some SERIOUS restriction in your exhaust. I think that's what tektrans was getting at. I'm sure there's a little pressure between the ex manifolds and the turbo(s), but it shouldn't be near that much. Pressure there and boost pressure are two completely different things.

Summerkruse13

Umm, yes you are! Boost is psi. Psi is the measurable unit of boost. Between the engine and turbo it is also called back pressure, measured in Psi, Kpa, etc. I see 30 plus psi in the exhaust side every time I drive it. In fact more.. Sorry but you both sound very out of your realm. Is my question that hard?? Just asking if the manifold will hold up at the 2 bolt flange.

MRSUPRA

mn_vette

Reading the original post there isn't much details in there. There is no mention of a turbo, so I didn't want to make an assumption. Also "30+ boost" can also be taken in multiple ways. My initial thought was 30psi intake pressure, but in your other post it seems that you are talking about turbo backpressure. It just helps to be specific to help us understand the exact question.

The 2-bolt flange will hold back pressure fairly well with the gasket. I would worry more about the physical setup in the vehicle and what works best for that. If you are doing a max effort vehicle I would suggest looking into doing custom headers that will get you the best velocity in the exhaust.

Creamo3

Can you cutoff the 2-bolt flange on the LS3 and weld a v-band flange to it? A 2-bolt flange with a flat gasket is less than ideal unless there's some sort of lip between the manifold and up-pipe/cross over to the turbo. I'm not sure if you're planning a big single or twins, but make sure wastegate priority is good and fit as large a wastegate/s that you can to help with backpressure and boost creep.

tektrans

You asked for any thoughts, so people are giving you thoughts, lol
Then saying "seems like a simple question"
I may be out of my realm, meaning I don't have any idea and that's fine if you must point out what I pointed out at the onset but I do know that I wouldn't put 30+ psi through a 2 bolt connection. Granted I didn't know it see's that much before the turbo but still, sounds like YOU should know better.
Hey everyone, no one needs v bands anymore-those LS3 2 bolt flanges are the ****!!

Summerkruse13

And this was the thoughts/response I was looking for, thank you.