LS3 intake on cathedral heads?
I just picked up a set of CNC ported cathedral port heads from my local machine shop. I know the owner of the shop and trust him. He was selling these heads for a customer that was running them on a 6.0 and he has seen the heads on the engine. Owner did an LS3 head swap.
He says the guy also has an LS6 manifold so I tell him to let him know I'm interested. Manifold shows up at the shop and turns out it's an LS3 rect. port intake. The original owner of the engine claims this is the manifold that he was running. I checked the gasket imprints on the heads and they do appear to match the LS3 gaskets.
I didn't buy the intake. This sounds like a very bad idea to me. The lower part of the CNC ports closely match the LS3 profile, but it looks like there will be a lot of turbulence when the air hits the square shoulder of the upper part of the cathedral port which I would assume would kill a lot of flow.
Has anyone ever heard of this? I didn't know they would even bolt up.
Word has it that the car the engine was in was fast and won a lot of races. I can't say for sure, but if that's true, it probably would have been a lot faster with the right intake.
Looks like I'm still looking for an LS6 manifold. Might have to go with a Dorman.
My reason was to go from LS-1 to LS-3 port, not found.
Would you like more information ?
Lance, BTW this is a great idea. (LS-3/LS-1)
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Thanks for the replies.
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I just picked up a set of CNC ported cathedral port heads from my local machine shop. I know the owner of the shop and trust him. He was selling these heads for a customer that was running them on a 6.0 and he has seen the heads on the engine. Owner did an LS3 head swap.
He says the guy also has an LS6 manifold so I tell him to let him know I'm interested. Manifold shows up at the shop and turns out it's an LS3 rect. port intake. The original owner of the engine claims this is the manifold that he was running. I checked the gasket imprints on the heads and they do appear to match the LS3 gaskets.
I didn't buy the intake. This sounds like a very bad idea to me. The lower part of the CNC ports closely match the LS3 profile, but it looks like there will be a lot of turbulence when the air hits the square shoulder of the upper part of the cathedral port which I would assume would kill a lot of flow.
Has anyone ever heard of this? I didn't know they would even bolt up.
The ports are approx. 1 1/8" wide. I did a rough comparison to a stock LS port and it appears that they are about 1/8" wider. The height is about the same as stock.
The CNC heads are 806 castings. I was looking for a set of 243's when I found these. My engine has the very early 337K castings. The CNC heads have titanium retainers, double springs and can take up to about .640 lift. I don't have much info on them as to who did the porting, but they have to better than what I had. I would have preferred a center bolt valve cover, though. I still need to CC the chambers to make sure I'm not cutting my CR.
My engine is a 5.7. As unbelievable as it sounds, this engine is practically new. I bought it out of an old unfinished project. Supposedly has only been test fired. I'm planning cam, PCV, and oiling upgrades as well as the heads.










