Ls7 Exhaust Manifolds/Swap material?

[zgeezer]

Well, I spent the afternoon rubbing up against a Ls7 out of the car and on the garage floor. Neat engine: 427cu and 505hp out of the box and many think that GM is lying in it's teeth and understating the actual HP of this engine.

 

The manifolds are hydroformed stainless steel, center dump, but the collector is flat. These might be usable in any swap using Corvette motor mount stands and a cross member. These will not work for those of us that are using the JCI mounts because they are center dump.

 

I had a set of new Ls3 exhaust manifolds for a visual side by side comparison. The Ls7 manifolds appear to fit much closer to the engine block and they are , in a word, flatter than the Ls3 exhausts. If I read my tape measure correct, I think the Ls7s are close to fitting about 3/8- 1/2 inch closer to the engine block than the Ls3.

 

Unlike my Lm7 truck engine, these manifolds are "D" ports and huge at that. I mounted the steel gasket from the LS7 on my Lm7 to see if these headers would bolt on and, most important seal well. The flat floor of my oval Lm7 matched perfectly to the flat floor of the Ls7 gasket. So I can say with some confidence that the Ls7 exhaust manifolds will bolt onto and seal to a 2004 Lm7. By extension, I think the same would be true for all the ls1 engines.

 

Sometime in the next week, I'll be mocking my Lm7 back into the engine compartment and I'll check clearances on the passenger side.

 

These sell for around $375 to $500 on the various ebay sites and would certainly look good on an Ls1 in a Z.

 

[zgeezer]

Sorry about the multiple photos, I'm still trying to sort out the new program.

 

g

[zgeezer]

Ok here's what the collector looks like: stainless steel and 3 inches wide.

 

 

[grobb284]

I have made a .dxf file for machining a matching set of bottom flanges for these LS7 exhaust manifolds.