LS3 ERod exhaust

[TigerBill]

Anyone installing the LS3 "ERod" crate motor with catalytic converters? I am curious how you fit the catalytic inverters in and what headers you used. My engine is mounted and everything is going well, just not sure about the Cats. What happens if I just leave them out. Will the engine still run ok? Thanks

[Data]

I've got the ERod in, but not finished with the exhaust yet. I'm using the corvette manifolds that come with the motor to have the exhaust drop as far forward as possible (without going so far as having the manifolds on backwards, becuase that won't fit with the CTS-V low-mount accessory drive). The ERod cats are flanged for the Camaro manifolds (2.25 inches) vice the 2.5 inch Corvette flanges. I've cut off the Camaro flanges and I'll weld on Corvette flanges. The back end of the cats are 2.5" and I've cut them off to end just forward of the first "through the frame" location. I'll adapt them to the rest of the kit's 2.25 exhaust there. In the end, the "oval" cats look like they'll have about 1/4-1/2" clearance from the frame just under the firewall/footwell area once I get it all welded together.

I'm not sure how the engine will run without the cats (besides the obvious CEL/MIL that will result). I know guys are running LS engines without them, but retune the ECM to bypass the O2 sensors.

[first time builder]

I used an LS 3 back in 2007 when they were first available for over the counter sale. They didnt even call them EROD yet. I installed it in a 1959 Corvette Resto mod with long tube headers and NO CATS. We got the wireing harness and ECM from GM when we bought the engine. The engine runs great with no cats. The trick was to keep the MAF at least 10 inches from mouth of throttle body. Its hard to do that in most cases. Some aftermarket companies make a small air cleaner that has the MAF next to it and mounts to the throttle body and they run like do -do, I have told people the "trick" and then they try it and thank me. Its in the directions from GM. I don't know what ECM you have but if it came from GM with the engine , you should be good without the cats.

Kenny

[TigerBill]

Thanks guys. Data, let me know how it goes with the Cat installation. I put the corvette headers back on and held the cat unit up to it, but it look like there would be some interference. Particularly on the drivers side with the exhaust manifold flange hitting the engine mounts, but I will check again.

[TigerBill]

See my post to thread "Cats on a '33". I went with corvette exhaust manifold and cut off second stage cat.