LS6 running issue solved

[john chesnut]

I have an LS6 in my Cobra. In fact the whole drivetrain and suspension is C5 Corvette. I know that it's not "correct" but it is a great driving car.

I have been building a new car, my "Spyder for almost 4 years." Last summer I bought a new LS6 long block, switched the cam for a mild Comp Cam, high performance springs and push rods and bolted on a FAST 92 mm intake and throttle body. I have custom 1 3/4 inch headers into individual side pipes. The engine would start right up and run fine until it warmed up. Then each bank of cylinders would alternately shut down and then start back up. It also was running full rich. I switched every sensor, the 02 sensors, and even the computer from my Cobra into the new car. But, nothing made any difference.

I took the car to a "tuner" that had a chassis Dyno this past Thursday. (I had not driven the car. I have been busy working on my business and had not been able to spend time on the car.) It ends up that the 02 leads had been mislabeled by the wiring harness manufacturer. Once they were switched the engine ran great. After a full tune a couple of pulls were run. We had to shut the pulls down at 5800 rpms. I wasn't flowing enough fuel and at that RPM it was starting to lean out. At 5800 rpm the engine was producing 380 hp to the rear wheels. I will sort the fuel delivery system out and go back for another try. I am thinking that it will peak at more than 400 rwhp at 6800 rpm. This is more than enough for me and my light car. Throttle response is fantastic.

I know that some of you, particularly in Australia are running LS engines. Maybe this info will help if the same problems come up.

Happy motoring.