LT1 performance question
Thread Starter
Melting Slicks
Joined: Nov 2012
Posts: 2,276
Likes: 380
From: Waltham Ma.
LT1 performance question
I've come over here from the C2 forum hoping to get some feeback. I've installed a stock 1996 LT1 engine and trans from a Z28 Camaro in my 67 Corvette coupe. I had the computer reprogramed to remove the Vats and the mass air flow. I also eliminated all the emmissions including the EGR valve. I'm running headers right into 2 1/2" side pipes wich are all new including new delco o2 sensors. My problem is the motor starts and runs great but the passenger side side pipe gets extremely hot before the chamber portion. It's so hot that it turns the pipe blue but right where the chamber portion starts it's only warn after about 5 minutes running. I thought the side pipe may have been partially blocked so I cut it open and it looks fine. The drivers side is fine, the car runs great with no misfires. I pulled all the injectors and had them checked and cleaned. Any ideas where to go next after I weld the sidepipe back together? I'm not that familiar with this Opti Spark set up. 
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I've come over here from the C2 forum hoping to get some feeback. I've installed a stock 1996 LT1 engine and trans from a Z28 Camaro in my 67 Corvette coupe. I had the computer reprogramed to remove the Vats and the mass air flow. I also eliminated all the emmissions including the EGR valve. I'm running headers right into 2 1/2" side pipes wich are all new including new delco o2 sensors. My problem is the motor starts and runs great but the passenger side side pipe gets extremely hot before the chamber portion. It's so hot that it turns the pipe blue but right where the chamber portion starts it's only warn after about 5 minutes running. I thought the side pipe may have been partially blocked so I cut it open and it looks fine. The drivers side is fine, the car runs great with no misfires. I pulled all the injectors and had them checked and cleaned. Any ideas where to go next after I weld the sidepipe back together? I'm not that familiar with this Opti Spark set up.
Thread Starter
Melting Slicks
Joined: Nov 2012
Posts: 2,276
Likes: 380
From: Waltham Ma.
I doubt that the Optispark has anything to do w/it...but the first that that *I* would do is try to find more facts. How hot is the exhaust really getting? Are both sides about the same temps? If it were my car, I'd get an infra red temp gun, fire it up, and shoot both sides to compare. At idle, I wouldn't expect the surface of the pipe to be more than ~600*F.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I just ordered an infra red temp gun. I will report what I find next week. I know for a fact that the passender side is much hotter than the drivers side. The drivers side is running normal all the way through. The passenger side pipe is turning blue in the front and is so hot it started to melt the insulation on the side pipe cover. I had to remove the cover. I want to point the gun at each cylinder and see if one is much hotter than the rest. If not I'm back to the exhaust pipe.
- restriction (I know you've checked that once)
- Excessively retarded timing
- Excessively rich af ratio
Team Owner
Joined: Sep 2001
Posts: 62,159
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
To that I would double check the Fuel pressure, and see what it does after the engine is shut down. It should hold steady.
Thread Starter
Melting Slicks
Joined: Nov 2012
Posts: 2,276
Likes: 380
From: Waltham Ma.
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Team Owner
Joined: Sep 2001
Posts: 62,159
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
I'm asking you to check it in case the one side's injectors have gone bad. If a couple on one side are dumping fuel all the time, well theres a problem. You wouldn't know which side or how many, but you'd know the AF is way off and causing this.
Thread Starter
Melting Slicks
Joined: Nov 2012
Posts: 2,276
Likes: 380
From: Waltham Ma.
The injectors have all been cleaned and checked. I also pulled the fuel rail and pressurized the fuel system to see if any injectors were leaking. None leaked a drop. I appreciate any input at all though, thanks! Obviously if I knew what I was doing it would be fixed by now.