Header / Test Pipe / Exhaust (70mm)
 

Hello:

I have a Hytech Header / Test Pipe(Header to 70mm) and a 70mm single exhaust on my car and experienced a burnt valve on cylinder # 3 due to what appears to be a "lean condition". I am untuned - MY05 (2.2).

Do you folks think these mods could have leaned the car out to the point where I caused damage to the head or is that a long shot and it was something else that caused the lean condition (bad gas, O2 sensor gone bad, injectors)?

Thanks!!

Just a test pipe and exhaust likely won't change the factory tune enough to worry but a good header like the one you have absolutely could have. You really don't get the most of those kinds of mods unless you tune for them on top of keeping the tune safe. It still could have partially been something else but I wouldn't fix anything and not also consider some kind of tuning option before you really go out and drive it after getting it all fixed.

Did you check the valve clearance? To tight is probably the biggest cause of burnt valves.
You are most likely very lean in some rpm ranges so a tune would be good either way.

Its possible for sure. The Ap2 runs a much more ideal/lean tune from factory compared to the Ap1, especially the 00-01 years, so de cat and changing the entire system like you have done is something I would not recommend without adding fuel. You really should have a wideband to check your afr and at least a adjust rate fuel pressure regulator to run safe. It works if you don't have a EMS to get a full tune. The ecu at idle/partial throttle compensates for breathing mods since its in closed loop ecu operation there, but past that you get into open loop and need to add fuel and the FPR can do this mechanically.

I too had burnt valves on my 06, cylinder 3 and 4. The one thing we both have in common is the Challenger 76mm exhaust if I'm not mistaken. Was told that the 76mm makes the engine work harder to get the exhaust gases out of the block. He also told me that the pulsing airflow actually cools the exhaust valves as it works but the 76mm doesn't do that. You do get the performance gains but lose in other ways. I know that fuel economy went out the window also with the exhaust. Hope this helps man. Later BD

Thanks for the input guys. This is all basically what Bill alluded to. The reason I am shocked and I was asking is that my MY04 SSM had the same setup for 82K miles and the car was completely fine. Bill explained that some cars are just a bit on the leaner side of a safe parameter and adding high end pipes like this just do the trick enough to make the car run leaner than it should. The car is probably running lean at the higher RPM range and prolonged WOT so my damage probably occurred at the dragon. The elevation changes could have further added to the lean condition.

Bama Dave (fellow exhaust junky) - BTW I had the 76mm for 2 seasons on the mamba but this year I switched over to a 70mm Cleib. I also changed the Hytech Test Pipe to 2.75" version from the 3.00" version.