Air leaks with slip fit collectors and EFI causing rich A/F?

[C5GTO]

Thanks for all the good information and feedback on this topic! My impression based on the feedback from this forum and GT40s.com is that the majority of EFI outfitted engines with single slip collectors have an issue with air leaks sometime in their service life. Some of these air leaks have been successfully resolved with sealants and some have not. For some, it's an ongoing maintenance issue where the sealant (or gasket in a flange situation) needs to be replaced to repair a recurring leak.


The goal I have for my Miura's headers and exhaust system is to build it right the first time such that I don't need to re-engineer/re-build it later. I plan to have it ceramic coated and this makes welding on it later a real pain. So I relayed the information provided by you all back to Vince at Burns Stainless. He then offered to swap out the single slip stacked collector for a double slip version. I can't weld the collector on as the header installation can only be done without the collector in place. The Holley Terminator X EFI system that will be used only has a single wide band O2 sensor so I only need to make sure that the collector where it is mounted is leak free. I will leave the other "flat" collector as a single slip because it would have to be much wider if double slip and getting it to fit under engine oil pan would be much harder. If the flat collector leaks some air in, I don't think it will cause any issues as there will be 30" of secondary pipe downstream of the collectors prior to all the exhaust being merged together with a Y pipe.


I now have a revised plan and just need to get all the U bends, replacement double slip collector and Y pipe to fabricate it all up. If you're interested in seeing this Miura project car, I maintain a build thread here: https://www.gt40s.com/threads/modern-day-miura.54786/


Thanks again for the feedback!!