Re: 6.4 exhaust manifold impulse buy
I was able to find a pair of 6.1 exhaust manifold take offs from Modern Muscle out of Virginia. Cost me about $500 including shipping (to upstate NY) which is not bad IMO for how hard it is to find the specific Jeep srt8 manifold and considering these cost around $1.1K brand new from the dealer.
Took the jeep to my local exhaust shop today for a planning/design session. After months of researching other forums and similar builds we are planning on chopping about 6" or so off of the top of the stock midpipes (y pipe) and fabricating flanges onto them that will fit the 6.1 manifolds. The plan is to weld new O2 bungs into these fabricated flanges at the top of the midpipes. Either that, or put them into the ends of the manifolds themselves as they are about 6" longer than the stock manifolds and that is roughly where the upstream o2 sensors are now. The hard part is going to be welding onto/altering these midpipes as they taper out wider into dual walled pipes and back into single wall pipes at the connection points (flange, just upstream and just downstream of each cat). The weird part is that the two downstream o2 sensors seem to be in the middle of the cats. Worst comes to worst we'll just chop the cats out and weld them into fabricated shop pipes. I'd love to use high flow cats but I'm too worried about throwing 02 sensor codes and there needs to be SOME amount of back pressure for proper engine performance.
Finally laid eyes on the little piece of transmission housing on the passenger side that gets in the way of the 6.1 manifold, it's a connection piece that the Ram trucks use (my mechanic is a Ram guy) and won't be an issue to chop it off. I was quoted at about $900 which seems on par with the complexity of the work and what I've seen charged for similar jobs on multiple forums.
We're going to pull the trigger and start chopping into it within the next two weeks.n Any and all help/suggestions on this project would be greatly appreciated!
2010 Jeep Grand Cherokee Limited 5.7, Gibson cat back, SRT exhaust manifolds w/ modified mid pipes, K&N CAI, Modern Muscle "85"mm throttle body, Diablosport catch can with custom Home Depot bracket, Diablosport Intune with Hemifever CMR