The only thing bad about the one piece manifolds is that they are more prone to eventually cracking either the block or the manifold at the mounts because of the manifold getting hotter than and expanding more than the block. More so if you have high egt's. The 3 piece manifolds were developed specifically prevent that problem. The joints can move during high heat preventing a load across all the block flanges at once.
That's the AFE ductile iron Bladerunner, I run one myself...very heavily built and flows good too, I checked it on a flowbench compared to my ported stock exhaust manifold. Ran better on my engine up the Test Hill I use.
My experience is on a 1996 12 valve. I bought on July 30-31 2019. Overall a very nice piece, very solid. My dislikes at the time were only 3 items.
1st, on the front runner between 2 and 3 the manifold looks like it was ground down for some reason. Very ugly looking. I contemplated returning it for another but figured since i was putting a blanket on it, it wouldn't matter in the long run.
2nd, after have run it for a short period of a couple months, just a couple thousand miles if that, the whole thing is a red/orange rust bucket of a manifold. More unsightly than the stocker. Even the spacers they sent are rusted up.
I am in the midst of doing an overhaul on the engine, so I will be sand blasting the manifold and spacers, then painting them with grill paint, or DIY heat coating. Just something to make it look better. I still have the blanket on it, but the blanket doesn't cover all of it.
3rd, the EGT threaded bung is too small. I can not put my EGT probe in the manifold using their spots. I have it in the elbow of the turbo right now, but will be drilling and tapping the manifold to the proper size. It was frustrating to find that out during the install.
I did actually get the aFe stainless header installed, I have almost 1500 miles on it now. No issues, but it doesn't seem to affect performance significantly. It's already installed so I'll leave it in there, but I don't think it's worth what it costs.
I just Bought one of these after reading for 3 days about different manifolds 😂 I read the 3 piece have issues sealing after a while but not many have had this issue. I did not read about any of the one piece manifolds cracking head studs/bolts from expansion. The Ductile Iron is supposed to combat the expansion and contraction very well and not allow this. I guess I will see.
Thats good info tho about it not being coated and it getting rusty fast. I plan to do just a coat of some High heat paint on it and call it a day. I don't need anything fancy fancy.
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