I have a custom manifold that is a begi replacement, and I've had trouble with it cracking at the welds for years. I sent it back once and the builder happily fixed it and reinforced it at no charge, but it cracked again so I welded it myself and then put relief cuts in the flange hoping that would reduce the stress. Now it is cracked again and I'm not sure what to do. The photos show the bigger crack, and the overall manifold (the smaller crack is a mirror of the big one, but hard to see in the photo)

Are there any tried-and-true Begi tubular replacement manifolds I can buy that would put the turbo in the same location?
Do you have any suggestions for how to repair this so it won't crack again?

 

That looks to be pretty close to where the cheap ebay log manifold locates the turbo. I've been running one of those junk manifolds for years. No cracks so far.

 

Holy smokes, those ARE cheap! Like, cheap enough that I might just buy one so I can still drive the car while I figure out how to get the nice tubular manifold fixed/replaced. It seems like a poor strategy to permanently replace a nice tubular manifold with an inefficient cast one, but right now inefficient cast that isn't cracked is better than not driving the car.

 

I seriously doubt you will notice much difference in performance, if any at all, between this one and the one you have currently.

I did a little porting on my manifold.. I don't know if it helped or not since I did that at the time of first install. You see what I've run with this manifold (although ported), so it cant be horrendous.

 

To properly fix your welded manifold, you have to grind out the welds until an initial weld pass has 100% penetration. No unfused butted gap on the inside surfaces. Then add however many passes it takes to complete the weld. You can even have a space between the pieces that the welder has to bridge with that first pass.

If there is any unfused butted surfaces, then that is an inclusion that will eventually form a full crack.

DNM

 

I'm not sure how the builder welded it the first time, but I'm pretty certain that is what caused my own welds to crack this time. I doubt I actually ground them out but it was a few years ago so I don't remember. I'm not a professional welder, just a half-decent hobbyist. And now I'm out of practice and don't work at a factory with good tig welders anymore!

 

The ebay manifold arrived, and some of my exhaust studs are too short. Did you have to buy longer ones, or did I shorten mine and forget about it?
Looks like just the corners and the one I know I shortened don't reach. Just need to figure out what to buy.

 

I am using stock studs except for the 4 corners. On the corners I'm using bolts.

 

that amnifold doens't look too bad.
have it blasted and welded....then ask the welder to put on some re-inforcements.

could be sold and make some money back to put back if it looks strong enough.
get a good welder...not some corner muffler shop with a guy made out of muffler outside. find a reputable shop and ask to see their work.

 

If I remember right, ARTech used to build a manifold similar to this , then stopped. Probably from the same issues you are having. That Is why I stayed with the Begi log. Someone still makes that , I believe, or you can use Flying Miata’s manifold which is basically the same. Be nice if someone made these in stainless. I made 304 hp on the dyno but the tuner said I could have made more with a different manifold. It will just have to be good enough for now as ,I do not have but just a six speed tranny.