So my exhaust manifold cracked, badly... I'm looking to get a new one, one that I can use a t3 flange on. trying to find the damn ihi turbos is a pain in the ass. The motor is the b6t, so I'm wondering if the b6 in the miata has the same bolt pattern for the exhaust, and if so where can I find and buy a turbo manifold for it? I'm thinking I want to switch to either a t25 or t28 turbo, and I would also like to use an external wastegate! Right now my little gtx is back on the road and making real good power with the ihi vj-5 on it... but I need it to spool faster, no power below 3700 rmp kinda sucks when your only doing 10psi!

Can you just have the existing manifold welded?

I just got done trying that, because its cast iron it didn't go so well. It just cracked my welds, and they were damn fine welds if I do say so myself!

can't get much harder than welding cast iron.

And how! I have been welding for years and knew I really shouldn't bother on a manifold like this! I don't know how much exhaust this crack is going to going to leak, but I honestly don't care. I would really like a nice tubular manifold, all bright and shiny and stuff!

I thought you might find this cool:
http://www.modified.com/projectcars/0009scc_mazda_323_gtx_part_3/index.html
http://www.modified.com/projectcars/0101scc_mazda_323_gtx_part_4/index.html

Haha! I have been looking for parts 1 and 2 for a long ass time! Love those articles though!

You can weld cast just fine. You need the proper welder and rod, however, with the right amount of heat.

Tubular manifolds are the creme of the crop as they make more power and help turbo spool but they typically don't last as long as a cast manifold and crack much more often.

If you are handy with a welder just cut off the flange of your existing cast manifold and then you can build a manifold off that...or I'm sure you can find a flange somewhere.

t25 and t28 are pretty old school anymore. shit if you really want low end power put a vj11 on there. they're good for up to 12psi in this altitude

you can weld cast, but you definitely want to get it super hot before you weld it. i believe nickel rod is the ticket, but im not sure if thats for welding cast to mild steel