3f/fe downpipe at the manifold.

[Trollhole]

Need some help.

Going from two into one. Anyone done this? Trying to figure out what I need.

I have a tubing bender for 2" Do you think I could just fab it up?

Couple of problems I see. From what I understand the downpipes are smaller than 2". I've searched for the flanges that go on the ends of the exhaust but haven't found any.

Anyone have any ideas on what I should do or have a comment on the design of the pipe?

 

[RockDoc]

Not sure about sourcing the flanges, have you taken the manifolds by an exhaust shop to see if they have any that will fit.

I think the stock down-tubes are 1 7/8" (by Cruiser88's post in the 2 1/2" exhaust thread), I suppose 2" would be a good choice considering you have slightly more displacement than a 3FE.... Diameter and length to the Y will play a role in what engine speed the exhaust side is "tuned" to. Longer and skinnier will be better for low speed, shorter and wider will be better for higher revs. I would find some equations/solvers on the net and play around with that. If it were me, I would be tuning it for the 2500-3000 range. blah, blah, blah....

 

[Godwin]

Find a used set of down pipes for the flanges. Many of the FJ62 owners who have had a new exhaust built have run the pair of pipes to a muffler with a 2 pipes in/1 pipe out configuration.

 

[FJ40Jim]

There are also available aftermarket generic cats that are two inlet, one outlet.
If the engine is injected, then it should have tight enough mixture control to run a cat without trashing it.

Just a thought.

 

[Moby]

I run dual 2" into a dual inlet/dual outlet cat than into a dual inlet single (3") outlet Flowmaster. Both pipes are now inside the frame rail.

 

[Trollhole]

This is what I came up with.

It's all 2"

 

[tonkota]

That is pretty nice. You should get it ceramic coated to hold in the heat better. Just a thought.