3f/fe downpipe at the manifold.

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Supporting Vendor
Mar 6, 2005
Mauldin, SC
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?

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....
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.
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.

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