Benefit Of A 2 1/4" Exhaust On Hipo 289

[mikesponycar]

Hello 'Stangers: I'm new at this forum so bear with me. My '66 K code 2+2 is in the middle of a restoration back to mostly stock, which was a 2" diameter exhaust system. I want to use the cast iron manifolds which have a 2" outlet (actually 1 7/8"). It looks like there's enough thickness there to hog out a little to increase the opening. Is this advisable? Would I get any benefit from going to a 2 1/4" system? Does anyone have any experience with aftermarket iron manifolds? Thanks for your help.

Mike

 

[LILCBRA]

I can't speak from experience, but you should gain a little power from enlarging your exhaust. If memory serves, someone somewhere offered exhaust manifolds that were advertised to increase power similar to headers. If you could find them, they might work for you. Or a second option you could do is send your manifolds in somewhere to have them extruded to open the whole manifold instead of just the ends. These are options if you have/want to spend the money. Grinding and enlarging the opening should help a little, just not quite as much. Hope this helps a little.

 

[mikesponycar]

Thanks for that, LILCBRA. I want to use the OE manifolds. Good idea about Extrude Hone. I'll check with them, but I'll bet their services are too pricey for me. Sounds like it's down to grinding.

 

[LILCBRA]

No problem! I was looking to see if I could find the manifolds that I was talking about, but really wasn't having any luck. I wonder if what I was remembering were probably what you already have. K code manifolds already flow better than average Windsor manifolds, so maybe what I was remembering were reproduction K code manifolds? Anyway, this *could* be a cheaper option if you wanted to keep manifolds instead of going with headers and didn't have K manifolds already? Or if you didn't want to risk damaging some OEM manifolds, you could get some reproduction, or maybe even used 351W manifolds and grind/extrude on them?

(Copied from DIYFord.com...)

The 289 High Performance exhaust manifold looks like an iron shorty header. It also resembles the 351W exhaust manifold. This is a C3OE casting number manifold that may have been cast by an outside supplier. There are no foundry markings on this manifold.

 

[mikesponycar]

Thanks for your latest input. Those aftermarkets will do the job, but they just don't look as nice as the originals. Markings aren't as crisp and who knows what the inside is like. I have an OE service replacement with a D3 date - pretty late for a mid 60s engine. Maybe the OEs are smoother on the inside and might flow a little better than the repops.