Coffee Talk - Custom 1 7/8" Stock Sized Exhaust Manifolds

[SteveWK]

Imagine manifolds that have 1 7/8" tubing that also replicate the stock manifold's dimensions. Any gains here? It just pains me to see the size of the runners on the stock manifolds compared to long tube headers. Maybe the stock manifold runner size has characteristics that match the cam and torque profile desired by Ford.

 

[1 Alibi 2]

Imagine manifolds that have 1 7/8" tubing that also replicate the stock manifold's dimensions. Any gains here? It just pains me to see the size of the runners on the stock manifolds compared to long tube headers. Maybe the stock manifold runner size has characteristics that match the cam and torque profile desired by Ford.

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Not sure I follow the point you're making ? Top pic, Kooks 1 7/8" LT's, bottom pic, stock exhaust off my 2014. Several Mfg. offer shorty headers, but those offer very little hp gains.........( pic 3 )
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[SteveWK]

Well damn, thanks for the pics. For some reason I had it in my head the stock exhaust manifolds were much smaller. I am apparently wrong.

 

[SteveWK]

My main thought was increasing volumetric efficiency and thus reducing boost and heat.

 

[Jam421]

Headers are not cheap but if the long run goals are to make bigger power they are worth it. Mine only made 22rwhp on the dyno ...not so impressive I guess but they did knock down boost a bit + I felt like it revved faster especially beyond the Tq peak. The stockers are 4:1 . Maybe someone can hog out your stockers a bit ? Pretty labor intense experiment ->) .

 

[SteveWK]

Thanks for the input.

I swear the stock manifolds I saw were noticeably smaller in diameter than the headers, but then again my memory hasn't been up to par lately. Need to find a picture of a header and stock manifold next to each other and I know somebody who might have one.

I use to have ARH 1 7/8" long tubes with a 3" h-pipe to the stock mufflers. Was too loud and attracted a lot of attention I didn't want. Jam421, I did feel the same performance gains you felt going to long tubes. It was definitely something I could feel in the seat of my pants. I noticed it immediately.

Also, I learned with the last year or so that my h-pipe is 2.5" in diameter and not the stock 2.75". I wonder how much that is costing me. I do plan to up grade that though.