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Discussion Starter · #1 ·
I have a 260 engine, which I hear mostly the heads are different. I'm looking to replace the old rusty cast iron exhaust manifolds.

I'm very interested in the Shelby style high performance manifolds after seeing they flow better, but also look somewhat like regular manifolds.

Does anybody know if the hipo mani's will fit the 260 engine?

I was leaning towards long tube coated headers, but would rather mix performance and original-like look. Will the high performance manifolds do well enough for a 260? :scratchchin Is headers an overkill for the 260? What do y'all recommend?

And, I'm putting on Edelbrock intake and 4 barrel carb, and already have dual exhaust. Auto tranny.
 

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Long tube headers will definitely out flow any cast manifolds or shorty headers. One of the Mustang mags. recently did a flow test of the standard, HIPO, and long tubes. Surprisingly they found the HIPOs didn't flow much better than the standard cast manifolds. There was a definite difference with the headers, though.

There is a misconception, and this goes way back, that there needs to be some restriction to exhaust flow (back pressure) to gain performance. This couldn't be further from the truth. Engines are air pumps, the easier the intake and exhaust flows, the better.

Why would someone go about porting and polishing a set of heads to increase flow and velocity, then add a restriction to the exhaust for backpressure to increase performance? Would you breathe better if someone tightened a rope around your neck and then tell you to go for a jog? Would this increase your performance?

The HIPO cast manifolds do look better than the standard manifolds and the cast manifolds do reduce underhood temps, as will coated headers, but if you are looking for performance gains, long tube headers with a low restriction exhaust would be the way to go and the coated headers will look good for a long time.
 

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Discussion Starter · #4 ·
Sounds like we have 2 opinions here. I've read on back pressure before and not sure about cars without computers, but I think new model cars with all the sensors may not work correctly when back pressure is changed a lot. But that's really a guess.

Greek, do you remember what magazine had that article? I wouldn't mind seeing some more detail there.

If I went the long tube route, does anybody have recommendations over others? :scratchchin I don't want to do other car modifications to get them to fit. I've heard some don't fit without cutting this, or adding a hanger to that.
 

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There is a difference in limiting the diameter of the header tubes to match the exhaust ports on the heads and restricting the exhaust flow in or after the headers creating the so-called "needed backpressure".

Limiting the header tube tube size to match the ports isn't causing backpressure, but is streamlining flow, promoting velocity and exhaust scavenging, thus increasing torque and HP.

If the header tubing is smaller than the exh. ports, this would create a back pressure and a resistance to flow in the same way an exhaust system with backpressure would.

If you restrict exhaust flow, velocity and scavenging is gone, you'd lose power. The engine wouldn't be breathing effeciently.

You have to be careful with cylinder head selection on the 260 engine because of the smaller cylinder bore. Using a set of heads meant for some 289/302 applications may cause problems with intake valve interference or extreme valve shrouding. The shrouding will impede intake and exhaust flow due to the valves' closeness to the cylinder walls. The size of some of the open combustion chambers may be an issue also.

I have had good luck with Hooker Comp headers. They are reasonably priced and fit well. If you have a manual trans., make sure that whatever headers you decide on have clearance for the clutch linkage.

If you have power steering, all of the vintage Mustang headers that I know of will require the use of a bracket to lower the rod end of the steering's slave cylinder. They cost about 20 Bucks and are easy to install.

The article that gives the comparison of the exhaust manifolds is located at: www.modifiedmustangsandfords.com
Go to the "Tech section" Page 2, about half way down the page. The title is, "Installing Performance Exhaust For a Ford Mustang-Exhausting the Possibilities"
 

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Discussion Starter · #6 ·
Thanks Greek for the magazine info. That article has some nice info. So we do get gains with both selections as long as we have good tubing. I already went from single exhaust to 2 inch dual exhaust, leaving the old manifolds.

So now I just have to decide on more HP, or a less gain with a more stock look. Hmmm...
Thanks again!
 
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