[chiphead]

Time for a new exhaust system for the '67. Current engine is a warmed over '69 400, but future engine will be a full roller 434 with a whiff of N2O. D-port hooker headers, TH400 transmission.

What pipe size do I need, 2.5" or 3" to the mufflers?
Does H or X pipe really matter on a street car?
I have read the old Jim Hand article that says the tailpipes can be 2.5", that still hold up?

I'd like the ability to remove the exhaust system to do engine/trans swaps. So I'd like to be able to separate the exhaust from the tailpipes. What's the best way to do that, band clamps, 3-bolt flanges or what behind the mufflers?

Anybody got pics of how their system ends under the quarters? I like that 45 degree turndown that hides the exits behind the bumper.

[65 Lamnas]

Originally Posted by chiphead

Time for a new exhaust system for the '67. Current engine is a warmed over '69 400, but future engine will be a full roller 434 with a whiff of N2O. D-port hooker headers, TH400 transmission.

What pipe size do I need, 2.5" or 3" to the mufflers?
Does H or X pipe really matter on a street car?
I have read the old Jim Hand article that says the tailpipes can be 2.5", that still hold up?

I'd like the ability to remove the exhaust system to do engine/trans swaps. So I'd like to be able to separate the exhaust from the tailpipes. What's the best way to do that, band clamps, 3-bolt flanges or what behind the mufflers?

Anybody got pics of how their system ends under the quarters? I like that 45 degree turndown that hides the exits behind the bumper.

I'm doing a complete 3" exhaust system with x-pipe on my '65 for the 462. I'm like you and want the ability to remove the pipes between the headers and mufflers. I'm cutting off the 3-bolt flanges from the header collectors and going with band clamps, and going to use ball and cone connectors at the muffler inlets, as they allow some wiggle room. Sounds like you want the ability to remove the mufflers, too? Why not leave the mufflers and disconnect at the inlet? There still should be plenty of room for a trans swap with muffs in place.

I would think if you go with 3" pipes and mufflers, you could drop to 2.5" at the muffler outlets without that being restrictive. I won't have pics til this summer, but also can't stand to see the tails hanging below the quarters, so planning on tucking mine up in and out of sight.

[Formulajones]

2.5"-3" can be a bit of personal choice and depends on how far you want to push this effort but for sure the 3" is going to make a bit more power. Muffler choice is just as if not more important.

It's also going to help with an "H" or "X" cross over. Theyve been shown to help HP a pinch in just about every test ever ran on them, with the X getting the edge. I personally use X's these days.

I make the entire center section removable on my exhaust installs. I prefer to do it with V-band clamps. Simple, easy, doesnt require gaskets and easily comes off. Looks much cleaner when done as well. Commonly used on turbo systems.
I have used simple band clamps that don't crush the pipe with slip joints but find them difficult to slide apart if it's been together a while usually requiring a bfh for persuasion and sometimes heat so I've gotten away from that method when I want a removable section on the exhaust.

Like mentioned I leave the mufflers in place and put my V-band in front of the mufflers. With the factory hangers utilized the mufflers will simply hang in place. The entire x will drop right out. Great for clutch changes and such.

[chiphead]

The rear is Ford 9", so it'd be nice to get the mufflers out of the way so I could change 3rd members. So sounds like I should put the V-bands behind the mufflers.

Does the X pipe have any impact on drone with a given muffler?
What mufflers make the most power? I usually use magnaflow.

Check out the 2.5 vs 3" exhaust test. 2.5" exhaust cost 20HP on a BBC. They don't use a H or a X during the test. Would 3" exhaust still be required when using an X?

https://www.youtube.com/watch?v=_PVXvHkr-Vs

[Formulajones]

Yes going to 3" is worth some power even on a mild build. There has been a bunch of h and x testing that shows it's beneficial on 2.5" and 3" exhaust.

As far as drone I've found how the system is mounted to the car has more affect than muffler choices.

Factory style hangers that allow more movement and isolation plays a huge part in how noise is transmitted inside the car. Most of them are reproduced but so seldom used by most people since exhaust kits come with hangers. Problem is the kits supply hangers that are much more ridged.

Magnaflow makes a great muffler. I typically go for dynomax, usually their ultra flow line.

[Steve C.]

I didn't read Jim Hands comment regarding the tail pipe size. However if there is a fitment issue you don't lose much by reducing tailpipe size according to some internet testing. This stated....

"Also depends on how far down the exhaust you are. You can usually reduce the tailpipe to one size smaller than the main exhaust and muffler because the gas is cooler - reducing the actual cfm.
Also there is less pulsation after the muffler. Pulsation means the peak cfm is higher than the average cfm."




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