Exhaust Porting

cntinuum

cntinuum

Registered User
I am exhausted from searching on exhaust porting. Tbird88 had a lot of posts and pictures, at one time on the site. Didn't see any pictures at this time. Would have liked to see the cross section of the head.

What I gather is;
1- Expand the outlet of the exhaust manifold to 2"
2- Gasket match the head side of the exhaust. Be careful to leave enough material around mounting points to avoid cracking.
3- Polish the surfaces.
4- use a 2-1/4" down tube

'94-95 exhaust manifolds are the ones to use.
Saw an old reference to using '95-96(?) Mustang manifolds. Required modifying the LH manifold. Cut the collector off and reposition 180*.

So, is this the jist of porting the '94-95 stock exhaust manifolds?

One post talked of setting up the manifold and using a drill press. Did the cutting in couple minutes. RIGHT!!! Didn't say how much setup time it took. Might try this with a 1-7/8 hole saw and sand out the rest. As something to screw around with, I was going to run a brake cylinder hone thru the opening to finish it off. Might be a waste of time, but will not know until I try it.
-Dave
 
been a while since i posted but here goes....

u should be able to get just over 2" on the outlet of the exhaust manifolds. i wouldnt go any bigger or you'll trouble with sealing. also wouldn't go bigger than 2 1/4 pipe cuz you'll again have trouble sealing.

unless something changed, a golden rule has always been DO NOT gasket match the exhaust side of the heads. just cleaning up of rough edges and smoothing should be done. and unless you really know what you're doing, i would leave head porting to someone who does know what to do.
 
cntinuum said:
I am exhausted from searching on exhaust porting. Tbird88 had a lot of posts and pictures, at one time on the site. Didn't see any pictures at this time. Would have liked to see the cross section of the head.

What I gather is;
1- Expand the outlet of the exhaust manifold to 2"
2- Gasket match the head side of the exhaust. Be careful to leave enough material around mounting points to avoid cracking.
3- Polish the surfaces.
4- use a 2-1/4" down tube

'94-95 exhaust manifolds are the ones to use.
Saw an old reference to using '95-96(?) Mustang manifolds. Required modifying the LH manifold. Cut the collector off and reposition 180*.

So, is this the jist of porting the '94-95 stock exhaust manifolds?

One post talked of setting up the manifold and using a drill press. Did the cutting in couple minutes. RIGHT!!! Didn't say how much setup time it took. Might try this with a 1-7/8 hole saw and sand out the rest. As something to screw around with, I was going to run a brake cylinder hone thru the opening to finish it off. Might be a waste of time, but will not know until I try it.
-Dave
Click to expand...

Okay ... here are my thoughts.

For the head cross-section, look for posts by MannySC. He reposted a pic that Tbird88 took (I think), with a head cut open. (Tbird88 disappeared a long time ago. Just up and left. So don't bother to PM him, haha.)

#1 - Yes, expand the manifold outlet. Don't bother with the upper end (at the head). For tools, you need a good carbide cutter bit, a hefty tool, and a lot of patience to remove that much cast iron. A cylinder hone will npot remove any material to speak of, but might be good for final polishing. A hole saw might work for cutting but there will be a good bit left over. It would also be hard to keep in position unless you set up a decent jig.

#2 - You could try to enlarge the manifolds at the head end, but there's really not much meat there. I would just leave it alone unless you can find specific areas that you are sure will improve things. I would be afraid of a cracked manifold if I removed too much material.

#3 - Sure, polish away.

#4 - Yes, 2-1/4" is the largest tube that can still seal to the ball flange. Stock is 2" or slightly less.
 
Thanks

Thanks for the responses. Confirms what I thought was the thinking.

Back in the dark ages, when I was single and making lots of money, I was spending 200-400 a month on my 1970 AMX in 1973. If I remember correctly, having the upstream piece smaller in volume to the connecting downstream piece does 2 things, 1-causes a pressure drop(scavenging) and 2-helps block the reverse wave backflowing.
I just want a nice driver with a little bit of the pucker factor.
-Dave
 
Dropped off my ported manifolds with the local machine shop.

We are working on a set up to mate the 2 1/4 tubing with no sealing issues.
The manifolds I bought are ported to 2 1/8 so here is VERY little lip for sealing...hence the work to find a solution.

Looking to do the sae thing you were talking... stepping up, yes the scavenging and the stop of reverb back up the pipes.

As for the head side... I AM NOT TOUCHING THAT!
IF I send out heads and manifolds to one of the SC porting guru's... they can do the port match.

Will let you know when it is done.
 
BOT named Tbird88

S_Mazza;887281... (Tbird88 disappeared a long time ago. Just up and left. So don't bother to PM him said:
I just thought 'bird was just a computer BOT that was programmed to run CNC equipment! As a sideline to experiencing "humanness" would use manual tools to machine SC parts. Sort of like the brother of DATA's from Star Trek, but in cyber form :)
-Dave
Click to expand...
 
cntinuum said:
I just thought 'bird was just a computer BOT that was programmed to run CNC equipment! As a sideline to experiencing "humanness" would use manual tools to machine SC parts. Sort of like the brother of DATA's from Star Trek, but in cyber form :)
-Dave
Click to expand...

That might explain a lot. There's probably a lot we'll never know. :)

"All Thunderbird knowledge gained. Terminate user account."
 
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