Looking for clarification of which welds need reinforcement when porting 2.8 exhaust manifolds.

A number of threads talk about reinforcing the welds where the exhaust runners join the "log" portion of the exhaust. From what I see, porting is just opening up the oval slot cut in the log, and doesn't actually involve the removal of any weld material. I don't really see any benefit of adding more material over top of the existing bead.

Where the tubes join the exhaust flanges, all the weld looks to be internal to the manifold port, I figure most of that will be removed during porting. Makes sense to me to run a bead on the outside where the tube enters the flange. Is this correct?

Cheers

quote Originally posted by TiredGXP: Looking for clarification of which welds need reinforcement when porting 2.8 exhaust manifolds. <snip> Where the tubes join the exhaust flanges, all the weld looks to be internal to the manifold port, I figure most of that will be removed during porting. Makes sense to me to run a bead on the outside where the tube enters the flange. Is this correct? Cheers

YEP!

Norm

A good port job removes almost all the weld ,and the inner stainless sheet metal ,including as much as you can get inside the tube that runs to the Y pipe..make sure the welder knows he welding stainless to iron
you can clamp the m,anifolds together to prevent warping
It is time consumming to do a good job, the flange entrance should be the same size as the tube and when you feel with your finger inside almost all the protruding "flange" has been removed.. I wish I could post photos the difference between a regular port job and a well done one is about 2 or 3 hp but this is a critical area and frees up the exhaust which helps other modification..
A typical port job on the manifolds will yield 5 horse power add the Y pipe clean up you can add another 1 or 2 hp,, a real porting will add 8 to 12 and add cooler running and a good increase in M P G a regalar port jod adds .5 to 1.5 extra mpg
If you do a thorough port job ,,you must run a bead all the way around the flange
When you run your finger inside the tubes you should feel a smooth port that goes toward the Y pipe the back side is not so important and if you feel some protruding stainless this is O.K..
the best modification you can make to a V6 2.8 is to clean up the manifold and Y pipe,just eyeball it..
Port matching is very worthwhile tho some here do not think so ,only go in about an inch taper a smooth flow
Do not port the head unless you really know what you are doing best to clean it up using normal porting procedures, do not screw with the basic flow pattern this is well designed ,,do not open up the ports unless you are building a fuel dragster

[This message has been edited by uhlanstan (edited 06-24-2008).]

I've got one head done now. There's some "in progress" pictures in my build thread. (The 120 grit finish in the intake ports looks way rougher in the pictures than it actually is.)

My porting effort was limited to gasket match on the intake, removing the raw cast finish inside all ports and bowls, removing major casting flaws, slightly opening up the valve thorats - especially on the "short side", and then polishing as much of the exhaust bowls and runners as I could reach. Stock port shape and size was retained, except for what was required to smooth things out.
Cheers

I actually opened mine up just a wee bit too much and my power band shows it. I have peak hp (132 rwhp) from 4,000 to 5800 rpms but not so good in the 2000 to 3000 rpm range.

On my new engine I'm taking out less on the intake side, but I'll still be smoothing out the bowls and unshrouding the valve seats.

On the exhaust side I'll be doing the same as before, polishing up as close to "mirror" as I can, and removing the lump beside the sparkplug hole. I think that if you use inside calipers, you can get the exhaust port to about 1+1/8" diameter. The inside of the curves do have to be smooth like Tired said.

You have to remember that the ports were balanced in the factory to go with a low flow intake and a low flow exhaust manifold in an effort to meet emissions standards. These heads do need porting to perform well.

Arn