Engine/Transmission (1994 - 1998) Learning as I go! Porting?

[Tom Trujillo]

Going to install my new ATS Manifold next weekend as well as my new exhaust. Quick question:



How do I go about porting the exhaust manifolds as stated in some of the posts ? Never done that before but an old dog is looking for a new trick.



Thanks in advance.



Tom

 

[BTighe]

i am also interested in how this is done. what are the best tools to use. thanks

 

[keimmmo]

Unless you have the special equipment to extrude hone the inside of the manifold, you can not port the whole thing. However, you can make it better than stock!



Using a die grinder or fairly high speed drill, knock the rough off the cast with burrs and stones as far into the port on both the inlet and outlet as possible. You can remove casting flash or defects, but don't worry about removing metal at this point... ESPECIALLY on the outlet!



You want to port match the manifold to the head. That is where a lot of flow is gained or lost! To do so, carefully cut a paper template of the ports on the head. A hobbie knife works best for cutting the paper. I recommend using one long piece of paper if possible to keep things from moving around too much. Stick the paper template to the head with grease. Check again that the template is RIGHT! It might take a few tries since this will be your first attempt.



Silicone the gasket surfaces on the exhaust manifold that mount to the head. Mount the manifold and let the silicone dry. When dry, remove the manifold. You will be able to see the relationship between the manifold and the ports in the head.



On the exhaust side, you WANT some mismatch... with the manifold inlet being bigger than the port. As long as the step is from a small port to a larger manifold, leave it alone. If the manifold intrudes into the port any place, remove metal to make it match to being slightly bigger than the port.



Make another template and retest as needed.



On the outlet side, do the same thing. Again, if there is any mis match, you want it to be from small to big.



You can make a tool to reach deeper into the ports and knock the rough off the cast. Use a straight piece of heavy wire or rod about 3/16 inch diameter... the length you want. Cut a slit into the end with a hacksaw... the depth you want. This is kind of like making a slot for a screwdriver, only much deeper. Mount it in a drill, NOT a die grinder, with the slit on the end of the rod away from the drill. Cut strips of wet/dry sand paper or emory cloth a little wider than the depth of the slit you cut into the end of the rod. Insert the strip of sand paper into the slit and wrap it around the rod to make a roll... and go to work. Start with course paper and work your way down to finer paper until you are happy with the end result. Again, you will probably have to practice and experiment a little, but it works well when you get the hang of it.



I hope this helps. I'll be watching the thread for a few days. If you have questions, I will try to answer them.



Steve Keim

 

[Extreme1]

My version (this is how I've done it and it's the only way I've ever seen port matching done): Clean the head side of the exhaust manifold with brake cleaner (Solder Seal/Gunk brand works best). Apply layout dye to the surface. Take one of your new exhaust manifold gaskets and the some mounting bolts and positioin the gasket over an opening. Notice that the gasket is pretty well retained by the bolts and can't slide around much. Take a sharp scribe and mark around the inside of the gasket. Repeat 5 times.



Since this is cast iron, use a die grinder and a cutting bit. I have one with an extra set of flutes around it to keep from getting plugged with aluminum which keeps the chips small and allows light cutting. Start grinding the openings out to the line you scribed. The ATS manifolds are pretty well cast, there shouldn't be much junk inside to remove, just match the openings and blend it into the mainfold about 1/4-1/2".



As kiemmmo mentioned, since the opening is larger than the part feeding it (unless your going to match the head too) it's not too terribly critical. If you do plan on gasket matching or porting the head, take a few extra minutes and do a real good job of matching the lines and blending into the manifold.



Do the same thing on the turbo end (outlet side) of the manifold. Be sure and use the right fasteners so the gasket is held in the right spot. Then do the turbo inlet, there is typically a lot of mismatch on between the head and the manifold but it's nothing compared to the manifold outlet/turbo inlet. If your going to do the manifold, do the turbo otherwise leave them both alone. You don't have to pop the exhaust housing off the turbo to gasket match it, just be sure to blow it out good when your done.

 

[keimmmo]

I would never open the ports on the head to match the manifold. The small port to large manifold opening helps reduce reversion flow. Although it sounds bad, it is actually a good thing! If matching the port to the manifold were good, why don't race motors match the port to the header tube???



You are matching the gasket to the manifold. I am talking about matching the ports. I have seen core shift on head castings that moved the port positions almost 1/4 of an inch!!! Either way, it should be an improvement over stock. Just make sure the gasket and/or manifold do not intrude into the exhaust port!



Steve Keim

 

[HEMI®Dart]

Here is a GREAT thread from NW Bombers. A member that has experience in porting explains as he goes when he ports his ATS manifold. alot of pictures are missing. You really need the pics. I PM'd Bob Wagner.



http://www.nwbombers.com/forum/index.php?showtopic=5406

 

[HEMI®Dart]

I did mine about 5 years ago. Something to keep in mind: Don't go crazy porting it. A fully ported ATS manifold will probably give you 0 HP over a unported one. In other words, it does very little in gained HP & torque.

 

[Mad Bomber]

Dave (HDM48) does a wonderful job. He's been doing this for about 30 years. There are LOTS of his threads you should read. BTW you can also PM ???'s

http://www.nwbombers.com/forum/index.php?showtopic=5406&hl=porting

http://www.nwbombers.com/forum/index.php?showtopic=10231&hl=porting

http://www.nwbombers.com/forum/index.php?showtopic=7373&hl=porting

http://www.nwbombers.com/forum/index.php?showtopic=6234&hl=porting

http://www.nwbombers.com/forum/index.php?showtopic=5383&hl=porting

http://www.nwbombers.com/forum/index.php?showtopic=5382&hl=porting

http://www.nwbombers.com/forum/index.php?showtopic=4970&hl=porting



Here are a few to read though BTW there are alot more.

 

[TRCM]

I would never open the ports on the head to match the manifold. The small port to large manifold opening helps reduce reversion flow. Although it sounds bad, it is actually a good thing! If matching the port to the manifold were good, why don't race motors match the port to the header tube???



You are matching the gasket to the manifold. I am talking about matching the ports. I have seen core shift on head castings that moved the port positions almost 1/4 of an inch!!! Either way, it should be an improvement over stock. Just make sure the gasket and/or manifold do not intrude into the exhaust port!



Steve Keim

They do... and they don't. You want the exhaust tube to be larger if there is a mismatch, not the other way around (and if you are in a class that restricts what you can do, you do the best you can).



If the port is smaller than the tube, they usually don't mess with it much, unless it needs to flow more air. If the port is larger than the tube, they get bigger headers. If it is a cast manifold, they will open the manifold as much as possible to match the port.



To match ports, you must match the gasket. You mark the head and the exhaust with the same gasket, in such a way that the gasket is positioned EXACTLY the same way on each. Using the bolts won't cut it either... too much play.





I've done plenty of heads/intakes, and it is time consuming, and if you take too much metal out, you will make it worse, not better. The exhaust isn't as critical as the intake, but I wouldn't go crazy with port work..... it does have forced air... not like a carb or FI.

 

[Mad Bomber]

They do... and they don't. You want the exhaust tube to be larger if there is a mismatch, not the other way around (and if you are in a class that restricts what you can do, you do the best you can).



If the port is smaller than the tube, they usually don't mess with it much, unless it needs to flow more air. If the port is larger than the tube, they get bigger headers. If it is a cast manifold, they will open the manifold as much as possible to match the port.



To match ports, you must match the gasket. You mark the head and the exhaust with the same gasket, in such a way that the gasket is positioned EXACTLY the same way on each. Using the bolts won't cut it either... too much play.





I've done plenty of heads/intakes, and it is time consuming, and if you take too much metal out, you will make it worse, not better. The exhaust isn't as critical as the intake, but I wouldn't go crazy with port work..... it does have forced air... not like a carb or FI.

When Dave did my ATS it had 3/16" on every port of the ATS to be removed. He spent the better part of a full day doing it.

 

[TRCM]

What I am saying, is that if you don't know what you are doing, and have no flow bench to test it on to judge your progress (I have access to one), you can make it worse by messing with it.

 

[keimmmo]

Yes, I agree that you shouldn't go crazy trying to port the manifold. Just remove any imperfections in the casting and fix anything that invades the exhaust port of the head or entrance into the turbo. I like to remove the worst of the rough on the casting where I can, but that is optional.



I am American born and raised. But, with having lived in Central Mexico for the last 18 years, I no longer think like a typical American. I would be the first to admit it!!! I am used to using what I can get... which often is less than ideal. But, my methods usually work and tend to be low dollar.



Steve Keim

 

[Tom Trujillo]

Wow! Thanks to all. I think its a little more than I want to (and have the time to) get into at the moment. Thanks again.