Jump to content
Sign in to follow this  
hdm48

Porting-do's and don'ts

Recommended Posts

Guest satmike

I am also getting ready to do some porting an a HTT manifold and was wondering where the pictures might be available

Thanks mike

Share this post


Link to post
Share on other sites

Can one of the admins dredge up the photo's and repost them?[/b]

 

An ATS porting is in my very near future and I would really like to see the pics to go along with HDM's text.

 

Thank you Russ. :)

 

:(

:p::hit:

Share this post


Link to post
Share on other sites

I'll get Russ' attention and see if there's a way he can re-link the pictures.

Share this post


Link to post
Share on other sites

I'll see what I can do - I've got backups - we will see... I think the pictures have been removed already, but I can restore from backups.

Share this post


Link to post
Share on other sites

Here ar all the pictures I believe (At least the ones that were modified on 12/14/03) - just tell me where to put them

Share this post


Link to post
Share on other sites

Here ar all the pictures I believe (At least the ones that were modified on 12/14/03) - just tell me where to put them

 

Right------> :mn: Russ! :right:

 

J/K

 

Glad to see the pictures back!

 

Share this post


Link to post
Share on other sites

I have more of the picts. I'll see if I can get them here..

IPB Image

 

IPB Image

 

IPB Image

 

IPB Image

 

IPB Image

 

Edited by HOTMOPR

Share this post


Link to post
Share on other sites

IPB Image

 

IPB Image

 

IPB Image

 

IPB Image

 

IPB Image

 

IPB Image

 

IPB Image

Edited by HOTMOPR

Share this post


Link to post
Share on other sites

Thank You Russ and Hotmopr for the pics. :D

 

:dance:

 

I was running out of microwave popcorn - Costco size. :right:

Share this post


Link to post
Share on other sites

Thank You Russ and Hotmopr for the pics. :D

 

:dance:

 

I was running out of microwave popcorn - Costco size. :right:

Great Photos

 

Joe

Share this post


Link to post
Share on other sites

Update to the porting thread. Dave ported a 2nd gen manifold and hx35 turbo, and I took pictures. He did the write up as well.

 

Exhaust porting 101

By hdm48

04/01/2012

First off, we need to discuss equipment. What I use may differ from yours simply because I do this a lot and I have specialized tools.

 

I use ¼” straight shaft electric die grinders for most of this type of work. They turn 24,000rpm and need to be respected. One wrong move or moment of inattention and it may ruin your work or at worst, injure you. And believe me, a cutter moving at that speed will remove soft body tissue faster than the government can remove your tax dollars. I also use a “Foredom” worm drive ¼” variable speed grinder for delicate work.

 

Cutters (Burs), these can be acquired from most speed shops, Summit racing, Jegs, machine shop suppliers, and sometimes Harbor freight tools. You may use single or double cut burs. Which size is up to you, but I use 5/8”diax1 ½” with a 3” length shaft ¼” drive single cut for most exhaust work. I also use a 5/8”x1” with a 6” ¼” shaft. Just make sure they are Carbide. For mandrels I use 3” and 5” lengths. Abrasive rolls are ½”x1 ½” straight. Abrasive rolls and mandrels, can be acquired same as cutters

 

Before we begin I feel the need to emphasize how dangerous this work can be. ALWAYS wear eye protection and hearing protection is a plus. A filter for breathing is also helpful because the fine particles will get into your lungs.

Pic #1. Manifold after glass beading. Notice the core shift. (Core shift, what is it? When manifolds, engine blocks, ETC are made with castings, there is an inner and an outer mold. If these two halves of a mold do not match exactly, the inner part will be offset from the outer part. Think small block Chevy cylinder walls. And in the case of our manifolds, all of the machining is performed on the outside with no attention to the inner parts due to the high volume of production ) They ALL have it simply because they are mass produced and Cummins never planned on anyone modifying their stuff so quality control is at a minimum. (Does it have a hole where it’s supposed to be? kinda. Will it seal? Yes. Good, ship it)

porting01.jpg

 

#2. Turbo exhaust housing. Once again, notice core shift

 

porting02.jpg

 

#3+4. Auto body sanding bar. These work very well for flat surfaces. I use 320 grit papers. But it is not very good for surfacing, just clean up. I use my glass beader to speed up cleaning and to remove that nasty smelling, lung clogging soot that is inside everything related to exhaust systems. A nice pad on a 90* die grinder will do a good job also.

 

porting04.jpg

 

porting05.jpg

 

#5. Template I use to mark both (manifold+exhaust housing) openings. The size and shape come from experience. The template, along with the thickness of the marker I use will keep you inside the safety zone as far as how far out to the sides you can safely remove material.

 

porting06.jpg

 

#6. Template on manifold prior to marking. Now you can really see the core shift. Also notice the plugs machined to align the template exactly in correct position. Take the time to make sure you are removing material where you need to. Failure to do so will result in a completely trashed component.

 

porting08.jpg

 

 

#7. Marking the manifold (exhaust is the same) using a magic marker. Yep, a magic marker. It gives me a mark I can easily see and work with.

 

porting09.jpg

#8. Manifold after marking and template removed.

 

porting10.jpg

 

#9. Stock at a different angle

porting11.jpg

 

#10. BEFORE you begin, anchor the pieces down to something that will not move. The last thing you want to have happen is for whatever you are working on move away from you. If you look closely you will see I have the manifold bolted to the work bench.

 

porting12.jpg

Share this post


Link to post
Share on other sites

When you cut, go slowly and ALWAYS use two hands to hold the die grinder. It WILL get away from you! Notice cutter wax stick in front of me. Cutters will last longer and cut better using it. Also, cutters get very hot and it assists in cooling.

 

When you start cutting, try to keep in mind what you are trying to do. Cut in as straight as possible. When you have that done, start working on your radius’ so the gasses that are trying to exit have a nice gentle (as large as possible) curve. You will see in later pics how core shift has forced me to leave certain areas alone and cut deeply into other areas.

 

Also, when going around the inside corners move your body and watch what you are doing. Remember, you are trying to achieve a nice continuous radius around and into the manifold so the escaping gasses do not have to change direction too much. The gasses are being forced to turn 90* and they don’t want to, help em out with smooth curves. Stick your finger in and around inside and FEEL it.

 

The sides need to be as straight as possible until it needs to start turning the corner and it varies from top to bottom. Core shift will also affect how straight you can make it but try to do your best.DO NOT try to make up for core shift by removing material. Stay within your template markings. You have to imagine a straight line in your mind so you don’t accidently make things worse. Removing more material is not always a good thing. In fact, you may cause less flow by doing so. You are trying to open up the center section to encourage less restriction as the gas pulses come together and enter the exhaust housing. Keep this in mind as you work. Simply matching the gasket areas with flair will do nothing for flow. You must re-work it all the way in. Remember the side wall thickness. It’s a fine balance between better flow and a weak manifold.

 

Remember, if you open up the manifold, you must open up the exhaust housing to match it. Plan ahead; see what you have to work with before you start. No two units are the same.

 

#11. Opening up. Notice marker still on sides. Why, you ask? Simply because the wall thickness of the manifold is thin on the sides. You may remove the top and bottom, but avoid the sides as much as possible. Just go out to the marker. And remember this word, “BLEND”. This means to blend all surfaces together. The longer the blend, the better.

 

porting13.jpg

 

#12. Notice the working into and around the corner. Go straight as far as possible then BLEND it to the curve and make them continuous. Taper off as you near your inside limit to cut so you don’t accidentally create a lip inside. Remember what I said about sticking your finger in there and feeling it? If you do this you will understand what I mean. (if you need assistance in understanding this concept, take your garden hose and place it in some soft dirt, make a groove and turn the hose on and watch what happens) Air and exhaust gasses have MASS. A thick, sticky, gooey mass that does not like to be confined or change direction. But since you have it trapped in this confined space and want it to perform a job, you need to come to an agreement on how it will do that as efficiently as possible. A smooth flowing gas is a happy gas.

 

porting17.jpg

 

 

#13. Bottom of manifold. Very short run here but try to make it as straight as possible then a nice smooth radius onto the manifold floor. Use your finger and try to make them equal as possible. If your manifold has too much core shift, then simply start the radius from the gasket surface. Notice the core shift in this pic. You will grow to share in my dislike of core shift and learn to do the best you can.

 

porting30.jpg

 

#14. Core shift really stands out in this pic

porting29.jpg

 

#15. Roof of manifold. Worked in almost 2”. Trick here is to go straight then blend into the top of casting. Try to make them equal.

porting28.jpg

 

#16. Ok, here is a pic of a little secret. Ever notice whenever you pull an exhaust housing after it’s been in service a long time and notice it is warped? Well, here’s a way to stop that. I always (unless told not to) put a slight concaved radius into the separator about .008”. Why? Because while the manifold and exhaust housing have all the outside surface area to help cool it, that separator hidden inside does not and it gets really, really, hot. And what happens to metal when it gets hot? It expands. It expands and pushes really hard on both manifold and housing until one gives in and bends, or cracks. Just don’t go any further in than .008”. More is not better.

 

porting23.jpg

#17. Abrasive rolls at work. CAUTION! Abrasive rolls will hurt you just as fast as a cutter. Pay attention!! Start out with a 80grit and then go to a 320 (course-fine) and go slowly.(Or you may simply use 320, takes a little longer but you have more control) Follow the contours you created with the cutter. And you may use the roll to not only create a good finish; you may use it to remove small imperfections. Cutters will leave a very rough surface and rolls will remove that and make it look pretty. But remember this when you are cutting and allow for it so you don’t go outside your marks.

 

porting26.jpg

 

Special comment: it is common for some porters to remove too much material in order to make it “look” like they did more work. Don’t fall prey to this concept. Looking good does not mean better flow. As I said before, remove too much material and you will reduce flow. And don’t waste too much time on a pretty polished look. That polish job will be gone after a few miles of run time. Just make it smooth.

 

#18. Notice the radius and how it is blended. Pictures in here are difficult but hopefully you get the idea. Use your finger and feel for smooth transitions.

 

porting29.jpg

 

#19. Another angle. And notice areas that are not worked. Working it will do nothing to improve flow. Remember, removing material indiscriminately will reduce flow. If it makes you feel better, you may smooth it with a roll.

 

porting27.jpg

 

#20. Pic with gasket in place. Core shift is why the gasket protrudes into port. You may trim gasket if you feel it blocks too much.

 

porting41.jpg

 

Not all manifolds will have as much core shift because not all manifolds are the same. I’ve had some that were almost perfectly centered, others so bad I really couldn’t do much to save them. Note: you may have noticed that there has been no reference to the mounting flanges (cylinder head side) of the manifold. This is due to the fact that the stock manifolds are already larger than the outlet ports in the stock head. Ported heads may be opened up but even then they most likely will not be larger than the stock manifold. “Aftermarket” manifolds need special attention paid to the inlet ports since a lot of them have a serious lip just inside the mounting flange which needs to be reworked or all your work will be in vain. Do that and some serious gains in flow will be realized.

 

 

 

 

#21. Waste gate (exhaust housing) flapper and port. Some really big horsepower guys will open this up. (Sled pullers, drag racers, ETC). 99% of the rest do not need to.

 

 

 

 

porting40.jpg

 

 

 

 

#22. Pic of cross drill hole as seen through waste gate. For 99% of us a .3750” (3/8th inch) is all that is needed. Why? Because all that you are trying to do is allow some “drive pressure” to pass to the waste gate side of the housing. NOT the gasses themselves, just pressure. Waste gates, when they open, only open a few thousandths of an inch, so you can understand why a larger hole is not needed.

 

 

 

 

porting39.jpg

 

 

 

 

#23. Exhaust housing showing how much core shift is present. See how the markings vanish? Not to worry though, this will not affect flow.

 

 

 

 

porting35.jpg

 

 

 

 

 

 

Share this post


Link to post
Share on other sites

I will say again, do not try to compensate for core shift by removing more material. Simply match the housing inlet using the same method you did on the manifold outlet (flange). Remember to anchor it down before working. I use either a vice or clamps

 

A couple things need to be made clear. With the housing, you will need to blend in a long way. You are trying to maintain a “taper” inside to encourage acceleration and compression of the gasses. DO NOT go straight in, maintain a taper. Any lips or bumps will have a diverse affect. So pay close attention.

 

Also, you will notice “bumps” on the inside that are because they needed to move the wall in so the mounting nuts will have clearance. You can remove about .080” from these bumps maximum and improve flow quite a bit. But remember to BLEND it in.

 

Special note: when you have been working on the manifold, you have been working on areas with the gasses moving TOWARDS you, with the exhaust housing you are working with the gasses moving AWAY from you.

 

 

 

 

#24. Cross drill hole as seen from the inside. Remember to de-bur the edges of this hole to help limit sharp edges and high heat/stress areas to help reduce cracks from forming. Not easy to do, but with a long mandrel and a roll you can get in there and do it. Don’t worry about it being pretty.

 

 

 

 

porting36.jpg

 

 

 

 

#25. 2 pics of rough cut housing to show how far to blend in. Pics don’t show distance but it is about 2”. I will go in as much as 4” sometimes to clean up casting flaws.

 

 

 

 

porting48.jpg

 

 

 

 

porting47.jpg

 

 

 

 

Surfacing of manifold and housing. You may have a machine shop do this and it will be worth it if the surfaces are really grooved from being mounted for a long time. Sealing is very important as any leak, however minor, will act as a continuous waste gate and boost will be difficult at best to make. Kelly (Skyking) is a master with a file and performed this task much to my amazement. Use a straight edge to verify a flat surface even if it “looks” flat.

 

 

 

 

Something that needs to be addressed. You may run ported exhaust housings on a stock manifold, but you should avoid running stock exhaust housings on a ported manifold. Why? Because the material you removed in the manifold will cause a very large “lip” and very high restriction when the stock housing mates up to it. I’m not saying you cannot do it, just you should avoid it.

 

Ok, so you want to tackle this project. I have been doing this for many decades and I will tell you this is a dangerous activity. Small HOT metal fragments flying at you at very high velocities, even smaller ones floating in the air for you to inhale, cutters and abrasive rolls spinning at 24,000rpm mere inches from your hands and face. If and when a roll decides to fail, which they will without warning, you have a dragon that wants to rip your face off in your hands and you are trying to either shut it off or yank the cord from the socket.

 

And if you have a friend standing there watching because they want to see what you are doing, they are in as much danger as you are. Chips can and will fly 10 feet!!!

 

What I am trying to say is, this is dangerous work, treat it as such.

 

Have fun and enjoy the benefits of a superior flowing exhaust (less heat, less drive pressure, quicker spool up, quicker cool down)

Share this post


Link to post
Share on other sites

A big thank you to Skyking for adding this to the porting thread. I will start a thread for the do-it-yourselfers to ask questions.

Share this post


Link to post
Share on other sites

It always amaze me to review these pictures. good job guys.

Share this post


Link to post
Share on other sites

It always amaze me to review these pictures. good job guys.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×