Head Porting resource! Learn how here!

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ICEMAN.KCMO
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Head Porting resource! Learn how here!

Post by ICEMAN.KCMO » Tue Dec 23, 2014 7:43 pm

So I decided to make this thread after reading several diy head porting thread across the interwebs. I have seen a lot of people comment that obviously didn't know the first thing about head flow.

So what I am going to attempt to do is start a resource for head porting. Hopefully take the guess work out of it. I am going to post up several links that I want you to read through before you ask any questions or comment. Before doing anything, save your self time and money and Research! GET INFORMED! The right combination of key strokes on google will amaze you.

So here are the links. Read each one all the way through. If you skim, you WILL overlook something. You will read through these links and become an instant (amateur)pro!

I can't find Porting School #1, but if I come across it, I will update this post.

David Vizard Porting School #2

David Vizard Porting School #3

David Vizard Porting School #4

David Vizard Porting School #5

David Vizard Porting School #6

David Vizard Porting School #7

David Vizard Porting School #8

David Vizard Porting School #9

David Vizard Porting School #10


Here is a great article about using a thread to visualize the airflow through the port, So you can actually see where the port needs work.
DIYPorting.com Shade Tree Head Porting

Check out the rest of his site. Lots of good information here.

How to CC your Heads.
If you are porting, you need to do this to keep consisncy.


Here is Motoman. I am sure most of you have heard of the "Motoman engine break in" Which by the way is the way to break in the engine... here are several links to his method of porting. The website is a little late 90's, but hey, we all weren't born web designers.. He is working on High RPM bike engines, But this all still applies. Just as the length of an intake runner is designed on the powerband you will be running, port size will differ too.

Motoman porting 1

Motoman Porting 2

Motoman Porting 3

Motoman Porting 4

Motoman Porting 5

All of Motoman's articles.
I highly recommend reading through these when you have a spare minute.


Here is a good example of something similar to the motorman porting: Pics of a ported head Dave Vizard style

I will try to update this first post with necessary information.
Steve.

Jason M
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Re: Head Porting resource! Learn how here!

Post by Jason M » Fri Jan 02, 2015 1:15 pm

Thank you very much for your contribution! I spent the entire day yesterday reading through all the articles that you've linked to this thread... I'm feel like I have a much better understanding on cylinder head ports, "porting and polishing", and flow bench design and interpretation of flow bench results. I'm going to work on a DIY shop vac style flow bench this weekend!

Most information online applies to older 2 valve engines, and very little information exists on modern 4 valve pentroof "quick burn" chamber cylinder heads. Questions that I have at this point are;

~How to deal with the port divider on the intake and exhaust. (Should the divider be knife edged or should it have a radius?)
~Should the valve guide be blended into the port or should it be left to protrude into the port for better valve support?
How a turbo charged engine either changes or does not change port design? (Is there a target air speed within the intake port to stay within?)

ICEMAN.KCMO
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Re: Head Porting resource! Learn how here!

Post by ICEMAN.KCMO » Fri Jan 02, 2015 1:48 pm

To answer your first two questions, My uncle has been very big into racing motorcycles since the mid seventies. The advice he has given me on the divider is to leave it blunt, and do not knife edge. Clean up the casting just a little bit, but leave the shape the same for the most part. If you look at a 747 jet or anything of that sort, they are all rounded noses. Only thing that has sharp tip noses are planes that go supersonic.

As for the valve guides, he said to shave down the intake guides, but do not touch the exhaust valve guides. The exhaust valve guides are still needed to absorb heat from the valves. I am going to play around with the exhaust port. I don't know how much more flow I can get without hurting velocity. I really don't want to hurt velocity.

For your last question, I have not found the answer to that yet. so I have decided to take one of my many spare cylinder heads, and find out for myself. I want to play around with some of that high velocity porting, and find out what kind of differences take place between a naturally aspirated engine, & a turbocharged engine. I just need to find someone willing to let me borrow their n/a car for a while.

however, I have considered putting my car back to N/A, and running on my test that way. Then put all the turbo back on.
Steve.

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Re: Head Porting resource! Learn how here!

Post by Jason M » Mon Jan 05, 2015 6:11 pm

I took some rough measurements of the intake ports and calculated air velocity at different cfm of air flow. Based off of my initial measurements it's no wonder why the ka responds so well to boost...

I'd feel better if someone else independently posted some numbers based off their measurements of the intake and ex ports and air velocity calculations to confirm my findings. I'm going to withhold my findings until I can review and confirm a couple things.

I found this little tid-bit of info, which imo, seems like sound reasoning.
A turbo application requires much less intake air velocity to make power then a NA motor will. But it also depends on the use of the motor and car. Lets say you're building a autocross or road course car. Well you'll want low end and top end, so you'll want a more traditional port design that keeps the intake port no bigger then 85% (IIRC) of the valve size. This will maintain intake air velocity during off boost conditions and obviously increase the ability of the "vacuum" to pull in as much air as possible.

The boosted drag motor on the other hand can be drasticly redesigned. If you have the ability to make a new intake manifold, you can increase the entire intake port entry and the port itself. Huge valves can be used and the velocity of the air is totally influenced by boost alone, with the exception of the intake manifold design. But it's runners to will be designed for maximum airflow.

In a NA application, intake air velocity must be kept up at all times. This has alot to do with port shape and size. As well as intake runner design. With low velocity, you very poor driving conditions unless you have somthing similar to Honda's VTEC which allows for the lower rpms to use an entirely different cam profile.

Jason M
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Re: Head Porting resource! Learn how here!

Post by Jason M » Mon Jan 05, 2015 10:23 pm

The speed of sound ~1125 fps @ 70*F, is a limiting factor for air speed (super sonic nozzle). I've observed from online research on intake and exhaust port velocities, people have "rules of thumb" stating target mean air speed velocities, and percentages of the speed of sound. Usually this is something like 50-65% the speed of sound on the intake side as a limiting factor of air flow, or 300-350 fps average. For the exhaust side recommendations generally target slightly higher exhaust port velocities.

The speed of sound changes with temperature. Temp within the intake port is probably closer to coolant temp then ambient, and temp within the exhaust can exceed ~1500F. What is the speed of sound within the intake and exhaust port? Is it different then outside the port? According to http://www.sengpielaudio.com/calculator-speedsound.htm the speed of sound increases with temp. I'm curious to as whether or not most online calculators and computational engine simulators factor in the change in the speed of sound due to temperature.

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Re: Head Porting resource! Learn how here!

Post by p00t » Sat Jan 17, 2015 7:05 pm

Those are some good links and I will be reading them. I remember reading about motoman's break in proceedure a long time ago.

Porting is very much an art form. I never had the time to dig into porting, maybe one day.

If it helps here are the head flow numbers of a stock head 53F casting. Measured these a while ago.

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ICEMAN.KCMO
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Re: Head Porting resource! Learn how here!

Post by ICEMAN.KCMO » Sun Jan 18, 2015 2:49 pm

I started putting together my diy flow bench.

I found this what box downstairs. I figured I could make a big hole for the head to sit on and a hole for the shop vac to plug into. I'm going to make a pressure port tap on the top and run that to a DIY manometer. I Halfway thought about getting the proper plates and figuring up CFM, but I really don't care about that at the moment. Just changes in flow and velocity.
http://www.imgur.com/QHlvqtq.jpeg

Here is a manometer. At least the beginnings of one. it's going to be a clear vinyl to bring secured to the back of that blue bored. There is also measuring duct tape I stuck on there. One will be open to the atmosphere, and the other will be attached to a port I put on the flow box. I will be able to see pressure changes here.
http://www.imgur.com/3WOsEQj.jpeg

sitting on the workbench is a head that I am measuring the combustion chamber.

This is called CC'ing. All this is a flat piece of plexiglass with a hole drilled in the center to fill it, & a small relief hole toward the outer edge. I am using a syringe that the Pharmacy gave me to measure the fluid used.they will most likely read in milliliters, which is the same as CC is. Very convenient.this did not cost me a dime. Below is a little better picture.

http://www.imgur.com/ByiRJXH.jpeg

that's where I'm at so far.I still need to figure up a small device to open the valve.I think I'm just going to make a little L bracket come off of my dial indicator bracket. Since they will be right in the same area, I'm just going to thread a little bracket and put a bolt through it.

EDIT: images didn't show up correctly.
Last edited by ICEMAN.KCMO on Mon Jan 19, 2015 11:54 am, edited 2 times in total.
Steve.

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Re: Head Porting resource! Learn how here!

Post by airman » Mon Jan 19, 2015 10:57 am

Awesome thread/resources on this. Stickied.
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