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DIY Port and polish on an LS head.

Discussion in 'Engine Building' started by MikeBergy, Jun 7, 2004.

  1. MikeBergy

    MikeBergy Blah blah blah....

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    Hey, was wondering if anybdy has done this. I have two ls heads, one of which is going back on my teg to get my car back and running while I save this summer for my b16a build. I want to just open the ports up a little bit and maybe just get some of the casting imperfections off of the surface. ANyone done this? Or any recommendations? I heard that if you polish the intake ports, that fuel condenses on the side, so I am wondering if that is true, if there is anyone that has any suggestions. I am also goingto do the Intake mani just for fun. Thanks in advance. Oh yeah, don't give me any garbage about how DIY is a stupid idea. I have two heads, so if I screw up on one, I am just gonna throw it away and use the other one. Darn cheap heads.
     
  2. MaaseyRacer

    MaaseyRacer Senior Member

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    Hitme up tonight Mike I will explain this to you. If I can get my shit together too, I will post up what I have done. It is not too bad, just a slight learning curve. I have a bunch of pics of my b16 head, that I am currently porting:
    http://home.csumb.edu/m/maaseric/world/headweb/
     
  3. MikeBergy

    MikeBergy Blah blah blah....

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    Cool Eric, I'll be off work around 930, home shortly thereafter, thanks. The pics you posted look good, you should whittle away at the valve guides a little bit imo.
     
  4. MaaseyRacer

    MaaseyRacer Senior Member

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    Yeah I know, I need to get in there, a bit more, but I do not know how extreme I want to go with this. Oh and also I have not put the final finish on the intake side so for anyone who wants to bitch that it is too smooth, it is going to get roughed up this weekend.
     
  5. hcivic.com

    hcivic.com Senior Member

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    good pics you may want to knife edge the transition between the two intake ports
     
  6. MaaseyRacer

    MaaseyRacer Senior Member

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    I am not planning on doing that as if they get two thin, which it is hard to do with the tools I am using you can create hot spots in the metal. If I had a long snout die grinder or something other than my porter cable electric drill and summit racing intake manifold porting kit, I would be all about that. Also those are way older pics than how the ports look now. Also this is my first head that I am porting, and I am learning from my pops who was a machinist for about 20 years and worked mainly with british motor cycles, and he has also had a ton of expereince with the older v8s. The main trick with porting heads is to use the gasket to mark off what you want to remove. Then start shaving, aluminum cuts like butter so always keep the dril/grinder moving. However you must not just open up the mouth of the port you need to get down into the port too. Bowl blending is a bitch and I do not recommend it until you see what has to be done, my bowls are deep as hell now, but I watched my pops start them and he kept an eye out for me when I took them over. There are a few tricks to the bowls, and it just takes some time to get used to. I also had a blown up D series head to practice on, and I have done a couple of ford 289 heads since then too, so I am getting better. This B16 head is just a light job to just help the flow out. :)
     
  7. StyleTEG

    StyleTEG Senior Member

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    In general rougher surface tends to produce better power than smoother, due to the boundry layer.

    Especially on the intake side, which needs some turbulence to keep the fuel atomized.

    The shape of the port is EXTREMELY important. You can't just remove material where ever you feel. Your best bet is to study what HONDA porters do, and where they remove material and try and do the same. Keep in mind that if you open up the ports too much, there goes your low end and midrange power.

    If you just want to remove casting imperfections, you should be good. Just lightly remove them, and hit the surface with some rough grit sandpaper when you are done to leave a rough finish.

    Definetly read into it more, because there are some imperfections which actually aid in swirling and you will lose performance if you remove them.
     
  8. MikeBergy

    MikeBergy Blah blah blah....

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    Okay, you are definitely speaking my language with the boundary layer stuff, I wasn't thinking too much about the fuel atomization. I am just looking to open it up a little to help out the head. The ls head is about as restrictive as a DOHC can come, and I do have two of them, so I am not too worried about messing it up too much. What grit paper do you recommend for roughing up the walls? And the exhaust ports can be smooth as silk, right? Or do you have to have to worry about exhaust flow reversion if they are too smooth? Thanks for the replies so far. Keep them coming.
     
  9. StyleTEG

    StyleTEG Senior Member

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    The boundary layer is the amount of turbulent area around the edges. If there is too much boundary layer, you effectively make the port smaller since only the center of the port is actually liminar flow.

    If a port is super smooth, the air tends to stick to it more. Think about a golf ball, and how the dimples allow it to move faster through the air. That is because it reduces the amount of boundary layer around the ball.

    So even on the exhaust side you want it slightly rough, (but it can be smoother than the intake, since it will be covered in carbon anyways).

    Most porters say they hit the intake with 80 grit cartridge, not sure about the exhaust.

    If you are going to open the ports out, slightly enlarge the intake port at the edge of the head to prevent reversion into the intake manifold. (the idea is that the head ports will be larger than the intake manifold, so air reversing has a dam on the edges).

    Other than that, only open the ports out on the edges of the floor. The idea being you get the ports to have a slight D shape instead of an oval.
     
  10. MikeBergy

    MikeBergy Blah blah blah....

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    I think it is more of a fuel atomization issue; if fuel is concentrated in one pocket of air entering the combustion chamber, it will lean out other pockets, and possibly cause detonation. Does this sound about right? I am still learning about the whole process of the science called combustion. Finding out it is a very delicate process.




    Wrong!!!!

    The dimples on the ball cause the otherwise laminar boundary around the front end of the ball to become turbulent from the getgo. This is called "tripping" the boundary layer, and it causes a supercritical flow case, and causes the boundary layer to separate later than it the ball were smooth. This reduces the amount momentum loss due to the turbulent eddies that form as the air flows around the ball, and therefore lowers the drag coefficient allowing for faster and longer flight. But you were along the right track. I was just not thinking about fuel atomiztion until you mentioned it. Thanks though.

    Oh yeah, a turbulent boundary layer is MUCH thicker than a laminar boundary layer.

    But yeah, so pretty much rough up the ports on the intake, but smooth out the plenum and intake runners, yeah? Looking for a porter's insight.



    I am guessing this is more of an antireversion technique than anything else. A slight amount of turbulence will provide for a more constant velocity profile across the cross section of the port, and will provide some resistance to flow reversion by making the flow more uniform. Good stuff.



    Hmm...Stepping the ports? That is also something I didn't think about...I suppose it will also work on the exhaust. On the intake side, it will also help to preserve the fuel atomization I imagine. Thanks. There are all kinds of things that make sense, but no one person thinks of everything. I appreciate the help. Keep it coming.
     
  11. vpSPOONsol

    vpSPOONsol Senior Member

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  12. StyleTEG

    StyleTEG Senior Member

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    Ugh, I grow tired of everyone picking an arguement with anything I post :p



    It has to do with fuel pooling on the walls of the ports. Not about fuel pockets.



    Roughing up the exhaust is not an anti-reversion thing. Again it has to do with the boundry layer. A perfectly smooth port is going to have a larger more turbulent boundry layer than a slightly rough one.

    If you think a smooth ball would have LIMINAR flow compaired to a dimpled golf ball, I have some pictures to show you that would shock you ;) B)

    Besides the exhaust side gets covered in carbon, and you rarely retain the same texture once that carbon builds up anyways.
     
  13. MikeBergy

    MikeBergy Blah blah blah....

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    Not arguing, just speculating. That part about the gas pooling on the walls of the ports is what I heard from someone else too, I just wasn't too sure.

    Regarding the ports, the shape of the port pretty much makes the boundary layer turbulent regardless at high engine speeds. The Reynolds number is going to creep up as the air velocity increases, but I definitely don't want fuel to pool up on the port walls. Thanks bro. Where did you learn about boundary layer theory. Fellow aero student? :D
     
  14. StyleTEG

    StyleTEG Senior Member

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    I wish, honestly aerodynamics and fluid dynamics fasinate me. And if you want a job in the racing industry, pretty much everything is aero related.

    So I have read my fair share online and in books I have picked up, but honestly wish I could take more time to study it.

    As far as port shapes, Endyn recommends using D shaped ports. Since air travels the fastest on the bottom of the port (since air likes to travel the shortest distance), they recommend only taking material out by widening the floor and making more of a "D" shapped port instead of a oval shape.

    Another major source of gains is deshrouding the valveseats. But its probably the most difficult.

    Make sure and post some pictures up when you are done ;)
     
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