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Thread: port-n-polish?

  1. #1
    hotrod180's Avatar
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    port-n-polish?

    A friend of mine wants to pump up his Pacer a bit. He was thinking of a 160-horse mod but apparenty there isn't an STC to put the higher-compression pistons in a narrow-deck 320. Now he's thinking of sending his cylinders to Lycon for a port and polish job-- he sez they get $250 a cylinder for the work, & from their literature it sounds like he might pick up about 16 or so horsepower. He hopes by doing this in conjunction with a Sutton exhaust that he will see some noticable performance benefits.
    Seems to me that this, maybe also with some sort of variable-timing electronic ignition (if there's one approved), would be a good way to go for more performance without increasing weight.
    Thoughts?

    Eric
    Cessna Skywagon-- accept no substitute!

  2. #2
    cubflier's Avatar
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    I think that port/polish/flow balance will help some but doubt that you will experience a gain of anywhere near 16 horsepower on a 150 hp 0320.

    As long as you put a muffler on after port/polish/flow balance the muffler, regardless of brand claims, will serve to restrict the benefits that might otherwise occur.

    I did my port/polish/flow balance in conjunction with a 160 hp pistons and a leading edge exhaust. My engine is strong but no where near what it should be if I added all the hp claims.

    The tell was when we did a pull test against other stock 160 conversions and Crash's 180 hp 0360. My engine pulled a slight bit more that the stock 160 but a fair amount less than the 0360.


    Jerry
    If it looks smooth...it might be

    If it looks rough...it is!!

  3. #3
    Darrel Starr's Avatar
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    The problem with upgrading to 160hp isn't the engine upgrade. That is expensive because it takes longer studs, banana plates and possibly other changes depending on the engine vintage but it doesn't require an STC. Both engines are included in the 0-320 Type Certificate Data Sheet E-274 available on the FAA web site. You can modify one engine configuration into another one within the same Type Certificate as a minor change. It requires stamping a "C" to indicate the "change" per Lycoming Service Bulletin 1304J.
    Legally installing the 160hp engine in the PA-20 airframe might be a little more involved because the Type Certificate for the PA-20, 1A4, is not the same FAA document on which the 160hp PA-22 was certified, 1A6. But I would bet that you can get a field approval since the airframes are so similar.

  4. #4

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    I have always wondered about the legality of this port n polish business. Nowhere in any overhaul manual I have read allows any such procedure, I know of no approved data for such procedure, and I doubt any manufacturer would approve it. I think they are selling pie.

  5. #5
    bearsnack
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    Which model pacer? The type certificate for PA-22/20 includes a 160 horse as I recall. Look at the type certificate carefully, sometimes there are items on there that you may think are STC items.

  6. #6
    StewartB
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    Balancing and flow matching make perfect sense to me. Given the choice, why wouldn't I want the engine to turn as smoothly and efficiently as possible? I had the choice. My engine is balanced and flow matched. I like pie.

  7. #7
    Tim's Avatar
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    Eric, I'm experimental, but here's what I did. I had a narrow deck 0-320 with 8.5 to 1 pistons. I rebuilt it with new Lycoming cyl. ( 9 to 1 pistons ) and had Lycon flow balance them. The engine was balanced and I have about 20 hours on it now. I heard claims about 10% increase in power, but I'm not sure about that. All I know is I get about 75 rpms more on takeoff ( same prop) and off the ground at least 50ft less than before and it's smooth, very smooth. At 2450 rpms my manifold pressure is .5 to .75 less.

    Tim

  8. #8

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    Stewart, I have no problem with the concept, i was just making a observation as to whether it is legal. I would like to run auto type fuse blocks but it is not approved. It is just a soap box issue. I do not understand why we have to run 50's tech in our airplanes.

  9. #9
    cubflier's Avatar
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    Quote Originally Posted by Glidertow
    I have always wondered about the legality of this port n polish business. Nowhere in any overhaul manual I have read allows any such procedure, I know of no approved data for such procedure, and I doubt any manufacturer would approve it. I think they are selling pie.
    This is one case where common sense has prevailed (so far). It's no secret that companies are port/polishing and flowing balancing cylinders that are going in certified engines. It's been going on since I got my plane which was 17 years ago. The feds are well aware of this and have yet to take issue with this.

    Lycoming does offer flow balancing in it's Thunderbolt line of experimental engines. I would imagine that the reason it's not part of the certified engine line speaks more about the approval process than it does about the safety of the process.

    Jerry
    If it looks smooth...it might be

    If it looks rough...it is!!

  10. #10
    StewartB
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    I don't know what Lycon does or doesn't do, but for example, Titan and Millennium cylinders on a Pponk engine conversion are rated at 275hp and stock TCM cylinders make 265. The difference is in the valves and flow efficiency. Titan and Millennium cylinders are PMA'd so their use is perfectly legal. I know Lycon prefers to work on factory cylinders. Maybe the factory cylinders have more potential for improvement? I have no idea how Lycoming cylinders stack up against the aftermarket.

    Of course keep in mind that a Pponk engine's data tag identifies it as an 0-470-50 rated at 235hp. Hmmm.

    SB

  11. #11

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    Port and Polish

    Just my two cents: Adding a little this or that for performance seems to me o.k. for those flying on the edge. I've never felt the need for anything other than stock Cubs for my flying out here in the East---small lakes, rough strips. Keeping personal and a/c weight down works wonders for really tight spots. Some serious practise may also be less expensive and more productive than the mods.

  12. #12
    SuperCub MD's Avatar
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    If you send me your jugs I'll give you a top notch port and polish, I promise at least a extra 50 hp on my dyno....Like the old saying goes, there is one born every minute.
    Thanks Airguide thanked for this post

  13. #13

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    port-n-polish?

    Cylinder head mods done properly will make the engine more efficient.It is just physics.Stock cylinders on anything have flaws.Some are better than others but all have shortcomings.Given free reign to re-design existing engines with today's knowledge these engines would gain a bunch.
    When you do this work yourself and do it methodically keeping careful records and testing different mods you find what works.It is painstaking work but can make a big difference in how an engine performs.
    The other thing to remember is that fuel economy goes up with better cylinder filling.I have had to lean considerably in some applications after mods because of the dramatic increase in efficiency.
    This site may give you some food for thought
    http://www.diyporting.com/

    Bill

  14. #14
    jr.hammack's Avatar
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    mods are a strange creation of man,some work and some are a fabrication in your mind,i just paid a lot of money and it just had to made a improvment!!
    cyl. head porting has made a major impact in most racing sports no matter what kind,the impact on a low r.p.m a/c engine will not be a major increase,but will be a improvement!
    my last cub was a lycon flowed engine pulled as hard as any of the 160 h.p. 0-320's iv'e owned(personal opinon only bob).
    sj flew it and thought it was a 0-360,but what dose he know!!
    wish bob butler would chime in,he works for rhear morrison racing engines in texas and could add a little to this thread.
    end product,guys flying out of crappy short places,overloaded,out in the middle of nowhere found what works and what didn't.

    jr.

  15. #15
    Steve Pierce's Avatar
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    They are balanced because all the cylinders are flowing the same amount of air. I installed a factory reman on a friends Bonanza several years ago. This was his third factory reman on his Bonanza that he has owned for many years. He flies 300 plus hours a year and is a very conservative kind of guy. Ken at Lycon took the cylinders off, flow matched them and reinstalled. The owner said that it was like flying behind a sewing machine. Smoothest engine he had ever flown behind. Here is an article on what Lycon does and it's approval. Barrett won't flow certified cylinders. Their interpretation is different. Talked to them about this a few weeks ago and have talked to Ken at Lycon at length about the same. Also Steve Knop told me he believes the investment cast cylinders that Superior and ECI are making are so close to each other that it is like flow matching. http://www.supercub.org/photopost/da...Power_0409.pdf
    Steve Pierce

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    Will Rogers

  16. #16
    StewartB
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    In my case flow matching involves the cylinders. Balancing involves rotating mass. Crank, rods, pistons and pins.

    SB

  17. #17
    Steve Pierce's Avatar
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    I was referring to the balancing effect flow matching has on making the engine feel smooth. I can only imagine how balancing the reciprocating parts would smooth things out. Good to see you back Stewart, still spending time in Texas?
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  18. #18
    StewartB
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    Thanks, Steve. I'll be in Aggieland on Sunday. I don't mind the empty nest but I miss my kid.

    Stewart

  19. #19
    Steve Pierce's Avatar
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    I can imagine.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

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