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Thread: O320 a2d upgrade options to 160hp

  1. #1

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    O320 a2d upgrade options to 160hp

    PA-12: Based on a low oil pressure problem I am going to have to open my engine up. (We already went through and eliminated the other possibilities and expect that it is a main bearing.) Considered just replacing the bearings and having the crank yellow tagged but if I have it off and open anyways why not start it over at 0?

    My objective: certified 160 hp engine and a 0 SMOH.

    Current engine: Lycoming Model o320 a2d 150 hp
    About 1000 SMOH
    New cam at rebuild in 1996
    Cylinders IRAN less than 100hrs

    It was installed using the Kenmore Air Harbor STC SA4-456.
    The a2d has the o-235 style front bearing and is not authorized for 160 hp upgrade/modification.

    What are the the options for reaching my objective without buying a brand new engine?



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  2. #2
    AZinAK's Avatar
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    A factory overhauled A2B wide deck with the parts/pieces to bump it to 160 hp, or the B2B. That’s all I’m aware of for a -12 but I admit I’m still fairly ignorant to a lot of this. I have the A2B Wide Deck upgraded to 160 hp and love it. Hard to argue against the power to weight for any of the 320 160 hp engines.

  3. #3
    stewartb's Avatar
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    Pick your fav engine shops and see what they have to offer. From what I’ve heard lately you’ll probably alter your course due to availability and lead times. Price is gonna hurt regardless.

  4. #4
    skywagon8a's Avatar
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    Changing the engine to 160 hp is only part of your question. After that you will need approval to use it with the increased hp in your -12.
    N1PA
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  5. #5
    Steve Pierce's Avatar
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    160 hp seems to fret cases more on a narrow deck. There is a service instruction for installing dowels. I would call a crankcase shop and see if they can modify your case or do an exchange. Spare cases are getting more and more scarce.

    Some info on fretting crankcases. https://www.supercub.org/forum/showt...t-Oh-CHIT-quot
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  6. #6

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    I neglected to say that it’s a wide deck. I was also told that the casting on the front right side of the engine denotes the o235 style bearing in the front of the engine. If it were the newer style bearing, this casting would be bored and a have a plug installed. Click image for larger version. 

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  7. #7
    skywagon8a's Avatar
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    That casting is bored for the oil line from the prop governor fitting to sent governor oil to the constant speed prop. It's not likely a wide deck engine would have an 0-235 style bearing. Best to look in a parts book.
    N1PA
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  8. #8
    skywagon8a's Avatar
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    A lot can be learned about your -A2D engine by reading NOTE: 5 of the Type Certificate E-274
    https://rgl.faa.gov/Regulatory_and_G...ighlight=0-320
    or
    https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/74c397f0d8fa23b886257b63006ba6a4/$FILE/E-274_Rev_22.pdf

    Notice there are a lot of notes saying "the same as ..... except"
    N1PA

  9. #9

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    So with the E-274 document do you chase the models all the way back to see what the case specs are?


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  10. #10
    skywagon8a's Avatar
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    Quote Originally Posted by akmarty View Post
    So with the E-274 document do you chase the models all the way back to see what the case specs are?
    Yes
    N1PA

  11. #11
    wireweinie's Avatar
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    Download a copy of SSP-110 from Lycoming. Descriptions of certified engines.

    Web
    Life's tough . . . wear a cup.

  12. #12

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    Quote Originally Posted by skywagon8a View Post
    Changing the engine to 160 hp is only part of your question. After that you will need approval to use it with the increased hp in your -12.
    I had an engine guy tell me that the FAA politely asked him to stop doing a 337/logbook upgrade and just have customers do the stc. Have you seen or done a recent 160hp upgrade without an stc?


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  13. #13
    stewartb's Avatar
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    What STC do you propose to use? Crosswinds’ STC is a great choice. What else is there?

  14. #14
    skywagon8a's Avatar
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    Quote Originally Posted by akmarty View Post
    I had an engine guy tell me that the FAA politely asked him to stop doing a 337/logbook upgrade and just have customers do the stc. Have you seen or done a recent 160hp upgrade without an stc?
    A PA-18 which had been converted via STC to 160 hp came to me for a float installation. This was an issue because the STC specifically said "land plane only". What to do? I called my friendly FAA person who issued me a field approval to derate the engine to 150 hp. This was done by moving the red line on the tachometer to the rpm which represented 150 hp. (Now legal on floats.) This legally made the 160 hp engine a 150 hp engine. It had no effect operationally because with the prop which was on the plane, it would not turn up over the 150 hp rpm on takeoff anyway.

    In your case move the engine red line to 150 hp. Simple, and you still have your engine where you want it. If the prop you have has the ability to turn the rpm higher than 150 hp, then it's the pilot's responsibility () to comply with the red line.
    N1PA
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  15. #15
    Cub Builder's Avatar
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    Quote Originally Posted by akmarty View Post
    I neglected to say that it’s a wide deck. I was also told that the casting on the front right side of the engine denotes the o235 style bearing in the front of the engine. If it were the newer style bearing, this casting would be bored and a have a plug installed. Click image for larger version. 

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Views:	56 
Size:	112.4 KB 
ID:	62478


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    Looking at the Lycoming parts book, the O-320-A2D does have a unique crankcase that is different from all the other O-320s and has it's own unique front bearing configuration and parts. I don't know if it is like an O-235 or not, but it is clearly not the same as the rest of the O-320 line. So, what you were told about it not being a good candidate to upgrade to 160 HP may very well be true.

    -Cub Builder

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