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Thread: Catto prop on C-90 Continental

  1. #81
    cubdriver2's Avatar
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    Quote Originally Posted by mam90 View Post
    Should be starting assembly this weekend, so maybe next year....this photo is from last month...
    Attachment 32887
    Like this Peter

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  2. #82
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    I've got a crankcase tray already, although it could be baffled a touch more.

    Potential conflict with adding a lower cowl scoop to blast the tank is equalizing the pressure above the cylinders and increasing CHT's. No CHT setup, so I think increasing cooling over the top is part 1, unless you can separate the sump air, and keep a low pressure in that area.

    I like the inlet idea to start.

    pb

  3. #83
    BC12D-4-85's Avatar
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    I wonder if experimental augmenter tube(s) over the exhaust outlet pipe would help flow more air through the cowl?

    Gary

  4. #84
    skywagon8a's Avatar
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    pb, How about showing us a picture of your bottom cowl opening. It is possible that it needs a larger opening and/or a lip ahead of the opening to create a lower pressure area thus drawing a larger volume of air through. Also a lot of the hot air escapes through the opening at the aft end of the side cowls.
    N1PA

  5. #85
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    Transmitted from my FlightPhone

  6. #86
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    This lip could be bent down more to deflect the outside air which would create more suction in the opening.



    ​Those vertical sides are doing nothing unless you can seal them against the bottom of the engine. Or at least close the gap as tight as possible. Try some stiff fabric impregnated rubber like the baffle seal material. Try to trap the air in this tray so you can force it to flow against the oil sump.

    N1PA
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  7. #87
    skywagon8a's Avatar
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    Quote Originally Posted by Farmboy View Post



    Another idea which is quick and easy. Tape over this cowl opening first to see what happens. This will increase the differential pressure above and below the cylinders. It may be all you need.
    N1PA
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  8. #88
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    Quote Originally Posted by skywagon8a View Post
    Another idea which is quick and easy. Tape over this cowl opening first to see what happens. This will increase the differential pressure above and below the cylinders. It may be all you need.
    We cover that up for winter, seems to keep it warmer in the cold weather.

  9. #89
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    I agree with where skywagon8a is heading...

    Before I went about on any external modifications, I'd spend some time ensuring that your baffles are sealing where you want them. I'd also spend some time making sure my upper cowling area (pressure plenum) and lower cowling area have the largest pressure differential you can get, and that your lower cowling area is as close to ambient pressure as you can get it. That ought to help increase your overall cooling efficiency, including your oil temps.

  10. #90
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    Quote Originally Posted by CamTom12 View Post
    I agree with where skywagon8a is heading...

    Before I went about on any external modifications, I'd spend some time ensuring that your baffles are sealing where you want them. I'd also spend some time making sure my upper cowling area (pressure plenum) and lower cowling area have the largest pressure differential you can get, and that your lower cowling area is as close to ambient pressure as you can get it. That ought to help increase your overall cooling efficiency, including your oil temps.
    I agree with you guys on the pressure differential, but bear in mind that temps are good with the original prop. Upper cowl baffling and seals are all good, tight, and working. I added the lower cowl lip to create a bigger differential and help suck hot air out last summer, and while I can keep playing with that, I'm not sure we can create enough vacuum to make up the different to lack of pressurization.

    I'll try blocking off the case intake just for kicks and see if the temps move from normal. If they do go down, then we would have been doing this wrong all last winter by blocking it off to increase case temps.

    If they go up as expected, the next step is to capture more air at the inlets, or find a prop that satisfies all the parameters .

    pb

  11. #91
    40m's Avatar
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    "or find a prop that satisfies all the parameters" .

    Give NC a call I'm sure you will get the help you're looking for.


    From Genesis: "And God promised men that good and obedient wives would be
    found in all corners of the earth."

    Then he made the earth round... and He laughed and laughed and laughed!

  12. #92
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    Quote Originally Posted by 40m View Post
    "or find a prop that satisfies all the parameters" .

    Give NC a call I'm sure you will get the help you're looking for.

    🤣🤣🤣🤣🤣


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  13. #93
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    Quote Originally Posted by Farmboy View Post
    Quote Originally Posted by Farmboy View Post
    I agree with you guys on the pressure differential, but bear in mind that temps are good with the original prop. Upper cowl baffling and seals are all good, tight, and working. I added the lower cowl lip to create a bigger differential and help suck hot air out last summer, and while I can keep playing with that, I'm not sure we can create enough vacuum to make up the different to lack of pressurization.

    I'll try blocking off the case intake just for kicks and see if the temps move from normal. If they do go down, then we would have been doing this wrong all last winter by blocking it off to increase case temps.

    If they go up as expected, the next step is to capture more air at the inlets, or find a prop that satisfies all the parameters .

    pb
    "I'll try blocking off the case intake just for kicks" That is my suggestion just for starters. That tray under the engine just looks like an oil pan to catch drippings. It needs to be turned into a closed chamber which blasts cold air on the oil tank. Since the only change was the prop, it can be assumed that the cooling while acceptable was only marginal. Keep the prop and tweak a few items to get the oil temp down. It sounds as though the prop is a keeper. Your differential is likely close enough.

    You do realize that some manufacturers place a blast tube on the Lycoming oil screen where the temperature bulb is located in order to BS the temperature gauge into thinking that the temperature is actually lower than it really is? The FAA approves this method. This and writings from Lycoming engine experts indicates that they do not become too concerned with running oil temps at the limits.
    N1PA

  14. #94
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    Actually Pete, I don't feel that it has marginal cooling before.

    I have a blast tube that I have already swapped back to the heat exchanger, for winter use. During the hot months of summer I use it as you mentioned, blowing on the case, which may be providing false temps as the data from Steve's friend showed in shortwingpipers, or it may be actually cooling the case, and therefore cooling the oil that passes through the case. Either way, it's another bandaid fix if I start using it just so I can use this prop.

    Std temps for me currently are 190-200, with a peak of maybe 210 after a long climb. With the change in prop it increases and stabilizes at 222-223, up to 225 often, and when it worried me was the long climb and it spiked up to 240 and sat awhile before it came down. I was headed for a landing strip when it finally decreased and stabilized back at 225, so rather than risk another climb out I continued back so I could swap out props.

    I swapped props in 15 minutes or so, and jumped back in the air, and from then on the rest of the day temps were stable at 200.

    So the prop change is a definitive 25 degree delta in temps, and under load it loses all ability to cool and the delta is 30-40 degrees. As others have stated, with modern oils this is probably not an issue, but I'd also rather not be the guinea pig by running over their redline all the time. Someone else can test that theory for a few thousand hours and get back to me on it. Our diesels like 190 degree temps hauling a load all day long. Our little Continentals aren't much different in that respect.

    Sensenich mentioned they might have a tall spinner for me to try, which I agree is a good thing to do as well. (Current spinner isn't deep enough to fit the hub)

    pb

  15. #95
    skywagon8a's Avatar
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    pb,

    I understand, perhaps the big spinner will will be the answer? It will smooth out the intake air flow.
    N1PA

  16. #96

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    Pete, Do you have the short or long temp probe? When I sent my gauge out to be reconditioned ( short ) and put in my long one from the SC project my temps were 20 or so degrees higher like 170 degree range. I almost got worried but it was summer time on floats. Bring the prop over and I'll see if it maybe just doesn't like your plane .
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  17. #97
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    170? The only time I see 170 is ski flying in January. Or did you mean 270?
    If I had a baggage area that would be a good excuse to visit!


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  18. #98
    cubdriver2's Avatar
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    I forgot, did you ever check this gauge for accuracy?

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  19. #99
    Farmboy's Avatar
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    No, but no reason to suspect an error in operating range. Appears pretty normal with std prop.


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  20. #100
    cubdriver2's Avatar
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    Every gauge I ever tested was off some. First thing I check when flying something new. Even the ones I had Keystone and John Wolf overhaul. Most i have tested have the most accuracy around 150 to 170F below or above that the farther away from center its not as accurate. Might want to check yours but its probably not off 20 + degrees.

    Glenn
    Last edited by cubdriver2; 10-12-2017 at 09:47 PM.
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  21. #101
    Farmboy's Avatar
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    Yeah, I can believe that. But if they're all off, maybe we shouldn't keep testing.


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  22. #102
    cubdriver2's Avatar
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    Quote Originally Posted by Farmboy;698in my yellow56
    Yeah, I can believe that. But if they're all off, maybe we shouldn't keep testing.


    Sent from my iPhone using SuperCub.Org
    The one that came in my new Cub never went above 150F, even in boiling water

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  23. #103
    40m's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    The one that came in my new Cub never went above 150F, even in boiling water

    Glenn
    Hell and that's where you operate most of the time

    From Genesis: "And God promised men that good and obedient wives would be
    found in all corners of the earth."

    Then he made the earth round... and He laughed and laughed and laughed!

  24. #104
    skywagon8a's Avatar
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    Quote Originally Posted by Farmboy View Post
    Yeah, I can believe that. But if they're all off, maybe we shouldn't keep testing.


    Sent from my iPhone using SuperCub.Org
    Quote Originally Posted by cubdriver2 View Post
    The one that came in my new Cub never went above 150F, even in boiling water

    Glenn
    That's the answer! Swap gauges with Glenn.
    N1PA
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