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Thread: O-320/ O-360 What do they really weigh?

  1. #1

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    O-320/ O-360 What do they really weigh?

    I have been dreaming of building a new cub for over a year now. My focus is extreme light weight with high HP. My dilemma is do I go with a high hp O-320 or O-360? I want to know what the weight difference is not including: exhaust, alternator, starter and prop?
    Thanks,
    H

  2. #2

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    I would love to know the answer to your question myself. I never could get a definitive answer to that question f.

    Need to get the total weight for the whole conversion, including Prop, engine mount and anything else that the O-360 requires.

    My best guess is 60 pounds but that is only a guess

    I think the best way would be have some one weigh before and after the conversion.

    Over the years I have owned several 160 hp cubs and one 180 hp cub. I loved the 180 cub on skis and floats but did not like the way the 180 cub landed on wheels, it always felt nose heavy and took 30-50 feet more for me to land. I do not know if it was just that cub or if all 180 cubs feel that way. I have heard that the Thrust line conversion will make the 180 land like a 160.

    Getting of the subject a little more, master guide Larry Rivers has flown the same cub for over 30 years. He put over 6,000.0 hours on that cub all with a 150 horse. He worked in and out of some of the worst sheep hunting strips I have ever seen all with a stock O-320 150 horse.

    I personally struggled trying to decide O320 or O360, went back and forth for 6 months before I decided what engine to put on my project. Since I already had a fresh O-320 I went with what I had.

    Good luck on deciding what engine to put in your project.

    Jerry Jacques

  3. #3

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    There is 30 pound difference between the two engines plus or minus five pounds depending on which models. Fuel injected 360's are even heavier.

  4. #4
    Bob Breeden's Avatar
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    I have been debating this also. Have flown behind a 150 horse that works for me everywhere, and takes cheap car gas. But more power would be nice getting out of high places.

    Have decided that on a new experimental cub, I would have to move the 180 engine aft an inch or two or three (based on engineered calculations), and this would have to be done with a change in the fuselage by moving the firewall location - at least the upper firewall above the rudder pedals.

    Has anyone tried this?

    Bob Breeden

    www.AlaskaAirpark.com

  5. #5

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    Having flown both 160 and 180 HP, I like the feel of the 160 hp better, it seems smoother on climb out, the 180 on climb out would shake the whole tail especially with a banner in tow. And like a previous poster, the 180 seems a little nose heavy.

  6. #6

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    There are ways to make up that weight difference and feel of the two. A pumped up 0320 will climb out great but a 0360 with a pawnee prop accelerates on the ground alot faster. just my experience with the 2. talking experimental here.

  7. #7
    mvivion's Avatar
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    Engine weights from Lycoming:

    O-320 B (conical engine mount-160 hp): 277-283 lbs dry weight
    O-320 D (dynafocal engine mount-160 hp): 278-286 lbs dry weight
    O-360 A (dynafocal engine mount): 285-301 lbs dry weight
    O-360 D (conical engine mount): 280-281 lbs dry weight.

    So, it looks like there's a good bit of variability amongst engines of the same model, but it also looks like there isn't that much difference in the DRY weights-15 to 20 pounds maximum for the dynafocal engines. But it could be less.

    Part of the weight issue is prop weights as well. Accessories should be relatively the same weight, I would think??

    MTV

  8. #8
    Steve's Aircraft (Brian)'s Avatar
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    From the Type Certificate data sheets

    O-320- Weight (dry) and ignition, dual. By Models
    Weight Lb.

    -A1A, -A1B, -A2A-A2B, -A3A, -A3B ---- 244lbs
    -A2D ---- 249lbs
    -A2C, -A3C ---- 243lbs
    -B1A, -B1B, -B2A ---- 250lbs
    -B2B, -B3A, -B3B ---- 250lbs
    -B2C, -B3C ---- 249lbs
    -B2D ---- 283lbs
    -B2E ---- 250lbs
    -C1A, -C1B, -C2A ---- 250lbs
    -C2B, -C3A, -C3B ---- 250lbs
    -C2C, -C3C ---- 249lbs
    -D1A, -D2A ---- 255lbs
    -D1B, -D2B ---- 254lbs
    -D1C, -D2C ---- 256lbs
    -D1D ---- 253lbs
    -D1F, -D2F ---- 255lbs
    -D2G ---- 251lbs
    -E1A, -E2A ---- 244lbs
    -E1B, -E2B ---- 243lbs
    -E1C, -E2C ---- 245lbs
    -E1F, -E2F ---- 248lbs
    -E2D ---- 249 lbs
    -E2G ---- 249lbs
    -E2H ---- 252lbs
    -E3D ---- 249lbs
    -E3H ---- 252lbs
    -E1J ---- 245lbs
    -D2H ---- 251lbs
    -D2J ---- 255lbs
    -D3G ---- 251lbs
    -H1AD ---- 253lbs
    -H2AD ---- 253lbs
    -H3AD ---- 253lbs
    -H1BD ---- 253lbs
    -H2BD ---- 253lbs
    -H3BD ---- 253lbs


    O-360 Models Wt. (Dry) Lb. Characteristics

    O-360-A1A ---- 258
    O-360-A1AD ---- 257
    O-360-A1C ---- 261
    O-360-A1D ---- 256
    O-360-A1F ---- 258
    O-360-A1F6 ---- 265
    O-360-A1F6D ---- 264
    O-360-A1G ---- 262
    O-360-A1G6 ---- 269
    O-360-A1G6D ---- 266
    O-360-A1H ---- 263
    O-360-A1H6 ---- 298
    O-360-A1LD ---- 259
    O-360-A1P ---- 292
    O-360-A2A ---- 257
    O-360-A2D ---- 256
    O-360-A2E ---- 256
    O-360-A2F ---- 258
    O-360-A2G ---- 262
    O-360-A2H ---- 263
    O-360-A3A ---- 257
    O-360-A3AD ---- 257
    O-360-A3D ---- 256
    O-360-A4A ---- 265
    O-360-A4AD ---- 265
    O-360-A4D ---- 297
    O-350-A4G ---- 270
    O-360-A4J ---- 269
    O-360-A4K ---- 265
    O-360-A4M ---- 261
    O-360-A4N ---- 296
    O-360-A4P ---- 295
    O-360-A5AD ---- 265
    O-360-B1A ---- 256
    O-360-B1B ---- 255
    O-360-B2A ---- 256
    O-360-B2B ---- 255
    O-360-B2C ---- 288
    O-360-C1A ---- 257
    O-360-C1C ---- 256
    O-360-C1E ---- 254
    O-360-C1F ---- 288
    O-360-C1G ---- 292
    O-360-C2A ---- 257
    O-360-C2B ---- 261
    O-360-C2C ---- 256
    O-360-C2D ---- 260
    O-360-C2E ---- 254
    O-360-C4F ---- 275
    O-360-C4P ---- 275
    O-360-D1A ---- 254
    O-360-D2B ---- 253
    O-360-E1AD ---- 262
    O-360-E1A6D ---- 269
    O-360-E2AD ---- 262
    O-360-E1BD ---- 262
    O-360-E2BD ---- 262
    O-360-F1A6 ---- 301
    O-360-G1A6 ---- 303
    O-360-J2A ---- 289
    HO-360-A1A ---- 257
    HO-360-B1A ---- 260
    HO-360-B1B ---- 260
    HO-360-C1A ---- 288
    LO-360-A1G6D ---- 266
    LO-360-E1AD ---- 262
    LO-360-E1A6D ---- 269
    LO-360-E2AD ---- 262
    LO-360-E1BD ---- 262
    LO-360-E2BD ---- 262
    LO-360-A1H6 ---- 298

    I took the liberty of removing a lot of the unnecessary information but this should get you the information you want. keep in mind the different model designations. Some are dynafocal mounts, others are conical ect..

    Brian

  9. #9
    Darrel Starr's Avatar
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    Note that these weights are for "Show Engines" with some chromed pieces.
    Darrel Starr

  10. #10
    PerryB's Avatar
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    If you build it with the focus on keeping it light, the 160hp O-320 would provide excellent performance and would definitely be lighter. Especially when you factor in the prop weights as MVIVION pointed out. Also, as Josh mentioned, the 180's are harder on the fabric and airframe due to increased prop blast. There's no way around it unless you start adding blades to the prop. Of course from a pure performance standpoint, the bigger engine is always going to win. Its also going to cost more and burn more fuel. Don't you hate that no free lunch crap? Who thought of that one anyway? If I were building a Cub, I would be doing it very much like you describe (as light as reasonably possible). Keep the panel down to what you actually need, install VG's, a thrustline mod., a decent set of tires and a 160. You'll have a rockin' little machine! Perry

  11. #11

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    Do not forget the prop. A 1A200DFA weighs almost 50 #.
    I see the nose heaviness positive. It is amazing what I can load in the back before worrying about CG.

  12. #12

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    Thanks guys, I was thinking it was about a 20lb difference. My cub now has a good performing 180 in it and I have flown a couple of 160 cubs. I know many of you will think I am crazy but I am shooting for a 999lb cub with 200-220hp. It will be a simple cub maybe even no electronics but be able to work in the AK Bush environment without worry of falling apart. The planning continues...

  13. #13

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    "Don't you hate that no free lunch crap? Who thought of that one anyway?"

    Jerry Pournelle's grandfather. Robert Heinlein made it famous. TANSTAAFL

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