Zenith Aircraft Builders and Flyers
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Engines ???????
I'm wondering what is the best engines everyone is installing or running? Also the pros and cons? I am building the Zenith CH 650 and have just started. I like the UL350iS or the Lycoming 233 but I see quite a few Corvair engines out there, so what are the pros and cons about them. I do not like the Rotax. I want something simple. So any input will be greatly appreciate.
Replies to This Discussion
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Permalink Reply by Jan Eggenfellner on
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I watched an O-200 installation done on a Zenith CruZer. It was not an easy install but I had no business posting this.
HOWEVER - great news:
Zenair has offer the 0-200 kit for about 2 years. They have developed a complete step-by-step photo manual for the 0-200. There are 13 Section to the manual. The baffle kit is CNC cut out and comes with all of the hardware need to finish. Zenair updated the cowling and added the blister for the spark plug this pasted year
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Permalink Reply by John DiMattei on
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Hi Jeremy:
I just started building my Cruzer - so I have at least 2 years to think about engine selection. I am leaning toward the Lycoming 233 due to the reliability and support capabilities of the manufacturer. I am concerned - that if a problem occurs during a cross-country out there somewhere - can my friendly local mechanic get a replacement part quickly (even off the shelf).
That said - I will be spending some time with reps from Lycoming, UL, and Rotax at Airventure 2016 (Oshkosh) to learn more about their engines and ability to support their product. UL has some potential - but I want to know that my engine can be supported 5 - 10+ years down the road.
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Permalink Reply by Ernest Christley on
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One of the aspects of all the engines you're looking at is the torque characteristics. Cars have wheels on the ground that help absorb a lot of vibration, but all our tiny airplanes have is sheets of aluminum. The torque profile of the engine has little to do with the manufacture, and everything to do with the engine setup itself. A 6-cylinder will have about 1/4th to 1/3rd the negative torque reversal of a 4 banger. This has implications ranging from the stress on prop bolts to the vibrational stress on hinges.
Really, I can't understand why 4-cylinders is still so prevalent in light planes. It's about the worst possible starting point for a viable light plane engine from a vibration perspective.
http://www.epi-eng.com/piston_engine_technology/torsional_excitatio...
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Permalink Reply by John Austin on
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Ditto the 6 cylinder comments! Someone recently was advising mounting the instrument panel on rubber bushings to absorb vibrations to prolong avionics life. My immediate reaction was "What vibration???"
That Jab 3300 up front is smooooth !
It's also doesn't hurt that I did a dynamic prop balance - got the vibrations way below the range of human perception!
John
N750A
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Permalink Reply by Samuel H Drake on
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I used to fly an old rental C172 with a 6-cylinder Continental 0-300. I am not sure what was wrong with it but I used to worry about the engine shaking loose at about 2000 RPM. Mostly just avoided running in this RPM range. They did get it to run better after we complained by adding balance weights to the prop spinner but this was not a total fix. Anyway, a flat 6 should be really smooth. A flat 4 is completely balanced by has higher torque peaks. An inline 6 in well balanced but an inline 4 needs some balancing help. Most of the newer automotive inline 4s have some active balancing. A V8 is well balanced but a V6 needs some balancing help.
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I'm thinking any configuration could be balanced or not. Throw a bunch of mismatched pistons in that V8, and it'll shake so bad the car won't need wheels.
But, once you get past the point of a competent engine builder, a particular configuration will have a vibration signature due to the overlap of power vs compression strokes. This will be measured at the shaft no matter how well the engine is put together, and can't be eliminated if you want to make any power. From that perspective, while you can still screw it up by either poor design or poor craftsmanship, the 6 cylinder is just a better "starting point" than a 4.
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Permalink Reply by Tim Croy on
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John,
Were your vibrations at a certain rpm range? Reason I'm asking is I bought a 601-XLB with a 3300 (it's 11 years old, 440 hrs) and after finishing some maintenance, I flew it for the third time at wide open throttle (previous owner of 6 months told me he was told to not fly it above 2800-2900 rpm for some reason I think by the previous owner..) I noticed a vibration at 3100 rpm, WOT. It has a Sensinich ground adjustable propeller set at index number 2 of 6 on it, which is a low pitch according to Sensenich, so I'm also not sure why it's only turning at 3100 rpm (with vibration) at WOT at that pitch.
When I back off the throttle a little in flight it smooths out. Just trying to get an idea of where to start first. Maybe a dynamic prop balance?
Thanks for any thoughts,
Tim
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Tim,
I didn't mean to imply that I was having any unusual or noticeable vibration! As I stated, "that Jab 3300 up front is smooooth!" :>)
But, of course all engines have some vibration! The dynamic prop balance all-but-eliminated any normal vibration ... normal for a 6 cylinder - which is to say not much! The Dyna-Vibe prop/engine balancer manual said the lower limits of human perception is .07 ips. By the time I finished the balance, I had it down to .03 ips!!!
If you think the engine doesn't have any unusual or alarming vibrations indicating a serious problem, then I'd definitely recommend the prop/engine balance! However, you might want to fine-tune your prop pitch and tracking prior to the balance as they can definitely affect the balance. I'm not sure if my numbers are relevant since I have a 750 and you have a 650, but I tuned for just-under 3100 on immediate climb-out after takeoff and between 3200-3300 at level WOT.
John
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Permalink Reply by Wayne Tyson on
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You know what's WOT, but I don't.
Wayne
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Sorry about that Wayne, it's 'wide open throttle.' Can't shake the acronym thing as a retired military guy.
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Tim, do you have index pins or number / lines engraved into the hub with a central plastic dial dart?
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