V-8 Engines

Discussion in 'Auto Derived' started by biplane bungee, Dec 29, 2006.

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  1. Dec 29, 2006 #1

    biplane bungee

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    Randy, I noticed some pictures in the users gallery about a V-8 Skybolt. Is that the 215 Buick Aluminum V-8? I thought you menitioned that you used V-8 Chevys? What's the Buick 215 like?

    In your previous post about auto conversions you mentioned that auto engines seize-up. There are a lot of corvair, subaru conversions out there that snap cranks, is that true of V-8's? I figure a V-8 would be a bit stouter.

    I would think if it is, than you can extend longevity (sp?) by reducing the rpm's and reducing torsional vibration. I would think, that one can reduce rpm by bringing the torque curve up into a lower rpm band by changing the camshaft profile. And maybe one can reduce vibration by using contra-rotating props (using a shaft within a shaft).

    Any comments?

     
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  2. Dec 29, 2006 #2

    Skybolt

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  3. Dec 29, 2006 #3

    Randy

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    The 1st V-8 was the Buick bored and stroked to 260 cid. 190-200 hp. To much weight. It was a study in development so I could work out the problems before going with a larger more expensive V-8. The 2nd was the 350 Chevy - ran like a charm - to much weight. Right now I am going through the development stages with a Mazda rotary engine in an Acro Sport 1 before I decide wether or not to move into a larger more expensive rotary engine.
    I don't think I said a thing about engines seizing up ???
    Torque is great for initial runway acceleration, planes fly on HP!
    You can hang a V-8 on the nose and do anything you want to it. Reduce the rpm, change the cam, reduce vibration, reduce the torque, reduce the hp but you cannot reduce the weight. when you get done you have an overweight plane with only part of the hp the engine is capable of. when you climb aboard with your chute and 1/2 tank of fuel you exceed the gross aerobatic weight but, you have a cheap engine. So, with the excessive weight and reduced hp you end up with a standard category aircraft at much less $$$$ than a good air cooled ackro mount with good performance and more $$$$. You make your choice and pay the bill.
    Going with counter rotating props and PSRU's will, in the end, cost as much or more to develop and build as a good aircraft engine will cost so what is the advantage?

    We seem to be having this same conversation in a couple other threads ?

    We need to move this into an alternative engine discussion thread so all this information and questions are together. I seem to keep answering the same thing. I will do that as soon as I have a few minutes.
     
  4. Dec 29, 2006 #4

    Beej

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    The thread is already in the correct forum. Randy, as usual, you answered specific questions very informatively. If Michael's passion for V-8's is such, then maybe weight is not a criticalfactor for him.
     
  5. Dec 30, 2006 #5

    biplane bungee

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    Yes, my passion is getting an auto engine to work in an airframe. that's what drew me to bipes and your web site. I figure the extra wing area will support a heavier engine. Right now I am thinking of a I-6 4.0 liter from a jeep due to its excellent hp and flat torque curve. The mazda looks interesting but like the lycoming is a rare bird and will be difficult to find people who are familiar with the inner workings.


    I noticed on the skybolt website that they've redesigned the wing for the heavier Russian (is ita radial?) engine.Right now that looks to be the ticket.


    Thanks for all your input it sure is interesting.
     
  6. Dec 30, 2006 #6

    Beej

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    Lycomings rare? did you mean something else....
     
  7. Dec 30, 2006 #7

    biplane bungee

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    They're quite common if you have 30 grand.


    They're rare in regard to the number of automotive engines.


    There's two problems with auto engines: theairframes are not designed for the extra weight(skybolt "R" appears to solve that) and two, torsional vibration. That's the bigger problem. So if I am to use an auto engine make it as stout as possible.



    Though interesting comment from article (posted above):

    "Any time a propeller is connected to an engine in any way other than directly to the crank it would be wise to realize that torsional vibration can be a problem. Basically, there are three propeller drive system configurations:


    1. <LI>Propeller speed-reduction unit alone
      <LI>Propeller speed-reduction unit with a shaft drive
      <LI>Propeller shaft drive alone"</LI>


    Is the author aluding to the fact that if you connect the propellar directly to the crank there is no vibration?

     
  8. Dec 30, 2006 #8

    Beej

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    Your quote didnt mention money, it implied skilledLyc mechanics were rare, which of course is not the case.
     
  9. Dec 30, 2006 #9

    Randy

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    The modern auto engines get their hp from short stroke, high rpm, multiple cams, multiple valves per cylinder, etc. How many moving parts in an engine like this, 100 - 200?? and every one a potential failure!
    There are only 3 moving parts inside my rotary engine, 2 rotors and the crankshaft. No rods, cam, valve train, etc. Very little to ever need any special talented mechanic for. (One of the BIG pluses for the rotary engine, it is extremely simple) There is also little viberation as the rotors are constantly turning in the same direction as the prop.
    "V" engine vibrations (and horizontally opposed) come from the constant direction reversals, constant start and stop mode and intermittent power pulses sent to the prop, very little to do with wether you are using a PSRU or not. If you don't use a PSRU your rpm is limited by the max. prop rpm allowed which is usually 2800-3000, You will have to find your hp/torque in that engine rpm range. This will be a problem with current auto engines. You would be better off using a good truck engine with a forged crank and beefier lower end with a longer stroke and lower rpm.

    John, I guess my point was that these questions are coming up in other engine threads. Are we going to have a thread for each alternative engine type? Or just alternative engines in general? We seem to have at least two, one on rotaries and another on "V" engines that I am aware of. Not complaining just trying to figure out the easiest way to respond to questions without having to repeat everything in another thread.
     
  10. Aug 24, 2007 #10

    bigblackmastiff

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    I was looking at a replica p51 recently. This particular one had a Ranger V12, but it started me looking at other replicas that use automotive/marine V6 and V8 engines. One fellow building a SAL Mustang has a pretty neat little website with some engine options displayed. Check it out.


    http://home.comcast.net/~ogoodwin1/engines.html
     
  11. Aug 24, 2007 #11

    Neil

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    I've been watching the auto engine idea for some time and I'm just not impressed with the idea. Randys approach with the rotary makes the most sense of all and I wish him well with it.
    My biggest concern is that people aren't paying attention to the difference between peak horsepower and continuous horsepower. Auto engines are usually rated at about 5,000rpm and not intended to be run there for extended periods, unlike aircraft engines which are rated much lower. Next time you are in a V8 equipped car leave it in first gear and run it up to 5,000rpm and see how comfortable you are with that. My truck turns 1,800rpm @ 70mph. I've never seen but 3,500rpm on the tach in a passing situation.
    I've run race spec engines a lot harder than that and I have the piles of scrap to prove it.
    I think the Prowler was the best attempt I had ever seen and it was an airplane designed for the powerplant. (Randy, weren't you involved in that?)
    Until I see some (a lot)of these conversions with a couple thousand trouble free hours on them, I wont be buying into the idea.
    Plus, if you don't have the capability to do the engine building and psru work, I don't see it being any cheaper. And as Randy says, they are heavy. Might be all right on a Beach 18.;)
    Neil

     
  12. Aug 24, 2007 #12

    Randy

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    I was George Morse' plant manager for a couple of years at Prowler Aviation. The 350 cid Chevy we built for the Prowler (I had the same engine in the SkyBolt) ran at 4500 rpm at cruise and I was never uncomfortable with it as it had been built for the higher rpm's. Everything was super strong. Unfortunately super strong also equals super heavy and that was my problem with it. It was to much weight for a SkyBolt. You are also VERY correct in your statement - if you aren't capable of doing the design, construction, and testing of everything needed to make the conversion you will spend just as much as a Lycoming installation.
    I see the occasional V-8 / V-6 conversion show up at Oshkosh but seldom see them there 2-3 years in a row cause they usually don't last that long for one reason or another.
     
  13. Aug 24, 2007 #13

    scottly

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    The guys that ran VW engines in the KR's and other such ilk seemed to be rebuilding them at 300-350hrs. Crank hub failures were common.


    I ran a Corvair....I nitrided the crank and used a Sterba prop. I never had a problem, and I ran it direct, no PSRU.


    What many people don't realize is that aircraft engines have prop harmonics to contend with at the crank. Aircraft engines have some really LARGE thrust bearings (as compared to auto engines). if you're gonna run a VW, I'd suggest a PSRU because of harmonics. When you add the PRSU, you then have entered the cost/weight realm of good used O-235...so why not just go that way?


    I like Randy's idea of the rotary, only because I have seen these buzzy little motors really do some amazing things, and they hold together really well.




    What I'd like to see is some knowledgable comments on the 400cid experimental engine that Superior Airparts is producing....or any of the "experimental" lycomings or continentals out there. Does that 400cid really make 220hp?
     
  14. Aug 24, 2007 #14

    bigblackmastiff

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    The fella building this mustang says though that he needs forward weight and wants 300hp/4800rpm takeoff and 3400rpm/200hp cruise. That doesn't sound to me like you'd have to push real hard for that. They are way expensive, but you can buy all that firewall forward for some of the mustang replicas and for the SeeBee now. It doesn't seem quite right to me for most lighter acro planes...but it seems like the cats meow for the replica fighters. I'm glad those fellas are still out there working on it...i think there will come a time when Lycs and Continentals will be left behind.


    I too think Randy has a good thing going with the rotary.


    I'm also closely watching the Aerovee engine. I think this may end up being the engine for my Jr Ace. The overhaul cost is so low its just hard to pass up.


    For me low TBO isn't so bad if the costs aren't bad. The rotax i had last was basically a deal where you open it up and sh*tcan every moving part every 300 hrs...but it would have taken me a long time to run the bill up high. Not that the same applies for the big V8's

     
  15. Aug 24, 2007 #15

    scottly

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    If it makes ya feel better, the Rotax only makes it about 300hrs in the Seadoos and marine applications before they are junk....It's the nature of the beast when it runs WFO all of it's life.
     
  16. Aug 24, 2007 #16

    bigblackmastiff

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    When i bought my kitfox it had 450 hrs on the engine. The fellow i bought it from said...TBO is 300hrs but it is running great..."i'd wait till it shows some sign of needing overhaul". Thats why the rotax had a really hard beginning and a really poor reputation. If you were to listen to the manufacturer it was spelled out in plain English that the engine would perform flawlessly until the crank snapped in half....somewhere around 400 hours. It was a simple matter of following instructions to keep out of trouble.


    I really grew to appreciate that engine.Edited by: bigblackmastiff
     
  17. Aug 24, 2007 #17

    scottly

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    Rotax is a really well run company. But they are what they are....they are NOT a 2000hr TBO engine. Bigdawg, you hit the nail on the head.




    For those so inclined, Buell has just come out with a Rotax-powered bike that is the shiznit......The 1125.


    I like Rotax. And from what I understand, Cessna is coming out with a LSA two seater powered by Rotax.
     
  18. Aug 25, 2007 #18

    dc8mech

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    There was one design on the market for a very short while with a direct drive ZZ4 Chevy 350. Don Suaser's 82% scale P6E. I know of only three copies flying. Don's bird now in a museum in Riverside, CA. One showed up a Airventure about three years ago. The third one is in Cedar Rapids,IA built by one of our line reps in Cedar Rapids. He has his picture and a story in our company rag. His plane was over in the replica parking near all the RV's this year.
    Don only sold 44 sets of plans for the P6E. Don has passed now, the family has left the design in the dust. Never to be revived. ErichEdited by: dc8mech
     
  19. Aug 26, 2007 #19

    CKeller

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    FWIW, I am not a motorhead (at least when it comes to auto engines), but the previous builder of the Firebolt project I inherited was gung-ho to install a Chevy V-6 (not -8) and passed to me multiple drawings from a place called Finch Engineering to that effect. I don't intend to go that route (I am a traditionalist) - its going to be the Lyc AEIO-540 for me, but obviously one of the things I am trying to determine is did he do any mods to the airframe/cowl/engine mount to accommodate the different engine?

    The plans do not say how much HP this engine delivers, but one sheet says "Also for the Buick 3800 V-6".

    I don't know if Finch Engineering is even in business any more, but it looks like someone named Richard Finch is the author of several welding books listed on Amazon, that have the byline "Converting auto engines to aircraft applications" so I guess that's his business.

    Colleen

     
  20. Aug 28, 2007 #20

    Video Bill

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