Airplane engine swap

Discussion in 'Introduce Yourself' started by beamishkenny, Jul 27, 2008.

  1. beamishkenny

    beamishkenny New Member

    I am interested in something more asthetic than a 2 stroke or the lawnmower
    type looking hondas.
    I have been looking at the giant scale size model airplane engines.
    Some are over 150cc over 15 hp.
    Has anyone concidered this application?
    Although these engines were only intended for model airplanes but do they have enough torque to power a mountain bike with a 185lb rider.

  2. stude13

    stude13 Active Member

    hi kenny; with proper gearing anything is possible. 150cc? 15hp? on a walmart bike? may be a bit much.
  3. mark2yahu

    mark2yahu Member

    Sure, why not :) I've seen these engines; they look similar to the HT's, but I'm sure they are built much better. Can you imagine this: a tiny replica Pratt & Whitney radial engine, frame mounted? Heheh!
  4. Unhappy Time

    Unhappy Time New Member

    I wondered the same thing - the good quality RC engines are much MUCH more expensive though.
  5. JemmaUK

    JemmaUK Guest

    Saito does twins & up to 5 cylinder single row radials

    Problem is all of them run on nitro fuel which is expensive - and Im not sure they could run reliably if at all on petroil mixes - even if they did they'd be down on power - or at worse you'd get a spine full of cylinder block shrapnel

    If I had a spare $700 I would experiment, but sadly I dont lol

    Jemma xx
  6. muddawg

    muddawg Member

    yeah its possible but maybe not practical

    a high quality weed eater chainsaw or blower would be more practical and less expensive

    zenoah makes rc engines and were used for years in green machine backpack blowers from 33cc-80cc
    and now they are used in redmax equipment

    good luck....and welcome

  7. Skyliner70cc

    Skyliner70cc Active Member

    Actually Zenoah are considered cheap and weak engines in the RC community. They are underpowered and overweight compared to other offerings and I wouldn't use a zenoah on any airplane unless it was a slow flyer and I was tail heavy and needed nose weight.

    I think the OP is talking about gasoline engines and not nitro engines.

    Some links:

    I'm partial to 3W engines and they serve me well. These engines will not work because they will overheat in a bike frame. Engine cooling from directed air flowing through the cowl is critical in an airplane application. Cooling fins are typically undersized to save weight.

    Oh, almost forgot. These use battery powered electronic ignitions. NO magneto. Batteries would definitely be needed on long rides.
  8. beamishkenny

    beamishkenny New Member

    Thank You

    Thank You to all who answered my question.
    What got me thinking about this swap was a couple of photos of radial powered choppers and and the workmanship is excellent.
    I happened to come across a photo that someone in some other site had of a 1930's bicycle with a motor with a supercharger.
    That is the wildest application ever.
  9. Skyliner70cc

    Skyliner70cc Active Member


    Most use batteries for ignition. Zenoah and Fuji engines don't and are magneto powered.
  10. beamishkenny

    beamishkenny New Member

  11. beamishkenny

    beamishkenny New Member

    Most likely I'll use a Lifan 50cc 4 stroke engine.
    I believe they a are Honda clone.
  12. muddawg

    muddawg Member

  13. Skyliner70cc

    Skyliner70cc Active Member

    Zenoah's are well made and VERY reliable. However, they aren't industry leaders in power output per cc or weight. Power and weight are important to us model airplane folks.

    Supertiger is a great brand but I fell out of love with them when manufacturing was switiched from Italy to China. I have a ST engine that is over 20 years old and runs like new.
  14. BoltsMissing

    BoltsMissing Active Member

    I hope improvising is not a sin around here.

    In principle, can a HT be converted to run like a deisel if some work was done on the head and whatever else might be required to modify ?

    There is nothing to say it can't, in theory. Then if it can be done, the HT or the motoredbike in general running on deisel with variable compression adjustments like these model airplane engines would be some show to see.

    This would then free up the magneto from the CDI and power lights instead !

    Attached Files:

  15. spad4me

    spad4me Member

    LOOK here
    The contra piston ( the thing that makes a diesel possible might work on a new engine.)
    If you send them your head and some money they maybe able to make you one.

    Look for Andrew Coholic ( on rc universe not here! )his email adress is at yahoo He might make you a diesel head.
    Last edited: Jul 28, 2008
  16. Warner

    Warner Member

    Diesel's typically run at VERY high compression ratios. I would think the entire engine would have to be engineered to be a diesel engine right from the start. But if you manage to convert one, that would be an accomplishment for sure!

  17. Skyliner70cc

    Skyliner70cc Active Member

    Hate to break it to you, but model airplane diesels aren't true diesels. 1/3 of the fuel is ether. Here is a common recipe for model airplane fuel **Kerosene 36% Ethyl Ether 36% Castor Oil 25% IPN 3%** Unless motorized bike fuel tanks were completely sealed, the ether would evaporate quickly out of solution.

    I would love to see a 70cc diesel engine. I think it would be so cool and it would serve me perfectly because I love torque! Another engine I'd love to see in motorized bikes is a nice little 25-30cc rotary engine. Rotaries are super engines as long as you don't overheat them or run 'em without oil.

    An average compression ratio needed for diesel (non turbo) is about 20-23:1. The use of ether is helps lower the compression ratio a bit, make starting easier, and improves "throttle" response. One of my diesels (car) has a 19.1:1 compression ratio but it occasionally sees bost spikes of 25psi and 21psi continuous from the turbo.

    Do you fly SPADS? If so, that's awesome. I'm a die hard spadder but got very little acceptance at my last flying club where I was basically an outcast for not flying airplanes costing in thousands of dollars.
    Last edited: Jul 28, 2008
  18. BoltsMissing

    BoltsMissing Active Member

    What I'm trying to get at is to find a way to be totaly independent from this need to rely on components of an engine, if these components break down it renders the engine useless. For example, if you have no spark the ya stuck.
    The deisel concept, it seems can be made from metals, lathe and bio-fuels.
    Therefore it's do-able if push comes to shove to not have to rely on manufacturers of engine's components not DIY fixable, such as a CDI unit.

    It ( deisel) can be a total DIY package at the extreme end of the scale.
    So ya take a HT and modify to suit.
    I would not pay to have someone do this, just be part of the project as a team effort, to "think-tank", develop, test etc.

    A bit like climbing Everest, why do they clinb Everest ? Because it's there to be climbed. Same goes with this improvised HT deisel conversion, it's there to try and give it a go.
  19. Skyliner70cc

    Skyliner70cc Active Member

    The HT engine block and components won't be able to withstand the increased compression ratio needed of a diesel engine. General Motors virtually destroyed the US Auto (not truck) diesel market by selling vehicles with gas engines that were converted to diesel. The jury rigged engines were horrendous and causes american's to swear off diesel cars while Europe was promoting small clean burning diesels that get 50+ mpg.

    Unforunately, china is in the copy mode (making clones of other successful producdts) and haven't figured out new product development on their own yet.
  20. Alaskavan

    Alaskavan Guest

    Welcome to MBc, Beam. I use a Lifan on my trike. Probably more power than I need, but she's hauled me over 2,000 miles so far. I did change from the stock carb to a little Mikuni, but I'm very happy with it.