Propane check this out

Discussion in 'Rack Mounted Engines' started by seanhan, Oct 10, 2009.

  1. seanhan

    seanhan Member

  2. Silvaire

    Silvaire Member

    These Lehr trimmers were mentioned here awhile back, and I think they are a great innovation for what they are.

    The engine they use is a Subaru EH025, with what I understand is a Lehr developed propane delivery system. For a few minutes of trimming every week I think they are an excellent product. They run clean, start easily, and have no "spring tune up" carburetor issues from the cruddy car fuel that we now have to put up with.

    One of the drawbacks for using one on a motorized bicycle is that they only use a 1 lb. propane cartridge, which has somewhere around the same amount of energy in it as a pint of auto fuel. Also, engines converted to propane have about 10% or so less power.

    If I were going to try to build a propane bike engine setup, I would take the Lehr fuel system off of a trimmer, adapt it to a larger EH035 engine, and come up with some sort of refillable tank of around 3 to 4 lbs. Then maybe you'd be cookin' with gas!
  3. AndyT

    AndyT Member

  4. Silvaire

    Silvaire Member

    Lehr propane powered scooters and Karts? COOL!!!

    The issue I have with the 1 lb. disposable propane tanks (which these GoPeds use) is their cost.

    You could probably make up a dual 1 lb. propane tank setup that feeds from one tank first and then automatically switches over to the other tank. There are valves that do this that have been used in the RV industry for years. You would still have that issue of the very high fuel cost when using disposable bottles. I know that there used to be valves sold to refill those disposables, but I doubt that they are legal anymore (if they ever were).

    Actually, a 3-4 lb. tank wouldn't need to weigh much more than twice what a 1 lb. tank would weigh. There are probably requirements that refillable tanks need to be made much heavier than the 1 lb. disposable tanks are though. I know there are aluminum propane tanks available, and they are somewhat lighter than steel tanks.
  5. Happy Valley

    Happy Valley Active Member

  6. RusticoRay

    RusticoRay Member

  7. Happy Valley

    Happy Valley Active Member

    Not without swapping out the 78mm drum and redrilling the channel. The Robin 25cc and most all the utility engines under 30cc come with 54mm clutch shoes.
    Staton does make 25cc engines available and his FD channels have two sets of holes and are drilled for the smaller engine clutches as well.
  8. machiasmort

    machiasmort Active Member

    If your going to refill small bottles, take some advice... They are easy to over fill and have a pressure relief valve in them!

    Get a store bought bottle (full) and make a simple balance scale, so that you know when your bottles that you replenished are full! If not, you might be in for a surprise on a hot day when the gas expands out of the safety valve!
  9. RusticoRay

    RusticoRay Member

    Thanks for the info on the smaller cc engine clutch shoes, and Staton option.
  10. UKtheBUNNY

    UKtheBUNNY New Member

    How is the oil mixture controlled in this setup?
  11. These are 4 stroke engines, so the oil from the reservoir is distributed through the engine the same as with gasoline fuel.
  12. give me vtec

    give me vtec Active Member

    I believe they are 4 stroke engines... and since there isn't fouling from burnt gasoline you dont have to change it as often.

    Only problem I see is that you cant just stop off at a gas station and get coleman propane tanks.

    you can get propane powered stuff at daves motors...;jse...34Pa38Ta38Lbh50?c=885035&sc=12&category=27854
  13. UKtheBUNNY

    UKtheBUNNY New Member

    Ahh that makes more sense. I was wondering what kind of modification would have to be made to the carb not to mention a way of injecting the oil in the right manner and timing. Thanks for clearing that up.
  14. give me vtec

    give me vtec Active Member

    Not much at all... a carb doesn't really care if the fuel is gas or liquid. You just have to figure out a way to regulate the propane.

    The oil doesn't get injected into the combustion process. It is squirted on the underside and skirts of the piston for lubrication.
  15. SimpleSimon

    SimpleSimon Active Member

    The propane engines are 4 strokers. Oil mixture is not an issue. Ptopane contamination of engine oil can be an issue, but not likely to be such.
    Last edited: Jan 1, 2010
  16. give me vtec

    give me vtec Active Member

    how??? Is propane detrimental to oil???
  17. SimpleSimon

    SimpleSimon Active Member

    Propane is a hydrocarbon gas. Oil is a hydrocarbon liquid. Propane can and will dissolve into motor oil, just as will most gases to a greater or lesser degree. As a quite small hydrocarbon molecule surrounded by an environment which is predominantly much larger hydrocarbon molecules, the propane can and will react with the oil to some degree, which may result in a variety of reaction products - some of which will not be effective lubricants. It is pretty much the same in gasoline fueled engines, which is why tars and such accumulate over time.

    With propane fuel, due to the size of the propane molecule, the reaction rates will be somewhat higher on average than with gasoline. Like I said, not likely to actually be a problem, but the potential does exist. Just change the oil occasionally, as with any engine.
  18. vtec, a carburettor cares very much if the fuel is a gas or a liquid. To operate correctly a gaseous fuel carb must be used. I had a friend run a small one cylinder generator on propane with a stock gasoline carb to charge a battery. It worked marginally at very low propane pressure and with the choke closed, but he couldn't vary the speed of the engine or put a heavy load on the generator without stalling it. These engines shown here have a propane pressure regulator and a gaseous fuel carb to operate properly.
  19. ibdennyak

    ibdennyak Guest

    That's interesting. I used to maintain a fairly large fleet of forklifts years ago. Most of them ran on propane (indoor use). The Continental Red Seal engine rep always recommended extendiing the oil change intervals 2-300 %. Of course he was concerned by combustion by product contamination rather than direct contamination. I also checked out a standby genset for a radio station transmitter site in Northern Michigan. It hadn't been run in 40 years according to the paperwork involved. As a matter of fact the propane in the 500 gallon tank was 40 yrs old according to the delivery ticket still in the folder under the cover. It was a 2 cylinder *water cooled* Wisconsin engine. I did change the oil which looked like brand new oil from 40 years ago. The only other thing I did was clean the points and it fired right up....quite a shock to me. Considering that I was being paid to get it running, and not hourly, I was quite pleased.
  20. SimpleSimon

    SimpleSimon Active Member

    The way that propane (gaseous fuel) carburetors work, if the engine isn't running there is essentially no propane in the engine, so nothing to react with the oil. As long as the engine is well sealed so you don't get serious water condensation insie the engine, it will stay good.