4 stroke Propane ??????????????????

Discussion in '4-Stroke Engines' started by seanhan, Aug 31, 2008.

  1. seanhan

    seanhan Member

    Has any one tried to convert a 4 stroke to run on LPG.
    I was thinking it would be Cool to use the 1lb screw in propane bottles like I use for my camping stove, You can buy a refill kit and recharge them from your 5 lb. Gas grill bottle, and could carry a spare or 2 safely.
    Just need the regulater and carb issues worked out..
    Talk about Clean Burning.

  2. BigDaddyT

    BigDaddyT Member

    My friend had a gas/lpg conversion on his 350. As I recall the lpg put out about 20% less hp. As long as that wouldnt be an issue it sounds like a neat mod.
  3. seanhan

    seanhan Member

    That the drawback..

    I drove a 5 ton truck in Montanna that had a LPG conversion and it was gutless,, Going up the moutain roads full loaded I think I got like 20-30 MPH Full Throttle.
  4. The regulator might be an easy hack, get an ajustable regulater for a oxy acetlyne setup, modify the fittings, the tough part is the carb. the smallist propane carbs i have seen are on propane buffersand they would be to big. the smallist propane buffer I have seen is 6-8 horse power.
  5. heathyoung

    heathyoung Member

    Most floor polishers as used by shopping centres are a 4 stroke engine, running off a 9kg gas cyl (cant use petrol indoors for obvious reasons).

    There is no reason why not - another thing to consider is the butane cartridges for those little cheap camping stoves...
  6. HoughMade

    HoughMade Guest

    This could be done- I'd like to see someone do it....not going to be me, though. Takes me over a year to finish one bike.
  7. It would be nice if some one would offer us a kit. till then it is on my wish list. I already have to many projects going.
  8. Honda50

    Honda50 Member

    The carb bowl atmospheric vent must be located and plugged. Remove the carb needle valve. Connect the propane hose to the fuel inlet nipple on the carb.

    I would think it gets tricky without a variable pressure regulator (see my idea below). Propane requirements will be different at wide open throttle and under load as opposed to idle and no load.

    Or, how about this: A propane storage tank running to a 'fixed', but adjustable pressure regulator to drop the pressure to a workable level. Then from the regulator, a hose to a ball valve with a lever, to control the valve opening manually, mounted on the handle bars. The ball valve could be limited in it's closed position to allow a metered amount to reach the carb for idle purposes. Slowly opening the ball valve would increase flow to the carb, in tern, the engine RPM and torque increase. The pressure regulator could be adjusted to suit full throttle requirements under load by dialing the correct line pressure for the best full throttle performance.
    Your engine oil would certainly last a lot longer!!

    Running propane on a fixed RPM engine is easier, such as a generator set, etc.
  9. Honda50

    Honda50 Member

    lets bump it up a notch. How about a Hydrogen assisted gasoline engine?
  10. eleseur96020

    eleseur96020 Member

    You are over-complicating it, you can make a vw or ANY other carbed 4 stroke run on propane just by drilling a hole in the carb and inserting a jet (for the propane). Remove the float and figure out a way to regulate the low pressure gaseous propane coming from the regulator (hi-pressure liquid to low pressure gas) to the carb propane jet. and you're good to go. you could even keep it dual fuel by leaving all the gas lines intact and minimal modification to the carb. There are plans on the internet for VW's that would give you a place to start. Honda50 has the right idea, a ball valve would work perfect. And for all the comments about how LP has lower power, that is simply not true. The reason you are getting lower power is because the engine's compression ratio is optimized for gasoline. Optimize it for propane and you get MORE power than gas. The reason for this is propane has a higher octane than gasoline. Look it up if you don't believe me. Very interesting idea by the way.
    Last edited: Sep 23, 2008
  11. heathyoung

    heathyoung Member

    Not entirely true - you need a greater volume of propane than fuel, so there is less room for the air. Energy density is lower as well.
  12. terrence

    terrence Member

  13. eleseur96020

    eleseur96020 Member

    but we're not talking about energy density, were talking about power. If fuel efficiency was a concern then yes, gasoline is a more efficient fuel. But overall propane has more power than gasoline if the engine is tuned for propane fuel. Even with reduced fuel economy, propane is a MUCH cleaner fuel, it bothers me that everyone is going nuts over hydrogen. You need electricity to get hydrogen, where does the electricity come from? Nuclear Plants, Hydroelectric Plants, and worst of all Coal Plants. Propane requires none of the above, is cleaner than gasoline, and most carburated engines can be modified to run propane for less than $200. Fuel injected systems are also available. Imagine if all the carburated engines in the us ran on propane, we would be much better off due to the fact that these engines are the gas guzzlers. They are the cars getting bad mpg's and the reason we are dependent on foreign oil.
  14. ozzyu812

    ozzyu812 Member

    how bout dog power
  15. eleseur96020

    eleseur96020 Member

    dog power has a lower specific engery thean propane and gasoline. But its cleaner.
  16. sjackson

    sjackson Member

    Not true. My friend's dog has some pretty strong emissions. Leaks a bit too.
    Dankoozy likes this.
  17. SirJakesus

    SirJakesus Guest

    LOL, I was thinking the same thing until I scrolled down another line and saw your post. Good completion.
  18. TWalker

    TWalker Guest

    I've had the set up for months. I bought 2 conversion kits for small 4 strokes at the beginning of summer. Sad to say they are still sitting there and all I really need is a handlebar throttle set up. It would take about an hour to set one up without the handlebar throttle.

    Fact of the matter is thought that propane is a by-product of oil/gasoline production so it may burn cleaner but its not necessarily any "greener".

    Back to school and work ....bike projects are staring at me every night but too busy to even start on em.

    I did build some cool push trailers this summer though.
    Last edited by a moderator: Sep 24, 2008
  19. terrence

    terrence Member

  20. Propane will work, but a much higher compression ratio would be needed to get the same performance. The Zamboni at our local hockey rink uses compressed natural gas which would be the same set up as propane. The big expense would be purchasing the hazardous gas compressor to compress the gas from the house. A fuel tax would also have to be paid to be legal. ;-)