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Thread: Oil injection fuel pump

  1. #46
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    Re: Oil injection fuel pump

    Quote Originally Posted by mmatt View Post
    Again, the point of this project is to develop a system that will work on ALL 2 stroke engines. I'm not trying to make anything better, I'm trying to make it more accessible.
    ================================================== ==========================================
    Ok, let's look at this way, there are litterly many Millions of 2 strokes in this World already using Factory Oil Injection Successfully. You do have a small % of them 2 Strokes used on Airplanes that do have a problem with their Oil Injection. Rotax, at one time held 80-85% of the World 2 Stroke market for Ultralight and Kitplanes.

    Since Rotax has made many different 2 Strokes, but used mainly (2) Types of Oil Injection, basically the same Oil Pump, but (2) different ways of driving the Oil Pump. Those (2) ways of driving the Oil Pump is what Fails. There are other Failure Points on the Oil Injection like the Oil Lines over Time, and People not hooking them up right, but that's Human Failures, not the Oil Injection fault.

    Since these are not Certified Airplane Engines, People/Repairman don't keep records on them, so we really don't know what Percent of them Fail. One person(Repairman) who has some insight into the problem is Rotax Rick who has rebuilt over 900+ Rotax's. I would have to ask him again, but I think he said, 1 out of ever 5 engine failures was from a bad Oil Injection problem, mainly the Gear or Shaft, and broken Oil Line. There was a small % that don't seem to meter right, some check valve can stick. Just 900/5=180 Engines. Now Rotax has built over 6 Million Engines for everything from Sleds, Jet Skies, Hover Craft, Jet Boats, Generators, Water Pumps, Snow gliders, Jet Boats, Ultralights, etc. Are we talking a high percentage over all, No I don't think so. I do know in Sleds it's very uncommon, never own a PWC. For most things used in the World an Oil Injection failure is not Life threating, but in Plane use it can be.

    Since we don't know if other Brands of 2 Strokes even have Oil Injection problems your just dreaming up a problem that may not even exist. Many of these Engines are not even used on Planes either, which put's them under the most extreme continious use.

    Like I said, find a way to fix the two main problems with Rotax's Oil Injection, the Plastic White Gear and White Plastic Shaft and that would be very useful and may even save lives. The third failure point to fix the Oil Injection lines is easy, just replace the Oil and Fuel lines every 5 years, with Tygon lines, the best we have for today.

    If we could get them White Plastic Oil Injection parts 3D modeled, you cold have them 3D printed in Nylon.

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  3. #47
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    Re: Oil injection fuel pump

    Quote Originally Posted by Armilite View Post
    Just make the Oil Injection parts that Fail better, and you solve 99% of the problem. Make the White Plastic Parts out of Nylon, High melting point (256 C/492.8 F).
    Or don't run things until they fail. If the typical oil injection pump has a 500h MTBF, just replace it around 3/4 life, or in this case when it reaches 375 hrs time in service. The inspect, repair and replace process is somewhat common in aviation in order to maintain reliability.

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    Re: Oil injection fuel pump

    Quote Originally Posted by mmatt View Post
    Again, the point of this project is to develop a system that will work on ALL 2 stroke engines. I'm not trying to make anything better, I'm trying to make it more accessible.
    Lets say there was an off the shelf system that met your design goals. How many people currently running premix would you guess would be enthusiastic enough to install a generic oil injection system? (That would be those that have no other option for oil injection)

    There seems to be a large segment of people in the two-stroke machine world where they do not trust an oil injection system. Not uncommon to see oil injection systems disconnected or removed and operation reverted back to premix gas/oil. I find that interesting because in the cases where a manufacturer goes through the effort to design and install an injection system, it is usually superior to premix.

    Also, if stale gas is a problem why not just by the highest octane gasoline available? Seems the shelf life would be improved as even with loss of octane rating (which may not be linear with age- I don't know) would remain above the minimum rating for a more reasonable period of time.

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    Re: Oil injection fuel pump

    IMO a system to make full power running good AND low power (descent from altitude) safe with increased oil lube would be of interest to several folk especially if it was simple and effective. BUT once you mod an approved engine without the maker's permission you are dealing with a "no longer approved" engine

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    Re: Oil injection fuel pump

    Quote Originally Posted by Turd Ferguson View Post
    Not uncommon to see oil injection systems disconnected or removed and operation reverted back to premix gas/oil. I find that interesting because in the cases where a manufacturer goes through the effort to design and install an injection system, it is usually superior to premix.
    All the reports I've read indicate that manufacturer designed injection systems are very reliable and vastly superior in terms of proper lubrication and reduced carbon fouling.

    Quote Originally Posted by Turd Ferguson View Post
    Also, if stale gas is a problem why not just by the highest octane gasoline available? Seems the shelf life would be improved as even with loss of octane rating (which may not be linear with age- I don't know) would remain above the minimum rating for a more reasonable period of time.
    I already buy the highest octane available which is 91. I still don't feel comfortable going a week - 10 days max - without burning it. Maybe it's paranoia (maybe it's Mayballine)

    Quote Originally Posted by Turd Ferguson View Post
    [...]
    There seems to be a large segment of people in the two-stroke machine world where they do not trust an oil injection system.
    As I look into this more, I am coming to the same conclusion which is why I've decided to abandon the project and simply save my money to buy an engine with oil injection instead. No sense in trying to solve a problem that doesn't want to be solved.

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    Re: Oil injection fuel pump

    Quote Originally Posted by Turd Ferguson View Post
    Or don't run things until they fail. If the typical oil injection pump has a 500h MTBF, just replace it around 3/4 life, or in this case when it reaches 375 hrs time in service. The inspect, repair and replace process is somewhat common in aviation in order to maintain reliability.
    ==================================================

    Yes, if we had that MTBF Data, we could do that, but we don't. Some have failed at very low hours on New Engines, like 150, 200, 250, etc. I would think, it would be more wise to just make the White Plastic parts out of a more durable material like Nylon. The Weak part of the Gear is the Center D Hole, on the Shaft it's the Small Square End that sticks into the Crank. You could probably fix the Shaft problem, by making an Aluminium Button that has the Square End on one end and a Hole on the other and just shorten the shaft an epoxy Glue the Shaft into the button. The Gear Center Section could be beefed up with a Steel Washer with a D Hole in it. Maybe epoxy glue it also.

    Here is some common Plastic Melting Points.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Re: Oil injection fuel pump

    GEAR STEEL SUPPORT FOR D HOLE.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Armilite; November 22nd, 2016 at 12:54 PM.

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    Re: Oil injection fuel pump

    PLASTIC SHAFT STEEL/ALUMINIUM BUTTON FOR END OF SHAFT.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Re: Oil injection fuel pump

    Quote Originally Posted by Armilite View Post
    ==================================================

    Yes, if we had that MTBF Data, we could do that, but we don't.
    Nor do we have any data on whether or not parts made from different materials will last any longer, or even as long as OEM parts. Either case requires collecting data either from the manufacturer or in the field for a reasonable period of time. In the meantime, I think I would adjust my operating procedures to fit whatever I had - oil injection or premix and follow best practices for the same.

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    Re: Oil injection fuel pump

    Quote Originally Posted by Turd Ferguson View Post
    Nor do we have any data on whether or not parts made from different materials will last any longer, or even as long as OEM parts. Either case requires collecting data either from the manufacturer or in the field for a reasonable period of time. In the meantime, I think I would adjust my operating procedures to fit whatever I had - oil injection or premix and follow best practices for the same.
    ==================================================
    No, we don't have any Test Data using these other materials, be we do have the properites of the different Plastic's to look at, just as we have the properties of Steel and Aluminium. Nylon is used on many Industrial Gears today and is at the top of the list of 500-535F Melting Point. I would bet that White Plastic is at a lower melting Point 300-350F. I think we can agree 6061 Aluminium is Stronger than the white plastic, and Steel is stronger than both of them. There are many thousands of Gears made of Plastic's, and Aluminium, that we maybe able to find and off the shelf replacement. Rotax is not going to do it, they are getting out of 2 Strokes!

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    Re: Oil injection fuel pump

    Quote Originally Posted by Turd Ferguson View Post
    Ya, there's a reason why 2 stroke powerplant companies never did it that way.
    TF,
    On the last road going two cycles Kawasaki used a multi point injection system. It pumped raw oil to the main bearings which would mix with the air-fuel mix in the lower end. The other points were direct to the float bowl/s. Pre-mix does have the benefit of providing the most lubrication when it is needed most. WFO. The biggest problem with most of the injection pumps was that they weren't set up to run lean enough with the newer synthetic oils. On some of the Kawasaki triples the R&D department recommended that you DISCONECT the throttle cable to pump. That way the amount of oil injected varied only with the RPM. The little quadrant the throttle moves varies the stroke of the pump. I am sure that they have fixed the over oiling problems by now. I never had a oil pump fail in motorcycle use, but as has been mentioned the duty cycle on an airplane is 10x as severe. If you are flying a 2 stroke powered plane any real distance from home and you don't bring your mixing equipment and some extra oil you should stop flying the plane until you can re-engine with a 4 cycle. Even with oil injection the most common failure I saw was the owner forgetting to put oil in the tank.
    Bill

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    Re: Oil injection fuel pump

    Quote Originally Posted by mmatt View Post
    Is this such a thing? If not, why not? How hard would it be to design a fuel pump (either vacuum or electric) to pump a ratio of oil and fuel? We mix fuel and oil by volume, right? Wouldn't a fuel pump that had a two draws, one for fuel (normal sized) and one for oil (50 times smaller) draw a ratio of 50:1 therefore negating the need for a more complicated carb injection system? Obviously the carb injection system is the way to go if your engine has that option, but since mine doesn't, I'm trying to come up with a solution.

    One of the unknowns is; will the ratio stay the same at different power settings (more likely a problem for the vacuum driven pump since the electric would probably just put out a constant 3 psi or whatever)

    Anyway, just a thought that hit me last night. Please discuss.
    ================================================== ==================
    I was thinking of this, and the Simplest way would be to Mark your Fuel Tank in both Gallons, and Qt Marks. Then have an Oil Tank with a Feed line to the Gas Tank also marked in OZ with a On/Off Valve. Think of it this way, a Part 103 Ultralight can only carry 5 gallons. You fill up at your Home Base, then go flying. Even if, you flew a Triangle Flight Path, say each leg depending on your GPH 1.8 to 3.5, to make it simple lets just say 40mph with a 2.0 gph, that gives you 80 mile legs, (2) refuels. (4) gallons each with a 50:1 Ratio is 10.24oz of Oil Needed per refuel. A (1) QT Oil Tank = 32oz, enough for (3) refuels. That would be a total of 8hrs flying.
    No Special Pumps needed, just a simple Scale on each Tank, with a on/off valve and gravity. You should have a Simple Scale taped to your Tank, so if you land early, you look at your Tank, it's 2.5 Gallons low, look at your Chart 2.5 gallons is 6.4oz of Oil needed. Open Oil Valve drian 6.4oz in, and off you go.

    For bigger tanks you just scale it up for what ever size it is.

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    Re: Oil injection fuel pump

    Sorry for the necro post but after 4 pages and no mention of this I thought I would throw it out there for anyone interested in this sort of thing. A pump about like the OP describes dies exist. It's the OLD Johnson Evenrude BRO fuel pump, and it incorporates an oil injection pump and is vacuum driven. I'm sure it could be adapted to other engines without to much effort.
    I'm right 97% of the time, who cares about the other 4%......

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    Re: Oil injection fuel pump

    Adding oil to fuel doesn't make it go stale faster. The best way to get stale fuel is to let it breathe. Keep it In a sealed can and it will last a very long time. I think nothing of using last year's gas come the new mowing season. My cans seal... For an airplane, I'd be a bit more careful and dump last year's gas into my truck! If my plane tank breathed, I'd not trust gas over a few weeks. Half of what I'll trust mowers for and don't have problems.
    I think trying to improvise a mixing system is going to be high risk. I've never heard of an oil pump failing in a bike. If you don't have a filter, you run a high risk of pump damage. I suspect that that may be where the tales of unreliable oil pumps come from.

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