Briggs vanguard conversions

Discussion in 'Firewall Forward / Props / Fuel system' started by Hephaestus, May 12, 2019.

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  1. Oct 2, 2019 #1061

    blane.c

    blane.c

    blane.c

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    I can see how that will require more oil quantity, but how is it going to get there in the same size line? Or do you ream out the line somehow?
     
  2. Oct 2, 2019 #1062

    Vigilant1

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    The assumption is that the bearings (tight clearances) are the "bottleneck" in the existing setup, and that the lines can flow more oil if it is available.
    The ugly answer would be just to tap some new external lines from that filter adapter shown earlier and run them wherever you need them (esp the heads, if run with "heads up).
    As with the stock setup, the pressure bypass valve doesn't open unless pressure is too high (usually due to thick oil below expected normal operating temps). If a wider pump or a two stage pump is fitted, it would be necessary to insure the bypass valves is up to the task of handling the new, higher flow rate.
    For me, if extraordinary cooling steps aren't shown to be needed for my required output, I won't be taking them.
     
    Last edited: Oct 2, 2019
  3. Oct 2, 2019 #1063

    blane.c

    blane.c

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    I am just curious, I think stock oil volume is sufficient for my purposes.
     
  4. Oct 2, 2019 #1064

    pictsidhe

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    I'd rather use fixed squirters. A 360 groove in the big end would drastically reduce the load capacity, and it is already on the marginal side. I'm fine with using unfiltered oil for cooling, so tapping into the cooler adaptor or cooler return line would work for me. I haven't looked into the pressure drop in the feed line to the filter, yet. Even if I have to take my cooling oil from the pump, that's not insurmountable.
     
  5. Oct 2, 2019 #1065

    Hot Wings

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  6. Oct 2, 2019 #1066

    Vigilant1

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    I think the heads-up oiling issues have already been addressed in the SE33 build, right? ( some pix and discussion earlier in the thread). Now, if the heads are bathed with lots of extra oil for cooling, maybe we'll have new issues to address.,
     
    Last edited: Oct 2, 2019
  7. Oct 2, 2019 #1067

    Hot Wings

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    Now that you stimulate my memory - I do remember a pic of an external oil line into the head between the valves and under the rocker arm cover flange. Maybe not all of the heads have the vestigial casting?
     
  8. Oct 2, 2019 #1068

    TiPi

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    In the heads-up installation, the oil is for lubrication of the moving parts. Most industrial engines use just the oil vapour floating around (one of the reasons they have the crankcase breather on the valve cover). Lubrication only requires a very small amount of oil. Check VWs and Jabiru, had some issues if not addressed.
    The oil circuit on the 49 is very conventional: oil pump (with relief valve) - oil cooler - oil filter - lube points.
    Many people don't understand how a hydraulic circuit actually works. The oil pump does not create the pressure, the pressure is the result of the downstream restrictions. In an engine, the restrictions are variable with temperature, base oil viscosity, rpm and clerances that can change with rpm and temperature. The pump output is pretty much linear with rpm.
    At operating temperature, the oil pressure is not cotrolled by the relief valve, it is just a funtion of oil volume delivered by the pump and the leakage rate of the circuit. It balances itself at what we know as "normal oil pressure". For the Briggs, this is 1-3.5bar
     
  9. Oct 2, 2019 #1069

    Vigilant1

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    The pictures are earlier in this thread, from a slideshow. I'll find them later and link to em (I'm on my phone now).
    With the production move of some of the assembly lines and incorporation of new equipment, it wouldn't be surprising to see subtle differences between older/ present engines and model lines.
     
  10. Oct 3, 2019 #1070

    Vigilant1

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    The post here has some pictures of the oil lines on the SE33 (and a link to slideshow with other pictures on the SD-1 and engine installation).

    You posted here, inserted the picture below, and said:
    [​IMG]

    TiPi, from looking at the pictures above, it looks like oil lines have been plumbed to the heads of the engine (whether the oil is for lube or cooling) and that the oil comes from a new tap into an in-block oil passage. Do you think we've got that wrong, that the rockers/etc depend on oil mist and that these AL lines are for something else?

    One observation: In the SE33, the crankshaft bearing on the flywheel end is also the propeller bearing. It already has an area smaller than the PTO bearing, so I would think that when it is under load (e.g. gyroscopic prop forces, etc) that the need for solid delivery of high pressure oil is pretty important. Using that particular oil channel to supply both heads would require some careful research to determine that the oil supply to that critical bearing remains sufficient. Maybe that concern has already been considered and this approach (possibly including restrictions in any spray "nozzles" in the heads, etc) indicates that it wasn't found to be a problem.
     
    Last edited: Oct 3, 2019
  11. Oct 3, 2019 #1071

    Hot Wings

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    Yah, my brain is kind of mushy today. Too many hours in front of the CAD screen.:rolleyes:

    Took a look at my 810 and it's heads are different than the spares I got of eBay by part number. The new heads do not have the casting material for a top oil port.
     
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  12. Oct 3, 2019 #1072

    blane.c

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  13. Oct 3, 2019 #1073

    TFF

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    Someone is showing of their CAD skills
     
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  14. Oct 3, 2019 #1074

    Vigilant1

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    Why the weldments? Couldn't you just have oil lines from the valve covers to the reservoir (in green on your drawing) and another to the suction side of the pump? Then the reservoir can go on the firewall, be lashed to the engine mount, etc.
     
  15. Oct 3, 2019 #1075

    Hot Wings

    Hot Wings

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    My version with a dry sump - Rotax style::
    dry oil.jpg
     
  16. Oct 3, 2019 #1076

    pictsidhe

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    The existing breather on the end of the cam tunnel would be one good drain point. I'm pondering dry sump, but don't know enough about oil/air seperation and would like to see if I can get by with wet sump first.
     
  17. Oct 3, 2019 #1077

    TiPi

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    I think people are over-thinking many areas. These engines are designed to work hard in zero-turn mowers, used by professional mower mobs. The engines have achieved 2,000h and more in those applications.
    What is required for a successful conversion is to maintain the status quo:
    1. adequate cooling (engine & oil)
    2. uninterrupted oil and fuel supply
    3. address any issues arising from turning the engine

    1. Needs to be addressed by the installation
    2. Requires the modification of the oil sump, oil pump pickup, oil level indicator to meet original operation. Fuel delivery has to meet 125% of max flow
    3. Identified issues: valve gear lubrication: a dribble of oil at the right point will fix that
    Anything else is to reduce weight (flywheel) or facilitate the prop mounting (taper shaft, adaptor etc).
    There are a couple of reliability improvements from the racing people:
    - Billet valve retainers
    - Replace the alu pushrods with steel pushrods (intake)
    - Keep the ignition coils and rectifier/regulator cool
     
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  18. Oct 3, 2019 #1078

    blane.c

    blane.c

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    Seen a lot of those oil line connections. They all leak like sieves eventually. Near the bottom of the gravity well not good.

    Notice that the idea is to have the oil level below the "O" ring level. And to the extent possible mimic a wet sump. Also riding on "O" rings the idea is not to add any additional weight (or at least not much) to the valve covers, the reservoir will have "independent suspension" regards vibration and will be held in place at the heads or block. Also this is a crude drawing of an idea (dare I say) and refinement will raise the reservoir up quite a bit I am sure and shorten the pick up tube.

    I do not want a scavenge pump. Weight and another thing to break.
     
  19. Oct 3, 2019 #1079

    Vigilant1

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    I'm probably just not following your concept well. But I do think the area under/around the heads will be pretty valuable/crowded real estate in a heads-down installation with the induction runs, a carburetor, fuel lines, exhaust pipes, etc. Putting 1/2 gal tank down between the heads, too, will be something.
    An unrelated question regarding maintenance access and oil leaks--did you happen to design any British Leyland products in the 1970s?:)
     
  20. Oct 3, 2019 #1080

    blane.c

    blane.c

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    810cc HEADS DOWN OIL RESERVOIR 2.png
    See already loosing weight.
     

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