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Thread: Engine Failure - Dry Sump Lubrication

  1. #11
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    Rabsimran,

    Your schematic looks OK. However, it is important that all the little details are also done correctly.
    ~o0o~

    OIL-LINES - The most important oil-line to get right is the feed-line from external-tank to main-pressure-pump. Given that the main-pump has to SUCK oil through this line, the line should be as short as possible, and have a large enough diameter to give low restriction. My guess is that your AN-12 line is big enough, but maybe try to make it shorter (see below...).

    It is also very important to check that this flexible oil-line is not so flexible that it gets flattened out by the suction, and so blocks-off the flow. This "flattening under suction" is a very common problem on the suction side of water cooling lines. The flattening-under-suction is more likely on the inside of tight bends of the line, so check this.

    Also make sure that there is no joint in this line that allows air to get sucked into it. It seems that your main-pump-suction-line attaches to the sump as an AN-hose, and then I guess there is a gallery up through the sump that mates to another gallery in the engine-block, that then leads to the inlet of the main-pump? Make sure that none of these mating joints can allow air to get sucked into the line. So "O-rings" or "gasket-goo" may be needed.

    The other lines, from sump to scavenge-pumps, then to external-tank, should be OK. They could be smaller, but no problem as is.
    ~o0o~

    EXTERNAL-TANK (aka "Swirl-Pot") - Your tank is tall and narrow, which is good. (I originally worried that you made a low and wide tank, which would be worse than the original wet-sump.) Standing the tank up vertically, rather than at the slope you have it, would be better (see why below). An even taller tank would be even better, perhaps with the upper section of smaller diameter.

    Your infeed to the tank is done correctly, being tangential to the circular tank, which gives the swirl that helps separate air-bubbles from oil. A smaller diameter hose/inlet-nozzle here, and a smaller diameter of tank, would give much increased swirl and so even better air-oil separation. But maybe OK as is.

    I think your biggest problem is at the bottom of the tank. The times that the engine-bearings most need a good supply of oil is when the throttle is wide open (WOT) and engine is spinning fast. So typically during hard longitudinal acceleration. Under these circumstances any fluids in any tanks are sloshed to the REAR of the tank. So the fact that your main-pressure-pump is sucking from the FRONTMOST point of the tank is BAD. The rearward leaning tank also makes this worse.

    Furthermore, looking in plan-view, your tank-inlet swirls the oil in an anti-clockwise direction. The tank-outlet should take advantage of this, but your outlet is better suited to picking up CW flow.

    So one "quick-fix" would be to relocate the tank-outlet (ie. suction-line to main-pump) to the rearmost point of the tank, but still close to bottom of tank. So shift it from right-side to left-side of tank, as seen in your side-view photo. A vertical rear wall to the tank would also help. Also a horizontal mesh-screen/baffle, at about half-height of the tank can also help to keep the air-bubbles up top, and pure-oil down below.
    ~o0o~

    BOTTOM LINE - The "... tick-tick..." sounds you heard from the engine are just as expensive whether the engine has the most exotic dry-sump system fitted, or just a bog-standard, no-cost, wet-sump. In either case the preventative cure for the "tick-tick" is usually very inexpensive in itself, being only a matter of adjusting a few details.

    But figuring out those details ain't always easy!

    Keep working at it.

    Z
    Last edited by Z; 01-09-2017 at 08:57 PM.

  2. #12
    Cloth braid lines should have a support spring inside if exposed to vacuum...if that's been overlooked. Hardline with tube nuts and sleeves might be even lighter if chasing grammes.

  3. #13
    Z,

    The hose we are using is a polymer braided bought from BMRS with the innercore having internal glass fiber reinforcement and wall thickness of approximately 3mm. The bend radii are pretty large too, so, I'm sure we are not running into "flattening under suction" condition.

    It seems that your main-pump-suction-line attaches to the sump as an AN-hose, and then I guess there is a gallery up through the sump that mates to another gallery in the engine-block, that then leads to the inlet of the main-pump? Make sure that none of these mating joints can allow air to get sucked into the line. So "O-rings" or "gasket-goo" may be needed.
    Yes, you are absolutely correct about our design. It's exactly the way you described. We use an o-ring at the mating surface of gallery in the sump and gallery in the block which leads to the oil pump.

    A taller and narrower oil tank with conical base has been designed and is ready to be manufactured. The tank has been relocated to allow a vertical and narrower design. It will be tested on the car soon.

    The oil pump was opened today and damaged at the tips. The images are attached below:

    IMG-20170111-WA0001.jpg

    IMG-20170111-WA0002.jpg

    The oil jet of 3rd cylinder (which sprays oil on the walls of 3rd cylinder) was found to be clogged by some sealant. Though there weren't any scuff marks on the liners, and the piston rings were OK as well.

    IMG-20170111-WA0003.jpg

    IMG-20170111-WA0004.jpg

    The clogged oil jet is marked with red.

    oil flow scematic cbr600rr stock.jpg

    We are planning to clean all the oil galleries with kerosene and passing compressed air before assembling the engine. Can you suggest a better way of doing that or maybe checking if none of the galleries are blocked?

  4. #14
    And then there is the really obvious: Is there enough oil in the tank to start with?

    Forbes

  5. #15
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    Rabsimran,

    We are planning to clean all the oil galleries with kerosene and passing compressed air before assembling the engine. Can you suggest a better way of doing that or maybe checking if none of the galleries are blocked?
    Yes, it is important to make sure all oil galleries are thoroughly cleaned before building the engine. And sometimes too much gasket-goo is worse than too little. Many an engine has been destroyed because a large lump of sealant blocks an oil line. Worst is if the sealant blocks the entry to the main-oil-pump.

    The standard way of modifying an OEM motor for "more reliable oiling" is to drill out the main galleries to a larger diameter (typically out to 1/2" or 13mm +), then fit screw-in end plugs rather than the original press-fit plugs. This way, after the major engine parts are bolted together, or even inbetween races, the end-plugs can be unscrewed and the galleries visually inspected for debris, lumps of sealant, etc. Also much easier to clean a large diameter hole than a very narrow one.

    But it may not be possible to increase the diameter of the galleries on your CBR? Probably not enough wall thickness? Nevertheless, you should be able to remove some of the press-fit plugs and replace them with screw-in plugs (<- just drill-and-tap, then fit a short bolt + loctite). This makes it much easier to clean/inspect all the galleries.

    Main thing is to be careful when bolting everything together. Clean everything thoroughly first. Use just enough sealant, but not too much. Use compressed air to blow out the galleries before, during, and after assembly. Blow in and out every orifice you can find, with motor turned every which way up. Sometimes little things get stuck in the funniest places.

    The above careful build-process, together with an external-tank that is guaranteed to always feed pure oil with no air-bubbles to the main-pump, should cure your "...tick-tick..." problems!

    Again, my current guess for most likely reason for your problems is the main-pump sucking from the wrong place on external-tank (ie. too far forward), and occasionally gulping in some air.

    Z

  6. #16
    Forbes,

    Is there enough oil in the tank to start with?
    The recommended volume of oil by the manufacturer and the volume of oil in plumbings along with a buffer volume was calculated and used.

  7. #17
    Z,

    The conical bottom reservoir with spiral baffles in ready to be put up on the car. The plumbings are now way shorter, with minimum bends. Also, main pressure feed line has been replaced by a -16 line just to be on safer side as we have the Indian event coming very soon.

    Two failed engines were cleaned thoroughly and assembled after changing the bearing, bolts and gasket. The engine was run on a jig for about an hour without any tick-tick sound.

    We are currently waiting for our pressure sensor which should arrive within 2 days. The new dry sump setup will be tested on the car after that.

  8. #18
    I suspect you're not running with enough oil. You mention 3 litres? I would expect you to need over double that volume to ensure there's enough air-free oil in the bottom of the tank at all times especially at high RPM and WOT.

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