Adding Auxiliary Oil Volume, or, How to Expose One’s Fluid Mechanics Ignorance

[n3303j]

Due to valving I think there's a bit of negative pressure in crankcase.
At least my V11 has a ball check valve on the vent set to allow outflow only.

[Kev m]

You can't count on a vacuum to be present to keep oil from flowing the wrong way on an accent and expect it to flow the right way on decent.

I mentioned crankcase pressure earlier as a complication. There are alternating vacuum and pressure pulses in the case. Past a certain point the pressure is vented but if you add a second plumbed sump it needs to be vented as well for transfer.

Now let me approach this problem from a completely different perspective.

If you're worried about an extra 25-45 mm of a sump spacer for ground clearance. Why not just increase ground clearance. How about mitigate it with larger diameter tires and slightly taller suspension?

[n3303j]

I wouldn't count on vacuum to do anything except further complicate the issues of an auxiliary oil tank.

As far as crankcase pressure goes it seems to me that internal pressure would alternate between atmospheric and negative pressure. This us assuming no blow by on the rings, check valve doesn't leak, air doesn't find any other entry points etc.

So far I've never measured this but I'd be really curious to see a real graph of running engine crankcase pressure.

 I'm assuming you loose power pushing pistons upward but regain some of it as the lower pressure sucks them back down?

[Dirk_S]

Now let me approach this problem from a completely different perspective.

If you're worried about an extra 25-45 mm of a sump spacer for ground clearance. Why not just increase ground clearance. How about mitigate it with larger diameter tires and slightly taller suspension?

Already done, and now you just reminded me of the good times I once had with the center stand before I added the extra length in suspension. Mmm, those were the days…easier tire changes. Sniff.

The aftermarket suspension added enough ground clearance so that the sump protector wouldn’t seem so dang low. Add the sump spacer, and we’re back to square one, albeit with more oil

 Don’t get me wrong—I’m not planning to take this bike out on the most rugged Class IV Vermont roads or super steep Moab trails—but any dirt, even some simpler forest roads can lead to some bumps in the oil noggin, and so I’m extra biased toward maintaining the clearance I currently have.

[Kev m]

I wouldn't count on vacuum to do anything except further complicate the issues of an auxiliary oil tank.

As far as crankcase pressure goes it seems to me that internal pressure would alternate between atmospheric and negative pressure. This us assuming no blow by on the rings, check valve doesn't leak, air doesn't find any other entry points etc.

So far I've never measured this but I'd be really curious to see a real graph of running engine crankcase pressure.

 I'm assuming you loose power pushing pistons upward but regain some of it as the lower pressure sucks them back down?

Wouldn't it alternate between negative and whatever it takes up overcome the crankcase ventilation valve?

[n3303j]

I honestly don't know. And don't have the equipment to measure the pulsation. I assume a pezio gage and an oscilloscope?

[tris]

How  do these spacers work, do they push the oil pick up down too?
Oherwise with regard to this issue  it won't achieve anything as it couldn't reach the extra oil

Thinking outside the box,
How about an oil level sensor that lights giving you a warning before oil pressure is compromised ?
Internal vertical baffles to keep the oil near the pick up?

[Huzo]

maybe even leaning forces)

This is what made me think it was a solo.

[Bulldog9]

My .002.

I think an overflow/aux oil reservoir that feeds
through the drain plug is a recipe for disaster and
MUCH more fragile and prone to breaking and leaking
And dumping your oil than an extended sump.

Are you rock hopping your V7? Jumping logs? I
Understand the concern, but many of us have sump
extenders and I haven't heard of a bashed in sump
with or without a skid plate.

Will you off road sans (without)
the side car? If not, I cant envision a situation where
a lower sump would be a liability as the sidecar would
Limit your off road terrain options.

[Kev m]

How  do these spacers work, do they push the oil pick up down too?

IIRC yes the pickup is part of the pan. But it's been 10 years so someone confirm that for us.

[cappisj1]

I would make sure the engine is healthy first. Adding a means of carrying extra oil on a bike that losses oil is a lot of work to just prolong putting oil in it anyway.

[fotoguzzi]

Really though? Say I fill the theoretical aux container up with oil and connect it to the drain plug.

If I ascend, the oil in the sump is going nowhere, because there’s already oil in the aux container.

If I descend, the oil from the aux container … flows into the sump…? Does it for sure? Wouldn’t there be a vacuum? How does air replace the oil in the aux container if the air in the sump doesn’t reach the small passage between the reservoirs?

by going glug, glug, glug, like when you pour gas out of a can with a spout and no vent. ?

[guzzisteve]

If you had a tank under trans and connected the return hose spigot and drain plug spigot together so to have two lines connecting both pan & tank. The tank would need a pump to circulate oil some how to go round & round. Now to get it to work.
You might try the pulsing fuel pumps, one in & one out. Ought to be slow enough.

[n3303j]

There's your dry sump. See above post.

[Dirk_S]

Are you rock hopping your V7? Jumping logs? I
Understand the concern, but many of us have sump
extenders and I haven't heard of a bashed in sump
with or without a skid plate.

I also don’t know of anyone on here who’s taken their V7 on the types of roads that I have in recent years:













And a video example:
https://youtu.be/_B7s-pCqBGU

 I’ve done a few roads worse than these, but don’t always feel like dealing with photo/video recording.

I’ve heard and felt the bashes and bangs, and I’ve had to bend the bash plate back to form a couple times. I don’t want the clearance to be any worse than it is.

by going glug, glug, glug, like when you pour gas out of a can with a spout and no vent. ?

But the can only does that when air makes its way through. If the aux can hose/pipe is under the surface level, the air won’t be pulled down/in. It’s why you have to “prime” a hose when transferring liquid from a tank (higher in elevation) to another. Right?

I would make sure the engine is healthy first. Adding a means of carrying extra oil on a bike that losses oil is a lot of work to just prolong putting oil in it anyway.

The load of the sidecar and passenger and extended high speed/throttle are what burned the oil. Outside of that moment, it was doing fine.

How  do these spacers work, do they push the oil pick up down too?
Oherwise with regard to this issue  it won't achieve anything as it couldn't reach the extra oil

Thinking outside the box,
How about an oil level sensor that lights giving you a warning before oil pressure is compromised ?

Yeah, it was a bummer that the oil light came on when the damage had already been done. I’m surprised it didn’t give an earlier warning.

Help my brain grow—why does there need to be a return line for circulation? I’m guessing if the aux can doesn’t have an easy way for air to get in, it won’t feed the actual sump if the sump level drops?

[Kev m]

I don't think siphons work the way you think siphons work.

But I've never siphoned something from a sealed container (the jug example, glug, glug, glug).

[moto-uno]

  Did anyone say "Another oil thread ?"  Peter

[Kev m]

Did anyone say "Another oil thread ?"  Peter

"From a certain point of view" - Obi Wan Kenobi 

[AJ Huff]

Mill out all the extra metal inside the pan, thin the walls. Probably add a 1/2 quart of oil at least that way.

-AJ

[John A]

There's your dry sump. See above post.

Small blocks are already half way to being a dry sump with their separated crankcase. A scavenge pump and some plumbing with a snazzy tank would be interesting.

[krglorioso]

There is an old expression that if you gear a piss ant low enough it will pull a freight train, but I think the small block simply is not up to the task presented to it.

That opinion may be worth even less than .02c but I think I'm on target.

Ralph