Milwaukee Midget

[fordboy628]

Scraper/windage tray: Sometimes hard to see the hp but occasionally significant gains can be had. If you don't have a source already, talk to Kevin Johnson at Ishihara-Johnson (www.crank-scrapers.com). He made a custom one for me. They take some work to get the closest fits but are well done.

Good call - they already build one -

http://www.crank-scrapers.com/BMC.html

Sizing will be a bit different - my crank is custom - but at least I'll know that the pan bolts line up.

Thanks, Jacksoni!

Midget,

No need to re-invent the wheel, er, windage tray.   Pictures of their stuff on the site look good.   And they probably have some thing for 970S stroke or something close enough for you to do the final fitting.   Their prices are really right too.    The Teflon coating sheds the oil better than uncoated.

I think I only saw about half of the booths, too much catching up with guys I hadn't seen in years . . . . . .    including some I didn't want to see again . . . . . . . . other than that though, I really enjoyed the trip.
 
Fordboy

[Milwaukee Midget]

Midget,

No need to re-invent the wheel, er, windage tray.   Pictures of their stuff on the site look good.   And they probably have some thing for 970S stroke or something close enough for you to do the final fitting.   Their prices are really right too.    The Teflon coating sheds the oil better than uncoated.

Well, I'm thinking they probably don't have anything for a crank as odd as mine, but they seem okay with custom work, and at least they'll have a template to start with.

Thanks, too, Mark - for pulling me away from this Packer debacle . . .

[fordboy628]

Well, I'm thinking they probably don't have anything for a crank as odd as mine, but they seem okay with custom work, and at least they'll have a template to start with.

Thanks, too, Mark - for pulling me away from this Packer debacle . . .

They might surprise you with something pretty close.   They have plastic strips you can fit up to your Grenade, giving them a perfect template for your application.

You will find this interesting:   http://www.youtube.com/watch?v=SmjQn3IBsP8

From where I'm watching, Packers are still in it with 12 minutes to go in the 4th.
 
Fordboy

[Interested Observer]

Midget,
You may want to reconsider all this oil system modification.  We don’t know exactly what the circuit diagram is, but assuming it is as you described, the touted advantages seem to have been heavily stretched.

First off, the oil being reintroduced into the pickup is not as heavily aerated as oil drawn from the pan.  Secondly, it permits the oil in the pan more time to dissipate the air that it has accumulated.  Third, it makes the system somewhat self priming.  4th, it gives you more pressure on the intake side – pressure above atmospheric - which takes the power you’ve already spent pressurizing the system - the portion that's being bled off - and lowers the power necessary to pull oil back into the pump.

“First off--”  One of the best ways to aerate oil is to drive it over a relief valve, which is exactly what happens to the excess oil as it is “bypassed” from the system.  Hard to say whether it is less aerated than the pan oil.
“Secondly”  Assuming that the oil in the pan isn’t being completely thrashed by the crank, this may have an actual, but minor, benefit.  The scraper/windage tray would be much more effective in reducing aeration.
“Third”  How does it improve priming if the bypass flow doesn’t exist until the pump is running and providing more flow than the system requires?
“4th”  Is nonsense.  The bypass oil is vented across the relief valve to the pressure that exists in the intake tract--which, neglecting flow friction losses, is the “head loss” in the suction line due to the elevation difference between the pan and the pump inlet.  If the pressure in the line was any higher than that, oil would flow back into the pan!

I'm seeing this as a better use of energy wasted, reintroduced to the system as less energy required. 

The energy “wasted” by pumping the oil to pressure and then venting it across the relief valve is exactly that--wasted, right then and there--producing somewhat warmer oil.  You can’t recover that energy or reintroduce it to the system.  The only thing useful is that due to the reduced flow velocity in the suction line from the pan, friction losses may be somewhat lessened, resulting in minimally less depressed pressure at the pump inlet.  A possible detriment in the scheme is that the bypassed oil may be more aerated than the pan oil.

What you need is an electrically driven pressure compensated pump--that would only pump as much oil as is needed to maintain the desired pressure.  Next best would just be an electric fixed displacement pump--which might be nice, as it could produce system pressure when turned “on” with the ignition before cranking the engine.  The tricky part is sizing the system and determining the flow rate needed at various engine operating conditions. 

[fordboy628]

Thanks, too, Mark - for pulling me away from this Packer debacle . . .

From where I'm watching, Packers are still in it with 12 minutes to go in the 4th.
 
Fordboy

This morning's headline from the Green Bay Press Gazette:

                              BELIEVE IT!

All you need for Christmas is:   A/  Aaron Rodgers cleared to play!
                                             b/   Packers must win out,
                                             2/   Bears must lose 2 games,
                                             d/   Lions must lose 2 games.

It could happen . . . . . . . . . . .
   on the Packer win
Bearboy

[jacksoni]

When I did my scraper, they sent me templates of modifiable material. Crank, rods, oil pump position on my engine are all different than stock so I cut new notches for everything and sent back. Did have to move a couple of bolt holes as well. They then made up the scraper which also needed final fitting for the minimal clearance to the rotating assembly. Relatively easy process.

Moving the oil around in an engine does take some power (considerably more that water etc) There are electric water pumps and alternator deletes maybe worth a little. I remember seeing recently a dyno test in Hot Rod or something trying to show some power difference on a dyno with various water pumps. If you believe you can repeat stuff within a hp or two, they found something but it wasn't much. And on a V8 of course. But I have never seen someone do a dry sump with electric power ( the fact that I have never seen/heard of this of course doesn't mean I has not been done but for sure is not common).  How big is a several HP electric motor?

[Milwaukee Midget]

IO,

So – like the bored Rabbi said to the bored Priest, “Let’s have an argument.”

I’m not married to this idea – I’m no engineer – but part of this build diary is to bounce these ideas.

My understanding and my questions.

The pump works by atmospheric pressure on the inlet compared to negative atmosphere created by the pump.  In the crankcase, relative high atmospheric pressure is what the pump needs to draw oil to it.
 
The overflow oil exiting the relief valve still carries pressure in excess of atmospheric, but providing less volume than the demand of the intake of the pump.  By directing the oil pressure to the pickup – pressure that would be completely wasted otherwise - the pump sees the equivalent of a higher pressure in the pickup side compared to the atmospheric pressure alone acting on the oil in the sump - thus requiring less power to draw oil.

The demand of the engine is in excess of the oil provided by the overflow, so oil continues to be drawn upward through the column from the pan.  The combination of the overflow oil in conjunction to the oil provided by atmospheric pressure causes the pump to see a higher relative pressure in the pickup than would be the case if the pump were only drawing from the sump.

Because the quantity of oil in the sump has less demand on it – lessened by the quantity of oil provided from the oil bypass - it has more time to settle out and release the air in it.

And yes, this is ALL minimal.
 
Regarding aeration at the bypass valve – where would this air come from?  The oil is under positive pressure, and any air in the oil circuit is going to tend to bleed through the path of least resistance, which would include oiling holes on the bearings, the rocker shaft, the cam bearings.  If that is already the case, I’ve got bigger problems than where I should route a return line.  Directing it to someplace other than the pan, where it is certain to take on air, seems like a better solution than adding it to the milk shake.

Tag - you're it! 

[jacksoni]

IO,

So – like the bored Rabbi said to the bored Priest, “Let’s have an argument.”

I’m not married to this idea – I’m no engineer – but part of this build diary is to bounce these ideas.

My understanding and my questions.

The pump works by atmospheric pressure on the inlet compared to negative atmosphere created by the pump.  In the crankcase, relative high atmospheric pressure is what the pump needs to draw oil to it.
 
The overflow oil exiting the relief valve still carries pressure in excess of atmospheric, but providing less volume than the demand of the intake of the pump.  By directing the oil pressure to the pickup – pressure that would be completely wasted otherwise - the pump sees the equivalent of a higher pressure in the pickup side compared to the atmospheric pressure alone acting on the oil in the sump - thus requiring less power to draw oil.

The demand of the engine is in excess of the oil provided by the overflow, so oil continues to be drawn upward through the column from the pan.  The combination of the overflow oil in conjunction to the oil provided by atmospheric pressure causes the pump to see a higher relative pressure in the pickup than would be the case if the pump were only drawing from the sump.

Because the quantity of oil in the sump has less demand on it – lessened by the quantity of oil provided from the oil bypass - it has more time to settle out and release the air in it.

And yes, this is ALL minimal.
 
Regarding aeration at the bypass valve – where would this air come from?  The oil is under positive pressure, and any air in the oil circuit is going to tend to bleed through the path of least resistance, which would include oiling holes on the bearings, the rocker shaft, the cam bearings.  If that is already the case, I’ve got bigger problems than where I should route a return line.  Directing it to someplace other than the pan, where it is certain to take on air, seems like a better solution than adding it to the milk shake.

Tag - you're it! 

Not being an engineer can't really comment on the above other than to say that there is an effect of pressure in the pan on the oil pressure the pump puts out. I think that is clear. However, I think it is also clear that relative pan vacuum is far better for power than pan pressure, thus the use of exhaust driven pan evac systems, good dry sump scavenging systems or plain old vacuum pumps to the pan. Considerable dyno proven power is available with relative pan vacuum. I hear this does get to diminishing returns with very high numbers (over 15" or so) . Dry sumps don't necessarily in an of themselves make more power or use less HP but are considered more reliable in high g force situations- which we do not have to deal with- but would help cooling if, for instance, you had a more marginal coolant system, due to the large oil tank volume and can give some pan vacuum which is beneficial. Dry sumps take room in the engine bay that may be in short supply and are not inexpensive but as you have said, you are down to the high cost per HP gained area, even if they are few.

[Interested Observer]

MM,

Given the system in the pdf diagram attached, which is a reasonable schematic of the system we’re concerned with...

“The overflow oil exiting the relief valve still carries pressure in excess of atmospheric...”

Says who?  This is the crux of the issue.  What basis is there for saying that?  Can one really maintain that the pressure at B is greater than that at A or C or D?  How can that be?  They are all connected to each other.  The pressure essentially equilibrates throughout that manifold.  And the pressure at A, B, C, and D is  somewhat less than that in the pan due to elevation differences and flowing friction loss.

Aeration at the relief valve would largely arise from air or other vapors that are entrained or dissolved in the oil.  The oil came from the pan, that is, it is already well aerated, and vapors are very hard to remove from the fluid without subjecting it to time, temperature, and vacuum.  Rapid decompression through the relief lets the vapors expand.

[Koncretekid]

I wouldn't spend a lot of time on this system.  The oil pump is pumping against a given back pressure created by your bearing clearances at a given RPM and temperature.  Being a positive displacement pump, it will require a given amount of HP to do this, and will depend on the back pressure it sees (like 40 psi) against an inlet pressure of say -1/2 psi.  Routing the oil from the bypass valve to the inlet will do nothing that I can see, as I.O. has shown, it can simply run back into the pan because the pump won't pump anymore than it's designed to pump at these conditions.  If you want to reduce hp consumption, you need to open up those clearances (dicey) or use less viscous oil (also dicey).

As far as using electric pumps, these could help, but you'll have to have enough extra battery capacity to begin with, as generating electricity to run the pumps is probably less efficient than mechanically pumping.  Of course with large enough batteries, pre-charged, with no charging system, you would essentially be running a hybrid, which in my opinion should not even be allowed (that should raise some eyebrows!) 
Tom
P.S. Even I use a total loss battery system to run my ignition system, but that's only because I'm too cheap to buy a crank mounted self generating ignition.

[Milwaukee Midget]

Borrowed from Steve Maas - his site is http://www.nonlintec.com/sprite/



Directly above the pressure relief oil return is the oil pressure relief valve.  On mine, it's adjustable - we've had it as high as 95 psi - we've since cranked it down to ~ 70 psi.  What the pump is actually able to produce as far as maximum pressure is unknown, but we know it produces sufficient volume to get us at least 95 on the positive high pressure side, and that by increasing the flow through the valve, we've introduced flow into the return side.

The energy that produces that flow is energy used by the oil pump.

The oil pump has three forces working against it - the constricted columns of oil on the positive pressure side - constricted by the passages at the bearings and the pressure valve, the weight of the oil it is trying to draw from the sump, and the lack atmospheric pressure in the pan - especially if we are to seek out the ideal of a low pressure - or at least well vented - crankcase.

IO, I disagree with your assessment that the relief side of the valve carries no pressure.  Pressure is necessary to produce flow - if there were no pressure, what would cause the excess oil to return to the pan?  

If you partially constrict a garden hose, the pressure between the spigot and the constriction increases, but there still remains pressure after the constriction.  Think of a garden hose nozzle as the constriction, and we'll call a leaky washer at the spigot an oil passage.  You can still hose down your car even if your hose has a leaky washer at the spigot because of the remaining pressure after the leaky spigot.

Let's take the analogy one step further.  Let's say we're dealing with a birdbath with a small fountain in it, actuated by an electric pump.  

We're trying to maintain a fountain height of 6" above the surface of the water.

The pump produces pressure sufficient to throw the water 12".

We install a T in the high pressure side, one line going to the fountain, and the other line has a valve in it, directing fluid to the collection pan.

We adjust the valve to bleed off sufficient water pressure to achieve our 6" fountain height.

One of the demands on the pump is to produce sufficient draw to permit atmospheric pressure to force water into it.

If we want the pump to consume less power, where can we look?

Constricting flow on the low pressure side can give us the proper fountain height, but the pump will work inefficiently - turning the applied power into heat rather than fluid flow - wrong way.

We can better size the pump to the conditions at hand - ie find one through whatever method that provides us our 6" fountain height - but we really don't want to buy 2 dozen pumps to find one that will deliver the height we want, and this method leaves us no margin for error.

So all things being equal, the bypass valve on the HP gets us our best pump performance and the result we're looking for - a 6" fountain height.

But how can we increase the efficiency?

The pressure at the pickup is nominally atmospheric.  If we localize a high pressure zone in the intake of the pump by reintroducing the flow from the bypass - which because it is flowing, is under pressure - back into the intake, we create a relative high pressure environment that requires less power to draw water.

We know that the volume of liquid has potential, because if it's drained directly into the pan, it raises the level of the water against atmospheric pressure.

We also know that the demand of the pump is more than the amount of fluid we are looking to reintroduce to the input side from the bypass.

By combining the volume of liquid acted on by atmospheric pressure with the higher pressure fluid being wasted at the bypass, we have a higher relative pressure on the input of the pump than would be provided by atmospheric pressure alone.

We've decreased a pumping loss through a feedback loop.

Are there gobs of horsepower here?  I doubt it.  Is it worth pursuing?  Maybe.  Will it hurt anything?  THAT'S WHY I'M POSTING IT - I'M NOT SURE.  ,

 

[Crackerman]

Borrowed from Steve Maas - his site is http://www.nonlintec.com/sprite/



By combining the volume of liquid acted on by atmospheric pressure with the higher pressure fluid being wasted at the bypass, we have a higher relative pressure on the input of the pump than would be provided by atmospheric pressure alone.



 

this is an interesting thought... if you are familiar with a jet valve, it uses higher velocity flow to draw fluid up, or through a tube.

could that bypass pressure be used to feed a jet valve in the pick up tube, essentially increasing VE of the oil pump, reducing all suction, or lifting losses associated with oil pump intake?


the other benefit of lower crankcase pressure (even lower than atmosphere) is the increased tendency for air to be released from aerated oil.

[Jack Gifford]

Jes' a bunch o' PSI'ing into the wind, if you ask me...

Sorry... cabin fever setting in.

[fordboy628]

Jes' a bunch o' PSI'ing into the wind, if you ask me...

Sorry... cabin fever setting in.

Good one Jack!!

[Interested Observer]

MM, I tried to annotate your earlier reply much in the manner that Fordboy has done in the past but can't get it to work acceptably.  So, below is a lame approximation of the technique.  Text in quotes is from your reply, unquoted text are my comments.

That portion of the energy stored in the fluid to be vented before the RV is converted into high velocity turbulent flow that almost immediately is converted to heat due to the fluid viscosity.  The energy, in the form of heat, is no longer available for hydraulic work.

"IO, I disagree with your assessment that the relief side of the valve carries no pressure. Pressure is necessary to produce flow - if there were no pressure, what would cause the excess oil to return to the pan?"
I don’t believe I have ever said there was no pressure at the RV outlet, only that the pressure there is essentially the same as that at other locations in that manifold.  The pressure at the RV is not determined by the RV or its flow, it is determined by the pressure in the piping system into which the flow is introduced.  (Same as the way the nominal oil pressure for the engine is determined by the galleries, bearing clearances, etc. etc. in the oiling system.)  So, in conjunction with gravity, the pressure loss due to friction in the flowpath to the pan will be seen at the RV outlet and that drives the oil to the pan.  Or, more correctly, the incoming flow displaces the fluid ahead of it down the pipe, creating a back pressure due to viscous friction in the pipe.   

"If you partially constrict a garden hose, the pressure between the spigot and the constriction increases, but there still remains pressure after the constriction." 
No!  There remains flow.  What is the pressure in the stream of water after it leaves the end of the hose?  Only atmospheric.  Same deal as the oil going back to the pan.

"If we want the pump to consume less power, where can we look?" 
We look for a pump that doesn’t pump excess fluid.

"Constricting flow on the low pressure side can give us the proper fountain height, but the pump will work inefficiently - turning the applied power into heat rather than fluid flow - wrong way." 
The pump is doing the same amount of work, but part of it is to overcome the suction head that was introduced.

"So all things being equal, the bypass valve on the HP gets us our best pump performance and the result we're looking for - a 6" fountain height."   
Or, we just calculate the pressure needed for a 6” height (p=rho*g*h), decide how much flow we want, and look through pump performance curves to find an optimum pump.

"The pressure at the pickup is nominally atmospheric. If we localize a high pressure zone in the intake of the pump by reintroducing the flow from the bypass - which because it is flowing, is under pressure - back into the intake, we create a relative high pressure environment that requires less power to draw water."  No!  See discussions above.  “...the pickup is nominally atmospheric..” therefore, the recirculated fluid is also nominally atmospheric---ergo, no supercharging of the pump inlet.

"We've decreased a pumping loss through a feedback loop." 
Perhaps by edict, but not via fluid dynamics.

What’s so hard about this?  Once it is accepted that the pressures at A, B, C, and D are essentially the same, the only question is what is that pressure.  And that, per the above discussion, is atmospheric less the frictional and gravitational losses in the pan pickup plumbing. 

Noting that you have an external oil line on the engine, it wouldn’t be all that hard to re-rig it to include a flow rate sensor of some sort to monitor the actual oil rate used by the engine on the dyno or wherever.  Then, after determining the displacement of the oil pump the portion of “wasted” flow could be used to assess excess power going into the pump.  But probably not worth the effort.