For All the Engineers Out There in FJ Land …

[fj1289]

I am looking to modify a single rotor gerotor pump for two pickup tubes:
The larger diameter of the two pickups will be a scavenge line - and may not have constant flow available - but needs to be the "priority" for the pump when there is something to pump.
The second pickup will be a little smaller in diameter and will have constant flow available from a sump.

Will having the larger line for scavenge "bias" the pump flow for this?  Will the smaller diameter pickup restrict or lessen the flow from that side all things being equal?

Thanks!   

[Pat Conlon]

That's a David Raforth question....

[ribbert]

I am looking to modify a single rotor gerotor pump for two pickup tubes:
The larger diameter of the two pickups will be a scavenge line - and may not have constant flow available - but needs to be the "priority" for the pump when there is something to pump.
The second pickup will be a little smaller in diameter and will have constant flow available from a sump.

Will having the larger line for scavenge "bias" the pump flow for this?  Will the smaller diameter pickup restrict or lessen the flow from that side all things being equal?

Thanks!  

Chris, my understanding of your question is this, a single pump with 2 inlets of different diameter, the smaller constantly pumping oil and the larger only pumping oil occasionally, as demand requires, and sucking air when it's not, presumably the intention is for the second pickup to start sucking as soon as it's immersed in oil and once the oil's sucked out, flow returns to the constant supply inlet.

The pump is always going to draw from the source with the least resistance, in this case that would be the scavenge pipe sucking air when there's no oil, which means the constant delivery one is not working either. It's like trying to drink through a straw when it has a hole in it, but push the straw further into the drink so the hole is now immersed and keep sucking, you'll get drink but from which hole is the most drink drawn? Many factors come into play here.

So, as for which inlet is prioritized when they are both primed, it depends on a range of factors but one thing's for sure, the physics involved are set in stone and can't be tweaked and if it were me, I'd be looking for another solution.

From what you describe this just sounds like some sort of high tech catch-can alternative, don't you only run your bike for literally seconds per run?

It might be easier to understand if you described the application, but from my interpretation of your question, I can't see it working.

This is of course only my opinion and I hope it's of some help, haha, if it's not, just ignore it.

Noel

[Motofun]

This may be partially possible IF the sumps are above the pump.  NPSH limitations would preclude drawing the oil up but gravity and check valves could be made to work.  The partial part is I don't see how to keep the 2 sources from mixing without the use of a positive (ie electronic) control.

[fj1289]

OK.  Didn't want to open Pandora's box yet since I'm just thinking through possible future projects (probably way in the future - I tend to "grind" on details like this for a while).

Trying to work out the best way to use the oil cooler portion of the FJ oil pump to scavenge a low mounted turbo. 

Easiest answer is don't and use a purpose made electric pump.  That is a viable option, but is more failure prone and failure = destruction of the turbo center section and possibly the shaft too. 

Pretty sure I have worked out a way to convert that outer portion of the pump the scavenge the turbo (and route the extra lines inside the case and out of harms way - crank weights, clutch basket, etc).  But then I lose the oil cooler flow. 

Possible to use an electric pump for the oil cooler (would need to fab a pickup - prefer to not tap into the existing pickup and "fight" the mechanical pump with an electric pump - don't know what the "balance" might be on the intake flow between the two).  And failure of the electric pump in this case does not cause a catastrophic failure of anything (at least not in a short period of time).

So, the thought is to try to use the section of the pump for both purposes.   Pretty sure there will be mostly consistent "pull" through the turbo center section since it has pressurized flow into the bearings (albeit through a restrictor) - but I don't know how "smooth" the flow will be (how aerated is the oil at this point?).  Sounds like the concept could work - expect to have less total flow through the oil cooler - but sounds like it could be a workable compromise 

[Pat Conlon]

I understand the concern of an electric pump failure cooking your turbo. (Murphy was an optimist) I think what would work is an electric pump with an audible alarm, like the kind we run with our dry sump systems. If you lose a belt on the 2 stage pump that alarm will raise the dead. Crazy ass loud.
Circulate the turbo oil thru a separate reservoir with a separate oil cooler....although for short runs I'm not sure you will need an oil cooler. With the turbo oiling system being separate from the engine system will allow you to run special oil.
If you are set on combing engine oil with your turbo you have to decide, do you want feed the turbo with the oil cooler supply line? (pre-cooler) If so, you are putting hot oil from the engine into your turbo.
If you feed the turbo from the cooler return line (post cooler) now the hot oil from the turbo is going into your engine.
For a track bike, I think a separate system is what I would consider.

[Carson City Paul]

I understand the concern of an electric pump failure cooking your turbo. (Murphy was an optimist) I think what would work is an electric pump with an audible alarm, like the kind we run with our dry sump systems. If you lose a belt on the 2 stage pump that alarm will raise the dead. Crazy ass loud.
Circulate the turbo oil thru a separate reservoir with a separate oil cooler....although for short runs I'm not sure you will need an oil cooler. With the turbo oiling system being separate from the engine system will allow you to run special oil.
If you are set on combing engine oil with your turbo you have to decide, do you want feed the turbo with the oil cooler supply line? (pre-cooler) If so, you are putting hot oil from the engine into your turbo.
If you feed the turbo from the cooler return line (post cooler) now the hot oil from the turbo is going into your engine.
For a track bike, I think a separate system is what I would consider.

Why send the signal to a "Crazy ass loud" alarm? send it to an engine kill switch, zero lag time, off right now.

[Pat Conlon]

I understand the concern of an electric pump failure cooking your turbo. (Murphy was an optimist) I think what would work is an electric pump with an audible alarm, like the kind we run with our dry sump systems. If you lose a belt on the 2 stage pump that alarm will raise the dead. Crazy ass loud.
Circulate the turbo oil thru a separate reservoir with a separate oil cooler....although for short runs I'm not sure you will need an oil cooler. With the turbo oiling system being separate from the engine system will allow you to run special oil.
If you are set on combing engine oil with your turbo you have to decide, do you want feed the turbo with the oil cooler supply line? (pre-cooler) If so, you are putting hot oil from the engine into your turbo.
If you feed the turbo from the cooler return line (post cooler) now the hot oil from the turbo is going into your engine.
For a track bike, I think a separate system is what I would consider.

Why send the signal to a "Crazy ass loud" alarm? send it to an engine kill switch, zero lag time, off right now.

Nope, there could be a time when an engine kill would be dangerous. Like mid corner....best to do it manually when it is safe... tether switches excepted.

[RPM - Robert]

Me thinks this is for a drag bike, which would make Paul's suggestion very useful. No turns, no one to run into the back of you if you suddenly lose power, turbo saved. Them borgies are expensive you know. (I don't know what brand Chris will be running but any turbo other than the cheap crapola on eBay is pricey)

However, I don't know if I would do this on a road race bike or street bike.

[fj1289]

Actually this (if it ever actually happens .....) will be for the street bike.  First I just have to get it back on the road after forever - which comes after getting the race bike back up!  There just might be an cylinder head torqued in place on that right now ...

I thought about a separate oil system for the turbo - but with a low mount that means 2 electric pumps!  Unless you mount the turbo higher and can fit the sump under the turbo.   Trying to "hide" as much of this as possible - no need to "advertise" your old ass 80's bike has the potential for that much power !  A little turbo mounted low in an aftermarket fairing lower (or better a slightly modified larger stock-style belly pan) and a full exhaust, who'd be wiser at a casual glance?  Or maybe go high mount behind the engine - rotate the turbo 90 degrees and fab an intake "box" under the rear portion of the seat to hide that .... Carefully route the exhaust - maybe snake an oval pipe up behind the swing arm pivot (after modifying the arm a bit - might be easier if it is a steel swing arm!) ... lots of possibilities - all have their difficulties - looking for options aka "the art of the possible"!

[RPM - Robert]

I stand corrected. He is a street madman.

[RPM - Robert]

Could you put a Y in the oil cooler line with both inlets in the V sections allowing both the regular oil flow and the scavenge pump to put oil back through the cooler without fighting against the regular oil flow?

This would allow you to run a single pump. And pump it through the cooler to be picked back up in the pan. Have to do some thinking on the bypass valve etc in the oil pan if that would work or not.

Not to scale or even routing but something like this doodle.

[Motofun]

Just out of curiosity, how did Kawi/honda/yamaha do it back in the day?

[fj1289]

Not sure on the other manufactures - but the Yamaha XJ650 Seca Turbo used an adapter plate on the oil filter housing to add an oil cooler, so the main engine oil pump lobe is what also sent oil through the cooler.  I need to find the oil diagrams - curious if Yamaha sent the oil thru the filter or the cooler first?

Then the second lobe of the pump was just used to scavenge oil from the low mounted turbo.  The standard XJ650/750 oil pumps only had one lobe. 

When I had my XJ650 Seca I used the turbo oil cooler adapter to add an oil cooler.   Turns out US XJ models (other than the Turbo and the 900) did not come with oil coolers - but most of the other markets had them as standard!

Maybe sending the scavenged oil directly to the cooler alone might be enough volume anyway?  Certainly keeps it (relatively) simple ...

On a race bike I'd just go with an electric pump activated by the fuel pump relay so you can't forget to turn it on.  If it fails during a run the worst would probably be blowing oil past the seals and smoking pretty bad?

[RPM - Robert]

If you are talking about the oil circuits for the FJ. One side of the pump flows directly to the oil filter and main oil galleys, the other loops to the oil cooler and pan only.