SF oil cooler outlet/inlet

No worries Julian. Always good to get info from someone else's point of view. That's how we learn stuff.

My knowledge comes from theoretical principles rather than practical experience. It's easy to boil theory down to its simple components, but I'm well aware that there are variables in the real world that are not easily accounted for with simplistic analysis.

1/2 lb pressure loss through a 90 deg bend sounds about right. But I'll stand by my assertion that such a pressure wouldn't bother the flow rate of the oil pump too much.

You can't convince me that oil is compressible either, otherwise I'll have to throw my hydraulic jack away!!

If the oil exiting the oil pump had a lot of air entrained in it, then it would have some compressible element within it, but I don't reckon it would because oil pump intakes are invariably placed well below the level of oil in the sump to avoid sucking air. Cavitation generally only happens in regions of low pressure or high temperature, or both. I wouldn't have thought the conditions in an engine oil pump would be sufficiently extreme to produce cavitation. If the pump was delivering oily froth then I reckon that would be a more serious worry than a few bends in the pipe!

I quite enjoy these technical discussions. You never know where they'll end up.  :D

Cheers,
Cam
 
If you want to avoid the oil pump sucking air in on an SF on acceleration, you want to consider some serious sump baffles.
I have an oil pressure warning light plumbed into the radiator line on my SFC and it lights up every time I open the throttle with enthusiasm which is to say every time!

ciao
Paul
 
:D
To be honest the cavitation part was inspired by my winch on my competition vehicle, we used to use it for speed winching etc and it was a serious bit of kit running up to 200bar and run of a Power Takeoff from my gearbox that could run 25% faster than engine speed with a 50cc/min gear pump. (also below oil tank level)  Anything over about 2000 revs in high gear would have that cavitating so much that the winch would not go any faster and the line pressure would actually go down!  But the winch was hauling arse by then so it didn't really matter.  ;)
Am sure you are right with engine oil pumps and sensible pressures Cam.

Julian
 
Dellortoman said:
sfcpiet said:
You will at least need to check that the pump manages the height.  Pump in good condition should be OK. 
Click to expand...

See above. With a pump in good condition (internal clearances not worn to excess) you should be able to pump oil to a great height. The static pressure limit of the pump is determined by the strength of the pump components and the horsepower available to drive it. There's no reason Chris couldn't mount the oil cooler on top of a very tall sissy bar. It would get plenty of cooling air that way. ;)
Click to expand...

Not so sure 'bout that, Cam!

Brings me back about 30 years when I was at the beginning of my Matchless saga.  This particular engine is the ultimate version employing a Norton gear oil pump.  After starting, I checked oil flow to the rocker box, a good 30cm/12" above the pump.  The clapped out POS couldn't manage even that!  Granted, the feed side of the pump is considerably smaller than that of a 750 Laverda and the drive speed is also quite a bit lower, running at about 1/4 engine speed, the Lav pump runs at 1/2 engine speed.  Needed quite a deal of TLC to get it up to scratch, seems to work OK now, finally!

I'm certain the stock Lav pump also has its limits concerning its abilities to overcome heights.  Once the cooler is filled, the oil travels downwards(easy on the pump) but must then be pushed back up to the rockers.  Always best to check... suck it and see! :D

piet
 
I agree as the Pump rpm increases the flow will probably drop = Efficiency. As for Pressure it would be interesting to find out just how much pressure Laverda pumps could handle: That is operating into a Dead End with a Pressure Gauge - I would imagine, particularly at moderate RPM's - where the pump is most efficient, the Gear Pin Key may break before reaching Maximum Pressure. That 3 or 5 psi pressure we are reading is really nothing more the weight of the Oil Column to reach the Top End.

Remember the law that states. If all else is equal, ie constant pump speed etc.  If pressure in the system goes up. flow goes down.
Click to expand...
That's why I said earlier, with a Gauge tapped into the Gallery, an increase reading in pressure may indicate blockage to the Top End - perhaps, the Barrel Stud blocking the Feed Line.

Roller Bearings as in our Laverda's do not create pressure - Babbitt Bearings on the other hand, depending on Temp, Viscosity...etc,  can run any where between 25 to 75 psi. Our  Positive Displacement Hydraulic Brake Systems have to be Efficient to Work.

 
You blokes are making my head spin  :o

OK then, it's going on the sissy-bar, I'm just working out how to reroute the upswept pipes as to not surerheat the oil, as the outlets are at the top of the sissy-bar.

This track bike is going to look so groovy man 8), I may even go tassels for the 18" ape-hangers too!

Thanks my Righteous Brothers :D

 
I can't believe this pump debate hasn't spilt any blood yet!
I am in the middle here, with good tertiary college qual's in engineering yet with loads of practical experience.

Laverda SF said:
I agree as the Pump rpm increases the flow will probably drop = Efficiency.
Click to expand...
Well, if pump rpm increases then flow will most likely rise, as will losses also so yes, worse efficiency.

Laverda SF said:
As for Pressure it would be interesting to find out just how much pressure Laverda pumps could handle: That is operating into a Dead End with a Pressure Gauge
Remember the law that states. If all else is equal, ie constant pump speed etc.  If pressure in the system goes up. flow goes down.
Click to expand...
Click to expand...

The answer to Laverda SF's question is hopefully void as being positive displacement the pump will have a relief valve somewhere, without this the pressure could go astronomical and break something big time.

Most of the pumping examples of losses, cavitation and general doom are at much higher pressures/flows on bigger systems than our pissy little low-pressure motorcycle gear pumps.
So if pressure is resistance to flow then our Laverda pumps are very lightly stressed as they are very low pressure.
 
SimonR501 said:
I can't believe this pump debate hasn't spilt any blood yet!
I am in the middle here, with good tertiary college qual's in engineering yet with loads of practical experience.

Laverda SF said:
I agree as the Pump rpm increases the flow will probably drop = Efficiency.
Click to expand...
Well, if pump rpm increases then flow will most likely rise, as will losses also so yes, worse efficiency.

Laverda SF said:
As for Pressure it would be interesting to find out just how much pressure Laverda pumps could handle: That is operating into a Dead End with a Pressure Gauge
Remember the law that states. If all else is equal, ie constant pump speed etc.  If pressure in the system goes up. flow goes down.
Click to expand...
Click to expand...

The answer to Laverda SF's question is hopefully void as being positive displacement the pump will have a relief valve somewhere,
Click to expand...
Would that be that rubber ball thingy that comes out the top of the motor with that black rubber those thingy, what the hell does that thing do? I pulled it out and gave it to my kids to play handball with, little fuckers lost it in the garden...
 
That would be the Crank Case Breather Valve Cosi,

Or in your case now, the oil drippy pipe thingy with no valve action handball play and loose game device.  Critical bits, they are!  :D :D :LOL:

Julian
 
1000/3C_Stefan said:
Mmmh, on my replacement pump with 10mm wide gears there is a big hole in the pump case beneath the lower gear. Never found any oil pressure relieve valve on my triple engine so would assume this hole acts as a pressure relieve valve limiting the pressure which the pump is able to deliver. Rather crude design but fully up to the job for a system designed for flow and not for pressure.
Click to expand...

?

Do you mean the hole where the "idler" gear axle is located?  This is for production purposes only, the pump has no relief valve whatsoever!  If great amounts of oil seep out of said hole, the pump is fucked!

Past experiments showed pressure at 2000 pump rpm (equals 4000 engine rpm) of 3-3.5 bar with cold oil measured at the cooler take off just after the pump.  Falls to under 1.5 bar once the oil gets to about 80?C.

piet
 
Simon - Yes! That's exactly what I was trying to say, but you said it more succinctly. Positive diaplacement pumps are capable of delivering astronomically high pressure. The only reason that Laverda pumps don't is that they're pumping against very low resistance.

BTW, no blood spilled here. We engineers are intelligent and civilised people.  ;)
Maybe a bit of spilt oil though.

Cheers,
Cam
 
Commercial Intertech series 330, 350, 365 hydraulic gear pumps are rated to 3,500 psi, exact same principal as our oil pumps
main difference is material used in their construction, better seals, different shaped gear tooth form, etc
but principal remains the same


 
redax5 said:
Commercial Intertech series 330, 350, 365 hydraulic gear pumps are rated to 3,500 psi, exact same principal as our oil pumps
main difference is material used in their construction, better seals, different shaped gear tooth form, etc
but principal remains the same
Click to expand...

Absolutely right, as mentioned about my winch pump using up to 3000psi.  That pump is also a gear pump of similar style but just a "tad" bigger than the Laverda one  :D 

Julian
 
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