SF oil cooler outlet/inlet

chriskay said:
Thanks Steve, looks good.
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Yeah Steve's conversion does look very nice and it's a lot closer to the factory solution for oil cooler outlets.
Looks like the way to go for a cooler.

When we did my conversion for the oil filter we initially looked at going in lower too (as per the SFC) but decided to go for the option of tapping into the galley higher basically for aesthetic reasons as I wanted to have the oil filter balance out the dynamo and fill that empty space.

Nature abhors a vacuum!

Peace Out

T.
 
There's plenty of depth in that thread. Only problem is that the gallery enters the hole half way up the thread. You could use the full depth of the thread if you were worried about it stripping. Screw a full-length fitting in and tighten it fully home, put centre punch marks on the fitting and on the case as a reference, take it out and drill matching holes through the sides of the fitting to line up with the oil galleries. Then screw it back in and tighten it until the punch marks line up - job done.

Cheers,
Cam
 
Cam that's basically what I did. Tapped to the far side of the Gallery and after seating the Brass Fitting home I ran a Drill Bit into the gallery and through the exposed threads of the Brass Fitting to open the Gallery.

I can't overstress how careful you have to be as there ain't much material to work with.

I can't quite understand what Steve did by tapping into the base of the Oil Pump - Shit if I can remember what that Gallery is.
 
Hi Cam,

My concern with that way was that if it starts to unscrew even slightly you totally block the oil supply to the motor - unlikely but catastrophic if it happens. The extremely low oil pressure on these things means that it will never fail due to pressure, only overtightening. Swings and roundabouts but I prefer it this way.  With the 750 the oil cooler can stay attached for just about any engine work.

Ron, you need to block the gallery between the two new outlet ports, otherwise you have two parallel oil circuits and it will just go the path of least resistance. From memory what I did was clearance drill down just past the new angled port and tapped a thread just past it and inserted a grub screw to block the gallery.

Finding these photos again was good because I forgot that I'd actually done it to two sets of cases.

Cheers
SteveB
 
Just had a look at the oil ways etc on my crank case and I think it's a daft idea  :D :D
Making an oil system that is low no pressure anyway flow round sharp right angles is not in my opinion the best way of doing things.

Personally I will be making a spacer plate in the filter plate on the bottom of the sump, pickup the hot oil with a nice mocal electric pump and pump it round a cooler and back into the sump.  therefore not affecting the std oil supply in any way at all.  And, only working when needed on a thermo controlled switch.

Simples like!
Julian
 
Julian: I agree, as I said earlier: The SF really does not need the modification: however, Tapping the Gallery for a 10 or 15psi 1.5" Oil Pressure Gauge is nice as you can tell you're getting Oil to the Top end.

Not bad Idea for an Electrically Power Sub-Pump for an Oil Cooler on a Thermal-Sx or Filter but you have to consider them old Bosch 30amp Generators don't put out much. Converting to a GTL Alternator or modifying a Small Alternator from a Japanese car may be beneficial.

You might be able to fabricate a Mechanical Sump Circulation Pump driven off the Generator Belt or Pulley: Something like a Dual Pulley on the Generator with a short belt to drive a small Oil Pump mounted on top of the Generator - You could use a Thermal-Valve with a Piddle Hole in the Gate to keep the pump lubricated when the Valve was Closed - Just a thought ;o)
 
julian said:
Personally I will be making a spacer plate in the filter plate on the bottom of the sump, pickup the hot oil with a nice mocal electric pump and pump it round a cooler and back into the sump.  therefore not affecting the std oil supply in any way at all.  And, only working when needed on a thermo controlled switch.

Simples like!
Julian
Click to expand...

Why not go one step further and have a two way valve for the electric pump so you can prime the oil system before starting the engine! (I talked to a guy who primes his Mustang P51D merlin engine like that, he reckons it really helps the engine last longer).
 
Sub pump may well be an idea, but there is no charge system on this one and I'd rather keep some battery power in reserve for the ignition.

In regard to the cooler mounting position, I'm thinking that mounting it near the top case height would stop any back-flow if it was mounted high when the motor is not running. (previously I had thought of mounting it within the fairing) Meaning start-up would be oiled rather than having to run dryish until it pushed more slippery stuff through.

Am I right in thinking the oil will run out of the cooler when not running?
 
chriskay said:
Am I right in thinking the oil will run out of the cooler when not running?
Click to expand...

No.

When the engine isn't running, only the feed hose to the cooler will empty itself, but it should take days as long as the pump is in reasonable condition.  Stock Laverda coolers have the feed union going to near the top of the cooler internally to prevent the cooler emptying itself.

After start-up, it's just a matter of filling the feed to the cooler, happens in seconds.  Stock 750 pump delivers about 7-8 litres/min (at 8000rpm)

If you choose to fit a different cooler, check how the feed works, you may need to feed it from the top.

piet
 
Chris,

Do you mean in the fairing nose?  Did that many vears ago on my triple.

You will at least need to check that the pump manages the height.  Pump in good condition should be OK. 

piet
 
julian said:
Making an oil system that is low no pressure anyway flow round sharp right angles is not in my opinion the best way of doing things.
Click to expand...

G'day Julian.
The oil system is low pressure, but that's only because there's little resistance to flow through the bearings. The pump is capable of delivering quite a high pressure. Gear pumps are positive displacement, so in theory for any given pump speed, the flow is pretty much the same regardless of the pressure it's pumping against (ignorng small leakage losses via the internal clearances in the pump). So friction losses around bends, through filters and coolers are pretty much irrelevant. The only proviso is that the feed to any such restrictors is taken directly from the pump outlet before the oil supply branches off anywhere else.

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. ;)

Cheers,
Cam
 
sfcpiet said:
Chris,

Do you mean in the fairing nose?  Did that many vears ago on my triple.

You will at least need to check that the pump manages the height.  Pump in good condition should be OK. 

piet
Click to expand...

Yep, in behind the nose and mounted off the the fairing stay with Swiss cheese venting holes in the front of the fairing, and perhaps a shroud to push hot air downward and away from the rider (me) (did you find you needed to deflect the hot air?). New HV pump is on the way.
 
Dellortoman said:
julian said:
Making an oil system that is low no pressure anyway flow round sharp right angles is not in my opinion the best way of doing things.
Click to expand...

G'day Julian.
The oil system is low pressure, but that's only because there's little resistance to flow through the bearings. The pump is capable of delivering quite a high pressure. Gear pumps are positive displacement, so in theory for any given pump speed, the flow is pretty much the same regardless of the pressure it's pumping against (ignorng small leakage losses via the internal clearances in the pump). So friction losses around bends, through filters and coolers are pretty much irrelevant. The only proviso is that the feed to any such restrictors is taken directly from the pump outlet before the oil supply branches off anywhere else.
Cam
Click to expand...

Hi Cam,
Your theory only applies to the pressure measured actually "at the pump" as the restrictions apply in the system before the various outlets etc the pressure is progressively lost "after" the 90 deg restrictive bends. I do know what you are saying and it's sort of OK but in practice you can see about 1/2 lb loss "after" every sharp 90 degree bend in the system if it's trying to flow a relatively high amount of oil.  I actually tested and measured a system to find these results.  (but it was an 80psi stytem)
So "in theory" and "in the instance used to measure" it's best to stay away from sharp bends.
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. The gear pump will cope easily yes but you may end up starving something at the end of the chain without realising it.
Although in the instance of this thread on the SF I am picking holes more than a little  ;)

Regards,
Julian
 
julian said:
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 certainly true of centrifugal, axial and other impeller type pumps, and to some extent positive displacement pumps operating on a compressible fluid (eg. an air blower) but it doesn't apply to positive displacement pumps that are pumping a non-compressible fluid such as oil or water.

The rule of thumb for PD pumps working on liquid is that for a constant speed, the flow rate is constant regardless of the delivery pressure. The other thing that increases is the torque required to maintain the pump speed. There are of course practical limits such as described before (strength of pump casing, leakage around the pump gears, available hosepower). With a well-made pump in good condition, any slippage (fluid leakage around the gear rotors) is minimal.

Think of as equivalent to a piston pump (also a positive displacement pump). Whatever the pressure, for the same piston stroke, the same amount of fluid is displaced.

What that means to us is that any restriction in the oil delivery pipe will result in a higher fluid pressure at the pump rather than a lower pressure at the bearings. The bearings won't see any difference in pressure or flow at all. I reckon the practical limit to pump pressure in a Laverda would be the little pin drives the pump shaft. But as long as it can take the increased torque, everything should be OK.

Cheers,
Cam

 
Hi Cam,
I do agree with the principles of what you say. however in practice you have a few irritants.
1. Thick type engine oil exiting a gear pump like the one in the SF is rarely in-compressable.
2. Gear pumps work best at low speeds and loose efficiency quickly at speed.
3. As pressure rises, so does heat, and therefore density decreases. You may move a similar amount of oil in Volume through the restrictor but not density, so when it cools back down due to lowering pressure you have less oil. and therefore less flow!
4. The gear pump system you describe is never more than 80% efficient unless running extremely slow as it beats the hell out of the medium causing heat and cavitation very quickly.

As I say, on an SF at the pressures we are talking about I am being picky to the extreme. Specially looking at the original oil routing last night.

Several years ago I did measure this on one of our race engines and we did see about 1/2 lb loss for each 90 degree "cast" airquipe bend in our racing dry sump system running about 80 odd psi and fairly serious flow.  so reality is proving the things we perhaps expect to be insignificant and "ignorable" in our theory are actually sometimes significant.

Julian
 
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