Downside to Straight 50 weight for Harley Evo???

[BusyLittleShop]

Originally Posted By: Shannow

No, a positive displacement pump moves the same volume every revolution, regardless of the oil's viscosity.


Positive Displacement Pumps are the superior choice because they are:
1 self priming
2 more or less constant flow regardless of pressure.
3 the effect of viscosity doesn't negatively affect flow...

all good things that will produce a given Gallons per Minute
(GPM) based on the flow rate of a 50 grade viscosity but if drain the
less flowing 50 and install a freer flowing 40 you will definitely
note an increase in Gallons per Minute...

So technically speaking Dr.Haas statement still rings true...

 

[Shannow]

Originally Posted By: BusyLittleShop

all good things that will produce a given Gallons per Minute
(GPM) based on the flow rate of a 50 grade viscosity but if drain the
less flowing 50 and install a freer flowing 40 you will definitely
note an increase in Gallons per Minute...

So technically speaking Dr.Haas statement still rings true...


No it doesn't...pumps "slip more" when viscosity is lowered.

http://www.liquiflo.com/v2/files/pdf/Gear_Pump_Basics.pdf

They have pump performance "curves" on water and oil...as can be CLEARLY seen, the lighter viscosity, in a positive displacement pump moves less volume, due to internal slippage.

And the higher viscosity displays less variation in flow versus pressure rise.

Dropping from 50 to 40 will bu definition increase slippage and reduce flow, but probably not enough to measure.

it WILL NOT increase flow.

 

[BusyLittleShop]

Originally Posted By: Shannow


No it doesn't...pumps "slip more" when viscosity is lowered.

http://www.liquiflo.com/v2/files/pdf/Gear_Pump_Basics.pdf

They have pump performance "curves" on water and oil...as can be CLEARLY seen, the lighter viscosity, in a positive displacement pump moves less volume, due to internal slippage.

And the higher viscosity displays less variation in flow versus pressure rise.

Dropping from 50 to 40 will bu definition increase slippage and reduce flow, but probably not enough to measure.

it WILL NOT increase flow.


Question to Titanspeed manufactures of Gerotor oil pumps

Given your gerotor pumping system would I see more GPM running a 40
versus a 50 grade oil or would the GPM be the same???

Titanspeed's reply
Slightly more would flow as there is less viscosity which resists flow.

I've asked Liquiflow the same question but no reply yet... standby...

 

[Phishin]

Busy...

You are getting torched in this thread.

How many wrong statements can you make on one page? You still got a few more posts on this current page, before we start page 3. So go ahead...

Just kidding...kinda.

Listen to these fellers. They know what's going on. I'd believe Shannow and OVERKILL before I believe anyone answering your questions at a machine shop.

 

[Robenstein]

They best analogy I see to this is the pump is like a syringe. You can fill it will maple syrup or water. It is going to take more effort to push the plunger with the maple syrup but in the end the same volume is going to come out. So thicker oil will cause resistance and some loss of power but in the end, the volume should be the same.

Now...flow in regards to the engine it self, it depends how you define flow. The lighter weight will sure splash around and drain easier and faster(more flow) but on the pump side should stay the same.

 

[BusyLittleShop]

Originally Posted By: Phishin
Busy...

You are getting torched in this thread.

How many wrong statements can you make on one page? You still got a few more posts on this current page, before we start page 3. So go ahead...

Just kidding...kinda.

Listen to these fellers. They know what's going on. I'd believe Shannow and OVERKILL before I believe anyone answering your questions at a machine shop.


Thanks Phis but I think we are getting along just fine... the only thing I abhor is not knowing something...

 

[Shannow]

Originally Posted By: BusyLittleShop
Thanks Phis but I think we are getting along just fine... the only thing I abhor is not knowing something...

 

[Shannow]

A little sneak peak on where I grasped the viscosity flow loss/slip...

Back in the turbine engineer days, eeplacing an aged Vickers 6 piston (picture Corvair style) positive displacement pump, in a shaft jacking system. 10 bearing feeds, with hydraulic flow control to each of them, meaning that max volume was controlled, so if one bearing went "open", the others would still receive their quotient of oil. Operating pressure 3,000 psi (but that's neither here nor there).

Chose a gear pump that was matched volume wise, installed it and it worked. (PN150)

After running the machine, it wouldn't raise the required pressure...30C thinned the oil out enough that the pump volume dropped enough to not make the flow/pressure required.

70(ish) cst dropping to 20(ish) increased leakage enough to do that...

 

[Shannow]

Originally Posted By: Robenstein
They best analogy I see to this is the pump is like a syringe. You can fill it will maple syrup or water. It is going to take more effort to push the plunger with the maple syrup but in the end the same volume is going to come out. So thicker oil will cause resistance and some loss of power but in the end, the volume should be the same.


Fair analogy really, and if you want to refine it some more, consider the piston to have some leakage around it, similar to the piston in a shock absorber...lighter oil, more leakage, less pressure...on top of the displacement/flow that you have described.