How to Determine The Effect of Oil Viscosity on Flow Rate?

[NeilDS]

I am trying to determine the end of life oil flow requirements of an engine with the oil viscosity at minimum specification limit. I have the flow requirement data based on testing and calculations for end of life (all bearings at spec limit) for a nominal viscosity (14.7 cst) for 40w oil but am tring to find what the flow would be at 12.5 cst. I am ultimately trying to determine if the oil pump end of life output can meet the demand of the engines end of life oil requirements with the oil at the minimum required viscosity. I don't currently have access to the engine for testing. Any ideas on trying to calculate this?

Thanks
Neil

 

[Latexman]

At most flow will incease 17.6%.

Good luck,
Latexman

 

[NeilDS]

That is a significant amount for a relative small change in viscosity. What are you basing that on?

 

[Latexman]

Laminar flow. Poiseuille's law. If it was turbulent, it would be less dramatic, but you did not give enough information to determine.

Good luck,
Latexman

 

[IRstuff]

14.7/12.5 = 1.176

TTFN
faq731-376

 

[NeilDS]

I was just doing some calculations using the Hagen–Poiseuille equation and wondering if that was the best method. I don't have much more detail. I do know the new engine flow requirment and pressure and have use that to calculate a d^4/L value and have used that to try and calculate flow with the lower viscosity.

 

[Latexman]

If flow is laminar, it should be highly accurate. More data is needed to determine the flow regime.

Good luck,
Latexman