Relief Valve Reset

[Darrel Starr]

Thought you might want to see the results of taking two 0.063 inch thick washers out of the relief valve in the O-320 Lycoming in N18SY. Tim Hieb @ Bolduc Aviation, Minneapolis, said that two washers would equal a 10 psi reduction, I got an 11 psi reduction --- pretty accurate prediction. See attached before & after pictures. Ain't iPhones great?
In a previous thread, PerryB suggested that I should knock down the oil pressure to the middle of the green and I agreed but just now got around to making the change. I'll run it a while and into warm weather this way. I have one more washer I could remove.

 

[PerryB]

I think you're right where you should be now. When that oil gets some hours on it and/or heats up more, the pressure will come down a few more psi. I was just looking at your airspeed vs. rpm. Are you running an 82-42?

 

[Darrel Starr]

160hp, 82/44, 8.5x6 tires

 

[barbwire]

DS ----I like your panel.

 

[Darrel Starr]

Thanks, barbwire; we actually laser cut three of them before settling on this one.

 

[Steve Pierce]

My experience is each washer equals 4-7 psi of oil pressure.

 

[Darrel Starr]

Steve, that matches what I just saw - 5.5 psi/washer. Right in the middle of your observation range.