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  #1  
Old 03-08-2018, 06:17 AM
KatanaPilot KatanaPilot is offline
 
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Default Christen Inverted Oil System

We have a full Christen inverted oil system on our Titan/ECI IO-360. First ground run on the airplane occurred the other day. The oil pressures were consistently lower than those from the test cell run at Penn-Yan (without the inverted oil system of course).

So, I either have an indication issue, or the inverted oil system somehow affects engine oil pressure. I have a call in to Aviat and waiting to hear back from their "expert". The factory service rep that answered was not the expert, but indicated they frequently have to adjust the oil pressure when they install the Christen system.

For those who have installed the full system, have any of you had to adjust the oil pressure following installation? I'm going to temporarily install a mechanical gauge to verify the electronic reading.

None of the readings are outside limits, but the pressures should be higher on a new engine with cool 50W mineral oil.
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  #2  
Old 03-08-2018, 06:27 AM
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jthocker jthocker is offline
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Default Oil pressure

Yes you certainly will need to crank the pressure back up when installing the inverted system.
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  #3  
Old 03-08-2018, 06:35 AM
KatanaPilot KatanaPilot is offline
 
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Default Thanks Jon!

Do you know why it affects the oil pressure? I know there is additional plumbing and a big change to the oil flow pattern of the engine, but I'm not sure I understand why it affects the pressures.
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  #4  
Old 03-08-2018, 06:42 AM
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Kahuna Kahuna is offline
 
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Default

Fluid dynamics. Pressure drops from friction. Any liquid, in any transport medium, suffers pressure loss over distance. In your application, you can expect ~15-25psi drop with the added inverted system.
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  #5  
Old 03-08-2018, 06:44 AM
Michael Henning Michael Henning is offline
 
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Default

Be sure to post what Christen has to say.
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  #6  
Old 03-08-2018, 06:52 AM
KatanaPilot KatanaPilot is offline
 
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Default

Understood. We have changed the oil pickup point from directly below the pump in the sump where it now has to flow out the lower sump hose, through the inverted ball valve and back through the pick up hose.

Good to hear confirmation from a couple of guys who have experience with this or similar systems.

I'll post what I find out from Aviat, but I expect it will be the same information.
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  #7  
Old 03-08-2018, 12:00 PM
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RV8JD RV8JD is offline
 
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Default The Christen Manual Says ...

My previous RV-8 has a Christen inverted oil system. Here is an excerpt from an older Christen Installation Manual (Issue C).
Your issue is addressed in Section 3-2, paragraph 5, for the reasons given above.

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Last edited by RV8JD : 03-08-2018 at 12:47 PM.
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  #8  
Old 03-08-2018, 01:29 PM
KatanaPilot KatanaPilot is offline
 
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Default Thanks again

Talked to the Aviat Pitts test pilot. As has been posted by several of you, given the extended flow path and restrictions due to elbows, springs and check balls - it is expected that the oil pressure will be lower than that of a stock oil system.

He says he has to adjust 3 full turns or so on the pressure adjuster on the Pitts.

Good to have confirmation that the indications we had were normal and adjustment is needed - before we go and start chasing our tail trying to troubleshoot a non-existent problem.

I appreciate your input.
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Last edited by KatanaPilot : 03-08-2018 at 01:30 PM. Reason: corrected grammatical error
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  #9  
Old 03-08-2018, 05:03 PM
jrs14855 jrs14855 is offline
 
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Default Pressure

On the Pitts in cooler temps the pressure will be lower at first and will increase as the oil temp warms up.
The Christen system is not a perfect system. There will be momentary drops in OP, sometimes to near zero for a split second. For that reason I set oil pressure at the top of the green in the belief that it would be better for those momentary drops in pressure.
I don't think any one is doing sustained knife edge flight in an RV, but if the oil pot is on the right 90 degree left wing down will cause the oil pressure to go to zero. Right wing down has little or no effect on OP. I did quite a bit of left wing down knife edge before I discovered this. Engine didn't seem to mind. In 1000 hours never more than a few tiny flakes in the screen. A lot of that time was spent at 3300-3500 rpm.
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  #10  
Old 04-13-2018, 04:27 PM
William William is online now
 
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KatanaPilot pm sent.

Thanks
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