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  #1  
Old 07-29-2012, 10:13 PM
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UnPossible UnPossible is offline
 
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Location: Granbury, TX
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Default Oil Pressure Questions from Phase 1 testing

Hey - still plugging away on Phase one testing and I have a few questions for the engine experts as to what is normal/acceptable for oil pressure. BTW - the engine is a new IO-375 from Aerosport Power with about 30 hours on it now.

Today I started working on some of the climb / glide tests and got some low oil pressure warnings from my G3X system (set to alert below 55psi).

Below are a couple of charts of the data from the G3X.
The first chart shows the MAP, % Power, Oil Pressure and Oil Temp for the whole flight. As you can see, when MAP is above 20" my oil pressure is in the range of 65-75 psi. On a recent flight where I spent the majority of my time in cruise around 65% power the Oil Pressure was around 73-74psi.



However, there are a couple of areas that seem a little funny.

1) Around the 1810 mark on the chart, you can see that I increased power from around 10% power to around 75% power. During this time the oil pressure started at around 70psi, dropped to 39psi, then ramped to near 80psi before falling to the upper 40's. Below is a larger chart of this specific time period... any ideas as to why the oil pressure would vary in this manner? At what oil pressure should I start to get worried that something could really be wrong?



2) Around the 2400 - 2700 range (in the top chart) you can see that the engine power varied quite a bit from a low of around 20% to a high of around 80%.. however oil pressure remained in the 55psi range....looking at these charts it appears that oil pressure generally mirrors % power (and MAP) but for some reason during this period it did not change when the power level was adjusted up or down.

I hope this is not too much info, but just trying to make sure that I don't have a problem that I need to address before proceeding with phase 1 testing... I really don't want to do any damage to my shiny new engine.

Thanks,
Jason
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RV-10 in process (@#$$%# Cabin Top & Doors)

Last edited by UnPossible : 07-29-2012 at 10:45 PM.
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  #2  
Old 07-30-2012, 02:27 AM
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Andy Hill Andy Hill is offline
 
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I am no expert... but:

Generally OP is regulated by an adjuster except at low RPM when the Oil Pump cannot create enough pressure. The early drops on your second graph would appear to be at low power? I would suggest RPM is a better measure than MAP/% to analyse?

Secondly, the 2 drops below ~55psi appear to be momentary, and associated with the start of a signficant speed increase. Might one ask what minimum 'g' values you had / how you increased speed without increasing power?
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Old 07-30-2012, 07:51 AM
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Oil pressure has nothing to do with manifold pressure. The oil pump output is directly related to RPM, which is not on the supplied charts.

Can you plot oil pressure vs RPM?
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Old 07-30-2012, 08:21 AM
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Quote:
Originally Posted by DanH View Post
Oil pressure has nothing to do with manifold pressure. The oil pump output is directly related to RPM, which is not on the supplied charts.

Can you plot oil pressure vs RPM?
Sure - the first chart is the full flight, and again the second is the same snipet.





Really curious as to why in the first chart the at around 2241 the oil pressure dropped from around 70 to near 50 without a significant change in engine RPM.

Thanks for any suggestions,
Jason
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Old 07-30-2012, 08:57 AM
Norman CYYJ Norman CYYJ is offline
 
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Check your electrical connections on the wire from the monitor to the pressure sender. IMHO the spikes in the oil pressure are to rapid for an oil pump or engine problem.
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  #6  
Old 07-30-2012, 09:17 AM
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Quote:
Originally Posted by Norman CYYJ View Post
Check your electrical connections on the wire from the monitor to the pressure sender. IMHO the spikes in the oil pressure are to rapid for an oil pump or engine problem.
Agree, in particular the sender ground.
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Old 07-30-2012, 11:39 AM
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UnPossible UnPossible is offline
 
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Thanks for the suggesitons - I checked the connetctions and everything looked fine, but I went ahead and replaced the connectors on the ground line from the oil pressure sender... I'm planning on flying tonight and will be thrilled if the fix is a couple of new connectors.

Thanks again,
Jason
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RV-7A (Flying and Sold)
RV-10 in process (@#$$%# Cabin Top & Doors)
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  #8  
Old 07-30-2012, 08:20 PM
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Well - once again the VAF experts were correct.... I replaced the connectors on the ground wire for my Oil Pressure transducer, and my Oil pressure in cruise flight tonight remained between 71 and 74 psi.

The only time I got a warning about oil pressure being below 55psi was on short final with the engine pulled all the way back to idle.

Thanks,
Jason
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RV-7A (Flying and Sold)
RV-10 in process (@#$$%# Cabin Top & Doors)
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  #9  
Old 07-31-2012, 10:55 AM
TS Flightlines TS Flightlines is offline
 
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Proud of you Jason!!!!!
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Teflon Hose Assemblies for Experimentals
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Ridgeland, SC
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