Modifying Engine Oil Relief Valve

LBZ

Super Moderator
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Jul 2, 2007
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last melling i installed with .0025-.0027 main clearance and .0022-.0023 rod clearance, i saw about 10 psi increase at idle and up the RPM range. 15w40 oil and around 90* outside temp. never saw under 28psi at idle and hot after running it hard.

it will be hard to say the actual PSI increase you will see because most are building an engine at this point and clearances in mains/rods/ect can open up more for higher performance.
Was it one of these?
https://m.summitracing.com/search/y...y/duramax-diesel-v8?keyword=Melling Oil Pumps

This is the only one summit lists. Standard flow and pressure. Not sure if that's what I would want or not.
 

LBZ

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Jul 2, 2007
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What I run.
30psi at 700 rpm idle at 190° oil temp
70psi at 2100 rpm at 190°
Mains/rods are low mid .020s
Pegs 83psi cold @#2 main journal via mechanical gauge
What oil pump?
I run 10 to 20 degrees hotter oil temperature running 70mph, 1950rpm, gcvw around 16000.

Oil pressure doesn't change though after it passes 190 degrees.
 
Last edited:

malibu795

misspeelleerr
Apr 28, 2007
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in the buckeye state
Melling 316.. one you linked from summit
When oil temps get upwards of 240° I see ~10psi drop at 2100 and 5-8psi at idle.... It was close to 50% increase in temp related drop with stock pump
 

moparkxracer

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Jun 25, 2010
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I have the original banana pan on mine, it holds abt 1 cup less oil then oem. Not sure how low the ppe deep one would hang down under the truck.