Looking for some guidance regarding a oil pressure problem I am experiencing.

Setup
428ci
wet sump - C6 pan (non GM)
crank scraper - no windage tray
Melling 10296 pump with COPO spring installed
Morel HIPPO solid lifters
Feeding 2 turbos and a fairly large oil cooler with 10an lines to and from (maybe 4-5ft total line length)

I installed these lifters when my engine was NA and i was running the OEM dry sump system with a Katech Blue Pump. Oil pressure was solid prior to the lifters. After the lifters, HOT idle pressure dropped to around 19psi. Before it was around 28-30psi HOT idle.

Fast forward... switched to wet sump due to location of the turbos. Melling 10296 oil pump with COPO spring installed.
Cold start oil pressure is ~55psi
HOT idle is ~35psi
HOT cruise is ~50psi
HOT WOT oil pressure drops into the mid upper 30s.

I did try a different oil filter and saw a small increase in pressures across the board. I typically run the Mobil 1 113A with no issues. Prior filter was something else and OP was lower.

Added an extra quart to the engine - no change in oil pressure

I tried to jack up the rear of the car to submerge the o-ring in oil - no change in oil pressure

I believe I am at the point to trying the Melling 10355 oil pump

Before I do that, does anyone have any other ideas to try? OP doesn't drop off a cliff at WOT but more of a gradual decline as the pull goes on.

 

Weird question here, but what’s your lobe lift at the camshaft? Some Morels are finicky about lift and the oiling hole location.

 

Roughly .740" on the current cam. Previous cam was the same on the exhaust side and intake side was .780"

Morel 5425 is what I am running

 

How are you feeding the oil cooler from the block and what oil cooler. Is something clogged there? This is mine on my C6 Z06. Number 10AN like you.

 

I wonder if you're having cavitation issues. You're feeding oil to a lot of things, more things to feed like turbos and an oil cooler is going to cause more resistance to flow, also if you're running a thicker oil at a lower temperature it's going to make it worse.

Maybe try bypassing the oil cooler and see what happens before swapping parts?

 

Pretty much the same way. A G-Plus brand block, no thermostat. All those pieces were new when installed. A clog in the cooler did cross my mind.

 

This is on my list for next steps

1 - verify the tune configuration is correct (had this issue once before and it turned out to be sensor configuration related)
2 - verify oil pressure with mechanical gauge
3 - loop oil cooler lines, bypassing the cooler
4 - maybe try a different oil filter? Recommendations?
5 - replace pump with Melling 10355
6 - throw it all away

 

Considering it was fine before lifters and not after, and considering those are Morels, I would say that's where I would look. The pump/pan combo may be an issue, as well, but you need to go one step at a time. Considering your pressure is down across the board, it's not the pan directly. You might pull a lifter and measure outside dia and lifter bore dia and see how much clearance you actually have. Like others said, you may have so much lift with those that it's pushing the lifter out of the bore too much and exposing the oil passage.

 

Definitely hope its not an actual lifter issue. I feel this pump should have much more pressure than i am currently seeing. So hoping its something as simple as a bad cooler or something.

 

What oil weight?

Are the lifters axle oiling?

What oil temps are hot?

I’ve seen 10296 losing oil pressure with revs on two engines now. They’re both still running. Stable and repeatable, but not what you want to see. It’s weird.

10355 on another engine I did worked great. Rising pressure with revs. Dropped from 80 to 75 psi by 7800 rpm but climbed all the way to 7200. Ls1 oil pan might just not like the rpm. Used the 10355 because of axle oiling lifters and piston squirters.

 

20w-50 VR1
Yes, high pressure pin oiling (Lost an extra ~10psi over Johnson axle oiling lifters after swapping them out originally on the dry sump setup)
I don't have a temp sensor for oil atm but 200+ I wouldn't be surprised with the turbos and such, even with the cooler.
Yeah pressure is solid while idling and cruising. Gradually drops during the pull.
I run the LS2/LS3 wet sump C6 vette pan. It's not OEM but I don't think there is much difference in the casting.

 

You can try the 10355, it's easy enough, but that may create a pan issue because that thing pumps some oil. It's all trial and error when you deviate from a 10295. It's expensive, but you might look at a Schumacher pump... They are hand built don't have the cavitation issues.

 

If it’s a cavitation issue, which it could possibly be, then porting the 10296 will fix the issue. I’m not sure what rpm you’re turning Jon but my ported 10296 works well with axle oiling lifters, a very big cooler, and -10 lines. My limiter is set at 7800 and I often shift at well over 8k. As Dave mentioned, the Schumann pumps are the Ferraris for wet sump LS builds. Expensive but they perform with very cool recirc tech.

 

In My opinion, I would try the 10355 Pump.

According to Improved racing the 10296 flows around 8 GPM while the 10355 flows around 9.5 GPM.

I Always port the pump inlet and discharge area's to reduce all the sharp edges. The sharp edges will create little swirling currents that lead to cavitation issues at the higher RPM range.

 

The (mostly) cavitation is caused from the large diameter oil pump tube, going into the much smaller oil pump inlet. The quick difference in size under suction is the huckleberry. Porting the pump greatly reduces cavitation in that regard.

 

My light blue line is oil pressure (10296 pump). It climbs as expected, and then falls off toward redline. It never drops to unsafe levels, but it doesn't climb as it should. Also, you can see how the oil pressure jumps up when load is released between shifts and when I lift at the top end. Really confused by that one..not sure what it means. It's like when I'm off throttle, the oil pressure is where it should be for the RPM.

I know I have a little blowby...my bottom end isn't perfect, but still strange. If it was a mechanical phenomenon like aerating the oil, I wouldn't expect the pressure to jump up exactly in line with throttle position.

 

So I had never heard of Schumann. They have many different pumps available it seems. The most interesting being the "energy recovery" and they even talk about an energy recovery vacuum system, but I find not parts list or schematic or pictures. They talk about maintaining oil flow even with a monster truck standing on the nose for 10+ seconds with a wet sump pan and pump. I'm intrigued. Do you know more?

The recirculation line from the output to the inlet tube does look like a neat feature. I only see that on their highest end pump with the external recirc lines.

 

I don’t know a whole lot more honestly. They have been around for years as lots of guys here on Tech used to use Schumann pumps and they were always in discussion. I’ve been intrigued as you are, about the energy recovery and recirc features. I’ve never had one in the shop honestly. I’ve seen several flow charts comparing their pumps against Melling and OEM and they outclass everyone by a large amount. Cavitation is a non-issue also with their stuff. It’s just hard to wrap your mind around paying $500ish for a wet sump pump, but it is what it is these days.

 

So I made the change in the software for the oil pressure sensor. It definitely helped. I never used to really see over like 61-62psi on light throttle blips while the engine was warming up. Now it gets into the 70s, where I feel it should be. (at least closer to where it should be)
I went out and made a pull in second gear and its still dropping. Definitely leaning more towards it being a cavitation issue.

I am still going to do the other checks I wanted to do and see what happens. I ordered a gauge and a 10an male/male fitting to bypass the cooler.

 

It's either cavitation or pan issue if it's dropping under load. I'm not saying the cavitation thing isn't a thing, but the 10296 and stock oil pan combo has a rep for not working well together. Considering what you have invested in your combo, I would look at an aftermarket pan that is known to work, Moroso, etc.