TomasTequila

Hopefully this is the right place since it is LS7 related. I'm new to LS and have some concerns on my setup. I bought an '11 Grand Sport that had a 437 LSX. 200 miles later I put a hole in the block (supposedly ~6K miles on the build). I ordered a 434 (long block, LS7) from one of the more well known companies. It was ordered with a wet sump since it had already been converted when the 437 was installed. As one can imagine, I have been a little a paranoid about the whole ordeal because I've already spent a substantial amount more than originally planned. From everything I have searched, read, etc it seems my oil pressure could be low. The issue is I'm having a hard time finding info on this due to it being a less common setup. So basically I'm not sure exactly what pressures I should be seeing. The break in oil used was 10-40 and they recommended going to 10-30 or 10-40 after the first ~300 miles. I drained the break in oil, which came out quite clean, and filled it with 6 qts of Mobil 1 10-30. I now have 90 miles with the 10-30.
The pressures I'm seeing are as follows:
Cold start - 60-65 psi
Idling at operating temperature - 19 psi
During regular cruising at any rpm - 40 psi
During acceleration - nothing over 50 psi.
No pressure drops whatsoever
The car runs absolutely flawlessly but I'm being told the gauge should be climbing to at least 70 psi or pegging out during hard acceleration. Weather during all of this has been between 50 and 70 degrees. I've also read though that dry sump setups read/operate at higher pressures. If this is accurate, how much lower should a setup like mine read? The oil pump is a Melling 10295. Some have recommended going straight to a 10-40 weight but I'm wondering if that will all of the sudden bump the pressures up to what they 'should' be. I've also spoken to the company from whom the long block was ordered and we agreed I should rig up a mechanical gauge. I will be doing that as soon as I get the chance but until then, can anyone shed some light on this?

Thanks

Nowanker

Hopefully the engine builder has some experience with that oil pump/bearing clearance combo, and can tell you what's normal on his engines... and is quality enough to tell you if yours are off.
Acceleration has nothing to do with the oil pressure, it'll be RPM and oil temp dependent.
IMO, readings are low. Vaguely disturbing, but not alarming so.

C6z06man

General rule of thumb is 10 psi per 1000 RPM. I would say the bearing clearances are set pretty wide giving you the slightly low readings. They’re not terrifying though. I always shoot for 20 psi minimum at idle on my engines. To boost it up some I’d run a 10w40 or 5w40 next oil change.

Apocolipse

With todays synthetics no reason to run 10w

TomasTequila

Ah, I should have stated that a little better. What I meant was - as the RPMs climb the pressure climbs, too. But instead of 10 PSI per 1K it's more like 1 to 2 PSI per 1K. But I've only taken it 7K once and 6K maybe twice. I think I'll bring someone along for another pull to watch the pressure for me. The builders have been excellent as far as communication goes so I'm wondering if maybe I'm not understanding everything they're relaying to me. But they did say the same thing - Pressure does seem to be slightly less than it should but nothing super alarming.

Could you elaborate a little? Are you suggesting a 0 or 5 instead?

I really appreciate the feedback, guys!

Esser

Your numbers are fine, just drive it!

Apocolipse

Correct - with today's technology you should take advantage of the benefit a 0w or 5w offers up.

subfloor@centurytrans

Your oil pressure does seem low across the board and the fact you're seeing 19psi at idle was the biggest red flag for me. Although GM does have their "10 psi per 1000RPM" rule, it's basically a load of crap. My 2013 ZR1 idles at around 700RPM so by that logic I shouldn't be concerned if I was only seeing 7psi. I'm also of the opinion that yeah, you could see a bump in the pressure by running a different oil but all you're really doing is masking the problem.

I ran the exact same oil pump in my wet sump LS7 and for the first several months the lowest it would get after making a pass at the track (it's strictly a race car now) was 38psi and that was with Mobil 1 5W-30. It would also hit at least 70psi at 7600-7700RPM which is where I had my shift points set.

One night last spring when I was racing it dropped down to the high 20s suddenly after making a pass and it was only a few weeks after that it would drop down as low as 18psi. Since I was in the middle of racing season and wasn't in the mood to rebuild it I kept going and eventually stopped when it would start going below 10psi at idle. When I finally tore it down ALL of my bearings (main, rod and cam) were completely shot.

If you're only driving it on the street then you might get several more months out of it, but based on having gone through this similar scenario several times (on both wet and dry sump setups) it's more a question of when, not if it's going to need to be rebuilt. I say "might" because there's a best case/worst case scenario you'll be facing by continuing to drive it. In the best case scenario the oil pressure will continue to drop as the bearings get worse and eventually you'll start to get a rod knock or else the oil pressure will drop so low that the warning light on the DIC will flash. In the worse case scenario the rod bearing seizes on the crank and ends up coming out the side of the block which makes the rebuilt a lot more expensive.