How low of oil pressure is concerning at a hot idle on a 5.3? My motor idles hot at 20.

 

Hi,
20psi hot idle is fine. How about the more important high rpm psi?

Thanks
Christian

 

It runs 50-60 psi driving. If 20 is not a bad sign yet then I will relax some.

 

20 psi at hot idle is fine. 50-60 psi is really good at cruise.
My 440ci big cam stroker idles at 975 rpm and hot idle is 24 psi with 50psi cruise and 90 psi at 7000 rpm.

Thank you,
Christian

 

Gen4 5.3 Engines generally run lower oil pressures due to the AFM/DOD. I am actually surprised that you are running anything over 52-55 psi due to the Secondary Oil Pressure Relief in the oil pan that goes off at 55 psi.

Anyways, 18-25 psi hot idle is normal. 35-50 psi during rpm while hot is normal.

I removed the secondary oil pressure relief valve in the oil pan and blocked it off, replaced stock oil pump with Melling 10295 and used lower pressure spring, removed all AFM/DOD Hardware, used Sac City Corvette Billet Barbell and O-Ringed Front Oil Galley Plug, and am running at 38 psi hot idle, 50 psi at 2,200 rpm, and max out around 60 psi. Realistically, anything over 55 psi is not needed.

 

Hi 07NBSChevy,
Thank you for your business and running our products!
I know it's said that 55-60 psi normal and that's all you need, but I just want to say that we heve a LS6 CTS-V that is a medium performance build and our C5 Z06 that is 440 ci Big Cam N/A that doe around 630rwhp. The CTS-V shifts at 6600rpm and the C5 Z shifts at 7000rpm.
We have been running both of these engines with higher oil pressure for our test purposes and when we tear these engines down the rod and main bearing look much newer and less wear than the engines running the 55-60 psi.
Just our opinion, but we prefer the higher pressure even though it cost a little hp. We feel it keeps the hydraulic lifters pumped up better at higher rpm and floats the bearings better so they don't touch the crank. 55psi doesn't even meet the so called 10 psi for every 1000 rpm.
Just our opinion and what we see when we open the engines. That is how we test our Oil System Improvement Products.
Thanks
Christian

 

Thanks for the info guys... I'm glad I can relieve concern on the motor and just focus on the trans that needs replaced/rebuilt.
As far as AFM/DOD I have a Diablo tuner and just recently disabled it with it.

 

I was more referring to a Stock build or mild build where the engine doesn't see over 6,500 rpm.
Do you still recommend 60+ Psi on stock builds, or H/C/I builds under 6,500 rpm?

 

This is just our opinion and I'm sure some will disagree with us but for longevity on a stock or mild build personally I would like to see maybe 65-75psi at 6500 rpm. That just meets that 10 psi per 1000 rpm. Better a little high (75 psi) then a little low (55-60 psi)
And as long as you have a hot idle of around 25 you should be good to go. I hear a lot of people talking about how good their hot idle psi is, but its most important to check hot high rpm psi. I don't hear much talk about that.
Remember GM designers run the lower psi to help with fuel economy and that is just enough oil psi to get by.

Thanks
Christian

 

You need to know your oil temperature relative to your oil pressure before you should be concerned.

 

Strangely I found a datasheet for an LS9 that states...( hot minimums of course, Mobil 5/30 )

6psi @ 1000rpm
18psi @ 2000rpm
24psi @ 4000rpm

Sounds pretty damn low ! even more so when they list a stronger oil filter to handle higher pressures and they say the oil squirters have check valves that dont open til around 43.5psi.

So presumably these engines do make considerable more than their minimums

I know my LS2 with oil squirters rarely makes over 50psi when hot ! and it freaks me out. Tried both the 296 and 355 pumps, if anything the 296 was a little better. Shimming the 355 almost seemed to make it a little worse.

Baffling, unless those squirters dump some serious oil.

 

Apart from "10 psi per 1000 RPM" and "spec" "minimums", the "normal" OP for a 5.3 is around 20 - 25 idle and 45 - 50ish at 2500. "Normal" being, what the bulk of typical driving down the road ones that you might see as you drive down the road, will be observed to be doing, with the correct 5W-30 oil. Which is different from what GM allows dealers to warranty motors for.

 

Ya, that is to low. Its all about better EPA readings. Lower oil pressure = better MPG.

 

Interesting that Ben is aiming for around 55psi to 11,000rpm for his motor...

https://www.enginelabs.com/engine-te...s-race-engine/

 

It is interesting Steve, but that engine is can barely be compared to the noemal LS engine with its modified oiling system,small crank journals etc. And you never know, he might fine that he needs more then 50 psi once he starts putting it through it paces. Its going to be an awesome engine, cant wait to hear what it sounds like at 11k rpm.

 

I agree...but it does dispel the general "myth" of 10psi per 1000rpm.

Many other engines do operate at various ranges of pressure...ultimately as long there is sufficient oil flow to everything, pressure is slightly less important, as it isnt pressure that creates the barrier between metal parts, it's the oil composition itself.

That said...I'd love to know why the **** my oil pressure is *****.

I've tested before my filter, directly after my filter and also in the normal main gallery spot.

And at higher rpm I'm losing around 15-20psi between that first and last point. Although I also have oil squirters which I'm sure drain a lot of oil....although the LS9 data says they do not open til 43.5psi. ( which perhaps coincidentally my OP rarely goes above when measured at the engine )

But pre-filter I do see around 65psi. remote filter, large -12 lines. Tested with 3 different filters with little change. That's the Melling 355 pump with the relief shimmed a little.

 

We battleb with a similar issue, oil pressure was normal until around 4800 rpm 65psi after that pressure started falling off, by 7000rpm PSI drop to 45psi.
It was a nightmare! Went through a couple pumps, shimming them, then went from an-10 to an-12 lines to the remote filters and on and on. Turns out it was warn out cam bearings!
How new are your cam bearings?

Thanks
Christian

 

Block was a brand new LS2 first used by me about 3-4 years ago. Would be less than 8000 miles overall.

Although the only caveat was it was sourced via AES...so **** knows. The block certainly was brand new....and it didnt look like anyone else had installed the cam bearings, so I presume they were just GM installed.

They installed the squirters for me and billet/pinned main caps. I installed all caps/plugs on the brand new block ( it came without any, so in that respect I know it was new )
I also try and smooth the corners of the internal oilways where possible which was easier with no plugs installed.

I also pinned the cam bearings as I've had issue there before so I know they havent walked. I've tried various oils from as low as 5/40 to my current 10/60 and TBH they all made no real difference.

When cold it will make the sort of pressure I'd like though

It runs fine, even my old bearings I removed when it was apart doing other stuff last 2 times were fine although this time I did go to ACL from King just to try a change....so as much as it isnt good...it also doesnt appear to be a real problem at the minute. But it certainly is not how I want it to be.
Nothing bad to say about either brand as I've used both successfully over the years.

I'll maybe take a look at it more seriously over the winter and consider a different oil pan ( currently Autokraft I've been using for last 10 years or so ) and going back to the 296 but heavily shimming it or a much stronger spring

Oddly it did seem to make a little more pressure with the 296 ! and was a little more stable. But a small amount

 

Hmmm, have you check your bearing clearances? If you did what are they? I don't think changing the pump is going fix the problem. Sounds like you have a night mare like we did.

 

Crank measures fine, but no I have not measured actual bearing clearances...largely because if there was anything amiss....there is little could be done about it here.

But with 3 sets of bearings, 2 King and 1 ACL, 2 pumps, 296 and 355 ( and then 355 shimmed slightly )....I really doubt main/rod bearing clearance is an issue...except perhaps cam bearings as mentioned.

But something is not as happy as I'd like it to be. As said...it isnt an actual problem, it all runs fine etc...but via logging I know the oil pressure is not where it should be.

But of more interest...why the huge losses/pressure drop from filter inlet to engine main gallery !

Even the 8psi or so at higher rpm's across the filter seemed huge to me. And that is literally with a sensor either side of the remote filter housing, not even a few inches of hose too.