I have a built 427 LS3. At cold idle (right now it's about 40*F outside) oil pressure is 75-80psi. If I rev it to 2k and hold it oil pressure rises to 90psi. I've verified with a mechanical gauge. I've also changed the oil filter twice (napa gold)

When the engine warms up to around 150*F oil pressure is low 60psi. If I rev it to 2k oil pressure is low 70psi. I havn't done any driving so I don't know what happens when moving around.

My engine builder says that's normal (I guess for the pump and bearing clearances). I was initially using 5w30, so i tried 0w30 to see if I could bring down cold oil pressure but it remained as is. I thought about trying 5w20, but I don't think anybody runs that in their LS ... too thin at the hotter temperatures?

My only thought is either it is normal, or I my oil pump relief valve is stuck. Is there anything i can do for piece of mind short of pulling stuff apart? does anybody elses stroker motor run that high an oil pressure?

 

What pump and clearances?

 

Mines like that as well. LME built short block. Melling 295 high pressure pump. 10-30vr1.

 

That's why I went with the stock style pump. Cheaper and gives you free horses!
All you ever need is 55 psi hot. Anything higher wastes tq/hp. Grumpy Jenkins.

 

Sounds fine. Key is letting it warm up prior to loading the engine. not just coolant temp but also oil temp.

Tim

 

Sounds like I don't have to worry, at least for now. However, I'm wondering:

- If the high oil pressure were caused by either a faulty pump or clog somewhere, how would i identify that? For example, would the oil pressure remain high at both cold and warm engine temps?

- How high is too high for an LS3? I'm using a very good oil filter (napa gold) so I'm not worried about it bursting, but I remember reading at some point you ?float? bearings

- if i were to switch from 0/5w30 to 5w20, would that be an okay idea? When I google around I see most think 5w20 is too thin once everything's warmed up. I could see that being the case because in my C5Z06 my oil pressure is like 30psi hot. However, if I'm getting the oil pressure i am now with xW30, I think I would be okay at 5w20 if i lost 10-15psi? Or are there other factors that I'm not considering that would make it a bad idea to use 5w20?

I agree - i have another built LS motor, stock pump, and in the same conditions it's at 55psi. I don't know why people feel they need to get fancy with the oil pump.

 

I spent today reading about oil pressure and oil and am wondering if I should try switching to 5w20? I don't like the fact that I need to wait like 10 minutes to drive to let the engine warm up to get the oil pressure down into the 60s. However, I understand that 5w20 is thinner and won't protect as well at hotter temperatures. If my bearings/pump are setup for higher pressure do I lose anything/risk greater engine wear, by using a thinner oil to try to bring down the pressure a bit?

If my oil pressure were, say, 30psi hot and I used a thinner oil and it dropped to 10psi I could see that as bad, but what if I'm 60psi hot and drop to 45psi (which is where most of my other V8s are, albeit with completely different setups)?

 

May be your oil pressure sending unit. High oil pressure is good

 

It is not all about lowering the pressure but also a alum block main will gain almost .001 at 200 degrees.

The oil has to carry the load

On my car it would make 75-80 cold. I would warm it to 120 before driving it and wait to 180 on oil and water before putting any real load on the motor. never had any issues.

I would not put thinner oil in it. You are playing with fire. These engines need the volume to live long happy lives.

Tim

 

Where are you monitoring the pressure from? Closer to the pump will show higher if it is before the oil filter and pan relief. Agreed with some above. You're not really seeing much more than I am seeing also with a built 427. Ive got a Melling 10296 (ported), no oil relief in the pan, and I am monitoring from two separate locations. I'm seeing those pressures though I am running 10w40 but might be setup slightly looser than you.

 

I've tried it with 2 mechanical gauges; all 3 gauges (mechanical and electric) read the same. I know high oil pressure is good, but isn't there a point where you ??wash?? the bearings and can do damage?

I'm measuring directly above the oil filter (you know how there's usually a block-off plate there .... I've got an adapter and my oil pressure and temp taken from there)


I guess my whole concern is having a whole slew of 400-500cid engines (LS and Ford) all of them have similar oil pressures at hot/cold. Granted that's comparing apples to oranges since they're all built differently, but I just get a hair nervous since i've never had an engine with pressures that high.

But i guess from the sounds of it I'll just have to be more patient with it and let it thoroughly warm up before driving.


But one thing I don't know is, if the problem were a stuck oil pressure relief or a clog in the system somewhere, how would that be any different than what I'm seeing now? i.e., would the oil pressure be REALLY higher, or when it warms up would the psi remain unchanged?

 

Your oil pressure is normal and oil gets thinner as it gets hotter and clearances are closer when cold and open up when warm. My truck has a 4.8 with 211,000 miles on it. Cold start up pressure is 50-60 depending on outside temp and jumps to 70-75 when I pull out of the driveway. Warm pressure is 40-50 at idle and 60-65 while driving. I've read of more than a few LS engines running oil pressure in excess of 100psi in the lights at the strip, They weren't to concerned.

If the bypass is stuck open you'd have very low pressure at idle or most likely no pressure at, Happened to me once. Stuck closed you may or may not see a difference , That would depend on RPM's/clearances/oil type and weight.
It would stay the same at idle if stuck closed and may climb higher than needed in the upper RPM range but again how high would vary from engine to engine.

 

It will be fine. I know of 3 engines with pressures like that. I had 2500 miles on both of mine and the other has 1000 miles on it the last couple months with no issues.

Even with lower pressure if you don't warm it up you take a chance of grabbing a bearing.

Tim

 

Little curious about my pressure. Not as high as above but....

Stock clearance bottom end
Melling 296 HV std pressure spring (shimmed for proper install)
Johnson 2110 SLR's
Wix filter

Measured at port above cam with SPA gauge.

I get about 50-55psi cold idle. 45 psi idle hot.
At 1500-2500RPM I get about 80psi.
WOT I get 50-55psi as if the relief valve is only opening at WOT. Is this normal? I just want to make sure I don't start spitting oil out the rear main or pump up the lifters(if possible).

 

I would suggest contacting your engine builder. It may seem silly to run to them with a simple question, but depending on how tight your bearing clearances are. You don't want to put in the wrong oil and destroy your engine. LS motors aren't like a sbc they don't like heavy oil. The clearances are about half that of a sbc, so they aren't able to get the thicker oil moving through the motor. We run 5w30 in all our LS with the exception of a few very high horsepower motors (1200+).
Anyway, engine builder is your safest person to ask.

 

I build the engine myself and am 100% certain on all of the clearances. They are within stock tolerances if a little on the loose side.

Dial bore and mic are your friends. :-)

 

Oil pressure on my heads/cam/intake/full bolt-ons 02 WS6 is always between 60 and 80psi. I run Joe Gibbs LS30 and a Wix XP filter and always let the car warm up for a good 5 to 10 minutes before driving. I'm running the stock oil pump as well with some modifications.

 

From what I have read a good oil like amsoil 5w-20 will work and protect just fine. So there is a lot to this topic/conversation, and what you'll get are a lot of the older fellas who never used/ran/tested thinner oil. So you get the typical "I Wouldn't" or like above "you're playing with fire" which simply isn't true. Again there is so much here to argue. Thicker oil and higher pressures add a lot of stress on the pump and rob HP but I'm sure the total amount of power robbed is negligible. You can run the thinner oil but that all depends on what your personal tolerances are. I have run the 5w-20 amsoil and lower my hot idle to approx 36 from 44psi. When the oil was very hot (track day @ 110 ambient) it dropped to 24psi. Which IMO is below my personal tolerance of 35psi @ hot idle. My goal was 35psi hot idle 70psi hot WOT. So basically what I'm saying is this, now that its cold out side I don't like idling my car for ever and potentially fuel diluting my oil, I run the 5w-20 amsoil. When its hot out or I'm tracking my car the 10w-30 goes in.

The only real problem to having too much oil pressure would be blowing the filter apart. So unless you see a bulged oil filter then I wouldn't worry about it. We all know what too little oil pressure can do!

If you have doubt about 5w-20 go ahead and look at damn near every economy car coming out now running it. I have seen 200k+ hondas running it just fine. Apparently the manufactures run the thin oil to help improve gas mileage, which apparently was quantified to be around 1%. So ask yourself if that is worth it.

This should help: "SAE 20 at 190°F is about the same kinematic viscosity as an SAE 30 at 220°F, which is about the same viscosity as an SAE 40 at 240°F"

"If an SAE 50 oil at 260°F is as thin as an SAE 20 oil at 190°F, imagine how thin the oil film becomes when you are using an SAE 5W-20 and your engine overheats. When an engine overheats, the oil film becomes dangerously thin and can rupture."

 

That's awesome! Refreshing to not-hear plastiguage. I inquired with our engine builder and he said that 0w30 would be the oil to run in the winter. He also said that high oil pressure can be caused when the upper and lower bearings are switched (due to narrowed- chambered edges being on the wrong side of the crank.) This causes the oil that usually escapes on the chambered edge to hold in the bearing and push through the motor instead.
Not saying you did this, but the normal bearings don't have an upper and lower, so if you are used to those and not looking, it could happen to anyone.

 

I was pretty careful about which way they went in. Chamfer block side smooth bearing cap side. Even took pictures just for posterity's sake. Glad I did! Actually saw a spike of 100psi(warm) yesterday. Getting below freezing now. I'm almost wondering if the pressure relief valve in my Melling pump is getting stuck.

I've got a couple small oil leaks after the build and have to replace the oil pan gasket and front seal. I'll check the bearings then. Should have about 500-600 miles on them by then.

Thanks for the idea. :-)