is this too much oil psi?
 

My new motor makes 80 psi of ol pressure on a mechanical gauge at the filter. Am I the only one who thinks this is too much? the pump is a amoroso blue printed pump and the tech guy at moroso told me to use the colored spring and turn the hex head bolt 2 turns in from the factory preset. he said this should have given me 50 psi at idle. any suggestions before I pull the motor back out? the motor was primed with a drill and we had 50 psi. when we put it back in the boat it has 100 psi on the gaffrig gauge but 80 on the autometer at the oil filter. the motor is brand new so????????

That is fine. My engines will run almost 100 psi when cold and I have always done it this way. You can go to a little thinner oil if you are concerned, but I don't think it is a problem.
Eddie

well, yes and no. cold oil pressure is determined as a function of what the hot oil pressure will be. if the motor has extremely small clearences then it will tend to carry more oil pressure hot
than a motor with large clearences so the cold pressures can be lower to start... but having said that there are configurations that need hiogher oil pressures and without knowing what you are shooting for hot and what the clearences and configuration look like . a typical big unblown big block with a compression ratio of less than 10 :1 will want to see a solid 50 to 55 lbs at 4500 rpm with 220 degree oil.

less would make me nervous and more just mean higher oil temps, less hp and a worn out distruter drive gear .

there is also the danger of popping the bypass open if the pressure is too high which isn't any good either...

and i would really want to know why the two gages are different by 20 %

The only thing I can come up with on the gauges being different is that the gaffrig has an electric sender and the autometer is a mechanical gauge. Eddie would you not be concerned with the motor making too much oil pressure at rpm's? I am running 10w30 oil so I dont think I would go with a lighter weight oil. I am also trying to take into consideration that this is a brand new motor and that the oil pressure tends to be higher when the bearings are new. I dont want to adjust the pump down and regret it later but I also dont want to have any issues with too much psi. the mechanical gauge will jump up to 100psi with as little as a 500 rmp increase. keep in mind that I am not seeing any temp on the oil temp gauge as I only ran it 20 minutes on the hose but the oil was noticably thinner when I changed it after break in.

Well, I am a little concerned that you have that much pressure with 10W30 oil. As I said, my engines make almost 100 psi at idle when cold, but that is with a 20W50. Have you run it at rpm yet, or just idle?

I have only reved the engine very lightly to about 1800 or so rpm's. I did see the mechanical gauge jump up to 100 psi when doing this. the pump is a moroso blueprinted pump and I used the colored spring. their tech guy said to turn the adjustment on the spring 2 full turns so thats what we did. now this morning a different tech guy said only 1 turn. do any of thse people actually know what they are talking about. I might just change the pump to a melling hv pump and be done with it lol.

I have mellings pumps in my 540's and see 80psi cold, about 68-70 hot. Standard 500EFI placement but I have Pre-lubers coming off the filter bracket and the mechanical gauges there read the same as my electric dash gauges.

I had asked the same question a few days ago and was told from a few guys I trust on here that it is fine. I run 468's and have about 100psi at 5500 rpm's hot. Their at 50+ at idle. Had it out this weekend and the only problem that I can see is with that high a pressure it must be spraying the tops of the valve covers and I had some oil blow out of the breathers. New project, taller breathers.

well... it sounds to me like you have the relief valve preloaded closed with that spring at an unreasonably high number. but until you get temp in it, you can't know for certain...

without some compelling reason to run 100 psi of oil pressure, like monster clearences or astronomical compression ratios, then that number is too much. and don't forget... bearings don't "break in" if you put a pencil mark on a bearing and ran it for 100 hours with the correct lube at the correct pressure and temp and it was clearenced right to start with, then the pencil mark is still there when you take it apart.

More is not always better!
 

This is why for normal moderate unblown engines I like to use the Melling Select oil pump series and at Raylar we set them to deliver about 60-65 psi oil pressure hot at 5000 rpms with 15-40 or 20-50w oils and good filters. They will normally idle at about 40-50 psi hot. This is with 2-3 thousandts clearance on mains and rods and normal side clearances on the rods. I would shy away from higher pressures than these numbers as it tends to be create other problems like increased oil consumption from throw off and it can actually force oil across bearings so hard that an effective lubricating surface is actually disrupted and weakened. This is an example of where more is not better! This is why high volume pumps with less pressure are actually better at removing heat and lubricating through good even film layers, which is really what good lubrication does and what oils are really for!

Best Regards,
Ray @ Raylar

[FYI]Just To help you out a little bit All Mercruiser engine oil specks that I have ever remembered reading in a service manual is from 4 [psi] up to [80] psi On all their engines as standered specks. But a normal engine will read as low as [20] psi hot at idle up to 70 max [psi] when reved. Also I remember all the [HP] engines always seem to run right around 45 to 50 psi hot at idle and up to 75 to almost 80 [psi] hot when reved up, And also up to the low 80s cold when reved up. A 100 psi reading dose seem a little over the top [IMHO] and the part Raylr said about the oil being thrown around is varry ture and it will be a problem at some point. And last but not least the last thing you want to do after a nice day of boating is to clean up oil every time, If and when it finds a way to get out of the engine and into the bilge and you know it will. Well I hope all this info helps you out some, Because after all it's up to you if you truly want to lower it down some or not. Good luck with it.

I' ll tell this I just pulled a distributor today on a boat 2004 38 top gun with 572N/A 725 HP, top engine builder from FL, I warned the owner of running high oil press 0-80 gauge pegged at idle found the timing retarding it's self, dist. gear shot! worn out, cam gear the same. The reason I know this is from going into the other engine last year from the flame arrestor coming apart and going through the engine. Tore it down and repaired it upon testing the oil pump found it to about break my wrist testing the pressure 100 psi plus, checked the by-pass spring and found a degreeing bushing in it alittle over .200" thick, pump housing showed wear, called the builder about it he agreed he did that to all his engines installed new pump with about 70 psi on test. warned the customer of the problem with high oil press, so now it's pull the other engine and make repairs. Let you know the rest after it's apart. the rule of 10 psi oil pressure for every 1000 rpms really doesn't apply in todays endurance engines.