Need some help - loosing oil pressure at high rpm's

[vector1]

You say a consistent 65 psi before the cooler, lose the cooler and any sharp 90 fittings going into it and see what happens. Keep the cooler installed for the cool effect and put caps on the inlet and outlet. You don't need a cooler unless you are going to race, and if you do race you will probably have to change it out, seems it could be the restriction along with any sharp 90's.

[madmaxx]

Another tech from Mellon called me, WOW what customers service!!!!!! I described the saga and he said before i go through all the effort of removing the pan to just adjust he would send me a stiffer spring to install. He said stock pump with pipe plug almost flush is 60 psig which is the factory setting, and not to screw the plug in more than 3 turns. He felt the most a stock spring would do is 70 psig and the new low 80 psig.

[madmaxx]

I also discussed with blykins what a great guy!! I was trying to buy a carb off him but he wont take my money!! he said the one I have is good and just needs some cleaning and adjustment if that dont work he can spec something else.

Most feel it is not a bearing issue as the oil pressure would be low all the time, for some reason I am stuck on it. Physics would dictate a loose bearing would not drop 7 psig oil pressure over 300 rpm range and hold steady.

1) Path forward is try to find a stubby oil filter
2) try to find a hose to temporary use from remote filter to engine to remove the oil cooler from the equation
3) install stiffer spring in oil pump if needed
4) replace rod bearings and bottom of mains if needed. I have no desire to try to roll the upper bearing halves in and was told on the main the wear occurs on the bottom vs top for rod bearings.


i did order the new urethane mounts from oltoff racing, ebrake shoes not in until late December. Ceramic coater set up for side pipe and headers. once oil pressure mystry resolved the intake, water pump, brackets go off to polishing. Alternator and fuel pump already chromed.

[PLDRIVE]

Max call Precision oil pump he deals will this all the time from cobra guys. He will give u the guidance u need.

(yes i am referring to the spring in the oil pump.) ideally u would want to improve the efficiency of the oil circuit (shorter lines, bigger hose, high flow cooler, etc.) but if that is not a direction u want to go then change the spring so that the pump will bypass at a higher pressure. Its a cheap simple fix. I have not seen the pressure drop increase. good point though. Let us know what he says.


http://stores.precisionoilpumps.com/

[CHANMADD]

Maybe there is a flow issue in the pump.....a burr or elbow.........
that causes cavitation ,...ie air bubble in the pump......causing a drop in pressure..??
I think 1/2 inch at the pickup..is a little big........?

[vector1]

so you are going through 2 gallons or your complete oil inventory every 30 sec. at 2000 rpm, 4000 rpm is every 15 secs. Depending on how your oil returns, I see aeration could be a factor. Keep putting spring in it and next your cam or distributor gear will go, or if you are lucky the pump shaft. What weight oil are you using? I don't see how the pump would level out on psi unless it goes into bypass or there is a restriction on the inlet or they are taking something else into consideration.

just musings....

[madmaxx]

Mellon indicates above 4K rpm flow rate through their pump does not increase (linear) but very little. I agree the gpm per minute is mind boggling. I am using 10W40.

I dont know what i was thinking. I am going to use the existing braided line from the remote filter housting to oil cooler and just turn it around back to the engine. It has to be long enough and it has a 90 on just as the existing one does.

I will check when I get home. If I am sucessfull that will tell me if it is the cooler or not.

by the way a shorter filter to the motorcraf fl1a is motorcarft fl300 which is about an inch shorter.

as far as aeration i can make it do it 5 seconds after starting the engine in the driveway, not enough time for aeraition plus please rember i am getting 65 psig before the cooler rock steady. this is an identicle set up to every spf car.

[GBowman]

I went through a significant learning curve on lubrication on the build that Vintage did for me using Blykins 445CI SBF. Short story is that for every 1 PSI above the engines consumption (approx 45PSI on my engine) you will get an additional 1 deg of oil temp. So if you only consume 45PSI but are running at 70 PSI you are seeing 25 deg of add'l oil temp. Too much oil pressure is not a good thing, according to Roy Johnson/Johnson Performance who designed oil systems for Nascar, most guys running oil coolers wouldn't even need them if everything else was correct (like not running too much oil pressure). I am still messing around with the dry sump we put in to tweek everything but its tough since the weather is not great. I have noticed that the oil temp has gone down since I lowered the pressure though. I'm sure if you are running on the track the cooler is necessary but for a street car I'm not so sure.

[CHANMADD]

Ok......so its good pressure up to the cooler.....?........then it has to be a coooler remember too that every 90 degree turn in the oil line causes a loss in pressure.......I can't remember the numbers......
What cooler type are you using..?.....
Bypass the cooler up front at the cooler....just put a straight tube between the inlet and outlet hoses and see what happens then........

[madmaxx]

I plan on doing that buy you know how it goes, autozone and other parts store sell air freshners and batteries not car parts. the fittings should be here tomorow from summit.

[madmaxx]

Update: I bypassed the oil cooler. I had 66 psig at cold a big jump from from the 58 psig when cold before. In the end once the oil came to temperature it was back to 50 psig and would pull back to 46 psig above 4k rpm, which was better than the 43 psig. The 10AN lines and fitting result in less than 2 psig drop. The oil cooler pressure drop matched the one I had on my last cobra at 7 psig. So in the end the oil cooler is not the issue although I do not recommend them.

1) Oil pump, oil pump pick-up pan, baffles not an issue
2) Oil cooler and associated lines not an issue

I did pull the original dyno sheet and this engine from had 57.8 psig oil pressure at 6krpm. My last one had 70 psig. Who knows if the builders gauges were accurate.

I doubt it is the bearings. The condition of the engine is perfect, compression test checked great, no oil consumpiton, no contaminats found in pan and it is quite as compared to my last one which sounded like a box of marbles. In the end it might just be characteristic for this engine. Time to drive and enjoy!!

[blykins]

I would look very closely at pickup to pan clearance, and would throw an extra quart in there for giggles just to see what happened.

[DAVID GAGNARD]

Originally Posted by madmaxx

Update: I bypassed the oil cooler. I had 66 psig at cold a big jump from from the 58 psig when cold before. In the end once the oil came to temperature it was back to 50 psig and would pull back to 46 psig above 4k rpm, which was better than the 43 psig. The 10AN lines and fitting result in less than 2 psig drop. The oil cooler pressure drop matched the one I had on my last cobra at 7 psig. So in the end the oil cooler is not the issue although I do not recommend them.

1) Oil pump, oil pump pick-up pan, baffles not an issue
2) Oil cooler and associated lines not an issue

I did pull the original dyno sheet and this engine from had 57.8 psig oil pressure at 6krpm. My last one had 70 psig. Who knows if the builders gauges were accurate.

I doubt it is the bearings. The condition of the engine is perfect, compression test checked great, no oil consumpiton, no contaminats found in pan and it is quite as compared to my last one which sounded like a box of marbles. In the end it might just be characteristic for this engine. Time to drive and enjoy!!

depending on the oil cooler type/size and the size of the lines, 5 to 10 psi drop in pressure is normal with an oil cooler..........

David

[madmaxx]

Originally the dip stick was off 1.5 quarts. I corrected the level so it actually has 1.5 quarts more than when it exibited this behavior before the recent oil change. The pick up measured .5" from the bottom of the pan or 3/8 to .5". In addition when testing the oil pressure before the cooler the gauge was rock stead, zero fluctuation, if the pick up screeen was being starved I would think I would have seen a dip when i saw a dip on the block port and i did not one dipped the other did not.

Interesting note it is impossible to get the last quart of oil out of the pan due to the baffling. There are no holes to allow it to drain back to the plug. No big deal just a finding.

Just for grins and I am bored and it is supposed to rain all weekend I could throw some bearings in. With the 4 post lift its pretty simple, just take your time and dot you I's and cross you T's that will have exhausted all avenues. Main and Rod bearing cost $175 total and it would put to bed once and for all if the suspect oil pressure is causing any long term issues since I could inspect all of them. I am positive this did not occur overnight.

[madmaxx]

Oh I forgot another test a very intelligent person told me to do. He said to drive the car at 4K rpm and let off the gas and watch the oil pressure gauge. If it jumps it indicates clearance in the bearings. The problem is how much of jump is a problem? Once you let off the gas all the forces in the engine go opposite since the car is now driving the engine. it forces the crank up, rods down and closes any clearance in the bearings. I did the test and witnessed about a 3-4 psig jump. once again this was with the smith gauge. I wish I would have done with my last cobra to have a base point. Has anybody perform this test if so what did you witness?

[madmaxx]

On a very positive note the car just keeps running better. I guess it hadnt been driven in a while and now that I am playing with the carb is getting flushed. No where near perfect but much better.

The chassis on this one is incredibly solid. Brakes are much much better, body fit and finish wonderfull. I have not found a paint flaw on this one yet and I always find flaws. My last one had some but 99% of the population would never see them. These seats have more cushion also and the carpet is so much easier to vacuum. It does not hold any dirt, my last one had carpet you just could not get the little pieces of fuzz and crap out of unless you pulled it out. One thing that must go is the windsheild mounted mirror, thing vibrates like crazy but the dash mount was in the trunk. I just dont know if I can drill holes in the flawless dash.

[CHANMADD]

Two sided tape.........

[CHANMADD]

One other thing.........did you say if you are using a stock pickup or an aftermarket pickup.......I still think half inch at the pickup is too big and will cause a vortex resulting in a drop .......also I have seen a lot of problems with the aftermarket so called better pickups........trust me the factory spent a lot of money coming up with the correct design.......But again , why not pull the pump and take it apart and give it qn internal "flow" job..........there is a lot that can be done inside the pump.......and 1/2 inch is too far....

[madmaxx]

I am definetly not smart enough or have the experience to design or compare pick up designs, that is why my life is one of repetition. This pickup in this engine along with all other components in the block is identicle to my last one which had great oil pressure. I also have the hard data from the oil cooler testing showing zero pressure drop at 65 psig at 5500 rpm's. In the end at 4k rpm the pump is pumping the same regardless of 40 psig or 60 psig as long as the rv is not lifting. I think that is correct, who knows as my confidence is in question right now on fluid dynamics.

One option is the blue printed oil pump which is a work of art, it would help to compensate if this is in fact an issue. But i dont like to compensate i want to understand why why why why why!!

Originally Posted by CHANMADD

One other thing.........did you say if you are using a stock pickup or an aftermarket pickup.......I still think half inch at the pickup is too big and will cause a vortex resulting in a drop .......also I have seen a lot of problems with the aftermarket so called better pickups........trust me the factory spent a lot of money coming up with the correct design.......But again , why not pull the pump and take it apart and give it qn internal "flow" job..........there is a lot that can be done inside the pump.......and 1/2 inch is too far....

[madmaxx]

I think I figured it out!!!!!!!

1) The oil pump RV is set at 65 psig. Bottom line with the plumbing and current oil filter motrocraft fl1A (not fl1HP) the pump RV lifts as it is supposed to and the oil is going into the pan instead of the engine resulting at the 50 psig above 4K rpm.

The last engine was "identicle" to this one. 3 years ago i did some testing of different oil filters to determine the pressure drop across them when cold. I wanted to see if the oil filter internal rv in the filters would lift. I had the same gauge set up as I do now but that oil pump releived at 79psig!!!!!!! vs 65 psig on this engine. I found my notes last night. There 15 psig right there.

When i bypassed the oil cooler the other night the oil pressure dropped from 50 psig to 46psig vs 43 psig with the oil cooler.

I am 75% sure if I jack the rv screw on the oil pump i will get my 50 plus oil pressure above 5K rpm since it wont be releiving. Mellon gave me some bad info, he indicated max pressure was 70 psig, bullsheet, i got 79 psig on the last one same model etc.

Now why the fluctuation in pressure the step change between 4k and 4.4K. I credit this preminsion to my new found expert from SCOF. I can't get on the forum but this is probably better. The guy is an engineering wonder with engines. He substantiates his theory with physics. He educated my on oil filters. He explained the better oil filters like the FL-1Hp is alot more than the burst strenght of the can or o-ring it is the filter media does not collapse under higher pressures!!!!!!!!!! That never dawned on me and they sure dont advertise it that way. I remeber cutting open the Royal Purple filters, synthetic filter media encased with a ss expanded metal to maintain medai spacing!!!!! The FL1A (i never used before now but went cheap this time) has paper media with no support. I theorize at 4K plus rpm where the oil pump is hitting maximium flow (high volume) and pressure the media is deforming causing additional pressure drop across the filter!!!!! If my rv was set at 79 psig it would still happen but i would not notice as teh pump would drive the oil through it until the media collapsed or a hole was ripped in it.

Path forward. Obtain new spring from mellon and install in oil pump. change filter to Royal Purple ( i like better than fl-1hp) but fl-1hp is a good filter.

now its going to rain for 4 days so who knows when i can try it!!

PS

I cannot beleive the builder has returned all my emails (I am blown away) and it was him that told me make sure you use a FL1HP and it stuck with me and helped me to come to the aforementioned conclusion!!!


Now to be an asshole. Another install fukup. I guarantee if what i theorize above is true this has been like this since day one. Car was delivered with 100 miles from the reciept dont tell me they didnt see the low oil pressure on the gauge. Probably blamed on engine builder. builder doesnt know if you are going to jam a oil cooler and use pos filters.

Installer did wrong motor mounts - same as my last one
Installer used wrong thermostat. - same as my last one

i feel better now