oxyboxer turbo engine oil pressure too high

[lakis1982]

Hello,

after dealing with several issues on my engine rebuilt I have finally managed to start successfully my freshly built engine..

It is an Oxyboxer 2.1L EFI and turbocharged. In the following picture you can see the oil sytem layout of my engine

oil_system_layout.png

I am using a 30mm oil pump and Motul Sport Ester 5W50 oil.. I don't have any gasket in the 30mm oil pump so its end play is as tight as possible...

When i fire the engine it idles at around 60PSI.. As long as the engine starts getting hot, the idle finally settles at around 25PSI which i find them perfect..
However, with the engine already hot, when i start cruising or revving the engine I get quite high oil pressures.. For example at 3000rpm i get around 80PSI.. at 3800rpm it reaches around 90PSI...
In the following videos you can see how the oil pressure varies with respect to the rpm. (the rpm gauge is fluctuating due to electrical noise but you can understand what rpm it mainly shows)

https://youtu.be/22Y1RzBXpMQ
https://youtu.be/Jv-7uDUqYUM
https://youtu.be/YqRUP0b-dMk


So far I have only tried to replace the oil pressure relief piston and spring but it didn' help..I installed a spring that is just a little bit short and weaker but problem remains.

Also, my initial oil pump was a 24mm pump (with a gasket but i don't know how thick it was) before installing the 30mm one.. In that case my oil pressure at idle (with engine hot) was around 6-7PSI !! At high rpm it seemed normal around 50PSI.. But i was having issues with bad lubrication in the rockers bearings and between rockers and valve caps , so in order to be sure i installed a 30mm pump to provide more oil supply to the whole oil system.. Indeed it looks like the rockers lubrication is now normal and as it should.. Besides, with a turbocharger , an oil filter remote adapter and an oil radiator at front end of the car, the pressure drop and resistance is increased and i have seen other people with a similar setup using 30mm pumps..

So, can anyone start commenting on this (anyone that probable had similar issues) and suggest possible causes of the high pressure as well as possible solutions ??

Thanks a lot in advance.

[66brm]

Try changing the oil down to a 5w/30 or 10w /30

[lakis1982]

so, i have made a few changes..
I have taken out the oil pump and installed a gasket in the cover of the pump wih a thickness of 0.18mm
I installed a FRAM HP1 oil filter
And I also changed the oil from 5W50 to 5W30...


before the changes | after the changes
Pressure at idle (cold): 60PSI | 40PSI
Pressure at idle (90C): 25PSI | 15PSI
Pressure at 3000rpm (90C): 80PSI | 50PSI
Pressure at 3800rpm (90C): 90PSI | 65PSI
Pressure at 4500rpm (90C): over 100PSI(I dont know exactly ,it reached gauge limit) | 80PSI


Although much better , I guess its still quite high...

any suggestions please ?

[Ian Godfrey]

so, I am not familiar with the WBX internal oil pressure relief springs, but some where there will be info on the length and pressure they should be to give you appropriate factory case pressure. There is also a type 1 pressure adjust that might be able to be adapted. https://www.csp-shop.com/en/engine/pres ... 1595061885
On a Type one the oil bleed hole under the pressure relief piston needs to be made bigger as it won't flow enough to relieve the pressure with a decent pump. Thin oil is good 5/30 is good unless you have big bearing clearances. I would aim for 10 psi per 1000 rpm when the engine is good and hot. First I'd try to check the gauge, I don't recognise the brand but are they reliable?
Then I'd be looking into the oil relief system in the case, or consider an external oil relief like this http://www.petersonfluidsys.com/pump_remotereg.html or something similar.
good luck
Ian