Oil Pressure Help

[gtgroupe3]

Greetings,

I tried to post on the end on an old thread, but decided to start a new one.

I have been chasing high oil pressure for the last few weeks after verifying with a mechanical gauge.

Engine
2.3 liter (85mm p/c), freshly built on 2-liter case with oil bypass and later pump (claimed by builder). Later cam line restrictors, which should only account for about a 10% bump at the most if I have been informed correctly.

VSS
60 PSI at idle warm, 150 psi for anything above 4K, the pressure relief valve has been verified and changed to the later style 86mm with guide. The safety valve (side) has not been changed out, but will be this weekend (not sure it would effect since it operates above 130 psi).

I intend to replace the newer style spring with the original type (new 70mm same as safety/side relief valve) and use the later piston (no holes). I will also go verify the safety valve and spring and change if required.

Is there anything else I should check, change or verify prior to tearing down the case (and sending a strongly worded email to the engine builder)?

Cheers,

Lee

[Eagledriver]

I'd take the restrictors off and see what you get. I wasn't happy with how high my oil pressures went when I installed them.

-Andy

[JFairman]

I just can't understand why anyone would want to restrict the amount of oil spraying around on the cams, rockers, and valve springs with hopefully some getting by the valve seals to lubricate the valve guides...

Oil flow cools those parts, lubricates them, and rinses off the ultrafine metal particals that are constantly being rubbed/worn off the cam lobes and rocker pads as the engine runs... especially if the oil used is low in zddp.

Below 2000rpm there is not alot of oil being sprayed/splashed around in there to keep a fresh supply of clean cooled oil on all those parts.

The oil shoots straight up out of the 3 cam spray bar holes and bounces/splashes off the inside surface of the upper rocker cover, splashing over the cam and rockers and valvesprings/valvestems.
There is also a direct oil pressure feed hole in each cam tower journal for each cam bearing.

The cam chain tensioners spray oil from 3 seperate tiny holes to lubricate the chains and sprockets.

just my opinion anyway.

[cgarr]

Originally Posted by gtgroupe3

the pressure relief valve has been verified and changed to the later style 86mm with guide. The safety valve (side) has not been changed out, but will be this weekend (not sure it would effect since it operates above 130 psi).

You need both new relief valves! and when you say "verified" did you check them? if not make sure they move freely in the bores too. When they did the bypass what size did they drill?

[gtgroupe3]

Since I did not build this engine, I am left with deconstructing the builder’s choices.

Updating to the Turbo oil line adapters (901.105.361.01) is relatively common, especially on a fresh rebuild. It was standard on all engines 91’ and was common on most race engines. Since this engine does not have a 908/930 or 964 pump, it really will only wear out the cams and rockers faster which is not a good trade off for increased oil pressure.

Since I have enough oil pressure for two cars, I’ll check everything prior to talking to the builder, again.

I changed out both pressure relief valves today and the pressure did not change. 130 psi for anything above 4K and 80 psi at idle.

The builder stated that the bypass was 10mm.

Since backdating cam tower oil line and adapters is relatively inexpensive, that will be done next weekend. Even though I doubt it is the cause of the high pressure.

Do the newer fittings still have have a groove or must I remove the fitting to find out if it is a larger bore?

FYI: I use Brad Penn 20W/50 so zddp should not be an issue.

[Eagledriver]

The restricted fittings have a groove. The old fittings don't. I don't think unrestricted fittings are available new. You can also drill out the restricted fittings but of course that is not reversable if you change your mind.

-Andy