My 914-6 GT Tribute, low oil pressure when warned up. Options

[mlindner]

Every thing seems fine, start up, warm up all good oil pressure reading. But after a while at idle the oil pressure gauge is almost nothing. Running 20-50 valvaline for brake in. Should I go to straight 60 wt race oil. This car is mostly a track car, or when driven on the street it likes the 5 to 7,000 rpm range. Not a cold weather 914. Thanks, Mark

[infraredcalvin]

When warm does it build with rpm, if so how much? 60wt seems a bit excessive, should be fine with 20/50. Has motor been fully broken in?

[mlindner]

Thanks Pat, a little more information. The engine was a long block bought about ten years ago down in Florida by a guy taking 911 race cars back to street. All he new was it is a 2.2 E, with S pistons and cams. The engine now has PMOs, Mod-Solex cams, S pistons, good leak-down etc. No idea of main bearings/oil pump. I did install the reduced cam oil fittings. On start up ( garage at 68 deg) the oil pressure is at 30 psi or little higher. Backup, gauge is a 911 type combo gauge with 0-20-60-100-140 PSI. Warmed up 2 to 3,000 rpm 60 to 100 psi, at 6,00 rpm runs between 100 and 140 (10bar). All that looks and feels right. Oil temp is also normal, 180 to 200 deg F. But after with the thinner oil at Idle is when the oil pressure is almost nothing. The 911 forums, this comes up a lot. Oil light comes on at idle. Best, Mark

[wndsrfr]

What rpm at idle....keep mine about 1000 ...

[Justinp71]

Hmm, my 3.2 is a lot different than yours. Warmed up it is 1 bar idle, maxs out at 4bar around 4k. Running 20w50 oil. The oil should start to relieve at 67psi down by the pump as I recall. So 100psi warmed up even at 6k sounds like a lot. Is your pressure sender matched to your gauge?

I have heard the early engines have very little hot oil pressure at idle.

[sixnotfour]

Must be Racing Clearances ..Haha, general rule is 1 bar per 1k rpm,,we a carrera the othe day same way as yours,, But it has a ton of miles on it.Cut filter open and monitor,,at this point 20/50. Oil analysis.
Unknowns are always a gamble...Ask Eric Shea about his 2.5.. almost a total failure, before rebuild..really nasty rod bearings..
3 bar 4 bar oil pump ?? all makes a diff. ..shiny inst always best..

[stownsen914]

I believe 10 psi per 1000 RPM is the rule of thumb.

I think it's not uncommon for early motors to have essentially 0 oil pressure at idle. I recall my parents' 1970 911 did that when the oil was hot. Perhaps more likely if it has an early oil pump. Not saying it's ideal, mind you.

[stownsen914]

Re: the cam oil restrictors, I assume you did your research, but personally I wouldn't put them on a car used primarily on the track. I believe they're intended to increase oil pressure at idle. What I don't like about them for a track engine, is, well, they restrict oil flow to the top end. I get how it's good to increase idle oil pressure, but it seems like the wrong compromise for an engine that spends most of its time in the upper RPM ranges.

[IronHillRestorations]

I'm with sixnotfour, you should have 1 bar per 1000 rpm (1 bar is 14.5 psi) if you have less than that your on borrowed time, and maybe borrowed money too

[stownsen914]

This 1 bar per 1000 RPM guidance - is that for SC and later? And do you mean you want 6 bar at 6000 RPM? I'd think not ...

[mlindner]

Hi Perry, on my gauge the first number after 0 is 20psi so maybe I'm at 10psi and the gauge is not that accurate that low. I'l have to get a gauge to install on the engine to see what is really happening. But just need to ask what oil you guys run for hard street use and track. Mark

[Justinp71]

This 1 bar per 1000 RPM guidance - is that for SC and later? And do you mean you want 6 bar at 6000 RPM? I'd think not ...

That's one question I am always curious about, I believe the system is designed to relieve around 70psi at the oil pump and the pressure is measured after the oil galley before the oil goes into the cams. Mine reliefs at 60psi (4bar) when warmed up and doesn't go any higher which makes sense to me. When cold the oil is so thick and the oil cooler is bypassed so you can easily make 5-8 bar pressure, but I believe its over 100psi is bad for the oil cooler. My uncle blew his once revving too high with cold oil.

As for oil the most popular is 20w50 VR1, Mobil 1 15w50 and Penn Grade (aka brad penn). There are a couple others too I am not familiar with. Just don't use GTX anymore they stopped adding Zinc.


Here is an insanely long thread about oil (IMG:style_emoticons/default/smile.gif)-
http://forums.pelicanparts.com/porsche-911...m-oils-107.html

Another one about the relief system-
http://forums.pelicanparts.com/911-engine-...lve-thread.html

[infraredcalvin]

The old car loved Brad penn/penngrade, I switched to vr1 it ran hotter (about 10-20 deg) not much, but that’s also when I blew my motor…. I don’t think the two were related, I was on borrowed time with a bent valve…

[930cabman]

I believe 10 psi per 1000 RPM is the rule of thumb.

I think it's not uncommon for early motors to have essentially 0 oil pressure at idle. I recall my parents' 1970 911 did that when the oil was hot. Perhaps more likely if it has an early oil pump. Not saying it's ideal, mind you.

Another older thread, but the information does not change. Oil temp in the 180F range, green light is on solid at idle (1,000 rpms) and reading less than 10psi on a hard piped gauge. Fresh 2.7 with new bearings, etc, etc.

45psi at 3500 rpms when engine is warm

[technicalninja]

Have you put a mechanical gauge on it yet?

I would.

I don't trust electronic gauges...

Especially at the extreme ends of their ranges.

Ninja Golden rule: ALWAYS test your test equipment!

I've been down "The Primrose Path" far too often by trusting equipment that I shouldn't have!