High oil pressures when cold... Options

[jcwells]

Hello, all...

I'm new to the 914 scene, but have been having a blast reading up on all of the information that is available here at 914world!

I just got my 914 about six weeks ago (details in my signature), and have been able to get answers to a bunch of my questions by pounding on the search button. But here is one that I haven't been able to figure out on my own.

The car is currently running on Brad Penn 20W50 oil, which is highly recommended by Jake Raby and others. Here on the Front Range in Colorado, as the weather has started getting a lot cooler, I've noticed that my oil pressures are quite a bit higher than in warmer conditions. Specifically, with ambient temperatures between 30 and 40 deg, I'm getting better than 120 psi oil pressure at 2500-3000 rpm after running for several minutes. As the oil warms (15 minute commute), it drops to a bit below 100 psi at the same revs. I've got a very efficient front mounted oil cooler, and my oil temperatures rarely get to much more than 200 deg in warm weather, and was maybe 120 deg this morning at the end of my commute. In hot weather, my pressure is just a bit more than 20 psi at idle after extended running, but better than 40 psi after my commute this morning.

Couple of questions:

1. Are my hot weather oil pressures somewhat normal?
2. Are my cooler weather oil pressures too high?
3. Should I switch to the Brad Penn 10W40 now that the weather is cooler?

Go easy on me, I'm a noob... (IMG:style_emoticons/default/smile.gif)

[SLITS]

Recommened oil temp is about 210 degrees for maximum oil effeciency.

Not sure about the type 4 relief valves, but 80 psig is what I would expect on cold startup. Maybe the relief valves are a bit sticky. Maybe you have high pressure springs in the relief valves. Maybe you just have a really nice engine, with excellent clearances.

Since you are running a cooler and it sounds like no thermostat, the oil is going to stay cool and thicker than normal, which also lends to higher indicated oil pressure. In winter temperatures, various methods are used to block off airflow to coolers (both oil and water). If you look at diesel trucks you will see a cover over the radiator that can be adjusted for airflow to maintain optimum temperatures for extended engine life.

In years past, excessive oil pressure was thought to possibly pit the bearing surfaces (rods, mains). We ran almost 200 psi in the race car on cold startup, but it would drop to 60 psi running hot - never observed pitting. A GM study indicated that the pressure between the crankpin and bearing was somewhere around 5000 psi, so I doubt that 120 psi is going to do anything.

Pumping thick oil takes horsepower and does not lend itself to proper lubricating properites according to the engineers.

This is at least one answer .................. next!

[Elliot Cannon]

Sounds OK if it were a 3.2 six. Sounds a little high for a type IV.

[Ian Stott]

I would experiment with blocking off air flow to the oil cooler when outside temps are below 50 degrees where you live, oil is designed to flow and give best lubrication within certain temperature ranges, check the Brad Penn chart for its range, I think you will find you are running a bit cool. Does your oil cooler have the ability to be fitted with thermostatically controlled valves? I remember when we had to change all the vehicles over to 10 weight for the winter as the 30 was too thick to lub properly and made for hard starting which was hard on the batteries.

Ian Stott
Moncton
Canada

[tradisrad]

I see about 80 psi on cold California startups (50 deg.). When warm/hot I see 45-50 psi @ 3.5k rpm. My friend car is similar to mine...

[Jake Raby]

The stock pressure relief limits oil pressure to 85 PSI at max... If you are seeing more than that then either the pressure relief can't bypass enough oil (due to viscosity at that temp) or the pressure relief is not functioning correctly.

Your cold numbers would lead me to believe that the oil has too much viscosity but your warm and hot numbers are PERFECT.

Where is the oil pressure being measured?? Has anyone updated the oil pressure reliefs with the aftermarket "High pressure" set up??
I hate those damn things.

You will have to give up something here, if you swap to a lighter oil to help with the cold issues then you'll have lower pressures at operating temp.

[jcwells]

...Does your oil cooler have the ability to be fitted with thermostatically controlled valves?

Ian, I'm not sure. The car is new to me, but the it appears that the build was very meticulous and well executed. If you could tell me what to look for, I can check. Perhaps tonite I can get some pictures of the oil cooler installation.

[ME733]

(IMG:style_emoticons/default/popcorn[1].gif) Heres a good rule of thumb, ...10 PSI for every 1000 rpm,s..Years ago some of the riceburner race cars had so much oil pressure that the bearing shells were being pressed into the crank,lifted off the bearing saddles. Premature bearing failure was the result. Excessive oil pressure sucks out horsepower, puts a heck of a strain on the oil-pump-drive tang, causes leaks at the oil filter, and other seal areas in the engine. It was mentioned that you might have aftermarket ..oil pressure relief springs. you probably do. just get and install some O.E.M. oil pressure relief springs.(and compair them to the installed ones.)If you can maintain the oil temperature at or slightly above 212 degrees the moisture in the oil and crankcase will be seperated and vaporized and vented .(a very good thing).You will be removing the primary cause of oxidation,goop and crud buildup in the engine. All the previous comments are valid and excellent. Oil that is too cold will not flow properly, lube the engine or absorb acids and debris and clean it up.I.M.E. (IMG:style_emoticons/default/popcorn[1].gif)

[jcwells]

Where is the oil pressure being measured?? Has anyone updated the oil pressure reliefs with the aftermarket "High pressure" set up??
I hate those damn things.

Jake, I'm not sure where the oil pressure sensor is located. Can you tell me where it is on a stock motor? My guess is that it will be in that location.

I also do not know about the pressure relief valve. Is that valve accessible from the outside of the motor? If so, are there any telltales that I can look for?

The motor was built about a year ago by DTM Engineering there in the Atlanta area, using one of your cam/valvetrain kits, and with your race balancing. It runs beautifully! I guess that I'm trying to learn if there is any potential for damage when I see those high oil pressures, and if there are any downsides to switching to the 10W40 Brad Penn oil for fall/winter running. I am hoping to use the car as a "fair-weather" daily driver, since it is *so* much fun to drive!

(IMG:http://i277.photobucket.com/albums/kk70/jcwellsq8/Porsche%20914/914motor_DTM.jpg)

[jcwells]

(IMG:style_emoticons/default/popcorn[1].gif) Heres a good rule of thumb, ...10 PSI for every 1000 rpm,s..
...If you can maintain the oil temperature at or slightly above 212 degrees the moisture in the oil and crankcase will be seperated and vaporized and vented .(a very good thing).You will be removing the primary cause of oxidation,goop and crud buildup in the engine. All the previous comments are valid and excellent. Oil that is too cold will not flow properly, lube the engine or absorb acids and debris and clean it up.I.M.E. (IMG:style_emoticons/default/popcorn[1].gif)

ME733, thanks for the rule of thumb! As an engineer, I love those things.

What you say makes sense. Sounds like whatever we decide to do with the oil, I need to "cripple up" the oil cooling a little bit. I'll have a much closer look at that system tonite, and see if there is a clean way to obstruct the airflow.

[Ian Stott]

Just to do a quick test wrap the oil cooler with some thick paper and just use twist ties so you can take it off real easy. Monitor your oil temps/pressure while you go for a drive and see what your results are, DON'T LET IT GET TOO HOT. I've seen thermostactically controlled oil coolers for sale, google peformance products and see if they have them. Bottom line, whatever Jake says to do you should do. Switching to Brad Penn 10 W 40 won't hurt but if Jake overules that then listen to him, I do.

Ian Stott
Moncton
Canada

[jhadler]

Looking at the picture you supplied...

The oil pressure sender is mounted up on the fan shroud, passenger side. I pointed it out.

But I'm curious about the apparent fuel injectors. This looks interesting, and decidedly non-stock. I know that you're not totally familiar with the build, but if anyone else can chime in, I'd be interested. It looks rather unique...



-Josh2

[Cupomeat]

Yes, I am interested in your engine as well.

129 HP seems GREAT for a 2056, especially with D-Jet on it.

[Jake Raby]

Thats not D jet, its SDS.. It just looks liek it's stock becaus eit uses my EFI retrofit kit.

I tested that engine personally and remember it vividly including the 26 hour stint that I stayed awake because of it. The power figures were from my Dyno, they were backed up at SE dyno day earlier this year to near 105 RWHP if I remember correctly.

Just run it as it is, be glad you have excellent pressures..

[Cupomeat]

Damn, I want that!

[Jake Raby]

Open wallet and it will come :-)

[Ferg]

Saw, heard that beast at my coffee and cars show in Sept, its (IMG:style_emoticons/default/w00t.gif) and (IMG:style_emoticons/default/pray.gif) real slick motor.

Ferg

[tat2dphreak]

lol, Jake-tested, Raby-Approved (IMG:style_emoticons/default/biggrin.gif)

[Jake Raby]

Only tested.
I ONLY approve what was built under this roof.

[jcwells]

Thats not D jet, its SDS.. It just looks liek it's stock becaus eit uses my EFI retrofit kit.

I tested that engine personally and remember it vividly including the 26 hour stint that I stayed awake because of it. The power figures were from my Dyno, they were backed up at SE dyno day earlier this year to near 105 RWHP if I remember correctly.

Just run it as it is, be glad you have excellent pressures..

Thanks for the reassurance, Jake. I wasn't 100% certain on the details of the build, but the dyno plots that I have look just like the ones that you present on your site. I can also confirm your 105 RWHP recollection from chassis dyno results.

As I learn more about my particular car, I'm more and more tickled with my good fortune. Rest assured, I'll do all I can to enjoy and preserve this little gem.

Looking at the picture you supplied...

The oil pressure sender is mounted up on the fan shroud, passenger side. I pointed it out.

But I'm curious about the apparent fuel injectors. This looks interesting, and decidedly non-stock. I know that you're not totally familiar with the build, but if anyone else can chime in, I'd be interested. It looks rather unique...



-Josh2

Josh, thanks for detailing my picture. Indeed, the injectors are non-stock. They are off the shelf Bosch injectors, plumbed with a custom-built fuel rail, and driven by an SDS EM-4D EFI system. I love the simple programmability, and the flexibility offered by this system. The system was programmed in Atlanta, and so I still have a bit of fine tuning for running here at altitude, but it's working really well just as it is.

I can take no credit for the implementation, just the good fortune of finding a nicely set up 914 at what I thought was a fair price. With all of the great support from fellow 914world'ers, I'm hoping to enjoy this ride for many years! (IMG:style_emoticons/default/driving.gif)