'95 993 3.6L - high oil pressure

SirAndy · 06-14-2019, 10:12 AM

I apologize if this is the wrong forum for this question since i did not rebuild this engine, i bought it 2nd hand. I figured if anyone knows it's the guys (and gals) that hang out in the engine rebuild forum.

This is going to be a somewhat lengthy windup to the basic question:
What is the maximum oil pressure i should be seeing on this engine?

Some background info:
- '95 993 3.6L, race prepped by Jerry Woods Enterprises
- Extra light flywheel, headers with O2 sensor and PMS "Laguna" mufflers, modified air intake and a Steve Wong chip to make it all run right

I'm the 2nd owner and have no details on what JW did to the engine besides what's listed above. It had zero miles on it (since it got the JW treatment) when i bought it, the previous owner never ran it.

I'm running a oil pressure gauge that goes from 0 to 140 psi with the correctly matched sending unit.
The engine runs just fine and pulls hard but the oil pressure seems way too high as soon as i get above 2500 rpm or thereabouts.

I've been reading 993 manuals and posts all over the tinterwebs and all i can say for certain is that the stock 993 gauge seems to max out at 5 bar but according to all the info i found you'll get there already around 3k rpm and then the stock gauge just sits at max.
So that wasn't very helpful in getting any idea of what the max pressure should be.

I'll idle around 40 psi (sometimes drops to 25-30 when it's really hot) and hit 100 psi as soon as i get above 3k rpm and steadily climbs as rpms go up. I can easily hit 110 and more ...

100 psi is about 6.9 bar
110 psi is about 7.6 bar

One thing that may or may not be related, i run a large front mounted oil cooler with a thermostat close to the engine and i rarely see temps higher than 180 which is right around the opening temp for the thermostat. I have to run the car hard for long periods of time in hot weather to get to 200/210.

Question is, am i about to blow up my engine running these kinds of pressures? Is there something fundamentally wrong? Am i stressing over nothing?

Flat6pac · 06-14-2019, 10:42 AM

Check and make sure you’re ramming a 0-10 bar sender
A 0-5 bar will give you way off information.
Bruce

SirAndy · 06-14-2019, 10:51 AM

Quote:

Originally Posted by Flat6pac

Check and make sure you’re ramming a 0-10 bar sender
A 0-5 bar will give you way off information.
Bruce

I'll double check the sending unit, i distinctly remember matching the gauge and sender but it can't hurt to make sure.

SirAndy · 12:20 PM

Quote:

Originally Posted by SirAndy

I'll double check the sending unit, i distinctly remember matching the gauge and sender but it can't hurt to make sure.

Checked my records and this is what i bought:
https://patrickmotorsports.com/products/eng-36-oil-ps2-pms

It's a 0-10 bar dual sender with an adapter to fit in place of the stock 0-5 bar sender.

Went to look at the car (at work right now so i can't really take it apart) and snapped a quick pic, you can clearly see the adapter between the case and the sender.

So i'm going to assume i have the correct 0-10 bar sending unit ...

SirAndy · 06-14-2019, 12:14 PM

dwelle · 06-14-2019, 09:39 PM

andy, we gotta talk.

i have a 3.6 in my 914 with a cooler up front and i'm struggling to keep it cool this time of year. i'd like to know what your cooling system is as i've found limits of mine and it's not cool enough for my tastes.

and, sorry, i'm no help on the pressure or sender/gauge compatibility...

SirAndy · 06-15-2019, 08:15 AM

Quote:

Originally Posted by dwelle

andy, we gotta talk.
i have a 3.6 in my 914 with a cooler up front and i'm struggling to keep it cool this time of year. i'd like to know what your cooling system is as i've found limits of mine and it's not cool enough for my tastes.
and, sorry, i'm no help on the pressure or sender/gauge compatibility...

PM sent ...

targa72e · 06-15-2019, 11:54 AM

General troubleshooting at this point would be to hook up a known good mechanical gauge. If that disagrees with your gauges then either the sender of gauge are bad or miss matched. If the pressure is actually high then more troubleshooting. The max pressure is controlled by the oil bypass valves. These are accessible from the outside of the engine by removing the plugs that hold them. You can remove them and verify they have the correct springs and pistons. Its possible if the engine was built to be a race engine that the bypass was shimmed to make more pressure and it is designed to be that way.

thanks,

john

RedCoupe · 06-15-2019, 01:43 PM

My experience with my 3.6 and my 3.2 is that the 3.6 develops significantly more oil pressure withe same oil and at the rpm as the 3.2. Even with nearly 150k on it, the 964 would peg the factory gauge before the oil was up to temperature, and was still relatively high even when the oil was completely warm. Been consistent over 15 years and 60k miles.

bpu699 · 06-15-2019, 02:07 PM

If your worried about oil pressure, why not put in a weaker blow off valve spring?

Still figuring out how people get 110psi at the sender... I wonder if new motors did that...

Trackrash · Trackrash's Garage

Quote:

Originally Posted by bpu699

If your worried about oil pressure, why not put in a weaker blow off valve spring?

Still figuring out how people get 110psi at the sender... I wonder if new motors did that...

Well, my SC motor can get to 100 easily when cold. When hot it peaks around 85 psi.

911 tweaks · 06-16-2019, 04:04 AM

Why not drive car to Jerry Woods shop and get the correct answer and probably more information on how the engine was built ie it’s total build specs..
I would b chomping at the bit if I had a JW motor in my car and had a belief it was a race built motor and did not know it’s specs...

SirAndy · 06-16-2019, 08:10 AM

Quote:

Originally Posted by 911 tweaks

Why not drive car to Jerry Woods shop and get the correct answer and probably more information on how the engine was built ie it’s total build specs..
I would b chomping at the bit if I had a JW motor in my car and had a belief it was a race built motor and did not know it’s specs...

I thought about that, might be time to head down there again.

I actually picked up the motor at JW when i bought it but was so excited that i forgot to ask all the important questions.

911 tweaks · 06-16-2019, 09:22 AM

even if a while ago, i am sure they have records of the job... ask Rene, Jerry, Rich or someone in the office... they all have always been very helpful to me on stuff...
This way you are not wasting your time and get the correct info...JMHO...
good luck...!!