Oil Pressure Gauge Port to use?

[Andrew Stein]

I could answer this question with a test, but I’m feeling a little lazy at the moment. In the past I’ve connected my oil pressure idiot light and the mechanical gauge to the port on the intake side of the engine. In my new car & motor I connected the idiot light to that port and the mechanical gauge to the port on the front of the motor servicing the main bearing gallery. I am seeing hot oil pressures that are lower than I’d like. Coming off the track at near-idle speeds I’ve got 10+ (OK), but at speed it is about 35 @ 5K. Oil temp was about 110C (no cooler) and am using 40weight Redline. I did not build this engine and do not know if there is a restrictor on the feed to the cylinder head. Again, I could find that out and will if I need to, but you can refer to sentence #1 about laziness.


So, the main question is, would the oil gallery on the main bearing feed read significantly differently than the port on the intake side?

[BorkRacing]

Front of engine take off will show up to a 10 lb lower reading.
Switch the gauge to the other port, block the front take off and put a T in the line for your warning light.

See you at Pitt, Robby

[S Lathrop]

My $0.02 advise is to leave the oil pressure gauge as is and add an oil cooler. 110 C or 230 F is a bit high for the oil. I think things will be a lot better if you keep the oil 90C to 100C. What is you water temperatures? There is power in keeping the temperatures a bit low for water and oil right at 200F (just under 100C).

When I built engines, I had the oil plumbed into the left side galley that feeds the main bearings and I took the oil pressure on the opposite side of the engine. I did this after loosing oil pressure and just catching the engine before anything other than the bearings were damaged. The way I plumbed, 10 psi oil was not an issue because that was the lowest point in the system and the bearings were always higher than that.

[chrisw52]

could anyone post pictures to show the locations they used? I need to install a new oil sensor and the current location (right side, forward of the oil pump) doesn't have the clearance to install the sensor.

[Gary_T]

Unrelated to oil pressure itself, for the pressure transducers used with data systems, I won't thread it directly into the block anymore. I've seen 2 or 3 quit working, I believe, due to the vibration. I use 1/8" copper tube to remote mount the transducers on the frame. Haven't had an issue since.

Additional benefit, you can make the tubing fit in spots the transducers won't.

[Andrew Stein]

[QUOTE=S Lathrop;586665]My $0.02 advise is to leave the oil pressure gauge as is and add an oil cooler. 110 C or 230 F is a bit high for the oil. I think things will be a lot better if you keep the oil 90C to 100C. What is you water temperatures? There is power in keeping the temperatures a bit low for water and oil right at 200F (just under 100C).

Steve: It was a very hot weekend in New Jersey. Water temp was 190F . Car is a Crossle 35, so has much excess cooling capacity. Think I'll add the cooler - at least for next season. Not running in such hot weather again this year (I think).

[BorkRacing]

[QUOTE=Andrew Stein;586698]

My $0.02 advise is to leave the oil pressure gauge as is and add an oil cooler. 110 C or 230 F is a bit high for the oil. I think things will be a lot better if you keep the oil 90C to 100C. What is you water temperatures? There is power in keeping the temperatures a bit low for water and oil right at 200F (just under 100C).

Steve: It was a very hot weekend in New Jersey. Water temp was 190F . Car is a Crossle 35, so has much excess cooling capacity. Think I'll add the cooler - at least for next season. Not running in such hot weather again this year (I think).

Advice given to me by Keith Averil is the oil cooler in the 30/40 Series Crossle acts to de-aerate the oil since the small oil reservoir does not come with a baffle. I run a very small oil cooler that is taped over to avoid over cooling the oil.

Robby