I have been posting this issue in the HP500 Oil temp thread, but have not been getting any feed back, and I looking for some iput/advice.

Went out yesterday and got the following results:
1. Still no oil temp on gauge, gauge works, I ground the lead, and the neddle goes full over, Gauge is a 140-340 temp Livorsi
2. Oil Pressure at start up is 70-80psi, after running at 3000-3500 rpms, it drops to 60 psi, ( not sure if this really a problem).
3. After 3500 rpm , come back to idle, I get 40psi of oil pressure at idle 900 rpms.
4. Water temp is a constant 140 deg.
5. Bought an IR temp sensor/gun ,and shot the following readings after the 3500 rpm cruise with the engine off
a. oil filter:180 Deg.
b. oil thremostat housing: 185 deg.
c. Oil cooler: 85 DEG!
d. engine block: 120-145 DEG,
e. CMI headers: 85-90 degs
f. oil pan: 185 deg.
I run Mobil1 15-50wt oil in a 12 qt oil pan, this oil change has about 10 hours on it...
Engine dumps ALOT of water out the exhaust, and I have a water pressure dump valve set at 25 PSI.

NOW what really has me concerned. After watching the airshow, (Thunder birds were great). I headed back to the house, and ran 3000-3500, for a most of the way, (oil pressure sitting at 60-65PSI) I opened it up to WOT, hit 97 MPH for about 30 seconds, BUT the oil pressure starting DROPPING, down to 55PSI, so I backed down to 3000 RPMS, (55 mph), for the rest of the way home. After 5 minutes of this cruise speed, oil pressure came back up to 60PSI. This is the first time the oil pressure drop has happened while I have been trying to solve my no oil temp issue. Kinda scared me. At idle back at the dock, I get 40PSI of oil pressure, and oil pressure goes up as I throttle up...
I think that my Oil thremostat is not opening, how does I test it, besides removing it and boiling it in a pan? or is there something else going on?
Looking for some ideas, advice..
Thanks,
Dean

What is your oil thermostat opening temperature? If the temps are only getting to 185 at the filter and your T-stat opens at 210, the cooler is not going to get oil flow. It sounds like temps are just not getting that high. Also, your drop in oil pressure could be from foaming the oil. Bob Madara and I had a lengthy conversation about this and he recommended switching to Brad Penn oil as it has better anti-foaming properties.

Another data point to gather would be oil temp at the pan.

Matt,
I shot the oil pan with the IR gun and it said 185. I don't know if the Oil thremostat rating is or if it is even opening. Any ideas on how to confirm if it is opening?
Thanks,
Dean

Heres my guess at whats happening. At cruise, everything is working as it should. The oil stat is allowing your oil to warm up. However, at wot, now the engine is making some power/heat. The oil stat is sending oil to the cooler, but my guess, the cooler is too small, not providing ample cooling. Therefore the oil is getting too hot, and showing a loss of pressure. Once it cools back down, pressure comes back. The idea is use a oil stat to warm the oil until the demand for more cooling is needed. Then its the coolers job to keep the oil close to the operating temp of the thermostat element

dean, oil temp of 185is ok.i like to see 190 to 210.i agree with matt that the oil may be foaming.i would try brad penn,kendall,or valvoline,all 20w50 and see what happens.

could be a simple sensor. they do operate on different ohm ranges. make sure you have the right sender.

Mike,
What causes the oil to foam? The oil that was in the engine when I bought it was Kendall 40 Wt straight. And never had this oil pressure dip problem at WOT

The oil cooler is off a HP500 bulldog

Any chance it is a windage issue at high RPM's? What pan and windage tray are you running? Since oil temp seems to be OK when checking the pan, this is where I would look.

M,
I talked with Liviorsi and they gave the Ohms readings I took out the sender and boiled it and got the Ohm readings I was suppose to.... i think the sender is good....