jfrc

I figured I would get better responses in here, due to experience.
Brief summary. Last year i had to rebuild my motor due to 2 spun rod bearings and 1 spun main bearing. I did not cut corners on the rebuild- studs, new gaskets, chain, etc..... I replaced the oil pump with a new ported ls6.
We had a practice autoX today, and i started off @ 40 psi. As the day progressed, and coolant temp rose, my oil pressure dropped to 20. My last run, it would not even hit 10 psi w/out some throttle.
I did not even think to look at oil temp. But FWIW, the engine coolant never got hot enough to have the fan turn on.

What do i need to do? External oil cooler? An aftermarket oil pump? My last engine did the same thing- thats probably why i had to rebuild it. I really do not want to tear it apart for a d&mn oil pump, but i really do not want to rebuild another motor.

jfrc

oil pressure is fine, until i race it all day

what do you think about a higher volume oil pump and am oil cooler w/ a compact electric fan?

it should help in more ways than one- increase oil capacity, keep oil cooler, more volume, etc...

VetteDrmr

If you're pushing 400 rwhp, your oil temps are probably getting upwards of 300 degrees. It's hard to tell without your oil temps, but having oil pressures at idle in the low teens isn't unheard of with hot oil.

Not sure why your fans aren't coming on, I always turn my AC on between runs.

Did your oil pressure recover after it cooled down?

HTH, and have a good one,
Mike

AU N EGL

Oil should be in the 190-255 range. mostly likely you will need an oil cooler.

Always put the oil temp in your DIC.

Also what wt oil are you using ?

jfrc

ironically,that is the only setting i use on the street
but at an event, i am doing good to remember to turn off the traction control- which is what is the message left on the dash:o

yeah, if it sits for awhile, like a lunch break, the pressure will come back some.
since the rebuild, i could use a dyno tune, plus some code issues
this would be a good excuse to change fan settings

kelp

No explanation, only reproducable observations:

Every time after a 20-30 hard track run, my oil is about 225* and the oil psi is 7 (right, seven) when the car it immediately brought to idle. It picks right up with a slight rev. increase and when the oil temp cools down the "problem" goes away. Only under track conditions does my oil temp exceed my water temp.

bobmoore2

As everyone has said, your oil pressure went down because your oil temp was pretty high.

Here's what I do to make sure I don't overlook a high temp situation when I'm racing (HPDE's). I put the Coolant Temp display on the HUD. It's not the same as the oil temp, but coolant temp gives some indication of what is happening with the oil temp. If the temp bar-graph on the HUD rises too high, I take it easy for a lap, and the temperature will come down enough that I can start driving hard again. This one thing has probably saved me a small fortune in engine repairs.

Bob

01C5fan

If you're running a stock radiator without an oil cooler it's easy to get oil temps over 300. I have the DRM radiator/oil cooler combo. My oil temp seldom gets to 250 and the pressure generally stays above 30 hot. Car makes over 500 rwhp so it probably generates plenty of heat.

97coupechuck

I had my LS6 rebuilt and getting ready for new year now. I ran it in dec and I only was running in teens after motor got hot but would come up as soon as I bliped the throttle. I have been worried about that but since this post I don't feel to worried. My engine builder HPE (Houston) opened up oil pump port for more flow and I guess the by product of that move was lower oil oressure.
I'm running stock radiator with external oil cooler attached to front of radiator. It doesn't seem to change oil temps much, still running higher 200's with the little running I've done with it so far, and that was in december. I'll be running with the Apex group in cresson this coming saturday and I'll see what happens there.

VetteDrmr

You're the first person I've ever heard that had an external cooler plumbed in front of the radiator that didn't see significant oil temp reductions. What size cooler are you using? Mine is a 45,000 btu cooler, with a 180 degree thermostat (which reduces flow), and I see about a 35 degree drop in temps.

I'll be interested to see what happens at MSR. I run there with peak temps around 270 or so at the end of a 20 min session in July.

Have a good one,
Mike

97coupechuck

I don't know what size cooler it is. It's a standard over the counter auto parts cooler, mid size, about 6" X 8" ? You have a thermostat in line for street driving I guess. I'm not worried about that because the C5 is mostly used for track. I'm at MSR Cresson this saturday with APex and I'll find out for sure what's it doing.

VetteDrmr

Mine's 7.5x14x1.5, IIRC. Our club is having a cruise Saturday; if I don't go I'll head to MSR and hopefully meet up with you.

Have a good one,
Mike

97coupechuck

yea, if ya make it to MSR, look me up, it's a C5 white coupe with black roof and hood stripe. Sounds like I should have put in bigger oil cooler. I wuz thinkin any size would be a major improvement so I dodn't worry about it. chuck