do a lil thicker oil (probly not the problem but couldn't be to bad an idea).... maybe a titch over filled... and definitly a standard pump (most likely the problem..)...

 

ok.. reporting in.. oil level was about middle of the stick on the check section.. filled to top, it took a 1/2 quart.. then added a full quart on top of that... took her out let her come up to normal operating temp.. wound it up.. pressure drops still.. drops to 20 psi steady and holds.. that was adding 10w-30 to it.. somehow I don't think the viscosity is going to fix the problem, and I am not convinced the oil pump is the culprit as an extra quart and a half would have at least delayed the drop I think and I made a note on where in the rpm band it dropped before the overfill and it happened the exact same place... this is frustrating. I feel a new std pump is probably the right idea with the stock pan so I will change it out.. pumps are reasonably cheap for these cars. I am not runnign anything between the pump and block, just machined surface to surface.. I have seen some people use some rtv between it.. could it be sucking air here under hard acceleration due to a bad seal between the pump and the block? should I use something between the two to ensure a seal?

Chris

 

Dude, run it w/o boost to see if it is rpm related or boost related. That will tell you so much.

Also, if it was sucking air I'd have to think the idle oil psi would be lower, but anythings possible I guess.

 

does the same thing without boost... think I found the problem... under acceleration all the oil is sloshing to the back of the pan and up and hitting the rear crank weights aerating the oil and the bubbles in the oil are causing the pressure drop. tried revving it in neutral with the extra oil and got a slight pressure drop, drained some back out to normal and got no pressure drop.. got pressure increase and held steady. it does it but not as bad without boost... I am guessing this is due to the xtreme difference in acceleration, it only drops to about 45 psi without boost, and once the car is maintaining speed at rpm the pressure resumes. I suppose I made a mistake my not taking precautions for the windage tray, I am very glad I didn't hurt the engine or at least not showing signs of it just yet.

I am going to get a canton road racing pan for the corvette which has a built in windage tray and a crank wiper.. need one for our solid roller 96 NA car and will check and see if my crossover will clear it at that point.. that will add some oil to the system, add the needed tray, add the crank wiper, and lower the level of the actual oil line for better turbo drain back (not that I have run into a problem with this) but never hurts. it also uses a better pick up assembly.. probably what i should have done from the get go! I made a post in the advanced tech section of the corvette forum and this identicle scenario has happened to a couple people and was easily resolved by switching the pan. one guy even tried everything I had thought of like changing to std pump, changine oil thickness which I am still going to do since calloway recommends only 15w-50 in his production twin turbo vettes for better heat stability of the oil as it passes through the turbos and due to the higher oil temps I have been experiencing over a Naturally aspirated setup. so if anyone runs into a problem like this and has removed the windage tray.... this might have been a big no no.. I am ordering the pan now for the other car and will check and see how things go when i get it and put it on. thanks for all your help guys!!

Chris

 

Glad to see you got it figured out!