Hello,
Hope someone can help.

I have a 2003 C5 with 408 TSP short block, 243 ported heads, 1 3/4 LT, Thunder Racing (rip) ported oil pump, LS6 intake, Shaner TB, small cam, loads of torque.

Situation; Have always had same thing occur since new, 8,000 miles ago, oil pressure 32/33psi at idle hot with 16 kpa of vacuum, at 72 cruising, about 40/42 on flat surface but when going up and giving it slight throttle, oil pressure drops about 1 lb with the vacuum rise. Then pressure returns to same 40 psi after vacuum drops; all this while maintaining same rpm. Have good pressure at WOT, maybe 63/65 at 5000 rpm. never rev past 6700 as power is restricted by intake, TB, and smallish cam.

Normal? Bad seal? Please advise.

Thanks

 

Have you checked with a mechanical guage to confirm that it's not a bad sending unit?

 

Thanks for the reply.
Not checked with a mechanical gauge, but why would it show as a drop even if defective? And be consistant?

 

I'm not sure. I just figured that it would be nice to rule that out. If it is accurate then it sounds like something in the oil pump itself. I have never heard of an issue like this before. Usually you see people that have pressure drop issues with rpm increase, or just the opposite, low idle pressue but comes back with rpm.

 

Given the way these gauges work, I am not convinced a 1lb drop in the oil pressure reading concurrent with a change in engine load is an "issue."

 

I must have read it wrong. I thought he meant that the pressure was dropping to 1lb.

 

Thanks to both of you.

Waiting to change heads, intake, cam, TB and headers. Go faster. LOL
Have a new, ported LS6 oil pump, sitting in a box. Might change it out.

What have you heard about using the C6 oil pan? Can get the whole setup fairly cheap. I know it's easier to work around. Advantages/Disadvantages?