forum rules say we can't link to other forums, so i'm going to paste what i posted on the vette forum. as a BITOG-specific aside, i took a sample of the GC 0w30 that came out just before the new oil pump, i'm curious to see how obvious the bearing wear will be. i will post the UOA when i get it.
this is a '96 LT4 corvette.
here's the problem post:
--------------
i have a 396 in my '96, just went in a few months ago. i originally tried using the stock pan. since the stock windage tray would not clear the new crank/rod combination, it was left out, and the stock pan was not able to keep the pickup immersed in oil under hard acceleration without it. oil pressure would basically fall to zero when i floored it.
replaced the stock pan with a 240T, using the "pressure balanced" HV pump offered by canton. at first i thought it was all peachy keen, but soon realized the oil pressure was dropping under acceleration still, just not nearly as much. it would cruise at 60psi, but when accelerating hard the pressure would drop to about 50psi, sometimes 45psi. if i just revved it sitting still, it would maintain over 60psi until the last 1000rpm, then drop.
so, i bought a new stock SV oil pump and new pickup. i triple-checked pickup to pan clearance. figuring the initial oiling problems might have worn the bearings, i changed all the rod bearings. (a couple were on the worn side, as it turned out.)
now the pressure signature is really good under almost all conditions, except hard acceleration (again). even with hot oil it idles at 35psi, hits 60psi by 2k rpm, and will reach the oil pump's bypass pressure of 70psi by around 3k rpm if just free revving it. (so the oil pressure drop over 5k rpm before must have been due to wornish rod bearings.) but under hard acceleration it dips down to 50-55psi.
50-55psi is borderline palatable, except that i discovered it jumps to 70psi the instant i brake hard. so i can floor it all the way through 2nd, leave it in gear, jump on the brakes and even though it's still at very high rpm it instantly hits 70psi. so it's definitely an oil control problem within the pan.
last time the pan was off i did check to make sure all the trap doors appeared to be working fine. i couldn't spot any defect in manufacture. i'm starting to wonder if the conclusion needs to be that canton isn't doing a good job with those vette pans. what's especially frustrating is that i had no oiling issues with the stock pan on the stock engine, and the canton is specifically made for racing use.
i'm open to any input/suggestions. thanks.
------
i followed up with:
---------
i should add that i tried both 1qt over and 1qt under to eliminate that as a possibility. also, this signature remains regardless of oil weight (i tried 10w40, 10w30, 15w40, and 0w30, some petroleum, some synthetics, etc), oil filter, using the stock filter bypass or using the canton bypass eliminator. all combinations behave exactly the same way.
EDIT: oh, and i also tried a mechanical gauge, and i tried moving the sending unit location to where the oil temp sensor goes, just to eliminate that.
------------
thanks!
-michael
this is a '96 LT4 corvette.
here's the problem post:
--------------
i have a 396 in my '96, just went in a few months ago. i originally tried using the stock pan. since the stock windage tray would not clear the new crank/rod combination, it was left out, and the stock pan was not able to keep the pickup immersed in oil under hard acceleration without it. oil pressure would basically fall to zero when i floored it.
replaced the stock pan with a 240T, using the "pressure balanced" HV pump offered by canton. at first i thought it was all peachy keen, but soon realized the oil pressure was dropping under acceleration still, just not nearly as much. it would cruise at 60psi, but when accelerating hard the pressure would drop to about 50psi, sometimes 45psi. if i just revved it sitting still, it would maintain over 60psi until the last 1000rpm, then drop.
so, i bought a new stock SV oil pump and new pickup. i triple-checked pickup to pan clearance. figuring the initial oiling problems might have worn the bearings, i changed all the rod bearings. (a couple were on the worn side, as it turned out.)
now the pressure signature is really good under almost all conditions, except hard acceleration (again). even with hot oil it idles at 35psi, hits 60psi by 2k rpm, and will reach the oil pump's bypass pressure of 70psi by around 3k rpm if just free revving it. (so the oil pressure drop over 5k rpm before must have been due to wornish rod bearings.) but under hard acceleration it dips down to 50-55psi.
50-55psi is borderline palatable, except that i discovered it jumps to 70psi the instant i brake hard. so i can floor it all the way through 2nd, leave it in gear, jump on the brakes and even though it's still at very high rpm it instantly hits 70psi. so it's definitely an oil control problem within the pan.
last time the pan was off i did check to make sure all the trap doors appeared to be working fine. i couldn't spot any defect in manufacture. i'm starting to wonder if the conclusion needs to be that canton isn't doing a good job with those vette pans. what's especially frustrating is that i had no oiling issues with the stock pan on the stock engine, and the canton is specifically made for racing use.
i'm open to any input/suggestions. thanks.
------
i followed up with:
---------
i should add that i tried both 1qt over and 1qt under to eliminate that as a possibility. also, this signature remains regardless of oil weight (i tried 10w40, 10w30, 15w40, and 0w30, some petroleum, some synthetics, etc), oil filter, using the stock filter bypass or using the canton bypass eliminator. all combinations behave exactly the same way.
EDIT: oh, and i also tried a mechanical gauge, and i tried moving the sending unit location to where the oil temp sensor goes, just to eliminate that.
------------
thanks!
-michael