LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Oil pressure drop at WOT

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Old Nov 26, 2006 | 09:26 AM
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Question Oil pressure drop at WOT

Well ive been trying to chase down this issue for a while now and i have hear about a million different answers. At 4k rpm under WOT my oil pressure drops from 50-55psi to about 35 then shoots back up around 4700 rpm. It does it the worst when accelerating from a dead stop or a roll under 30mph. It will do it if i nail it from 45mph but its not as bad. If i get into it about half way it wont do it...

What do you guys think??

Ther car will be getting a GM Performance high pressure oil pump in a few weeks along with a cam and alot of other things. Im just hoping that i dont hurt the motor when i install my CC306. I doplan on pulling the motor and tearing it down a good bit incase something sneaks up on me and needs repair...like maybe the cam bearings.

Keep in mind my motor only has about 45-48k miles on it and was built back in feb. 2001. When i purchased the car it didt have a dipstick and had a pretty nasty intake oil leak that i fixed right away. So i dont know if it was ever ran really low on oil. The car still runs strong.
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Old Nov 26, 2006 | 12:30 PM
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How about when you slow down real hard. Does it drop then. If it is then You night have a little bit of clearence in your bearings..... probably the mains. How many miles, do you run it hard, ever used nitrous? Got any leaks? Check the oil pressure sensor. if any of these apply.... what happens is when you hit the gas..... assuming the front mains are the worse; the oil rushes back to the back of the oil pan or trys to and the oil that is supposed to be in your bearings rushes out as well. There is still alot of oil there just not enough to keep the pressure up. loose clearence in your bearings... loose oil pressure. Second, your oil pump may not be working properly under high rpm's.
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Old Nov 26, 2006 | 03:07 PM
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When i slow down hard it doesnt drop or anything, The motor has about 45k on it with the stock oil pump that has 111k. I do run the car fairly hard, but not to hard. I have a brand new oil pressure sensor but have not verified with a mechanical gauge. I do have a slight oil leak at the timing cover. The car has never seen nitrous or anything like that. The bearings only have 45k on them so im hoping thats not the issue, but like i said i dont know how low it has been ran since i dont have a dipstick and it had an oil leak when i bought it, but it still runs hard as hell...its still very strong. I just dont like seeing the drop.
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Old Nov 26, 2006 | 03:54 PM
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stock gauge is junk. its usually off and it doesnt read right sometimes.

you may have **** in the pickup tube screen hindering oil pressure, or the pump may be on its way out.
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Old Nov 26, 2006 | 03:56 PM
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Yeah, no glitter in the oil . Then your motor is ok . Just chang the gauge . Good to go.
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Old Nov 26, 2006 | 04:24 PM
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No glitter at all...hopefully when i get my new high pressure pump in it will take care of everything...im just happy i actually gotsome good detailed answers!! thanks guys, i appreciate it.
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Old Nov 27, 2006 | 01:27 AM
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from what i've seen the lt1 oil pressure drop is a fairly common problem with a stock oil pan

mine does the same thing the oil pressure will take a quick dip and then it will come right back up again and it seems to happen the most under the hardest acceleration 1st or 2nd gear possibly the pan is getting sucked dry for a split second due to windage?
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Old Nov 27, 2006 | 10:24 AM
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Thats basically the same thing mine is doing. It never did it until about 3 months ago...so i know there HAS to be a fix. Im hoping its just the oil pump and not bearing issues.
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Old Nov 27, 2006 | 10:54 AM
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I would stear away from the high pressure oil pump and go with a high volume pump made by melling. Thats what I run and I have awsome oil pressure, but if you run this pump then u will need to get a canton 6-quart oil pan and new canton pickup so the pump doesnt suck the pan dry. Just a nice insurance policy

When I took my stock motor apart I couldnt believe the cover over the oil pump pickup screen. Once somthing gets in there how does it get out
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Old Nov 27, 2006 | 11:02 AM
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I was going to go with a high volume pump but ive always been told to stay away. The pump im going to run has bigger gears, the white spring, and a larger pickup. I have not heard anything bad about the pump im going to be running. Yeah im curious to see what the screen looks like...
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Old Nov 27, 2006 | 11:26 AM
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Originally Posted by Matts94Z28
I was going to go with a high volume pump but ive always been told to stay away. The pump im going to run has bigger gears, the white spring, and a larger pickup. I have not heard anything bad about the pump im going to be running. Yeah im curious to see what the screen looks like...

the only reason people have told you to stay away (from my knowledge) is because of the relatively small capacity of the stock pan, the high volume pump will suck the pan dry
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Old Nov 27, 2006 | 01:06 PM
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Umm why do you not have a dipstick? I believe I would install one....
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