hrcslam

Alright, as the title states, my oil pressure is low when I accelerate. But only when I hammer it. Driving normal and there's no issues, but I hammer it and it fluctuates.

Here's a breakdown of the symptoms.

Engine cold:

Idle: 40psi
Driving: 40psi at idle that increases to about 70 psi at 6000rpms. No issues with fluctuation or dropping regardless of vehicle acceleration, including hard acceleration.

Engine Warm:

Idle: 10-15psi (not worried here as this is normal for LT1's)
Neutral: Revving with car parked or moving and pressure rises without issue to 60psi at 6000rpms. This is good.
Normal driving: No drops is pressure or fluctuation, pressure rises with rpms to about 40psi at 4000rpms.
Heavy acceleration: Pressure fluctuates, rises to 40psi by 4000rpms, then drops to about 30psi at 6000rpms. As soon as I let off of it and it rises to 60psi at 6000rpms and comes down with rpms as it should.

Anyone dealt with this before?

Wheelman916

My oil pressure doesn't react exactly the same as yours, but similar.

With the engine warm, after 15 to 20 minutes of driving:

Idle - 19-21psi
Part-throttle driving - around 38-40psi

Now, under hard load open throttle, I watch the needle, and it doesn't seem like it has any intention of moving higher than 40psi... So I usually chicken out by 4k to 4500rpm.

Once I'm off idle and under load, my pressure is immediately up to the 38-40psi range, and stays there throughout the rpm range, if I'm half throttle, full throttle, 2k rpm, 4k rpm... It stays right around 40psi.

SS RRR

iTrader: (2)

What oil pan are you running? Windage tray? How many quarts of oil? This reads like a textbook windage issue.

stevo9389

I vote windage also.

hrcslam

Stock pan and windage with stock oil pick up tacked on.

I was at 5 quarts, now at 6 quarts. Made no difference. It did it with a Microguard filter and now a Bosch filter. Tried 5w30 dino oil it did it, and 10w40 synthetic still doing it.

hrcslam

Got some videos, I did notice it does it when accelerating weather hot or cold. It is more noticeable when hot though. But happens warm or cold. I think this actually helps. It only happens when accelerating though.

Cold Start and Rev
https://www.youtube.com/watch?v=bwt8...ature=youtu.be


Cold Drive and Accelerate
https://www.youtube.com/watch?v=MBDi...ature=youtu.be

Warm Idle and Rev
https://www.youtube.com/watch?v=PS68...ature=youtu.be

Warm Drive and Neutral Rev
https://www.youtube.com/watch?v=t9ox...ature=youtu.be

Warm Drive Normal then Accelerate
https://www.youtube.com/watch?v=UF5N...ature=youtu.be

SS RRR

iTrader: (2)

You put 6 quarts in a stock pan? Don't do that. It's not helping your cause. Stock pans and windage trays are notorious for these problems. Moroso makes a windage tray that I believe works with the stock pan.

hrcslam

Yeah, I wanted to check to see if it was from oil running away from the pump during acceleration. It made no difference and I took it out. I'm now at the low end of full (vs over full from 6 quarts, and full at 5 quarts previous to that). I'm gonna see how 4.5 quarts does with the fluctuation/drop. Maybe it's cavitation.

Also I checked to make sure my pick up is still on where it should be and it is.

leadfoot4

iTrader: (1)

Is it a stock pump, or a high volume pump? Maybe a combination of centrifugal force forcing the oil to the back of the pan, away from the pick up, as well as a HV pump, pumping out the pan?

hrcslam

Not high volume, stock. I have a high volume sitting on the shelf though. Decided not to use it for this specific reason.... LOL.

hrcslam

Installed a mechanical gauge and verified reading on dash to be more or less accurate-ish. LOL. I replaced oil with SAE 50 Valvoline VR-1. Drop during acceleration is gone. I guess the .0035" rod bearing clearances plus the .0025" Main bearing clearances didn't like the thin oil.

hrcslam

Thought I'd give an update. Seems this is common with LT1s. I've got about 10k miles since I've started this thread and no bad affects. My dash Guage reads about 10-15psi when hot idle and drops still during hard acceleration. I'm back to using 5-30w oil too. It's more noticable when ambient temps are over 85°F. My mechanical Guage reads 25psi at hot idle though. I don't notice a drop on the mechanical Guage during acceleration either.

My mechanical Guage is hooked up just above the filter. I wonder if there is a pressure difference between the two locations due to the hydraulic lifters? Probably not I think. The other issue could be the electric Guage looses some voltage during acceleration. Not sure either way.

I'm no longer worried about it though. The drop only happens for a split second so I'm thinking is an indicating problem and not an oil pressure problem because my mechanical Guage works perfectly.

Catmaigne

iTrader: (6)

Holy rod bearing clearance, batman. Why so wide?

hrcslam

Just the way it came out. I'd like to go in and replace them to make them tighter. But life stuff first.

ringmaster72

iTrader: (8)

Mine has done this for over 3 years, I just quit looking at the gauge when hammering on it. If it flies apart, so be it, LOL.

AdsoYo

iTrader: (1)

My pressure dips at around 5,000 rpm. I asked my engine builder about it and he said as long as it has oil pressure, don't worry about it. So now I share ringmaster's attitude about the whole thing

Catmaigne

iTrader: (6)

Stock rods and crank? Aftermarket crap usually has a wider rod side clearance and makes oil being flung out of the rod throws more difficult to control. I'm guessing a wider rod bearing clearance could have the same effect.

Does pressure drop when accelerating in higher gears? Oil could be getting whipped up by the crank after climbing the back of the pan. Try rolling on the throttle slowly on the highway.

That's a lot of money to throw down the drain, fixing it should be a priority.

blk97z28

iTrader: (3)

I believe my numbers are like 15-20 when hot idle and 45-50 at wot which seems about right. Just something from a brother with an lt1

HISS

iTrader: (52)

Sounds like the pump may be cavitating.

hrcslam

Forged rods and pistons, stock crank ground , 10/10. It is high priority. But my life stuff is even more so.

I know the rods side is too big for sure. But, it's gonna be alright. My question is if, but when. And when I do it, to 383 or to not 383. ....