79 L82 appropriate oil pressure @ each RPM?
11-19-2017, 09:50 PM
#2
There is no correlation of oil pressure to rpm. After the oil reaches its operating temperature of around 180 to 190 degrees it'll show around 30 to 35 psi at idle and 45 to 50 psi at 2000+ rpm.
11-19-2017, 09:52 PM
#3
Race Director
depends on what oil you are using and how tight your engine is, + what pump you have.
My stock original 1980 truck - same engine as yours idles at 20# and redlines at 45# - Rotella 15-40 + Zedd, truck has 480k miles.
My 71 idles at 45# and redlines at 70# -high volume pump, Rotella + Zedd. Engine has 3k miles on it. Matching # motor.
Anything over 10# at idle is considered ok.
My 72 idles at 25 and runs at 45 on the highway - I don't rev the car - Rotella + Zedd - all original 26k miles.
85 idles at 60# and 80# same oil, but roller motor and 540HP.
All from memory - they are close..
My stock original 1980 truck - same engine as yours idles at 20# and redlines at 45# - Rotella 15-40 + Zedd, truck has 480k miles.
My 71 idles at 45# and redlines at 70# -high volume pump, Rotella + Zedd. Engine has 3k miles on it. Matching # motor.
Anything over 10# at idle is considered ok.
My 72 idles at 25 and runs at 45 on the highway - I don't rev the car - Rotella + Zedd - all original 26k miles.
85 idles at 60# and 80# same oil, but roller motor and 540HP.
All from memory - they are close..
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NewbVetteGuy (11-20-2017)
11-20-2017, 12:27 PM
#4
Melting Slicks
Thread Starter
depends on what oil you are using and how tight your engine is, + what pump you have.
My stock original 1980 truck - same engine as yours idles at 20# and redlines at 45# - Rotella 15-40 + Zedd, truck has 480k miles.
My 71 idles at 45# and redlines at 70# -high volume pump, Rotella + Zedd. Engine has 3k miles on it. Matching # motor.
Anything over 10# at idle is considered ok.
My 72 idles at 25 and runs at 45 on the highway - I don't rev the car - Rotella + Zedd - all original 26k miles.
85 idles at 60# and 80# same oil, but roller motor and 540HP.
All from memory - they are close..
My stock original 1980 truck - same engine as yours idles at 20# and redlines at 45# - Rotella 15-40 + Zedd, truck has 480k miles.
My 71 idles at 45# and redlines at 70# -high volume pump, Rotella + Zedd. Engine has 3k miles on it. Matching # motor.
Anything over 10# at idle is considered ok.
My 72 idles at 25 and runs at 45 on the highway - I don't rev the car - Rotella + Zedd - all original 26k miles.
85 idles at 60# and 80# same oil, but roller motor and 540HP.
All from memory - they are close..
Thanks for the references. If I am remembering correctly what I saw yesterday, I have about 35 at idle, 40 rapidly by 2,000 RPM and 60 PSI from about 4,000 and up.
It seemed high.
I just changed the oil and filter (napa gold) yesterday- added 3/5ths Amsoil Synthetic w Flat Tappet Zinc / Phosphorous additive 20w50 weight and 2/5ths 10w40 weight.
I wish I would've paid attention before, but after my last oil change I added SeaFoam -both to the carburetor and the gas tank and the oil quickly turned black and gunky--- I feel like, but am not completely sure that my oil pressure jumped up after that. -I also feel like after the SeaFoam is when I started to see more oil leaking from around my pan- does this make any sense?
I'm kind of worried that the pressure is too high because some sort of gunky tar-like deposit was loosened the SeaFoam and got clogged somewhere, but the top end and oil pan / pickup are all getting torn down before too long and it doesn't seem.
Adam
11-20-2017, 12:28 PM
#5
Melting Slicks
Thread Starter
Even your example shows one oil pressure at idle and another at 2,000+ RPM....
It certainly seems like there's a very strong correlation between RPM and oil pressure.
Adam
11-20-2017, 01:41 PM
#6
The stock 1970 to 1972 LT-1 oil pump put out 70 PSI hot, 60 PSI at 4,000 rpm is fine.
11-20-2017, 02:59 PM
#8
Advanced
oil pressure
[QUOTE=NewbVetteGuy;1596008628]Ok thank. I'll go worry about something else now. ;-)
The maximum oil pressure is determined by the relief valve located in the oil pump.
The maximum oil pressure is determined by the relief valve located in the oil pump.
11-21-2017, 09:16 PM
#9
Race Director
Member Since: Apr 2007
Location: South Western Ontario
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The pressures you list are fine.
Why mixing oil like that and why 20W50? If you're running synthetic then use 0W40. Thinner on cold starts but still the same as any other XW40 oil at temperature.
Why mixing oil like that and why 20W50? If you're running synthetic then use 0W40. Thinner on cold starts but still the same as any other XW40 oil at temperature.
11-22-2017, 11:22 AM
#10
Burning Brakes
) and ask why synthetic? I thought the consensus was that "older" engines do better on mineral oils, and especially those with high ZDDP. I use Millers 20-50, a mineral, high ZDDP oil, probably not available in the US but very popular in the classic world in the UK and Europe.As for the pressure, I was told many years ago that 10psi per 1000rpm was ideal, up to about 40 - 50 psi on a stock engine in reasonable condition. Our old '78 has about 30 - 35 at idle and rises to about 45 at normal autoroute (freeway) driving speeds - say 75mph
11-22-2017, 11:44 AM
#11
Le Mans Master
Actually, that was my thoughts. I'd go further (at risk of opening a huge can of worms!) and ask why synthetic? I thought the consensus was that "older" engines do better on mineral oils, and especially those with high ZDDP. I use Millers 20-50, a mineral, high ZDDP oil, probably not available in the US but very popular in the classic world in the UK and Europe.
As for the pressure, I was told many years ago that 10psi per 1000rpm was ideal, up to about 40 - 50 psi on a stock engine in reasonable condition. Our old '78 has about 30 - 35 at idle and rises to about 45 at normal autoroute (freeway) driving speeds - say 75mph
) and ask why synthetic? I thought the consensus was that "older" engines do better on mineral oils, and especially those with high ZDDP. I use Millers 20-50, a mineral, high ZDDP oil, probably not available in the US but very popular in the classic world in the UK and Europe.As for the pressure, I was told many years ago that 10psi per 1000rpm was ideal, up to about 40 - 50 psi on a stock engine in reasonable condition. Our old '78 has about 30 - 35 at idle and rises to about 45 at normal autoroute (freeway) driving speeds - say 75mph
Now to answer you question. My OEM L-82 before the rebuild ran 30-35 PSI at idle and about 45 at higher RPM's.
The newly rebuilt/upgraded L-82 355 with 10.2 compression runs about 40 PSI at idle and up to 60 PSI at high RPM's......
Last edited by jb78L-82; 11-22-2017 at 11:51 AM.
11-22-2017, 11:55 AM
#12
Can you explain that statement? -The clearances stay the same, but the pump speed increases with RPM -if the pump can't push any more oil through the clearances, pressure should increase as RPM increases.
Even your example shows one oil pressure at idle and another at 2,000+ RPM....
It certainly seems like there's a very strong correlation between RPM and oil pressure.
Adam
Even your example shows one oil pressure at idle and another at 2,000+ RPM....
It certainly seems like there's a very strong correlation between RPM and oil pressure.
Adam
Yes, the faster the crankshaft spins the more oil passes through its main and rod bearings because the oil gets heated a LOT by the momentary friction between the journals and the bearings. So even though the oil reaches the bearings as a 30 weight it momentarily gets reduced to perhaps a zero weight because of the momentary heat. Remember, the oil has to lubricate and COOL the bearings at the same time.
Last edited by NeverTooOld; 11-22-2017 at 12:02 PM.
