Oil pressure loss with accusump and Ron Davis
12-12-2005, 11:04 AM
#61
Drifting
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Drove my old car this past sunday at Road Atlanta. I'd say it was about 45° for the high temp of the day.
With the DRM oil cooler/radiator/remote filter combo, I never got the oil over 275°.
The oil pressure is still lower then with out the oil cooler. On a cooldown lap where the oil temp had dropped to 250°, I idle (in neutral) coasted down the back straight. the oil pressure dropped to 18psi. He was running M1 5w-30ep
That compares when I did not have an oil cooler at sebring/VIR in the summer heat. Oil temps where over 300° in 15-20 mins. When I coasted the car in neutral down the backstraight w/ oil still over 300° the oil pressure was 24psi at VIR and 28psi at sebring. This was with M1 0w-40.
We are talking about 6-10psi lower oil pressure with 50° lower oil temp with the oil cooler/radiator.
He was 1 full quart over the full line.
With the DRM oil cooler/radiator/remote filter combo, I never got the oil over 275°.
The oil pressure is still lower then with out the oil cooler. On a cooldown lap where the oil temp had dropped to 250°, I idle (in neutral) coasted down the back straight. the oil pressure dropped to 18psi. He was running M1 5w-30ep
That compares when I did not have an oil cooler at sebring/VIR in the summer heat. Oil temps where over 300° in 15-20 mins. When I coasted the car in neutral down the backstraight w/ oil still over 300° the oil pressure was 24psi at VIR and 28psi at sebring. This was with M1 0w-40.
We are talking about 6-10psi lower oil pressure with 50° lower oil temp with the oil cooler/radiator.
He was 1 full quart over the full line.
12-12-2005, 11:48 AM
#62
Former Vendor
SilverZ06,
Thanks for your track report. There are two reasons why I think your pressure is 6-10 lower at track temps. First off that system of ours you installed is our old setup. There is many more lines and fittings for the oil to run in. This could be as much as a few pounds of pressure. Than the other thing I saw in your post was the different weight oil. That could be a small change also, in pressure. But anyways very good data.
Did you see the pressure at any other rpm? The rule of thumb is 10 psi for every 1000 rpm. I would like to know if you are still reaching that rule.
Randy
Thanks for your track report. There are two reasons why I think your pressure is 6-10 lower at track temps. First off that system of ours you installed is our old setup. There is many more lines and fittings for the oil to run in. This could be as much as a few pounds of pressure. Than the other thing I saw in your post was the different weight oil. That could be a small change also, in pressure. But anyways very good data.
Did you see the pressure at any other rpm? The rule of thumb is 10 psi for every 1000 rpm. I would like to know if you are still reaching that rule.
Randy
12-12-2005, 12:00 PM
#63
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Originally Posted by Randy@DRM
SilverZ06,
Thanks for your track report. There are two reasons why I think your pressure is 6-10 lower at track temps. First off that system of ours you installed is our old setup. There is many more lines and fittings for the oil to run in. This could be as much as a few pounds of pressure. Than the other thing I saw in your post was the different weight oil. That could be a small change also, in pressure. But anyways very good data.
Did you see the pressure at any other rpm? The rule of thumb is 10 psi for every 1000 rpm. I would like to know if you are still reaching that rule.
Randy
Thanks for your track report. There are two reasons why I think your pressure is 6-10 lower at track temps. First off that system of ours you installed is our old setup. There is many more lines and fittings for the oil to run in. This could be as much as a few pounds of pressure. Than the other thing I saw in your post was the different weight oil. That could be a small change also, in pressure. But anyways very good data.
Did you see the pressure at any other rpm? The rule of thumb is 10 psi for every 1000 rpm. I would like to know if you are still reaching that rule.
Randy
This is the DRM oil cooler/radiator combo unit and not the other stand alone oil cooler that I had in the past.
Didn't get a chance to check out the pressure while driving. Will try next time. I'll see if I can get him to go with a 40wt next time.
Thanks!
12-12-2005, 01:07 PM
#64
Le Mans Master
Some may argue about the validity of the information. My
comment is while it isn't rigorously scientific, it is instructive
and the most comparative info posted here to date.
Different viscosity will result in different pressure readings
for a given oil temperature. Time on the oil while working it
hard is another factor (with mineral oil, anyway) - fresh oil
holds its viscosity and therefore pressure better than oil that
is tired.
I would caution AGAINST taking away the idea that it is best
to use oil with a big viscosity spread and a high upper value.
The wider the spread in the upper and lower index values the
more 'magic' there is in the additive package. Also, at least
one test has demonstrated that a large air-cooled 4-cycle
motorcycle engine has higher oil temps when heavier weight oil
is used.
Based on this, my approach is to use the narrowest weight
multi-grade suitable for the conditions. New conditions
means I change the oil weight. If I see the oil run hot,
I change the oil rather than use it again and run the risk
of it being tired when I need it to stand up next time out.
Then there is the matter of pressure drop due to fittings and
lines. Already discussed pretty thoroughly.
Question: How hard is it to change out (or shim) the relief
spring in the pump to bring the pressure back up to where it
should be? No one has mentioned this and yet it is part of
car preparation when you add external coolers, filters and
so on.
I don't advocate adding a higher volume pump unless
something has been done to bearing clearances or to otherwise
increase flow. But bumping up the spring to bring pressure
back into line is part of the drill when the guage indicates
this is required.
.
comment is while it isn't rigorously scientific, it is instructive
and the most comparative info posted here to date.
Different viscosity will result in different pressure readings
for a given oil temperature. Time on the oil while working it
hard is another factor (with mineral oil, anyway) - fresh oil
holds its viscosity and therefore pressure better than oil that
is tired.
I would caution AGAINST taking away the idea that it is best
to use oil with a big viscosity spread and a high upper value.
The wider the spread in the upper and lower index values the
more 'magic' there is in the additive package. Also, at least
one test has demonstrated that a large air-cooled 4-cycle
motorcycle engine has higher oil temps when heavier weight oil
is used.
Based on this, my approach is to use the narrowest weight
multi-grade suitable for the conditions. New conditions
means I change the oil weight. If I see the oil run hot,
I change the oil rather than use it again and run the risk
of it being tired when I need it to stand up next time out.
Then there is the matter of pressure drop due to fittings and
lines. Already discussed pretty thoroughly.
Question: How hard is it to change out (or shim) the relief
spring in the pump to bring the pressure back up to where it
should be? No one has mentioned this and yet it is part of
car preparation when you add external coolers, filters and
so on.
I don't advocate adding a higher volume pump unless
something has been done to bearing clearances or to otherwise
increase flow. But bumping up the spring to bring pressure
back into line is part of the drill when the guage indicates
this is required.
.
12-12-2005, 07:24 PM
#65
Former Vendor
Slamon4me,
You made a really good point about the weights. The bigger the spread the more additives they put into it. I also read that in Corky Bell's book about turbo charging.
To put a shim in a car is a major deal. The cradle has to be dropped and the pan must be removed. Then after that it is easy, take the plug out, shim and put back together. The shim must go on the plug side. This is a major project, with that said, if you are in the middle of a rebuild or something then it's a good idea to shim the pump.
Randy
You made a really good point about the weights. The bigger the spread the more additives they put into it. I also read that in Corky Bell's book about turbo charging.
To put a shim in a car is a major deal. The cradle has to be dropped and the pan must be removed. Then after that it is easy, take the plug out, shim and put back together. The shim must go on the plug side. This is a major project, with that said, if you are in the middle of a rebuild or something then it's a good idea to shim the pump.
Randy
