Standard Vs High Volume Oil Pump Pressure.
Moderator: Team
"The only thing HV pumps are really good for IS increasing low speed oil pressures below the point where the bypass valve opens or increasing across the board oil pressure if your leakage rate doesn't allow you to achieve your target operating oil pressure"
This comment by dano is correct as I visualize it. I'm just not sure in the original poster's comments that his problem lies in pump volume. 5psi at idle hot and 50 psi at 6000 may not be created by pump volume. If that were so an engine would have the same idle pressure as max rpm pressure. He won't have 50# in that engine at idle without a drysump or external oiling and pressure control or some serious work no matter what pump he uses.
See no problems with pressures that are exhibited.
As to the blower examples:
Neither blower would make more than 5psi boost with the pop off set at 5 psi. Might need a slightly larger pop off on the 6-71 at rpms but the bypass valve would dictate the pressure. Same with the bypass in an oiling system. The 6-71 would be the high volume pump.........its there if you want or need it.......more so than the 4-71. The HV pump simply has more capacity as would the 6-71. Now which one would get you to the 5 faster........671 for sure.
This comment by dano is correct as I visualize it. I'm just not sure in the original poster's comments that his problem lies in pump volume. 5psi at idle hot and 50 psi at 6000 may not be created by pump volume. If that were so an engine would have the same idle pressure as max rpm pressure. He won't have 50# in that engine at idle without a drysump or external oiling and pressure control or some serious work no matter what pump he uses.
See no problems with pressures that are exhibited.
As to the blower examples:
Neither blower would make more than 5psi boost with the pop off set at 5 psi. Might need a slightly larger pop off on the 6-71 at rpms but the bypass valve would dictate the pressure. Same with the bypass in an oiling system. The 6-71 would be the high volume pump.........its there if you want or need it.......more so than the 4-71. The HV pump simply has more capacity as would the 6-71. Now which one would get you to the 5 faster........671 for sure.
Joe Stalnaker
WV
WV
-
BlackoutSteve
- Expert
- Posts: 812
- Joined: Wed Jan 18, 2006 6:53 am
- Location: Melbourne, Australia.
- Contact:
Thanks guys.
I don't quite understand why pressures are what they are either.
(Although, what seemed to be prefectly normal pressures with the flat tappet, minus the 10-12psi that Isky confirmed with their roller lifters is exactly what I have ended up with. Is it really a mystery?)
Perhaps it's the remote System1 filter and System1 block adaptor that has no bypass, forcing all oil through the (unclogged) filter via -12 lines.
Perhaps it's the Detroit Diesel oil to water heat exchanger (with factory GM LS7 type bypass) I use also.
The oil I use is a 50 weight synthetic. Mobil 1 15W50.
All main and rod clearances are GM spec and using the 1.390" tall gear HV77 pump. I have shimed the pressure relief spring slightly (about 1/4") to maintain a 60psi max oil pressure with the external plumbing I have just mentioned.
I am also aware that the pressure balanced oil pumps bleed a lot are and inefficient low/idle speeds. I did the pressure balance mods to my pump.
The only oversight I made is not measuring lifter to bore clearances when installing these roller lifters. I assume they are within spec, but they could be wrong by how much? ..0.0005"?
Anyway, the bottom line is I'm scared to load this engine on the dyno at 7500rpm and a max oil pressure of only 45psi.
5-10psi at idle doesn't scare me ..as much!
I have to do something about this and closing up clearances to less than GM spec or using a lesser quality non-self-oiling lifter is not the answer.
Further enquiries I have made suggest a 10-15psi increase in idle pressure when swapping a standard pump with a high volume.
(Please forget I mentioned bypass/relief valves and springs and such. My question is to do with pressures lower thanwhat they operate at.)
I don't quite understand why pressures are what they are either.
(Although, what seemed to be prefectly normal pressures with the flat tappet, minus the 10-12psi that Isky confirmed with their roller lifters is exactly what I have ended up with. Is it really a mystery?)
Perhaps it's the remote System1 filter and System1 block adaptor that has no bypass, forcing all oil through the (unclogged) filter via -12 lines.
Perhaps it's the Detroit Diesel oil to water heat exchanger (with factory GM LS7 type bypass) I use also.
The oil I use is a 50 weight synthetic. Mobil 1 15W50.
All main and rod clearances are GM spec and using the 1.390" tall gear HV77 pump. I have shimed the pressure relief spring slightly (about 1/4") to maintain a 60psi max oil pressure with the external plumbing I have just mentioned.
I am also aware that the pressure balanced oil pumps bleed a lot are and inefficient low/idle speeds. I did the pressure balance mods to my pump.
The only oversight I made is not measuring lifter to bore clearances when installing these roller lifters. I assume they are within spec, but they could be wrong by how much? ..0.0005"?
Anyway, the bottom line is I'm scared to load this engine on the dyno at 7500rpm and a max oil pressure of only 45psi.
5-10psi at idle doesn't scare me ..as much!
I have to do something about this and closing up clearances to less than GM spec or using a lesser quality non-self-oiling lifter is not the answer.
Further enquiries I have made suggest a 10-15psi increase in idle pressure when swapping a standard pump with a high volume.
(Please forget I mentioned bypass/relief valves and springs and such. My question is to do with pressures lower thanwhat they operate at.)
Last edited by BlackoutSteve on Tue Apr 17, 2007 7:22 am, edited 1 time in total.
-
putztastics
- Expert
- Posts: 738
- Joined: Mon Nov 22, 2004 9:42 pm
- Location: ND
- Contact:
I look at oil pressure as a measurement of restrictions in the oiling system. Unless you are reading pressure at the pump this seems to be a good way to look at it.
On SB mopars I open up all the main oil passages to 1/2 inch, round or eliminated as many of the 90 degree turns as I can - and see a big increase in oil pressure/(flow) at the pressure sender. The regular volume pump didn't change, but restrictions were removed and it showed as increased oil pressure at the oil pressure/(flow) sending unit. (The oil pressure sending unit on a SB mopar is after #5 main - #8 rod, and # 5 cam bearings, everything else is after the sending unit.)
Sometime I want to check pressure at the back of the left lifter passage, that is the end of the road and I'm really curious what the oil pressure is there.
On SB mopars I open up all the main oil passages to 1/2 inch, round or eliminated as many of the 90 degree turns as I can - and see a big increase in oil pressure/(flow) at the pressure sender. The regular volume pump didn't change, but restrictions were removed and it showed as increased oil pressure at the oil pressure/(flow) sending unit. (The oil pressure sending unit on a SB mopar is after #5 main - #8 rod, and # 5 cam bearings, everything else is after the sending unit.)
Sometime I want to check pressure at the back of the left lifter passage, that is the end of the road and I'm really curious what the oil pressure is there.
Jesse Lackman
http://www.revsearch.com
http://www.revsearch.com
-
sanfordandson
- Guru
- Posts: 6046
- Joined: Sat May 20, 2006 6:28 pm
- Location:
i wouldnt worry to much about that. nextel cup engines typically run 45-50psi @9000rpm. i had a pressure reliefe valve stick on a motor while on the dyno...would climb from 15@idle to 35@6500rpm. we made 15 pulls with no trouble at all.BlackoutSteve wrote: Anyway, the bottom line is I'm scared to load this engine on the dyno at 7500rpm and a max oil pressure of only 45psi.
5-10psi at idle doesn't scare me ..as much!
I have to do something about this and closing up clearances to less than GM spec or using a lesser quality non-self-oiling lifter is not the answer.
BBC oil pressure
This is my opinion, the result of my experience, which is much less than other posters. If your hot oil pressure climbs to 45 with RPM, and then QUITS climbing, you have a serious problem, and I would not run the engine under load until I found out what. I have a M77HV modified to allow me to run the bypassed oil through a glass tube so I can observe what is happening.
Some observations about what has been said. Unless you can demonstrate your oil flowing from the pump into your engine with NO entrained air, the fluid you are pumping is compressible.
A M77HV has a bypass valve, the excess volume is bypassed to the pump inlet. This is great for reducing velocity in the pickup tube, but heats and aerates the oil BADLY.
The BBC oil system has a critical flaw for your application, the pressure regulator is UPSTREAM of all the restrictions (filter, cooler, plumbing, etc.)
You mentioned the LS7 diverter valve. Ensure that the oil is NOT flowing through it. It is a severe restriction, and I suspect you have a restriction somewhere.
You might try removing all your external fittings and either run with no filter or reinstall the spin-on adapter and use the 2 quart truck filter (either WIX 51773 or 51794, I can never remember, one's Ford, the other Chevy), to rule out any problems with your plumbing.
I have installed a pressure regulator under the intake manifold, tapping into the lifter feed passage in front of the lifters, and blocked the oil pump pressure regulator. My goal was 60psi at the end of the circuit, regardless of operating conditions. This also allowed spraying the excess volume onto the cam, a much better use of pump capacity, in my opinion. I'm sure I'll get blasted about windage, but for my application cam life was more important than a few extra horsepower.
These are my thoughts, most of them the result of expensive 'learning sessions'. I don't have a fat budget to explore the subtle nuances of problems, so I probably go in the direction of overkill. However, other than catastophic component failure, failures in the lube system kill motors faster than anything.
Some observations about what has been said. Unless you can demonstrate your oil flowing from the pump into your engine with NO entrained air, the fluid you are pumping is compressible.
A M77HV has a bypass valve, the excess volume is bypassed to the pump inlet. This is great for reducing velocity in the pickup tube, but heats and aerates the oil BADLY.
The BBC oil system has a critical flaw for your application, the pressure regulator is UPSTREAM of all the restrictions (filter, cooler, plumbing, etc.)
You mentioned the LS7 diverter valve. Ensure that the oil is NOT flowing through it. It is a severe restriction, and I suspect you have a restriction somewhere.
You might try removing all your external fittings and either run with no filter or reinstall the spin-on adapter and use the 2 quart truck filter (either WIX 51773 or 51794, I can never remember, one's Ford, the other Chevy), to rule out any problems with your plumbing.
I have installed a pressure regulator under the intake manifold, tapping into the lifter feed passage in front of the lifters, and blocked the oil pump pressure regulator. My goal was 60psi at the end of the circuit, regardless of operating conditions. This also allowed spraying the excess volume onto the cam, a much better use of pump capacity, in my opinion. I'm sure I'll get blasted about windage, but for my application cam life was more important than a few extra horsepower.
These are my thoughts, most of them the result of expensive 'learning sessions'. I don't have a fat budget to explore the subtle nuances of problems, so I probably go in the direction of overkill. However, other than catastophic component failure, failures in the lube system kill motors faster than anything.
-
BlackoutSteve
- Expert
- Posts: 812
- Joined: Wed Jan 18, 2006 6:53 am
- Location: Melbourne, Australia.
- Contact:
Thanks TRN for your reply.
I know the spur gear oil pumps are ineffiecent and their byapssing/pressure reliefing is not so good by design. I have been wondering if I could improve it by modifying it to bypass back to the pan instead of to the inlet. Another easy mod, but have the fear of creating another problem somehow.
Might be archaic design, but at least it's tried, true and reliable.
Having the pump relieve pressure however, is good in the way that they control the maximum pressure entering the engine, but then have no control of the minimum pressure furthest from the pump, like the far ends of the lifter galleries.
Mounting the pressure relief furthest from the pump is also good in that it controls your maximum pressure at what is usually the place of lowest pressure. Only downside with that, I assume, would be exessive pressures at the pump unless you really knew how much your engine "bled" and compensated for it.
I intend running my engine again momentarily without the cooler and filter connected for a pressure check.
Once again, all bottomend clearances have been checked and are good.
Perhaps there is excessive bleed off around the lifter bores, but if that's the case, I'll Band-Aid it untill the time comes to completely strip and bronze bush.
Right now I am modifying a M77HV to increase it's volume by a further 25%. I am hoping this additional volume restores the pressure I have lost from the roller lifters. I too expect to get yelled or laughed at, but they way I see it is I am simply providing the additional volume I am now using.
If I had a dry sump, I am sure all the advice would be "why don't you just turn up the pump and get over it?".
I post some pics shortly.
I know the spur gear oil pumps are ineffiecent and their byapssing/pressure reliefing is not so good by design. I have been wondering if I could improve it by modifying it to bypass back to the pan instead of to the inlet. Another easy mod, but have the fear of creating another problem somehow.
Might be archaic design, but at least it's tried, true and reliable.
Having the pump relieve pressure however, is good in the way that they control the maximum pressure entering the engine, but then have no control of the minimum pressure furthest from the pump, like the far ends of the lifter galleries.
Mounting the pressure relief furthest from the pump is also good in that it controls your maximum pressure at what is usually the place of lowest pressure. Only downside with that, I assume, would be exessive pressures at the pump unless you really knew how much your engine "bled" and compensated for it.
I intend running my engine again momentarily without the cooler and filter connected for a pressure check.
Once again, all bottomend clearances have been checked and are good.
Perhaps there is excessive bleed off around the lifter bores, but if that's the case, I'll Band-Aid it untill the time comes to completely strip and bronze bush.
Right now I am modifying a M77HV to increase it's volume by a further 25%. I am hoping this additional volume restores the pressure I have lost from the roller lifters. I too expect to get yelled or laughed at, but they way I see it is I am simply providing the additional volume I am now using.
If I had a dry sump, I am sure all the advice would be "why don't you just turn up the pump and get over it?".
I post some pics shortly.
-
caddycarlo
- Member
- Posts: 66
- Joined: Thu Sep 07, 2006 11:50 am
- Location: Albuquerque NM
-
rallye bob
- Member
- Posts: 113
- Joined: Sat Dec 30, 2006 10:06 am
- Location: N.Illinois Near Chicago
-
BlackoutSteve
- Expert
- Posts: 812
- Joined: Wed Jan 18, 2006 6:53 am
- Location: Melbourne, Australia.
- Contact:
-
BlackoutSteve
- Expert
- Posts: 812
- Joined: Wed Jan 18, 2006 6:53 am
- Location: Melbourne, Australia.
- Contact:
As promised, here are some pics of the modified pump.
As I expect to get flack from this sort of modification, but I just want to remind that I never expected to have to modify the stock oiling system in such a way, and keep asking myself "Am I sure?".. Well, unfortunately I know the existing clearances (which are all good with the exception of knowing the lifter to bore) and I know my existing oil pressure, which in my opinion, is low..
So.. here is the pump.
It has been increased in volume over the M77HV by 3/8", 0.375" or 27%.
I tried to calculate just how much additional volume I would require, but found no good info I could rely on.
The M77HV is only a 1/4" or 22% larger than the standard GM pump.
(That's the old standard GM pump by the way, as the "standard" GM pump today in all BB crate engines is actually the HV pump! Because of the factory fitted roller cams perhaps?)
I have gone 27% more than the M77HV or 55% larger than the old standard. I am hoping this is way too much.
I was going to add only a 1/4", but thought, what if I need 5/16", so I just went 3/8" to be safe, and will run the engine shortly, note the new oil pressure, pull the pump again and mill to reduce what additional volume I have added to arrive at the desired pressures.
Stay tuned.
As I expect to get flack from this sort of modification, but I just want to remind that I never expected to have to modify the stock oiling system in such a way, and keep asking myself "Am I sure?".. Well, unfortunately I know the existing clearances (which are all good with the exception of knowing the lifter to bore) and I know my existing oil pressure, which in my opinion, is low..
So.. here is the pump.
It has been increased in volume over the M77HV by 3/8", 0.375" or 27%.
I tried to calculate just how much additional volume I would require, but found no good info I could rely on.
The M77HV is only a 1/4" or 22% larger than the standard GM pump.
(That's the old standard GM pump by the way, as the "standard" GM pump today in all BB crate engines is actually the HV pump! Because of the factory fitted roller cams perhaps?)
I have gone 27% more than the M77HV or 55% larger than the old standard. I am hoping this is way too much.
I was going to add only a 1/4", but thought, what if I need 5/16", so I just went 3/8" to be safe, and will run the engine shortly, note the new oil pressure, pull the pump again and mill to reduce what additional volume I have added to arrive at the desired pressures.
Stay tuned.
-
BlackoutSteve
- Expert
- Posts: 812
- Joined: Wed Jan 18, 2006 6:53 am
- Location: Melbourne, Australia.
- Contact:
The pump volume is increase simply by making the housing and gears longer to displace more fluid during each revolution. (I thought the pics showed that.)
It's exactly the same way they increased the volume from the old stock 1.14" pump, to the 1.3" and 1.39" HV pumps.
Mine is now a 1.765", but will hopefully end up being much less, like 1.640" perhaps.
It's exactly the same way they increased the volume from the old stock 1.14" pump, to the 1.3" and 1.39" HV pumps.
Mine is now a 1.765", but will hopefully end up being much less, like 1.640" perhaps.
-
Ed-vancedEngines
Steve,
Your pics don't show much, but I downloaded them and enhanced them. I will be back in a little bit with a new pic post of what you did. You did a lot of work to increase the volume corretly. I hope you are as dilligent at setting the gear end clearances too.
I still do not understand why you could be having problems with getting oil pressures though. When you say that all of the engine clearances are right, I am wondering what is being called right? There seems in my mind to still be an internal oil leak.
How much oil pressure can you register and hold for 15 or more minutes using a pre-luber with a drill? How much rpm is the drill rated for?
I am imprssed with the work you have done. I am guessing you cut off a part of the gears from one pump and welded them onto the other gear but maybe mated the two pieces together by maching steps in each to mate them accurately?
I also see that you have sliced off a chunk of the body of another pump to use as a spacer? I am curious how you managed to get all of the internal machining to match up around the gears without increasing the gear side clearances, and I am also very interested in how you sliced it so perfectly. I am also wondering how you did mate the two gear sections together? I will probably nevr do this, but still I am impressed at your ingenuity and quality of work in accomplishing this.
Ed
Your pics don't show much, but I downloaded them and enhanced them. I will be back in a little bit with a new pic post of what you did. You did a lot of work to increase the volume corretly. I hope you are as dilligent at setting the gear end clearances too.
I still do not understand why you could be having problems with getting oil pressures though. When you say that all of the engine clearances are right, I am wondering what is being called right? There seems in my mind to still be an internal oil leak.
How much oil pressure can you register and hold for 15 or more minutes using a pre-luber with a drill? How much rpm is the drill rated for?
I am imprssed with the work you have done. I am guessing you cut off a part of the gears from one pump and welded them onto the other gear but maybe mated the two pieces together by maching steps in each to mate them accurately?
I also see that you have sliced off a chunk of the body of another pump to use as a spacer? I am curious how you managed to get all of the internal machining to match up around the gears without increasing the gear side clearances, and I am also very interested in how you sliced it so perfectly. I am also wondering how you did mate the two gear sections together? I will probably nevr do this, but still I am impressed at your ingenuity and quality of work in accomplishing this.
Ed