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Variable Oil Pressure ... can it be done?

cheekychimp

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Is there such a thing as an Adjustable Oil Pressure Regulator? I realize it is much simpler to use a restrictor to reduce oil pressure, but that requires testing various hole sizes until the required pressure or range is accomplished.

Could a fuel pressure regulator be used? Would the diaphragm be effected by temperature/viscosity? And irrespective of whether you use a restrictor or a regulator, won't a variation in your source pressure result in a similar variation in 'regulated' pressure? So even if you set your regulator or use a restrictor to give you 34 psi from a 70 psi source, won't your 'regulated' 34 psi pressure increase at start up (100+ psi) or higher rpms?
 

Terry Posten

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I would think temp and viscosity would affect the ability to hold a set pressure as would input pressure.
 

cheekychimp

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Yeah that's what I thought. I think variation in source pressure is going to be a big issue on a belt driven, RPM dependent pump.

Putting that particular issue aside for the moment, what started me thinking about this was a thread on another forum about how turbo spool up could be reduced by as much as 300 rpms in the 3000-4000 rpm range simply by varying the oil supply pressure to the turbo. I was just thinking if you could wire up an oil pressure gauge at the turbo and had a way to adjust oil flow and therefore pressure at that point you could tune oil supply for the best spool up.

300 rpms isn't a huge difference but reaching 18-20 psi at 3200 rpms instead of 3500 is to me a worthwhile goal and one which most other people seem happy to pursue by paying out for ball bearing turbos, NLTS and dyno time etc
 

Barnes

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If you really wanted to do this, I propose what might be a bit easier. Have your turbo oil supply line split and have a smaller restriction (more flow) in one line, larger (less flow) in another. Put a fail-open electric solenoid valve inline with the larger restriction. Open the solenoid with an RPM switch or some such mechanism so that after spool up, the turbo will be supplied with more oil.

I haven't thought this through, so you might have to spend time thinking about what line to use the solenoid on. However I think the concept is good, and the parts are readily available.
 

cheekychimp

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Barnes,

The issue is this, with the Balance Shafts in the engine removed people are seeing 100 psi on cold starts and up to 100 psi at WOT (7500 rpms). So whilst I think your idea might work to prevent cold start pressure surges, it will probably be worse for high rpms. I think I am going to have to port the oil filter housing relief valve and then experiment with different restrictors.

Paul.
 

Barnes

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I don't see how my idea doesn't work? You open or close restrictors as you need to vary your oil demand. /ubbthreads/images/graemlins/dunno.gif

However if the problem only stems from high oil pressure at higher RPMS, then having a oil relief valve that works well is all you need.
 

IncorpoRatedX

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i thought this problem was solved by porting the relief valve in the oil filter housing, someone correct me if im wrong...??
 

IncorpoRatedX

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yup, that was the case

click
 

Barnes

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Well, I guess here is the question. If you have proper oil pressure across all RPMs, is there any reason to regulate pressure to the turbo improve spool? Will it improve spool? Or is the extra lag only due to a very high pressure situation. If that is the case, just port your oil filter housing and you are set.

I think it would be sweet if someone made a smaller oil pump gear set since we need less oil with ball bearing turbos and no balance shafts. /ubbthreads/images/graemlins/grin.gif
 

IncorpoRatedX

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one might suggest the oil pump from a 1.6 colt or whatever it is the BSE kit comes from. Assuming the gears fit, they should be sized properly for the lack of balance shafts and lack of turbo oil supply lines...
 

Barnes

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Ahh.. interesting idea. You would probably need the pump cover. Or the entire front cover if it fits. If the front cover does not fit, then you might be able to use just the pump cover as I think that is the space the gears occupy, where as the front cover is flat.
 

cheekychimp

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Quoting Alpha Male:
one might suggest the oil pump from a 1.6 colt or whatever it is the BSE kit comes from. Assuming the gears fit, they should be sized properly for the lack of balance shafts and lack of turbo oil supply lines...



Josh,

I spoke with CutlassJim in PMs about this but he said the BSE kit is just an oil pump shaft from a 90s Mirage but that the pump on that is essentially the same since the Cyborg was a DOHC turbocharged engine so designed to supply extra oil. He said the SOHC pumps look the same but are different and that since the covers are all the same size the gears are also the same throughout the 4g engines even through the 4G64.

I'm confused here. Surely if this is true, all the 4G61T engines would be seeing insane oil pressures in stock form if they have no balance shafts. I'm beginning to think there must be a solution here.

Paul.
 
Last edited:

IncorpoRatedX

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Yeah, porting the relief valve..

But aside from that, maybe they have some part of the engine that is slightly different to relieve pressure.

Either way, I've ported the relief valve and had great results.
 

Polish

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I ported my relief valve years ago, I thought I took out a good bit of material. Upon first start up I had 115-120psi Oil Pressure on a Mechanical HKS gauge...

After that I just assumed either

A. The porting doesn't work and everyone is an idiot
B. I didn't take enough material out
C. My engines just love to make 120psi - this is the second one, on the second high end gauge that read this way. First was OEM 7 bolt with a Greddy gauge...
D. I am one of few who actually buy oil pressure gauges that read accurately over 100psi?

No idea really, I just chalked it up to another one of *those things* that didn't work out like the internet claimed it would /ubbthreads/images/graemlins/dunno.gif...

I fed my turbo from the head like Mitsu designed so I didn't worry about over oiling it and otherwise just went along with things. It always ran super high oil pressures, no matter the thickness of oil. I didn't have any leaks so I just let it be.

After being around these cars/engines for a while and now that I am out of the game I notice more and more that people need to K.I.S.S....

Keep It Simple Stupid.

You especially Paul, you seem to over think everything homie. Just get it built and enjoy it already. Not everything needs modified or messed with. /ubbthreads/images/graemlins/wink.gif
 
Last edited:

charmcity

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in the 300zx TT they had variable oil pressure system on the car you may want to see what that intells.
 

bazeng

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I used to have 100+ psi at cold start / full revs.

With a bit of porting (very little, only a few mm's and a big clean up of all sharp edges) it now sees a max of 80psi.
 

IncorpoRatedX

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Quoting Polish:
I ported my relief valve years ago, I thought I took out a good bit of material. Upon first start up I had 115-120psi Oil Pressure on a Mechanical HKS gauge...

After that I just assumed either

A. The porting doesn't work and everyone is an idiot
B. I didn't take enough material out
C. My engines just love to make 120psi - this is the second one, on the second high end gauge that read this way. First was OEM 7 bolt with a Greddy gauge...
D. I am one of few who actually buy oil pressure gauges that read accurately over 100psi?

No idea really, I just chalked it up to another one of *those things* that didn't work out like the internet claimed it would /ubbthreads/images/graemlins/dunno.gif...

I fed my turbo from the head like Mitsu designed so I didn't worry about over oiling it and otherwise just went along with things. It always ran super high oil pressures, no matter the thickness of oil. I didn't have any leaks so I just let it be.

After being around these cars/engines for a while and now that I am out of the game I notice more and more that people need to K.I.S.S....

Keep It Simple Stupid.

You especially Paul, you seem to over think everything homie. Just get it built and enjoy it already. Not everything needs modified or messed with. /ubbthreads/images/graemlins/wink.gif



The answer is either; B: you did not take enough material out
Or
E: you just plain did it wrong.

My silver galant hasn't been modified in that manner yet and has uncomfortably high oil pressure, I'll document it for ya /ubbthreads/images/graemlins/smile.gif
 

Polish

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I may not have taken enough out, it is surely possible. It didn't matter in the end though.
 

cheekychimp

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Quoting cheekychimp:


I'm confused here. Surely if this is true, all the 4G61T engines would be seeing insane oil pressures in stock form if they have no balance shafts. I'm beginning to think there must be a solution here.

Paul.



Quoting Alpha Male:
Yeah, porting the relief valve..

But aside from that, maybe they have some part of the engine that is slightly different to relieve pressure .

Either way, I've ported the relief valve and had great results.



Yeah but Josh that's just it. Porting the relief valve is a band aid and it's solving a symptom not the cause. If you guys don't want to discuss it,I understand. It isn't that you aren't trying to help and yes I know sometimes (alright a lot of the time) I DO over complicate things, but I think this is a pretty big issue that everyone really seems unconcerned with.

Quite a few years ago, people decided that it was a good idea to drop the balance shafts because you got 10 extra horsepower, it was one less belt and failure to worry about and they really didn't do much anyway. It raised oil pressures a bit but hey what the hell. You guys all know what oil pressures of 140 psi can do to an engine. Magnus has pages of tech articles on their site talking about oil supply issues relating to crankwalk and yet everyone breezes over this issue as if it is unimportant.

Porting the relief hole does work yes, but people have also documented that even after porting out the hole they have further reduced oil pressures by either cutting coils of the relief port plunger spring or backing out the retaining bolt using crush washers. This suggests to me that the plunger isn't depressing enough and even if you port the hole you aren't getting the full benefit because the plunger isn't going far enough to take full benefit of it.

And where are we measuring oil pressures? If we are taking a reading off the oil filter housing does it come prior to or after that oil relief port? If it is before the restriction, it is hardly surprising oil pressure is high and doesn't necessarily indicate what pressure is in the block and at the head.

I know nothing about 4g61s but I am damn sure they are not running around ten a penny with 140 psi oil pressures from the factory just because they aren't using balance shafts. Is no-one interested in why that is? I realize it is over complicating things if 10 minutes with a dremel "solves" the issue, but a lot of good mods evolved from people taking some time to think things through. I know you understand that Josh or you wouldn't be fussing around with EVO VIII axles when people have run 11s or faster on 1G and 2G stuff.
 

bazeng

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Feb 6, 2003
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Melbourne, Australia
Don't forget about this product.

I am using this also.

So far so good!

click

HLA_Pressure_Regulator_Small.jpg


Oil_Pressure_new_regulator_noted.png
 
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