Oil pumps for performance engines

[Dr.Jeff]

The topic of "performance" oil pumps has been discussed, here's a good example:

Oil Pump design changes

In a prior thread there was mention of oil pump design and part numbers for the X1/9 and for later models of Fiats: https://xwebforums.com/forum/index.php?threads/have-you-ever-wanted-a-16v-head-on-your-x-engine.29220/page-2 While rebuilding some X1/9 engines I compared the oil pumps and found...

xwebforums.com

The bottom line is there isn't a "performance" pump available for the X. By "performance" I mean high volume and/or high pressure compared to the stock pump. There are a couple variations of stock pumps for the SOHC with different part numbers (see the linked thread), but they are all about the same in terms of function - i.e. the same output.

So I was intrigued by a recent episode of the TV show "Engine Masters", where they tested a range of oil pumps - from stock to wild. The show runs a series of dyno tests to compare components with sensors to record relevant data. In this case they tracked oil output volume, pressure, and the engine's torque/HP output (to see if any of the pumps robbed it of power). As usual the subject engine was a American V8, but it used the same design of oil pump as the X so I think the general results might still apply to some extent.

The pumps tested were: #1) a stock one, #2) a high pressure one, #3) a high volume one, and #4) a custom super-high volume and pressure one (in that order). All but the last one were the same style/design made by the same company. The increased pressure pump (#2) was essentially a stock pump with a higher bypass relief valve setting. The higher volume pump (#3) had a longer body with longer ("taller") gears as well as a higher bypass setting (same bypass as #2). The last pump (#4) was a completely different design and a total overkill.

The results were quite interesting; there was a significant increase in pressure AND volume with all of the non-stock pumps (#2-4). Surprisingly as the pressure was increased (#2) so was the volume, with similar output as the larger high volume one (#3). This was due to less oil allowed to run through the bypass, thus providing increased volume into the engine. So a higher bypass relief setting (#2) had about the same volume as the larger (high volume, #3) pump. Vice-versa the high volume pump (#3) had about the same pressure as #2 (due to the same bypass level). Although the high volume #3 was able to bring the higher pressure at a lower RPM compared to #2. The last one (#4) had significantly higher pressure and volume than the others, but it was a completely different animal so my focus is mainly on #1-3.

As for the power needed to run the pumps, another surprise. Comparing the first three (#1,2,3), they did NOT have any significant effect on engine power (torque and HP). The most change was with #3 at about 1%. However the last pump (#4) did require more power to allow for the huge increase in pressure and volume, as might be expected.

So here is my thought for the X (SOHC) oil pump. Given there are not any performance pumps available, then simply increasing the bypass pressure setting (add shims to the relief spring) will serve to increase pressure AND volume, without any notable effect on engine output. If you are building a high performance engine intended for extreme use, then that might be the best option to help ensure it gets a good supply of oil to protect it.

Thoughts?

 

[Jonohhh]

It's a pretty loaded question...I certainly do not have the experience with this platform to answer for the SOHC specifically. I'll keep things general

For the below, i consider the relief valve and pump to be separate entities regarding tuning/upgrading/effects...and bearing clearances to be unchanged from factory.

I'm quite curious to see what responses you get. Generally, the advantage to a higher volume pump is more oil pressure at lower engine speeds. This can be somewhat necessary for a few reasons, mainly in builds creating cylinder pressures at low engines speeds that the original lubrication system was not designed for. The amount that you have to push most motors before the oil pressure/rpm relationship becomes inadequate is pretty significant in many cases...and simply using a thicker oil with a higher film strength is adequate. Many people seem to think they need a lot more oil pressure than they really do... typically the end result is the relief valve being wide open most of the time- wasting power and creating a category 6 hurricane of oil spray in the crankcase.

If someone (ahem, you, in this case?) is doing a build where they plan to use forced induction and a not-oversized turbo to create a torquey low and mid range, that of all situations would probably be the worst case for the stock lubrication system, and could potentially warrant some looking into.


For a high rpm build like how most modded SOHCs end up, I don't see any use whatsoever in an upgraded pump, though depending on the piston accelerations we're talking about, a higher pressure relief valve could come of some use to put a bandaid on bearing wear issues if they begin to show themselves.

The majority of the film strength in a hydrodynamic bearing doesn't come from the oil pressure itself- it comes from the relative rotation of the shaft inside the journal, trapping fluid between the two surfaces and creating a separation force. The oil pressure simply needs to be adequate to feed this journal, though there most definitely is a relationship between oil pressure and maximum acceptable force on the bearing. It is not the only/primary factor, especially at higher engine speeds. Because the rotation is such a large component of how these bearings work, at low engine speeds the benefit of higher pressure is much more significant than midrange and high rpm operation (until we start talking about crazy piston accelerations on extreme rpm builds).

Do these engines even wear bearings bad/at all? The FIRE 1.4T seems to have some incredible ability to not wear bearings at all, surprisingly, and by no means is it a modern bottom end. There have been 100k mile teardowns with bearings that look like they just came off the factory floor- and this is with a motor that readily makes 18lbs of boost and over 160lbft before 2600rpm.

 

[kmead]

The topic of "performance" oil pumps has been discussed, here's a good example:

Oil Pump design changes

In a prior thread there was mention of oil pump design and part numbers for the X1/9 and for later models of Fiats: https://xwebforums.com/forum/index.php?threads/have-you-ever-wanted-a-16v-head-on-your-x-engine.29220/page-2 While rebuilding some X1/9 engines I compared the oil pumps and found...

xwebforums.com

The bottom line is there isn't a "performance" pump available for the X. By "performance" I mean high volume and/or high pressure compared to the stock pump. There are a couple variations of stock pumps for the SOHC with different part numbers (see the linked thread), but they are all about the same in terms of function - i.e. the same output.

So I was intrigued by a recent episode of the TV show "Engine Masters", where they tested a range of oil pumps - from stock to wild. The show runs a series of dyno tests to compare components with sensors to record relevant data. In this case they tracked oil output volume, pressure, and the engine's torque/HP output (to see if any of the pumps robbed it of power). As usual the subject engine was a American V8, but it used the same design of oil pump as the X so I think the general results might still apply to some extent.

The pumps tested were: #1) a stock one, #2) a high pressure one, #3) a high volume one, and #4) a custom super-high volume and pressure one (in that order). All but the last one were the same style/design made by the same company. The increased pressure pump (#2) was essentially a stock pump with a higher bypass relief valve setting. The higher volume pump (#3) had a longer body with longer ("taller") gears as well as a higher bypass setting (same bypass as #2). The last pump (#4) was a completely different design and a total overkill.

The results were quite interesting; there was a significant increase in pressure AND volume with all of the non-stock pumps (#2-4). Surprisingly as the pressure was increased (#2) so was the volume, with similar output as the larger high volume one (#3). This was due to less oil allowed to run through the bypass, thus providing increased volume into the engine. So a higher bypass relief setting (#2) had about the same volume as the larger (high volume, #3) pump. Vice-versa the high volume pump (#3) had about the same pressure as #2 (due to the same bypass level). Although the high volume #3 was able to bring the higher pressure at a lower RPM compared to #2. The last one (#4) had significantly higher pressure and volume than the others, but it was a completely different animal so my focus is mainly on #1-3.

As for the power needed to run the pumps, another surprise. Comparing the first three (#1,2,3), they did NOT have any significant effect on engine power (torque and HP). The most change was with #3 at about 1%. However the last pump (#4) did require more power to allow for the huge increase in pressure and volume, as might be expected.

So here is my thought for the X (SOHC) oil pump. Given there are not any performance pumps available, then simply increasing the bypass pressure setting (add shims to the relief spring) will serve to increase pressure AND volume, without any notable effect on engine output. If you are building a high performance engine intended for extreme use, then that might be the best option to help ensure it gets a good supply of oil to protect it.

Thoughts?

This is the traditional way to more pressure and volume.

The big issue one will get into, if one were in a colder climate, is excessive cold pressure which can blow seals so more careful warmup is important.

Worth doing.

 

[Dr.Jeff]

It's a pretty loaded question...I certainly do not have the experience with this platform to answer for the SOHC specifically.

For the below, i consider the relief valve and pump to be separate entities regarding tuning/upgrading/effects...and bearing clearances to be unchanged from factory.

I'm quite curious to see what responses you get. Generally, the advantage to a higher volume pump is more oil pressure at lower engine speeds. This can be somewhat necessary for a few reasons, mainly in builds creating cylinder pressures at low engines speeds that the original lubrication system was not designed for. The amount that you have to push most motors before the oil pressure/rpm relationship becomes inadequate is pretty significant in many cases...and simply using a thicker oil with a higher film strength is adequate. Many people seem to think they need a lot more oil pressure than they really do... typically the end result is the relief valve being wide open most of the time- wasting power and creating a category 6 hurricane of oil spray in the crankcase.

If someone (ahem, you, in this case?) is doing a build where they plan to use forced induction and a not-oversized turbo to create a torquey low and mid range, that of all situations would probably be the worst case for the stock lubrication system, and could potentially warrant some looking into.


For a high rpm build like how most modded SOHCs end up, I don't see any use whatsoever in an upgraded pump, though depending on the piston accelerations we're talking about, a higher pressure relief valve could come of some use to put a bandaid on bearing wear issues if they begin to show themselves.

The majority of the film strength in a hydrodynamic bearing doesn't come from the oil pressure itself- it comes from the relative rotation of the shaft inside the journal, trapping fluid between the two surfaces and creating a separation force. The oil pressure simply needs to be adequate to feed this journal, though there most definitely is a relationship between oil pressure and maximum acceptable force on the bearing- it is not the only/primary factor, especially at higher engine speeds. Because the rotation is such a large component of how these bearings work, at low engine speeds the benefit of higher pressure is much more significant than midrange and high rpm operation (until we start talking about crazy piston accelerations on extreme rpm builds).

Do these engines even wear bearings bad/at all? The FIRE 1.4T seems to have some incredible ability to not wear bearings at all, surprisingly, and by no means is it a modern bottom end. There have been 100k mile teardowns with bearings that look like they just came off the factory floor- and this is with a motor that readily makes 18lbs of boost and over 160lbft before 2600rpm.

I agree a high volume/pressure pump is not required in most cases. However this thought was intended with those (limited?) situations in mind where a increased safety margin (i.e. more than ample oil flow in general) is desired....for whatever reason. Perhaps one example might be having a higher volume pump when a large external oil cooler is added to the system? As you say the turbo build is another example. The turbo requires a oil feed to it, and that comes off the engine's bearing oil feed circuit. Any time you rob oil from the bearings, especially when you are also adding load to them (i.e. boost), you need to consider the oil volume and pressure left to supply them (and the head).

The thing about the referenced tests (performed on the program) that got my attention was the fact increasing the oil pump workload for increased pressure/volume had zero negative influence on engine output. While I expected it to cause little draw, I would have guessed there might a noticeable change on the dyno. So why not add some insurance?

 

[Dr.Jeff]

This is the traditional way to more pressure and volume.

The big issue one will get into, if one were in a colder climate, is excessive cold pressure which can blow seals so more careful warmup is important.

Worth doing.

Agreed, too much pressure can create new problems in some situations.

I was a little surprised at how much the volume increased simply by upping the bypass pressure; as much as a larger pump will offer. That was my main point, especially considering there are no options for a higher volume pump for the X/SOHC engine. It's a simple mod to increase the spring tension for the X pump bypass. That is something I would do for a performance engine build anyway (just my personal preference). So to find it also improve volume and at no cost to the engine's output was a nice bonus. I guess it's one of those thoughts I've always wondered but never investigated or tested myself.

 

[abarth4]

Just a brief reminder.... pumps create volume, not pressure. Restriction to flow creates pressure.

 

[Jonohhh]

The thing about the referenced tests (performed on the program) that got my attention was the fact increasing the oil pump workload for increased pressure/volume had zero negative influence on engine output. While I expected it to cause little draw, I would have guessed there might a noticeable change on the dyno. So why not add some insurance?

That is an...interesting...result to say the least. I'm not entirely sure how they managed that. It's definitely measurable under controlled conditions and can be in the double digits for crank HP in some larger engines. At WOT, the difference in power might be a few HP, though because the parasitic loss does not diminish with engine load, it becomes an even larger % of the engines total output in low load scenarios. This is part of the reason so many modern cars come fitted with variable displacement oil pumps that can reduce the volume per rotation of the pump to increase fuel economy.

If you don't care about a few HP and hit on fuel economy during cruise, then whatever- go for it. There's not really another downside unless you're running crazy pressures. It may make the lubrication system as a whole grossly inefficient, but sure, it's some extra insurance that may be worth it if ultimate durability is the goal.

For all intents and purposes, a "high pressure pump" should just be one with a higher pressure relief valve, since the only real thing you can change about the pump is its volume pumped per rotation. Looking to see if the Uno Turbo has a higher volume pump (I would, but not sure how to find such info?) should tell you what you need to know about if that particular turbo flows enough oil to warrant a higher volume pump to keep pressures acceptable.

 

[Dr.Jeff]

Just a brief reminder.... pumps create volume, not pressure. Restriction to flow creates pressure.

Yes and no; yes restriction creates pressure, but in the case of a engine oil pump it is a little different...let me explain.

For this discussion on oil pump function, the terms "pressure" and "volume" need to be clear. For this application (engine oil pumps) I like to think of "pressure" as the rate of flow - how fast it moves, and volume as the amount of flow - how much is moved. While that is not the scientifically correct definitions of those terms it will help to explain things here. They are two different functions which are interrelated. As @abarth4 said, typically in fluid dynamics those two have an inverse relationship; to increase pressure you add restriction, which also reduces volume. An example is the air pressure regulator on your shop air compressor. By restricting the air moving past it, more pressure is need to overcome the restriction. Same with the fuel pressure regulator in a typical engine's fuel system. And vice-versa; to increase volume you reduce restriction, which lowers pressure.

And that inverse relationship between pressure and volume is why I was surprised by the test results on the dyno. I guess I was thinking the high pressure oil pump would have less oil volume and vice-versa. However in the case of a engine oil pump the oil can travel along two routes as it leaves the pump. One is to the engine's oil galleys (feeding all of the vital components) and the other is a "bypass" back to the oil sump (away from the vital components). Therefore oil pressure is controlled by how much oil is directed away from the oil galleys and through the bypass back to the sump. So the restriction is not to the oil galleys, but to the bypass. As you restrict oil from the bypass (increased pressure), you also allow more oil to travel through the galleys (increased volume). As Steve Brule said on the program, it depends WHERE in the engine you are measuring the pressure and volume.

That's why the same pump with a higher bypass pressure provided increased oil pressure AND increased oil volume. At least with respect to the oil galleys, which is where the oil flow is critical. But keep in mind with the high pressure pump there was a difference in pressure/volume at low RPMs (e.g. idle speed). That's where a high volume pump (one that is actually larger) offers more pressure and volume at all RPMs. Unfortunately no such pump exists for the SOHC that I'm aware of.

As I mentioned previously, when I build a performance engine I like to increase pressure (shim the relief spring) for added insurance. However I really did not consider that I was also increasing volume by doing so. And in the case of my turbo build the added volume is a real plus. But I'll discuss that more later.

 

[Ulix]

Jeff, the fact that in the engine masters example, a stronger spring resulted in higher measured pressure, surprises me.
This says that the relief valve was OPEN under normal operating conditions.
I would have expected that this valve only opens under abnormal conditions such as super cold oil.

For your deduction that a shim under the spring would make a difference to our engine, one should confirm that this is the case here also.

I would be interested in having a very good oil supply at low rpm, because I run a 1900.
I am collecting parts right now for another one for the 128. This will be a more docile, very driveable street motor with a euro cam which will probably produce even more torque at low rpm.
I have a shim under the spring, but don't expect that to help at low rpm.

A question that has not been asked in this thread: the Uno Turbo and later 1600s have oil squirters. Do these typically need noticeably more oil flow so that a different pump would be required? I have seen a number quoted that one such squirter can use up to 1.4 L/min.
I have seen pumps with 8, 9, and 10 teeth, but no pattern to where each was used.
A pump volume test with controlled rpm would be in order...

 

[Dr.Jeff]

That is an...interesting...result to say the least. I'm not entirely sure how they managed that. It's definitely measurable under controlled conditions and can be in the double digits for crank HP in some larger engines. At WOT, the difference in power might be a few HP, though because the parasitic loss does not diminish with engine load, it becomes an even larger % of the engines total output in low load scenarios. This is part of the reason so many modern cars come fitted with variable displacement oil pumps that can reduce the volume per rotation of the pump to increase fuel economy.

If you don't care about a few HP and hit on fuel economy during cruise, then whatever- go for it. There's not really another downside unless you're running crazy pressures. It may make the lubrication system as a whole grossly inefficient, but sure, it's some extra insurance that may be worth it if ultimate durability is the goal.

For all intents and purposes, a "high pressure pump" should just be one with a higher pressure relief valve, since the only real thing you can change about the pump is its volume pumped per rotation. Looking to see if the Uno Turbo has a higher volume pump (I would, but not sure how to find such info?) should tell you what you need to know about if that particular turbo flows enough oil to warrant a higher volume pump to keep pressures acceptable.

I think my last post (#8) may answer your question, as to why the high pressure oil pump did not reduce engine power output. The pump itself is not bigger and therefore it does not create more workload (as I erroneously stated earlier). It is the bypass route after the pump that is regulating pressure so the pump sees no change in workload (no parasitic loss); the total flow of oil through the pump itself is not changed...only where that flow is directed.

In the case of a high volume pump, the pump is actually larger and therefore does add some parasitic loss. However in their tests that loss was around 1% (if I remember the numbers correctly). In the case of our little X engines that equates to about three quarters of one horse power. I challenge anyone to detect that loss in actual use. But that's a mute point as there is no such pump for the X.

 

[Dr.Jeff]

Jeff, the fact that in the engine masters example, a stronger spring resulted in higher measured pressure, surprises me.
This says that the relief valve was OPEN under normal operating conditions.
I would have expected that this valve only opens under abnormal conditions such as super cold oil.

For your deduction that a shim under the spring would make a difference to our engine, one should confirm that this is the case here also.

I would be interested in having a very good oil supply at low rpm, because I run a 1900.
I am collecting parts right now for another one for the 128. This will be a more docile, very driveable street motor with a euro cam which will probably produce even more torque at low rpm.
I have a shim under the spring, but don't expect that to help at low rpm.

A question that has not been asked in this thread: the Uno Turbo and later 1600s have oil squirters. Do these typically need noticeably more oil flow so that a different pump would be required? I have seen a number quoted that one such squirter can use up to 1.4 L/min.
I have seen pumps with 8, 9, and 10 teeth, but no pattern to where each was used.
A pump volume test with controlled rpm would be in order...

You are correct, the relief valve is usually at least partly open. So oil is flowing in both directions, some to the galleys and some to the oil pan at all (most?) times. At idle speed the pump moves less oil and that's where the relief valve will be closed more (again, the volume vs pressure thing). In older threads it has been shown that shimming the relief spring on the X's engine does increase oil pressure to the engine. Therefore I presume the results will be similar to what the program tests found.

For you to get greater oil supply at lower RPMs you will need a larger VOLUME pump. That means a physically bigger pump. However I do not know of such a pump for these engines. Based on what I've said in these discussions, I think the next best solution is to increase the bypass resistance (shim the spring) to assure more oil is directed to the galleys. It may not help as much at idle, but the curve on their graph (in the program) showed a reasonable increase in flow as RPMs increased from idle. So it will offer some added insurance over a stock pump.

Back in post #8 I ended by saying, "And in the case of my turbo build the added volume is a real plus. But I'll discuss that more later." As this whole discussion has developed I've realized that it might have been better posted under the "turbo systems for the X" thread (linked below). Because that is where all of my thoughts on this topic have come from, my turbo engine build.

Turbo systems for X1/9's

EDIT: This thread started out talking about air flow and a intercooler. But it has grown as there is a lot more really great turbo related information to be learned from our members. So I changed the title and want to open up the discussion to any/all things relating to a turbo on a X1/9. In...

xwebforums.com

With a turbo engine there are a few factors to consider. The added boost creates more engine temperature due to greater combustion pressure. And the oil feed through the turbo unit also increases oil temperature. Therefore adding a sufficient oil cooler to the engine is a real benefit. That addition increases the demand on the oil pump. Now take some of the normal oil flow away from the oil galleys to feed the turbo unit and to supply the oil squirters and the oil pump's demand goes up even more. As you say, the oil squirters are effectively a "leak" in the system, so more flow is needed to compensate. Furthermore consider a turbo engine has greater performance potential and is likely to be worked harder than a NA one. That means greater loads on things like bearings, cylinder walls, etc., so it becomes more critical to have great oil flow to them. If we add a high lift cam (great for a boosted engine), now you've increased the need for good lubrication in the head as well. All of which tells me a high volume oil pump should be utilized for such a engine. In the absence of a high volume pump I'll take a high pressure one.

There are a couple of part numbers for X oil pumps. As you say, different number of gear teeth and some with spiral vs straight teeth. But according to a couple of automotive engineers I've discussed this with, they offer roughly no difference in oil flow (volume). As I recall the UT uses the same oil pump (part number) as all of the later SOHC's. So Fiat did not make a bigger pump for it (although they should have). I don't know of any bigger pumps from later engines that will fit in the X engine. But I'd love to find one.

 

[Bjorn Nilson]

I am thinking of having a modern oil pressure sensor connected to the ECU as I don't trust the stock sensor and gauge. The stock gauge is also somewhat hidden behind the steering wheel so it is hard to see it. I've found a good sensor from Bosch motorsport which is a combo of temp/pressure.

My oil pressure also drops when the oil cooler is active, especially when idling. It looks like the oil pressure is a little bit low in general (but again I don't trust the gauge), and oil temp rises under load. Therefore I will try a thicker fully synthetic racing oil this season. Racing oils handle high temps much better than standard mineral/semi synthetic oils. If this doesn't help rebuilding the relief valve seems to be a good alternative.
I also noticed that the oil temp is quite high on my Golf R; 90-120⁰C on a hot summer day, so high temps on turbo engines seems to be normal? Unfortunately I have no oil pressure gauge on the Golf for comparison.
Last year I posted a question about my low oil pressure on an Uno Turbo forum, but this is normal most people responded.

 

[Dr.Jeff]

I am thinking of having a modern oil pressure sensor connected to the ECU as I don't trust the stock sensor and gauge. The stock gauge is also somewhat hidden behind the steering wheel so it is hard to see it. I've found a good sensor from Bosch motorsport which is a combo of temp/pressure.
View attachment 60440
My oil pressure also drops when the oil cooler is active, especially when idling. It looks like the oil pressure is a little bit low in general (but again I don't trust the gauge), and oil temp rises under load. Therefore I will try a thicker fully synthetic racing oil this season. Racing oils handle high temps much better than standard mineral/semi synthetic oils. If this doesn't help rebuilding the relief valve seems to be a good alternative.
I also noticed that the oil temp is quite high on my Golf R; 90-120⁰C on a hot summer day, so high temps on turbo engines seems to be normal? Unfortunately I have no oil pressure gauge on the Golf for comparison.
Last year I posted a question about my low oil pressure on an Uno Turbo forum, but this is normal most people responded.

A drop in pressure when the oil cooler circuit opens would seem typical to me. You are allowing a much larger volume of oil to be routed to the cooler, and therefore away from the engine's internals. I don't want to say it's "normal" because that might imply it is good, when I don't consider any drop in pressure - for any reason - to be good. In my opinion a oil pump with a higher volume would help to negate that drop in pressure. More "reserve" capacity is on hand with the higher volume pump, to move more oil when and where needed. But unfortunately that doesn't really help you if no such pump exists. And that is my delima for my turbo build.

Likewise, higher oil temps with a turbo application is typical. Oil is routed to the turbo to lube and cool its bearings, and that is an extremely high source of heat. The super hot oil is then dumped back into the oil pan, making the overall oil temp higher. But again, I hesitate to call that "normal" for the same reason as above; any increase in oil temp (about the target temp) is not good. In my opinion a larger oil cooler would help to reduce the increase in oil temperature. This is one case where bigger is better. However you are back to the issue in paragraph one above; the need for a greater volume oil pump to supply that larger oil cooler. For my turbo build I am starting with a moderate sized oil cooler but locating it next to a electric fan so hopefully it can dissipate more heat without adding more oil volume (i.e. without a larger cooler). That is easy to do and would seem a good option for you as well.

 

[Dr.Jeff]

The comments from @Ulix in post #9 got me thinking more about a stock oil pump's potential. As Ulix alluded to, the stock oil pump must have the potential for more oil flow (volume/pressure) than is actually needed. That's why the bypass relief is open (at least partially) a lot of the time.

And that reminded me of some previous findings with the same style of oil pump on other engines. I'm very familiar with several German engines from the same era as the X, and they utilize the same design of oil pump and lubrication system (bypass relief, galleys, etc). Some tests were done to see what happens with oil pressure as the bypass spring tension is incrementally increased with a stock pump. Unfortunately the goal was only to determine how much the relief spring should be shimmed, so volume was not measured - just pressure. As the tension was raised (more shims) so was the pressure - no surprise. And it was nice to find that the increases in pressure were fairly linear with the increases in spring tension. However here is where it got interesting. When the bypass tension was increased too much (at one point it was completely blocked shut), the oil pressure go so high it blew the oil filter canister apart like a bomb. That's some serious pressure.

So a stock oil pump has the potential for much more volume/pressure than one might imagine...at least on those German engines. I have no idea what the Fiat engineers did in the 1960's when the SOHC was developed. So I can't say for certain the same is true for the X's oil pump. But that might explain why the UT did not get a larger oil pump; they felt the existing pump (as in the X) could provide sufficient oil flow for the turbo engine. However based on the comments made by @Bjorn Nilson, "Last year I posted a question about my low oil pressure on an Uno Turbo forum, but this is normal most people responded", it seems to me the UT could have benefited from a larger (higher volume) oil pump.

Going back to my personal interest in all of this. For my turbo engine build I think shimming the relief spring on the stock pump should provide a sufficient improvement in oil volume (and pressure), at least for my needs. Remember my build is with a small low-boost turbo and conservative tune on a relatively stock engine. The added oil cooler is not huge (as I described in post #13). The stock oil squirters are being retained (at least initially). And the cam is a late Euro spec 1500 item, with a reasonable (but not excessive) amount of lift increase. Furthermore this is a "street" only vehicle, not a track car. So the oil demand will not be quite as high as with a more aggressive turbo build.

 

[Ulix]

The oil pump is a "positive displacement" design. Like a roots blower on a V8.
So I imagine, if you throttle the flow enough, the pressure will increase to the moon.
And from your results mentioned above, it has enough flow to achieve sky high pressures at high rpm even under normal (non-throttled) conditions.

But all that is not the real issue, is it?
We are trying to get a higher oil pressure at LOW rpm.
With the design of the pump, flow increases linearly (I think, should look it up) with rpm.
The spring bleeds off pressure at high rpm to keep from blowing up the oil filter amongs other things. But this is at the high end of the rpm range.
The low end is dictated by the pump itself. Length of pump rotors is the main design criterion.
The question is, how much difference does the shape and number of teeth make?
Your info from some engineers suggest "not much".
This could well be true. While it is possile to imagine a tooth shape with more void area that would seem to move more oil per revolution, this imagined shape might lose the "positive dispacement" function. (Of course, the teeth do not only pump oil but also act as gears, so their shape is also dictated by that function. "Involute gears", point contact only, no slip at the contact point of the teeth).

 

[kmead]

I am thinking of having a modern oil pressure sensor connected to the ECU as I don't trust the stock sensor and gauge. The stock gauge is also somewhat hidden behind the steering wheel so it is hard to see it. I've found a good sensor from Bosch motorsport which is a combo of temp/pressure.
View attachment 60440
My oil pressure also drops when the oil cooler is active, especially when idling. It looks like the oil pressure is a little bit low in general (but again I don't trust the gauge), and oil temp rises under load. Therefore I will try a thicker fully synthetic racing oil this season. Racing oils handle high temps much better than standard mineral/semi synthetic oils. If this doesn't help rebuilding the relief valve seems to be a good alternative.
I also noticed that the oil temp is quite high on my Golf R; 90-120⁰C on a hot summer day, so high temps on turbo engines seems to be normal? Unfortunately I have no oil pressure gauge on the Golf for comparison.
Last year I posted a question about my low oil pressure on an Uno Turbo forum, but this is normal most people responded.

Nice sensor.

I wouldn’t equate a modern engine’s temperatures to our cars, modern engines are running much hotter and at variable temps to eke out horsepower, emissions and fuel economy. They have fast processors and many more levers to pull in regards to controls on the process (water flow, ignition, fuel flow etc) than you likely have in your engine management system, particularly a modern Golf turbo. We can’t control our car’s systems to the degree multibillion dollar development team can…

One could create a longer set of gears and a new lower half of the pump to enclose the additional gear length or a spacer if there was room in the sump between the two existing halves of the oil pump to house the gears. An extra 2mm of height in the gears would be a significant increase in the volume of oil it could pump

If the oil cooler is effective I would actually expect the cooler oil to keep its viscosity and raise oil pressure as the temp goes down. Temp will rise under load and oil is a very effective medium to cool the engine (an old VW flat four is notably oil cooled as well as directly air cooled), so having an oil cooler to dump heat is very worthwhile.

One could also consider running a second pump to only pump oil through the oil cooler which then dumps the cooled oil back into the vicinity of the pickup. One might use the turbo outflow as the source of this oil into the pulley driven pump normally used in a dry sump application. This could be thermostatically controlled to only bypass the turbo return when the engine oil overall is at temp. It would likely be safer to just pickup the oil in the sump near the turbo return and then output the cooled oil onto the engine’s oil pump pickup cooling the housing and placing cooler oil in that area. More complication but a pulley driven scavenge pump would be reliable and it if did fail it wouldn’t cause a catastrophic failure.

 

[Dr.Jeff]

The oil pump is a "positive displacement" design. Like a roots blower on a V8.
So I imagine, if you throttle the flow enough, the pressure will increase to the moon.
And from your results mentioned above, it has enough flow to achieve sky high pressures at high rpm even under normal (non-throttled) conditions.

But all that is not the real issue, is it?
We are trying to get a higher oil pressure at LOW rpm.
With the design of the pump, flow increases linearly (I think, should look it up) with rpm.
The spring bleeds off pressure at high rpm to keep from blowing up the oil filter amongs other things. But this is at the high end of the rpm range.
The low end is dictated by the pump itself. Length of pump rotors is the main design criterion.
The question is, how much difference does the shape and number of teeth make?
Your info from some engineers suggest "not much".
This could well be true. While it is possile to imagine a tooth shape with more void area that would seem to move more oil per revolution, this imagined shape might lose the "positive dispacement" function. (Of course, the teeth do not only pump oil but also act as gears, so their shape is also dictated by that function. "Involute gears", point contact only, no slip at the contact point of the teeth).

Exactly. And that was one of my points; a larger (longer) pump is needed to achieve that. Short of custom building one like @kmead suggests, a larger pump does not exist for these engines. So I'm suggesting the next best option is to increase the bypass relief pressure in order to improve oil volume to the galleys overall. As you say, not ideal at low RPMs. But what else is there?

In the dyno tests conducted on the program there was improved volume at "lower" RPMs with increased bypass relief pressure. They showed a graph of it and while it wasn't exactly linear, the gains were more than I would have expected. Naturally it was less at idle, but it built from there. So I do think there is something to be benefited by doing it.

Speaking of the various shapes of the available pump gears, from the information I gathered there is no significant difference between them in terms of volume.

 

[Dr.Jeff]

Nice sensor.

I wouldn’t equate a modern engine’s temperatures to our cars, modern engines are running much hotter and at variable temps to eke out horsepower, emissions and fuel economy. They have fast processors and many more levers to pull in regards to controls on the process (water flow, ignition, fuel flow etc) than you likely have in your engine management system, particularly a modern Golf turbo. We can’t control our car’s systems to the degree multibillion dollar development team can…

One could create a longer set of gears and a new lower half of the pump to enclose the additional gear length or a spacer if there was room in the sump between the two existing halves of the oil pump to house the gears. An extra 2mm of height in the gears would be a significant increase in the volume of oil it could pump

If the oil cooler is effective I would actually expect the cooler oil to keep its viscosity and raise oil pressure as the temp goes down. Temp will rise under load and oil is a very effective medium to cool the engine (an old VW flat four is notably oil cooled as well as directly air cooled), so having an oil cooler to dump heat is very worthwhile.

One could also consider running a second pump to only pump oil through the oil cooler which then dumps the cooled oil back into the vicinity of the pickup. One might use the turbo outflow as the source of this oil into the pulley driven pump normally used in a dry sump application. This could be thermostatically controlled to only bypass the turbo return when the engine oil overall is at temp. It would likely be safer to just pickup the oil in the sump near the turbo return and then output the cooled oil onto the engine’s oil pump pickup cooling the housing and placing cooler oil in that area. More complication but a pulley driven scavenge pump would be reliable and it if did fail it wouldn’t cause a catastrophic failure.

I wonder if there are any existing longer gears out there that could be used if the pump body was lengthened? A spacer sounds like the best method to lengthen the body.

 

[Bjorn Nilson]

Nice sensor.

I wouldn’t equate a modern engine’s temperatures to our cars, modern engines are running much hotter and at variable temps to eke out horsepower, emissions and fuel economy. They have fast processors and many more levers to pull in regards to controls on the process (water flow, ignition, fuel flow etc) than you likely have in your engine management system, particularly a modern Golf turbo. We can’t control our car’s systems to the degree multibillion dollar development team can…

One could create a longer set of gears and a new lower half of the pump to enclose the additional gear length or a spacer if there was room in the sump between the two existing halves of the oil pump to house the gears. An extra 2mm of height in the gears would be a significant increase in the volume of oil it could pump

If the oil cooler is effective I would actually expect the cooler oil to keep its viscosity and raise oil pressure as the temp goes down. Temp will rise under load and oil is a very effective medium to cool the engine (an old VW flat four is notably oil cooled as well as directly air cooled), so having an oil cooler to dump heat is very worthwhile.

One could also consider running a second pump to only pump oil through the oil cooler which then dumps the cooled oil back into the vicinity of the pickup. One might use the turbo outflow as the source of this oil into the pulley driven pump normally used in a dry sump application. This could be thermostatically controlled to only bypass the turbo return when the engine oil overall is at temp. It would likely be safer to just pickup the oil in the sump near the turbo return and then output the cooled oil onto the engine’s oil pump pickup cooling the housing and placing cooler oil in that area. More complication but a pulley driven scavenge pump would be reliable and it if did fail it wouldn’t cause a catastrophic failure.

I think my MaxxECU is much more advanced than the stock ECU in my Golf R despite the money VW spent on develop it. The Maxx is made for extreme applications compared to the Golf. In a way I consider my Uno Turbo build to be a modern motor, despite 8 valves, single camshaft etc. However, an old design like UT cannot handle all moden stuff like OW20 oils, but modern electronics makes it strong enough to handle twice the load compared to stock. How much power would a Golf R have without modern electronics? -Probably a lot less than actual 310hp.So why shouldn't the X1/9 and UT Turbo engines handle higher load and higher heat (just like my Golf) if we add modern electronics and feed them with oils that works at high temperatures with kept viscosity that oir engines demand?
Obviously, some stock components are not meant for a high output on the SOHC. But improving oil flow and cooling is important (despite modern race oils. Also, having the engine rear mounted din't improve the overheating

 

[Dr.Jeff]

There may be some differences in our older engines that might not allow them to be "modern" even with high tech electronic controls. Designs and materials have improved since the 60s when these were developed. But for the most part I agree, they can benefit significantly with enhanced control systems. And they definitely will benefit from improved lubrication and cooling, even if left stock.