Steve Thomas
True Classic
which is why I was saying you don't want that
Turbo systems for X1/9's
- Thread starter Dr.Jeff
- Start date
Dr.Jeff
True Classic
Understood. If you consider what "and/or" is referring to, it was a comment on what it is capable of doing - for whatever reason. In other words something of a theoretical point. There may indeed be cases where a higher pressure might be desired. Perhaps not for a stock engine or whatever you may be thinking of, but nonetheless. However we are way off the point that was made about optional oil pumps to fit the SOHC.which is why I was saying you don't want that
Since pressure vs volume has been brought up again, it reminds me of a theory I posted once before (this came from one of the engineers I noted previously). The primary "resistance" that makes oil pressure in a engine is not the relief valve, but the engine's lubrication system beyond the pump - e.g. all of the galleries, bearing clearances, filter, and other points where pressure is lost as oil flows through the system. One illustration is the example of a extremely worn engine; resistance at the bearings is decreased and without added flow volume to make up for the oil loss, the pressure will drop. So the relief valve is actually a "bleed off" separate from the main oil supply going out of the pump. Much like the way a wastegate on a turbo relieves excess exhaust flow, the oil relief valve relieves any excess oil flow beyond what the system requires (assuming the pump provides more than required). In contrast, if the relief valve was located at the very tailend of a closed system (like a fuel pressure regulator) it would be different (which can be done on some engines' lubrication system).
With that in mind, increasing the opening threshold of the relief valve (i.e. higher spring pressure) manages the system pressure by way of allowing less excess oil flow to escape that system. The physics of that actually influences two effects of the overall system; pressure and flow (which are interrelated). When external accessories are added to the oiling system (such as a remote oil cooler, remote filter, and a turbo) they act like additional oil losses from the main galleries. There is now a greater demand for flow to maintain the desired pressure throughout the entire (extended) system at all times. Furthermore, the excessive heat that a turbo imparts onto the oil will reduce its viscosity causing additional pressure loss. Therefore, provided the pump has the potential to keep up, increasing the spring pressure on the relief valve can act to increase flow to the added external oil circuit(s) as well as the internal circuits. In other words help make up for the lost pressure caused by the added circuits (the greater the distance oil must travel, the greater the pressure loss) and increased heat.
But like any theory there are limitations; the increased relief setting could also cause higher than desired oil pressure when the oil is cold, at redline, and/or when there is not a lot of added demand. Obviously too much pressure will push oil past the seals. An externally adjustable oil pressure relief valve (as some engines have) would help to dial-in the 'sweat spot' for each non-stock engine build. But as has been stated several times, a higher volume of oil flow from the pump is the best answer. In the absence of a high volume pump we have to look at other means of protecting the modified, turbocharged engine. If for any reason increasing the relative rotation speed of the pump becomes too difficult to accomplish, then increasing the system pressure appropriately may help (affordably/practically).
Steve Thomas
True Classic
yep, relief valve only sets maximum pressure and has no effect otherwise. "relief" says it all.Understood. If you consider what "and/or" is referring to, it was a comment on what it is capable of doing - for whatever reason. In other words something of a theoretical point. There may indeed be cases where a higher pressure might be desired. Perhaps not for a stock engine or whatever you may be thinking of, but nonetheless. However we are way off the point that was made about optional oil pumps to fit the SOHC.
Since pressure vs volume has been brought up again, it reminds me of a theory I posted once before (this came from one of the engineers I noted previously). The primary "resistance" that makes oil pressure in a engine is not the relief valve, but the engine's lubrication system beyond the pump - e.g. all of the galleries, bearing clearances, filter, and other points where pressure is lost as oil flows through the system. One illustration is the example of a extremely worn engine; resistance at the bearings is decreased and without added flow volume to make up for the oil loss, the pressure will drop. So the relief valve is actually a "bleed off" separate from the main oil supply going out of the pump. Much like the way a wastegate on a turbo relieves excess exhaust flow, the oil relief valve relieves any excess oil flow beyond what the system requires (assuming the pump provides more than required). In contrast, if the relief valve was located at the very tailend of a closed system (like a fuel pressure regulator) it would be different (which can be done on some engines' lubrication system).
With that in mind, increasing the opening threshold of the relief valve (i.e. higher spring pressure) manages the system pressure by way of allowing less excess oil flow to escape that system. The physics of that actually influences two effects of the overall system; pressure and flow (which are interrelated). When external accessories are added to the oiling system (such as a remote oil cooler, remote filter, and a turbo) they act like additional oil losses from the main galleries. There is now a greater demand for flow to maintain the desired pressure throughout the entire (extended) system at all times. Furthermore, the excessive heat that a turbo imparts onto the oil will reduce its viscosity causing additional pressure loss. Therefore, provided the pump has the potential to keep up, increasing the spring pressure on the relief valve can act to increase flow to the added external oil circuit(s) as well as the internal circuits. In other words help make up for the lost pressure caused by the added circuits (the greater the distance oil must travel, the greater the pressure loss) and increased heat.
But like any theory there are limitations; the increased relief setting could also cause higher than desired oil pressure when the oil is cold, at redline, and/or when there is not a lot of added demand. Obviously too much pressure will push oil past the seals. An externally adjustable oil pressure relief valve (as some engines have) would help to dial-in the 'sweat spot' for each non-stock engine build. But as has been stated several times, a higher volume of oil flow from the pump is the best answer. In the absence of a high volume pump we have to look at other means of protecting the modified, turbocharged engine. If for any reason increasing the relative rotation speed of the pump becomes too difficult to accomplish, then increasing the system pressure appropriately may help (affordably/practically).
Bjorn Nilson
True Classic
I want higher pressure at low revs and a bigger pump would probably fix that. With UT gearing my car revs 3k rpm@110 kmh (68.4 mph). An oil pressure of 3 bar@3k rpm is to little IMO. When going far from home, it happens that I cruise at 4-4.5k rpm for hours (4-4.5 bar pressure) so more pressure/flow would be beneficial.
But this is also related to oil temperature/viscosity and my experience is that a (heavily) tuned UT engine constantly running at high revs/high temperstures works better with SAE 50 oil as this increases the oil pressure a little bit.
Dr.Jeff
True Classic
Th
That might be one advantage to increasing the pump rotation speed to increase output. The output rate would be varied by engine speed, so something of a curve in pressure/volume increase. Although I guess a larger pump with a greater volume output would also be RPM dependent....if such a pump existed.
Last edited:
Dr.Jeff
True Classic
Getting back to the theory of how increasing the relief spring tension will also increase system volume. Basically it is just routing less oil through the relief valve and more to the engine. But this depends on the specific engine design.
It was proven on a different (but similar) engine with the same type of pressure relief valve. In that example the standard pump had sufficient volume that there was a relatively constant bypass happening to some extent to maintain the stock target pressure. In other words always more volume supplied by the pump than the engine needed. Therefore by increasing the spring tension there was less oil bypassing at any given time, which means more volume to the main galleries. Naturally it also increased the system pressure but that's where the balance between volume and pressure comes in; a modified engine requiring more than a stock one.
Unfortunately I doubt the Fiat pump has that much output volume to begin with. So this mod likely won't work on it.
It was proven on a different (but similar) engine with the same type of pressure relief valve. In that example the standard pump had sufficient volume that there was a relatively constant bypass happening to some extent to maintain the stock target pressure. In other words always more volume supplied by the pump than the engine needed. Therefore by increasing the spring tension there was less oil bypassing at any given time, which means more volume to the main galleries. Naturally it also increased the system pressure but that's where the balance between volume and pressure comes in; a modified engine requiring more than a stock one.
Unfortunately I doubt the Fiat pump has that much output volume to begin with. So this mod likely won't work on it.
Alex(Tenerife)
True Classic
I have heard that exactly that mod does work on our cars. Never tried it myself, just what I heard.
Steve Thomas
True Classic
It only increase the system maximum pressure. It has no effect until that pressure is achieved at whatever RPM that is. Flow is not affected except once system pressure reaches the old maximum. Flow at that pressure and up to new maximum will be higher. Flow below the old maximum will be exactly the same as it was.
Mxgrds
True Classic
If the viscosity reduces, the volume of oil will increase with the same oil pressure. So you don’t need necessarily a higher pressure for a better oil flow. That’s one of the reasons to wait for a good oil temperature before really start revving the engine. Although the oil pressure is lower when the oil is hot, I think that the flow is the same or even higher. That are my thoughts.
Dr.Jeff
True Classic
I'm not sure if I'm reading you right, sorry - maybe you can clarify a bit. Are you saying the volume increases as a function of lower viscosity? I know aside from the viscosity, pressure and volume are inversely related....all other things being equal. However changing the viscosity in the equation means not everything is remaining equal. And pressure is affected by viscosity (pressure goes down as viscosity lowers). Is that what you said? Thanks.
Dr.Jeff
True Classic
For proper management of a turbo system (e.g. on a SOHC engine) a fully programmable EFI must be utilized. Actually this is also true on a naturally aspirated "performance" SOHC build. For the most part that means a aftermarket "standalone" ECU. Here in the US the more affordable option for such a ECU is MegaSquirt (MS).
To build a basic programmable EFI setup on a SOHC (turbo or performance NA) the smallest, and most affordable, ECU from MS - the "MicroSquirt" - is a excellent choice. It runs around $300, or $350 with a wire harness. That will give you all the features needed to make a great functioning EFI system. But for certain builds you may want a more elaborate ECU with even more features. That means moving up to a higher MS model and spending a LOT more for it.
Today I received a message from Mike, a friend who owns the company that makes all of the preassembled MS products (EFI Source). They have just released a new model of ECU that is based on the top of the line, and most expensive, "MS3 Gold" series. The new model is a slightly "trimmed down" version of the MS3, called "MS3 Gold Lite" (link below). With some of the less commonly used features deleted it is a physically smaller unit, and it has a much lower price, than the MS3 at $750 (with harness). While that is a little over twice the price of the MicroSquirt, it offers a LOT more features. However many of those added features will not be used on 90% of SOHC builds. So I still believe the MicroSquirt is the better choice. It is also easier to incorporate and set up than the higher models. But for those who may want the added features here's the link:
Shopping tip: toward the end of the year EFI Source often runs a "black Friday" type online sale with 10 to 15% off all purchases. That gives you time to build the rest of your engine and related systems before buying the ECU. Why let the warranty run out as the ECU sits on the shelf while you build everything else?
To build a basic programmable EFI setup on a SOHC (turbo or performance NA) the smallest, and most affordable, ECU from MS - the "MicroSquirt" - is a excellent choice. It runs around $300, or $350 with a wire harness. That will give you all the features needed to make a great functioning EFI system. But for certain builds you may want a more elaborate ECU with even more features. That means moving up to a higher MS model and spending a LOT more for it.
Today I received a message from Mike, a friend who owns the company that makes all of the preassembled MS products (EFI Source). They have just released a new model of ECU that is based on the top of the line, and most expensive, "MS3 Gold" series. The new model is a slightly "trimmed down" version of the MS3, called "MS3 Gold Lite" (link below). With some of the less commonly used features deleted it is a physically smaller unit, and it has a much lower price, than the MS3 at $750 (with harness). While that is a little over twice the price of the MicroSquirt, it offers a LOT more features. However many of those added features will not be used on 90% of SOHC builds. So I still believe the MicroSquirt is the better choice. It is also easier to incorporate and set up than the higher models. But for those who may want the added features here's the link:
MS3 Gold Lite with 8ft Harness – EFI Source
EFI Source supplies Goldbox, MegaSquirt, MicroSquirt, LS, Hemi, Harness, and other programmable EFI systems and products o the performance minded automotive community.
www.efisource.com
Shopping tip: toward the end of the year EFI Source often runs a "black Friday" type online sale with 10 to 15% off all purchases. That gives you time to build the rest of your engine and related systems before buying the ECU. Why let the warranty run out as the ECU sits on the shelf while you build everything else?
Mxgrds
True Classic
If oil is cold, it is a thick slow moving substance (high viscosity). To get it through the tiny oil passages a relative high pressure is needed. If the oil gets warm and thinner (the viscosity lowers) it flows much easier through the same tiny passages, and so with the same pressure, the volume will increase. So if you want more oil to go around in the engine, just choose an oil with a lower viscosity.
Mxgrds
True Classic
I am using the standard UT ecu’s and are very happy with it. The extra boost as compared with a 1500 injection is considerable. With a little extra turbo pressure it is easy to get 115-120 hp. To really enjoy it, a UT transmission is adviced.
Steve Thomas
True Classic
The oil pump is a displacement type. Each revolution delivers a fixed volume of oil. Nothing to do with relief pressure or viscosity. When the oil is cold, the same volume is pumped but it takes more power. Yes, the overall system will develop pressure faster with cold oil, but the flow rate is fixed at any given shaft speed. The only way to increase flow is to change the pump volume or crank ratio.
Dr.Jeff
True Classic
Well sort of, but kind of backwards. The thinner oil will require greater volume to maintain the same system pressure.
Dr.Jeff
True Classic
Sorry, I was referring to adding a turbo to the X1/9 engine, not a UT engine where the turbo already exists. The UT's ECU was made for the turbo, the X's ECU (US spec FI version) was not and won't support a turbo...and cannot be programmed to do so.
Mxgrds
True Classic
True. But that were the relief valve comes in to play. With cold thick oil, the max pressure is reached with lower rpm. The additional volume above that rpm will be dumped through the relief valve. If the oil is hot and thin the max pressure is reached with a higher rpm. Higher rpm means higher volume because it is a displacement pump.
My conclusion: the volume of hot/thin oil displaced by the oil pump is greater than cold/thick oil because the relief valve kicks in very fast on cold oil.
Dr.Jeff
True Classic
OK I see what you are saying now. That is sort of along the lines of the theory I described earlier how increasing the bypass spring tension could increase oil volume to the engine, by reducing the amount of oil that gets bypassed. I guess it might depend on what the pump's overall output volume is, the pressure rating of the bypass spring, and the viscosity of the oil. All have an effect on one another so to some extent there will be a constant dynamic interaction between them. But if the pump doesn't have the capacity (potential output volume) to compensate for the loss in pressure (due to thinner viscosity) then the relief valve's opening value may never be reached, yet the oil volume will still be limited by the pump and not increase. I suspect that is likely the case with the SOHC's pump.
Mxgrds
True Classic
The question is, how much oil is required for sufficient lubrication?
Dr.Jeff
True Classic
That question gets back to the overall subject of this whole thread: "turbo systems for the X". Or more specifically, adding a turbo to the X's engine. The reason I cross-posted the discussion about oil pumps over to here is because adding a turbo to the stock X1/9 engine requires some improvements to make everything more reliable. Due to the significant heat a turbo generates, and the fact it is lubricated by the engine's main oil supply, means improvements in overall thermal management and in the lubrication system should be made. For example a oil cooler is imperative. And to do that a oil filter adapter is needed. But there isn't enough room between the engine's oil filter location and the chassis to add one with a suitable sized oil filter. Therefore a remotely mounted oil filter is also needed. Between the turbo, oil cooler, and remote filter there's considerably more load on the lubrication system. Hence the need for more pump output. But wait, there's more. Adding boost means thermal loads are also significantly increased inside the engine. So it's best to assemble the engine a little "loose" to allow for the higher heat expansion of internal components. That can drop oil pressure as more oil is allowed to pass by the larger tolerances. Things like this are why race engines use high volume oil pumps....and so should a turbo'd X in my opinion.
To put this into context. The Fiat Uno Turbo (with a turbo from the factory) increases oil pump output volume by increasing the oil pump rotation speed (compared to a standard non-turbo Uno). They achieve that by changing the drive ratios for the timing belt pulleys, turning the auxiliary shaft faster relative to the crank speed. Basically I'm suggesting the same for a X1/9 with a turbo added.
Aside from adding a turbo, there may be other reasons why the oil pump volume should be increased as well. But that's a different discussion for a different thread.