Melling's oil pumps
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On The Tree
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Melling's oil pumps I have seen lots of post about the M295 and M296 oil pumps on here and on other platforms.
M295 high pressure stand volume
M296 high pressure high volume
Everyone says go with the M295 for higher pressure standed volume pump. Because the M296 pump will drain the sump dry with high rpm use.
But I haven't seen anyone say anything about the 2 springs the M296 pump is supplied with.
Yellow spring is installed in the pump standard for high pressure high volume and the blue spring comes in a bag that you can swap for the yellow spring that then changes the pump back to high pressure standard volume flow the same as the M295 pump.
This is what I understand from what is written on the Mellings information for the M296 pump.
So from this if someone has bought the M296 pump and didn't want to risk draining their sump dry. Rather they a whole new pump, one could simply change the spring over at a much lower cost.
Is this correct?
Has anyone done just that and changed the yellow spring out for the blue spring suplied with the pump?
M295 high pressure stand volume
M296 high pressure high volume
Everyone says go with the M295 for higher pressure standed volume pump. Because the M296 pump will drain the sump dry with high rpm use.
But I haven't seen anyone say anything about the 2 springs the M296 pump is supplied with.
Yellow spring is installed in the pump standard for high pressure high volume and the blue spring comes in a bag that you can swap for the yellow spring that then changes the pump back to high pressure standard volume flow the same as the M295 pump.
This is what I understand from what is written on the Mellings information for the M296 pump.
So from this if someone has bought the M296 pump and didn't want to risk draining their sump dry. Rather they a whole new pump, one could simply change the spring over at a much lower cost.
Is this correct?
Has anyone done just that and changed the yellow spring out for the blue spring suplied with the pump?
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Is this correct?
The spring regulates the pressure. Changing it changes the pressure at which the bypass opens. The bypass regulates the max pressure the pump will put out by simply allowing enough oil to escape back to the pickup side of the pump, that the pump can't deliver any more pressure than whatever it takes to oppose the spring and open the bypass.
The volume a pump can deliver is a function of the gerotors and cannot be changed once the pump is manufactured.
M296 pump will drain the sump dry
A high volume pump, at any given pressure, delivers EXACTLY THE SAME AMOUNT of oil to the bearings, lifters, etc. as a std volume pump at the same pressure. The only time a high volume pump will move more oil through the engine is when bearing clearances and other "leaks" are sufficiently great that a std volume pump is maxed out just by delivering oil to the engine, and doesn't have enough output capability to develop enough internal pressure to open its internal bypass. Meanwhile, a HV pump under the same conditions will be more likely to still be moving enough oil that it can maintain high enough pressure keep its bypass open, bleeding off the excess volume to keep the pressure at the regulated value; in which case, the extra volume is simply circulated back to the pickup side of the pump, INTERNALLY. The "waste" oil doesn't even get shot back out into the pan, which might churn up the sump or otherwise cause improper behavior. It never even gets out of the pump, let alone goes anywhere else in the engine.
Just because people say stuff on the Interwebz that isn't and CAN'T POSSIBLY BE true, even if they say it ALOT, doesn't somehow make it true. This includes the "suck the pan dry" and "fill up the valve covers" myths.
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On The Tree
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No.
The spring regulates the pressure. Changing it changes the pressure at which the bypass opens. The bypass regulates the max pressure the pump will put out by simply allowing enough oil to escape back to the pickup side of the pump, that the pump can't deliver any more pressure than whatever it takes to oppose the spring and open the bypass.
The volume a pump can deliver is a function of the gerotors and cannot be changed once the pump is manufactured.
Here comes the myth again... it JUST WON'T DIE...
A high volume pump, at any given pressure, delivers EXACTLY THE SAME AMOUNT of oil to the bearings, lifters, etc. as a std volume pump at the same pressure. The only time a high volume pump will move more oil through the engine is when bearing clearances and other "leaks" are sufficiently great that a std volume pump is maxed out just by delivering oil to the engine, and doesn't have enough output capability to develop enough internal pressure to open its internal bypass. Meanwhile, a HV pump under the same conditions will be more likely to still be moving enough oil that it can maintain high enough pressure keep its bypass open, bleeding off the excess volume to keep the pressure at the regulated value; in which case, the extra volume is simply circulated back to the pickup side of the pump, INTERNALLY. The "waste" oil doesn't even get shot back out into the pan, which might churn up the sump or otherwise cause improper behavior. It never even gets out of the pump, let alone goes anywhere else in the engine.
Just because people say stuff on the Interwebz that isn't and CAN'T POSSIBLY BE true, even if they say it ALOT, doesn't somehow make it true. This includes the "suck the pan dry" and "fill up the valve covers" myths.
The spring regulates the pressure. Changing it changes the pressure at which the bypass opens. The bypass regulates the max pressure the pump will put out by simply allowing enough oil to escape back to the pickup side of the pump, that the pump can't deliver any more pressure than whatever it takes to oppose the spring and open the bypass.
The volume a pump can deliver is a function of the gerotors and cannot be changed once the pump is manufactured.
Here comes the myth again... it JUST WON'T DIE...
A high volume pump, at any given pressure, delivers EXACTLY THE SAME AMOUNT of oil to the bearings, lifters, etc. as a std volume pump at the same pressure. The only time a high volume pump will move more oil through the engine is when bearing clearances and other "leaks" are sufficiently great that a std volume pump is maxed out just by delivering oil to the engine, and doesn't have enough output capability to develop enough internal pressure to open its internal bypass. Meanwhile, a HV pump under the same conditions will be more likely to still be moving enough oil that it can maintain high enough pressure keep its bypass open, bleeding off the excess volume to keep the pressure at the regulated value; in which case, the extra volume is simply circulated back to the pickup side of the pump, INTERNALLY. The "waste" oil doesn't even get shot back out into the pan, which might churn up the sump or otherwise cause improper behavior. It never even gets out of the pump, let alone goes anywhere else in the engine.
Just because people say stuff on the Interwebz that isn't and CAN'T POSSIBLY BE true, even if they say it ALOT, doesn't somehow make it true. This includes the "suck the pan dry" and "fill up the valve covers" myths.
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No, I wouldn't say "better", necessarily; just, if you build a motor with loose clearances, that's what it's REALLY for. An engine whose oil flow needs are greater than stock. Otherwise, on an engine with factory-new-ish clearances, it doesn't do anything any different from a regular one except use acoupla extra .001s of horsepucker. Butt IN NO CASE does it "suck the pan dry" or any of the rest of that ... that.
When I said "leak internally" I was referring to all of the various places that pressurized oil goes besides the ones that we customarily control the clearances on; things like cam bearings, lifters, and so on. I would hope (yeah I know, not the most effective business plan) that there aren't any really egregious outright leeeeeeks in a motor. Although sometimes there are; cam retainer plates for example. Kinda just, the engine's overall appetite for oil.
When I said "leak internally" I was referring to all of the various places that pressurized oil goes besides the ones that we customarily control the clearances on; things like cam bearings, lifters, and so on. I would hope (yeah I know, not the most effective business plan) that there aren't any really egregious outright leeeeeeks in a motor. Although sometimes there are; cam retainer plates for example. Kinda just, the engine's overall appetite for oil.
