Cobra4B

Trying to understand exactly what happens when you run a high volume and/or a high pressure pump. I've run the high volume LS4 pump on two LS6s now w/o any issues. I'm building a LS1 for my father's Panoz that doesn't have the batwing pan so I'm taking a 2nd look at which oil pump to use; LS6 or LS4 with 42 psi relief.

I read all this conjecture about "sucking the pan dry" and putting too much oil in the top end of the motor.

1. Have there been any truly documented cases of sucking the pan dry? Or, is it internet hearsay?

2. Can you actually pump more oil to the top end of the motor?

My thinking is this... the maximum amount of flow through the engine is determined by the clearances right? So a high volume pump would just let the oil pressure come up faster and the bump would reach bypass sooner. If the stock bypass pressure is 32psi and you had a high volume pump with the same relief spring, then you'd just get to bypass sooner right? You wouldn't pump any more oil to the top of the engine?

Now how about pressure? Pressure is created from resistance to volume and/or increasing the bypass spring pressure in the pump. If you put a 52 psi relief spring in the stock pump then it'd keep on building pressure longer. If you had a high volume pump with a 52psi spring then you'd build that pressure more quickly at and at a lower rpm right? Would the increased pressure actually put more oil in the top end of the motor? Wouldn't the existing engine clearances limit actual oil flow?

Just trying to better understand what's going on. And how you could actually suck an oil pan dry.

Timz06

With higher volume of course you will pump more oil and the pressure will go up as a result.

IMHO the stock pump is fine, if you have low pressure there is something wrong with your motor.

Tim

RX-Ben

I think the best setup is the Melling 10296 pump (blueprinted), with Smith Bros restricted flow pushrods and the crankcase venting setup described in geerookie's post.
I searched the "dry pan" issue and never came across anything of substance.
Can you fit a baffled pan of some sort? There look to be many available.

Cobra4B

But if the relief spring pressure was the same then wouldn't the resulting maximum oil flow be the same? Isn't that the limiting factor? Isn't there a limit to how much the internal clearances can flow?

Yep... have a Kevko road race pan on the way.

TJM

That sums it up well. Been sold on the idea that high volume is to fill those 10AN lines and coolers!! Little resistance there.

M55A in the new motor [ and an Accusump]. After losing two motors in three years I will take the advice of those that haven't played musical motors

Cobra4B

Something else to consider. Apparently the bypass can't shut all of the oil flow the pump produces which is why you still see 70-80 psi oil preesure with a 42 psi relief spring.

As such the high volume pump will increase flow/pressure.

hemipanter

The pump is having two gears (or the like) type of pump that in most instances is of the same diameter but of different length. A longer gear will pump more oil since the pumping section is larger. The longer gear pump is therefore named "high volume". The pump also have a bypass section loaded by a spring valve that set the max pressure capacity of the pump.

That is about the oilpump.

The engine has an inlet and after that a number of oiling places, bearing play etc, that together acts as a sized restrictor. What creates pressure is the size of that restrictor. In other words, the pressure is dependent on the flow created by the pump. We can NOT get a higher flow without higher pressure, OR, higher flow without higher pressure.

Now, if a pump is creating a pressure of 60psi, a higher volume pump type will only recirculate oil within the pump at the same pressure. Recirculating oil within the pump is a BAD thing, only robbing power and make whipped cream of the oil.

What we need is a correctly sized olipump that give the pressure we need for the rpm in question without any recurculating oil, no more no less.
Goran