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Driven5
Driven5 PowerDork
7/29/24 3:07 p.m.

What prevents the scavenge pump from losing its oil and just sending air when any 1 of its 4 pickups is no longer submerged and need it the most?

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
7/29/24 3:17 p.m.

In reply to Driven5 :

That would be a real concern if there was one pump drawing from all the pickups, but typically the scavenge pump is actually a set of separate pumps (sometimes referred to as "scavenge stages"), with one pickup per pump, so if one sucks air the others can still suck oil.

JG Pasterjak
JG Pasterjak Production/Art Director
7/29/24 3:35 p.m.

The scavenge pump doesn't feed the main pump directly, it just feeds the well where the main pump picks up. 

Driven5
Driven5 PowerDork
7/29/24 5:40 p.m.

In reply to GameboyRMH :

Yeah, they're calling it a 'twin flow gear pump'. So I'm guessing it's basically a '2-stage' pump, which would answer my question. It looks like they're also using the turbo drains to also (gravity) feed each side and give it more capacity to keep up during prolonged high-G cornering.

deaconblue
deaconblue Reader
7/30/24 2:02 p.m.
Caperix
Caperix Reader
7/31/24 7:41 p.m.

The n55 also added variable oil flow with a bypass solenoid at the front of the engine.  As the similar n54 did not have as many bearing issues I wonder if that contributes to problems as well.  The s55 oiling system should help

russelljones48
russelljones48 New Reader
8/1/24 8:18 a.m.

I'm interested in your solution since we've had similar problems with OEM oiling in endurance racing.  I'd be even more interested in BMW's excuse for not designing a solution for the pan which would have cost them zilch..  but has now damaged their reputation...  

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/1/24 5:32 p.m.
JG Pasterjak
JG Pasterjak Production/Art Director
8/1/24 5:46 p.m.
Keith Tanner said:

Is this what was installed?

https://www.bimmerworld.com/S55-Oil-Pump-Upgrade-OEM-135i-M235i-335i-435i-N55.html $1649.99

It is indeed, along with the S55 baffled pan. We didn't replace the oil pump sprocket, though. Unless you're taking the front cover off (which adds cubic hours), the sprocket needs to stay in place to keep tension on the drive chain. I think BimmerWorld said this was like the third conversion they'd done and they've refined the package a bit each time. 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
8/2/24 7:17 p.m.
JG Pasterjak said:

The scavenge pump doesn't feed the main pump directly, it just feeds the well where the main pump picks up. 

So it's a kind of integrated dry sump.  Neat.

JG Pasterjak
JG Pasterjak Production/Art Director
8/2/24 11:56 p.m.
Pete. (l33t FS) said:
JG Pasterjak said:

The scavenge pump doesn't feed the main pump directly, it just feeds the well where the main pump picks up. 

So it's a kind of integrated dry sump.  Neat.

I'm going to call it a "moist sump" and good luck trying to stop me.

Pippins
Pippins New Reader
8/3/24 3:37 a.m.

In reply to JG Pasterjak :

I'm fine with "moist sump",  just be glad there's plenty of girth to it to make sure it get copious amounts of oil to squirt.

calteg
calteg UltraDork
8/3/24 11:37 a.m.
russelljones48 said:

I'm interested in your solution since we've had similar problems with OEM oiling in endurance racing.  I'd be even more interested in BMW's excuse for not designing a solution for the pan which would have cost them zilch..  but has now damaged their reputation...  

Yes, BMW's Stirling reputation for reliability was sullied by the N55. 

JG Pasterjak
JG Pasterjak Production/Art Director
8/3/24 12:29 p.m.
calteg said:
russelljones48 said:

I'm interested in your solution since we've had similar problems with OEM oiling in endurance racing.  I'd be even more interested in BMW's excuse for not designing a solution for the pan which would have cost them zilch..  but has now damaged their reputation...  

Yes, BMW's Stirling reputation for reliability was sullied by the N55. 

I chuckle because it's true, but know that I do it with a single tear running down my cheek.

genibrel
genibrel New Reader
11/13/24 1:53 p.m.
Driven5 said:

What prevents the scavenge pump from losing its oil and just sending air when any 1 of its 4 pickups is no longer submerged and need it the most?

Indeed, with more than one pick-up, the pump will suck air. In circle track racing, the problem is nonexistent, as most oil pick-ups are on the right side of the oil pan. When cars are turned right, the issue of low to no oil pressure arises.

The solution is to install a better oil pan design with judiciously placed baffles or a dry sump system.

By the way, this problem is caused by the tires! As tire design improves, greater G forces are generated, forcing the oil away from the pump pick-up.

PS: I wonder if the turbo may affect oil pressure. Do turbos affect the air pressure in the sump?

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