Just a quick update to this thread...
As some here may be aware, the BMW N20 engine does suffer from low oil pressure on the race track (primarily in high G left hand turns). To deal with this I recently installed a 3qt Accusump system into the Z4.
Here's the new battery bracket and Accusump mount being fabricated:
I replaced the Antigravity Lithium battery with a 15 lb Braille AGM battery, although heavier than the lithium one, the Braille is better suited to a car with all the electronics in the E89. It also works better with the intelligent battery charging system. Still a 25lb weight reduction over factory!
Bracket and battery installed into tray in trunk:
With the Accusump mounted on top:
To plumb the Accusump into the engine's oil system I decided to ditch the factory oil-to-water heat exchanger and install an external oil cooler.
Here's the oil filter housing with the factory oil cooler removed:
In place of the heat exchanger, we fitted the oil thermostat housing from the new S55 engine which is a direct bolt on. The thermostat in the S55 opens about 10 degrees earlier than the N55 version allowing more flow through the cooler and helping keep oil temps around 230F.
The S55 oil thermostat with VAC AN fitting adapters:
I used a universal oil cooler from Earls along with some quick disconnect AN fittings for serviceability:
Some supports fabricated to hold the oil cooler in place in front of the radiator:
Plumbing into the upgraded oil filter housing:
And another shot with the modifications made to the water loop to deal with the hose that used to run to the heat exchanger:
I'll have the car on track this weekend and will post a follow up afterward on how the system performs. - stay tuned.
-b