Scottish Borders
As you push the power on the N54 engines up past 400 bhp one of the design limitations that rears its head is the low pressure fuel pump.
All E89s from the 23i through the N20 powered cars to the 35is all use teh same low pressure fuel pump.
FWIW it seems that it looks to be a pretty reliable unit.
If it fails then the car goes into limp mode, some people assert that the HPFP can suck enough fuel through to keep the car running after a fashion, not sure on this?
It seems that around 450 bhp (crank) on normal petrol the pump runs out of pumping capacity.
I've deferred fitting my TTE500 turbo upgrade till the autumn, but at a predicted 550 bhp its certain to require more fuel than the existing pump can supply.
There are two options..one is to add a secondary pump, in parallel operated by a switch in the cockpit to boost it.
The other is an upgraded unit. Compounding the decision is that these pumps come bucketed and no-bucketed.
The bucket as the pictures show is a resevoir that the pump sits in that holds enough fuel to cope with the car movinga round under acceleration loads that with a less than full fuel tank could cause a pick-up to suck air rather than fuel.
There is a debate as to how mcuh of an issue this is.
For the E89, there's only one bucketed solution (AFAIK) and that's the Fuel-it pump upgrade
https://www.turnermotorsport.com/p-403475-e89-z4-stage-2-lpfp-upgrade/?pdk=AQ
It's referred to as a stage 2 as there is a stage 3 for those running ethanol and /or really big bhp numbers (650 bhp+).
I discovered this a while back and it looks I can only get one through US import..given that it took 3 months for my last set on US imports to arrive, its part of the deferral plans on the big turbos.
These pumps are variable speed and controlled by the EKP fuel pump controller which is told by the DME how much fuel is required and adjusts the pump speed to suit, just like the wate pump and oil pump control on the N20 engines.
But that's another story!
Pictures show the full pump and float level of stock system and the other the bucket /pump upgrade.
All E89s from the 23i through the N20 powered cars to the 35is all use teh same low pressure fuel pump.
FWIW it seems that it looks to be a pretty reliable unit.
If it fails then the car goes into limp mode, some people assert that the HPFP can suck enough fuel through to keep the car running after a fashion, not sure on this?
It seems that around 450 bhp (crank) on normal petrol the pump runs out of pumping capacity.
I've deferred fitting my TTE500 turbo upgrade till the autumn, but at a predicted 550 bhp its certain to require more fuel than the existing pump can supply.
There are two options..one is to add a secondary pump, in parallel operated by a switch in the cockpit to boost it.
The other is an upgraded unit. Compounding the decision is that these pumps come bucketed and no-bucketed.
The bucket as the pictures show is a resevoir that the pump sits in that holds enough fuel to cope with the car movinga round under acceleration loads that with a less than full fuel tank could cause a pick-up to suck air rather than fuel.
There is a debate as to how mcuh of an issue this is.
For the E89, there's only one bucketed solution (AFAIK) and that's the Fuel-it pump upgrade
https://www.turnermotorsport.com/p-403475-e89-z4-stage-2-lpfp-upgrade/?pdk=AQ
It's referred to as a stage 2 as there is a stage 3 for those running ethanol and /or really big bhp numbers (650 bhp+).
I discovered this a while back and it looks I can only get one through US import..given that it took 3 months for my last set on US imports to arrive, its part of the deferral plans on the big turbos.
These pumps are variable speed and controlled by the EKP fuel pump controller which is told by the DME how much fuel is required and adjusts the pump speed to suit, just like the wate pump and oil pump control on the N20 engines.
But that's another story!
Pictures show the full pump and float level of stock system and the other the bucket /pump upgrade.
