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Futrell Autowerks offers a rebuild/exchange program for
all 2.0L FSI customers. We stock a fully rebuilt/upgraded APR high flow fuel
pump rebuilt from a core exchange. For local customers we offer this exchange
outright with your old pump. Mail order customers are
required to pay a $200/core charge until your good used pump is returned to us.
While modifying the 2.0T FSI engine beyond factory power
levels, it became quickly apparent that an additional volume of high-pressure
fuel was needed to make horsepower, especially in the midrange (3000-5000rpm) of
the power band. To understand why this fuel is needed for the midrange, one must
first understand how the fuel delivery system works in the 2.0T.
A low pressure fuel pump (which varies from ~40-95psi)
delivers fuel from the gas tank to the engine. Then, in order to spray fuel
directly into the combustion chamber, a high-pressure, camshaft-driven pump
pressurizes the fuel to upwards of 130bar (almost 1900psi !). Unfortunately, on
cars that have many modifications the stock fuel pump cannot flow enough volume
of fuel to maintain the system pressure, and the car gets the familiar “fuel
cut” that so many modified customers experience.
The limitation of how much volume of fuel the high pressure
pump can flow is dependant upon the volume displaced by the pressurizing
cylinder inside the pump and the number of times the piston reciprocates inside
that cylinder. Since the high pressure pump is driven off of the engine camshaft
by a three lobe cam, the piston of the pump cycles at 1.5 times the engine rpm.
(Engine camshaft turns at one-half engine rpm multiplied by three for the number
of lobes on the high pressure cam lobe).
Because of this dependency on engine rpm for the high
pressure fuel pump output volume, the FSI pump is capable of flowing almost
370hp at 7000 rpm, but yet only 158hp at 3000rpm. The graph below illustrates
the maximum horsepower potential of the stock fuel pump compared to the APR FSI
fuel pump. Also on the graph are stock and APR Stage III horsepower numbers.
Clearly, the stock pump is insufficient for the output generated by this
upgraded kit. The only way to address this issue while maintaining a pump that
fits in the stock location is to change the volume of the pump’s internal
pressurization chamber.
To ensure flawless drivability the APR 2.0T FSI fuel pump
requires APR engine management recalibration to allow for the increased size of
the APR fuel pump. If you already have APR software installed this recalibration
upgrade is included in the fuel pump price, otherwise it needs to be purchased
separately. Currently, some APR Stage II and K04 turbocharger clients will be
able to take advantage of increased horsepower and torque up to 25hp and 35lb ft
with APR fuel pump specific engine management performance recalibrations.