APR Tuning Products for the Audi B7 - A4

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 powerband. 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.

In order to address the lack of fuel in the midrange, the APR FSI fuel pump increases the volume of fuel from the high pressure pump by over 40%. Simplified, this is achieved by modifying some key internal parts within the pump. Changing these components requires precision machining of the new components with special surface treatments, as well as enlarged, redesigned seals. Using inferior components on this critical part can lead to many problems from gasoline in the engine oil (from a bad seal) to complete engine failure (from a seized piston in the high pressure pump).

To give an idea of the tolerances involved, the final surface finish on the piston inside the fuel pump is so critical that it can be damaged by touching them with bare hands. The tolerances between the piston and the new barrel the piston rides in can only be measured by a multi-million dollar machine which uses air volumes to measure the part clearances to within microscopic levels.

The components used in the APR pump are also of a high caliber. The piston and barrel of the new pump are made of a certified and heat-treated bearing-grade stainless steel and have a special diamond like coating. The seals used in the pump are made of a high performance, filled polymer with a high modulus spring to retain the seal forces throughout the life of the product. The cross section of the seal is also of a proprietary design to maintain integrity over many years of use.

APR FSI pumps have been track tested for over a year now, with several hundreds of thousands of miles of combined usage. Each APR pump starts out as a brand new OEM pump, is modified with the new components by APR, and then undergoes a rigorous testing process on our high pressure fuel pump tester. Once a pump passes our standards, it is serialized and shipped to the customer.

The APR fuel pump tester is a key element in the APR fuel pump production process. With the fuel pump tester, we are able to perform several tests to ensure every pump is working to the high standards we have set for it. First, the fuel pump tester allows us to perform the critical initial break-in of the new pump. Also, by bringing the pump up to the full operating pressure, we can confirm that the seals in the pump are properly installed and not leaking. Finally, a performance test is performed to make sure that the pump output is within specifications. This level of quality control ensures a lifetime of worry free miles with an APR FSI high pressure pump.

The APR 2.0T FSI fuel pump requires APR engine management recalibration to allow for the increased size of the APR fuel pump to ensure flawless drivability and is included with your purchase. 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.

Show your APR pride with our APR Tuned badges. Our badges have a polished chrome finish to keep a factory-like look over the years. The badge is approximately 2 3/4" long and 1 1/2" tall, and nicely replaces the stock engine designation badge on the back of the car.

APR is proud to be the Authorized Distributor for Carbonio Cold Air Intake (CAI) systems. Manufactured from aerospace grade carbon fiber, Carbonio further improves this material by incorporating a proprietary thermal barrier layer in its construction. The result is an exceptionally light and strong part that minimizes intake temperatures. This ensures that the engine optimizes power by receiving the coldest and most oxygen rich air possible.

Carbonio’s line of intakes for Audi automobiles represent the pinnacle of induction design. Extensive testing has resulted in an intake that maximizes performance in all driving conditions. Power will come on sooner and the engine will pull for longer and stronger.

Benefits of the Carbonio CAI System include:

* Increases Horsepower and Torque
* Improves Throttle Response
* Decreases Turbo 'Lag'
* Flattens Torque Curve (engine is less 'peaky')
* Improves Fuel Economy
* Enhances Engine's Volumetric Efficiency
* Enhances Sound of Turbo Diverter Valve
* Works with All Aftermarket Diverter Valves
* Installs in an Hour (does not require bumper or headlight removal)
* Maintains All Factory Emissions Components
* Fits Both Manual and Automatic Transmissions
* Unique Thermal Barrier Composite Construction Ensures Low Inlet Temperatures
* Fully Compatible and Complimentary with APR Software and Exhaust systems

Each Carbonio A4 Kit Includes:

* Aerospace Grade Carbon Fiber Main Section Ensures Inlet Temparatures Stay Low
* Carbon Fiber Main Section has Show Quality Finish
* Complete Photographic Instructions
* Filter Design Eliminates Need for Secondary Air Pump
* All Necessary Hardware Included for Easy Install without Cutting Or Modifying

APR's Snub Mount Upgrade replaces the front engine mount on the car. This mount enhances upshifting and downshifting, reduces driveline shock, and helps power transfer by taking up excess drivetrain slack.

In typical APR fashion, our first turbo kit for the new 2.0T FSI engine provides a perfect balance of refinement and power. Making 298hp and 321lb/ft, APR’s K04 turbo upgrade for the B7 A4 will enhance your driving experience without compromise. With smooth acceleration and flawless drivability, the APR K04 turbo upgrade will exceed all the demands of a daily driver while providing instant acceleration and an appreciably broader power band throughout the entire rpm range.

From the efficient and reliable KKK turbocharger and manifold assembly to the included stainless steel catalyst replacement pipe and expertly re-calibrated engine management, APR’s K04 Turbo Upgrade offers performance and drivability that are perfect for the daily commute and week-end track event. Included as well, all the necessary hardware is OEM and helps maintain the stealthy fit and finish.

By incorporating OEM supplied components, we are able to ensure installation and service for your new A4 will be as smooth as possible. Providing a direct replacement fit, the APR modified turbocharger and manifold assembly will mount in the exact location as your existing turbocharger and manifold assembly. This allows the use of all other OEM mounting locations for such items as the exhaust and compressor inlet hose, making for an completely stealth installation. For best results, APR highly recommends using this kit with our APR B7 A4 Exhaust and Carbonio Carbon Fiber Intake Airbox. Optional to the installation but included in the kit is the APR stainless steel catalyst replacement pipe.

APR's A4 Exhaust is a complete stainless steel, mandrel bent, cat-back exhaust. On an A4, the catalytic converter is bolted to the turbocharger and then the exhaust begins with the downpipe. Unlike most other aftermarket exhausts, the APR exhaust includes a 2.5" downpipe. The exhaust then continues back to the innovative center muffler, where it splits into dual 2.25" pipes. Each of these mandrel bent pipes goes to its own muffler with a 3.5" rolled, round tip.

With this being the 3rd chassis A4 to hit the market, we at APR have had years to continue the development of the perfect exhaust for the A4. This has led to our newest and best system. Fully polished, mandrel bent, tig welded, CNC'd hangers, deep tone and superior flow culminating in the best money can buy. All APR systems come with a lifetime warranty. Buy today to get your A4 that look and feel that only an APR exhaust can bring!!