Audi A4R4 450HP CBEA (CR) Build

I mentioned earlier that I am using solenoid style injector (from oval port head) on a round port head. The injector fits the head properly but the valve cover and injector hold-down is completely different, as are the injector lines and return lines. In order to fit these injectors I designed a custom valve cover and a head side bracket to adapt the factory solenoid injector hold-down system.

This is the CAD model during the design process.


There was a few versions that were 3D printed to test a few design ideas and fitment (tolerances) until I got things dialed in. This is the finished CNC model.


This is a comparison on the two injector types. Piezo on the left, solenoid style on the right.

I started with a fuel rail from a CBEA or CJAA (same thing) and made some modifications to this set-up. The pressure sensor and the metering valve are both upgraded to units from a 2600bar rail.

Parts to be installed


OEM Rail


A comparison of the two pressure sensors shows the 2600 bar unit is shorter.


The problem with it being shorter is the mating surface on the sensor will not reach the mating surface on the fuel rail.


There is an easy solution, and its crude but effective. Using a cut-off disk on my grinder, I cut the end of the rail a bit shorter.


Here is the assembled fuel system. The lines from rail to each injector started life from a cbea and needed a lot of rework to fit. If I recall, it took me two days to get them fitting really well. Not kinking or notching them in the process was a real trick.

OK, here is a shot from under the hood. In this picture you can see an AirDog fuel pump and filter system. This is supplying fuel at 60 psig with enough flow rate for 600HP. Underneath that is a generic plastic fuel cell. I will be fabricating a custom aluminum fuel cell with internal baffling to replace it. The plastic fuel cell has been a pain for a variety of reasons: weeping bulk head fittings, too small, hard to fill, needs internal baffling to prevent slosh. This will be one of the best upgrades I can make before next summer. All the fuel lines are AN6 stainless braided hose and fittings. On the front left side of the fuel tank you can spot a CWA400 coolant pump. These take a PWM signal and vary in speed and current draw depending on the required demand. Maximum input current is 40 amps. this thing really pumps! I have been surprised how well the TDI coolant pump was able to circulate the coolant without this pump running, however, when running big power, its good to maximize the coolant flow to prevent hotspots in head and between cylinders. Finally, in the fore front there is a factory radiator at the front; this is used to cool the AWIC water. Behind this is an aftermarket aluminum radiator for cooling the engine. The two radiators are sealed together and there is an 30/60 AMP dual speed fan mounted to the set-up via a custom aluminum shroud.

Valve cover looking sharp! Good idea about the rail mod to accomodate the the sensor.

andy2 said:

Valve cover looking sharp! Good idea about the rail mod to accomodate the the sensor.

Click to expand...

thanks Andy. It was a bit of a crude method to cut it off but worked perfectly fine. lol Where are you at these days with your build?