Last spring I picked up a set of RS4 up pipes, metal throttle body boot, and RS4 throttle body. I was a bit surprised at the airflow improvement through the RS4 setup, even over the APR bipipe the gains were noteworthy, around a 10% increase in airflow (RS4 parts flow test).
A problem I faced incorporating these RS4 parts on the car would be the transition from the intercooler to the RS4 up pipe. The intercooler outlet on available options varied between 2 and 2.25 inches, while the RS4 up pipe inlet is 2.5″ in diameter. My desire was to have a smooth transition from the intercooler to the up pipes but I couldn’t identify a suitable intercooler to do this.
I contacted Silly Rabbit Motorsport (SRM) to find out about the possibility of having a customized set of intercoolers built that would use 2.5″ inlets and outlets. They said it would not be a problem, and so I began making plans to try this idea out.
Another issue cropped up relating to water/methanol injection. On my APR bipipes I have tapped the pipes for use with Aquamist nozzles, I have no desire to similarly tap the RS4 up pipes for use with water methanol injection. I decided that installing the nozzle bung on the IC endtank would be a preferable option, but I didn’t know if this would be possible. I contacted SRM again to find out about adding the w/m nozzle bungs onto the end tanks, once more they said it wouldn’t be a problem to assemble the IC’s with this customization.
With the basic design settled on I will soon begin working with SRM to have these intercoolers built and then I’ll be testing them to see if they meet my desires.
The drawing below illustrates the basic layout for these intercoolers.