After re-installing the motor I was concerned that the turbo blanket might be pushed onto the wastegate actuator arm due to the tight spacing on the driver’s side. I hooked up an air compressor to the wastegate activation lines and ran some pressure through them to check that the arm would still move as needed, it did.
My turbocharger candidate list is still open while I try and find an upgrade that fits what I am looking for. A potential contender is a revised FrankenTurbo F21 that Frankenturbo released some early prototype photos of.
A revised, billet, compressor wheel:
and even more interesting, a mixed flow turbine:
This looks to be an excellent combination for trying to maximize power on a stock motor while retaining good spool up characteristics.
Time will tell if the prototype lives up to the design goals.
Another turbocharger option is now residing in my basement. I came across a classified ad for a number of 2.7T parts that included this pair of low mileage BorgWarner RS4 K04’s. With only a little over 10,000 miles on them I could not pass up the opportunity to put some K04’s back onto my S4, or alternatively to use them as the starting point for an upgrade to a RS6 based hybrid.
For the time being I am sticking with BorgWarner K03’s to gather some additional performance data and to try and continue the Nefmoto Stage 1 Tuning thread , but my hope is to swap in the K04’s by summertime and get some numbers on them with my existing additional hardware.
