I tried MMP Stage 3 twin turbos, but never felt the “wow” factor I was hoping for. After worrying about wastegate rattle and smoking turbos for too long, I decided it was finally time to go big or go home. Meet the Doc Race 135i/335i N54 single turbo kit!
Once I decided to convert my N54 from twin turbos to a single turbo, I spent countless hours researching what kit I should go with, which parts needed to be replaced, what upgrades needed to be done, etc.
To save you that same hassle, I will share all the information you need to know below. With this complete list, I was able to safely make 749whp on the stock motor in my BMW 135i. Even if you’re not after a ton of horsepower, this is a great kit to go with when getting rid of the stock turbos.
I finally strapped my 135i onto the dyno after fine-tuning the new single turbo setup and am thrilled with the results. I did a handful of pulls at various power levels and attached the logs below. This should give everyone a good idea of what a properly set-up 6266 can do from low boost to high boost on an N54.
I want to kick off this post with a reminder that I’m installing the Doc Race single turbo kit outside of the car on an engine stand. Part of the reason I bought this kit was because I blew my motor which required to me remove and re-install a new motor. Great excuse to upgrade… right?!
The kit showed up about 4 weeks after I ordered it and came complete. I didn’t want to gamble with other vendors’ long lead times and kits that arrived with missing or poor-fitting parts. Doc Race knocked it out of the park and I’m glad I chose their kit!
Everything looked beautiful. I opted for the ceramic coating option and a ball-bearing 6266 turbo. The kit includes almost everything you need to convert to single turbo! Now let’s get these beautiful pieces where they belong…
Manifold studs replaced, manifold, heat shield and water pipe installed.