If you’re a diehard N54 enthusiast, you know that there are very few aftermarket intake manifolds available for us. You might also know that Doc Race has been working to produce an intake manifold since 2016.
Once mass-production was confirmed, I had to get one to match my Doc Race N54 single turbo kit. One of the reasons I wanted this intake manifold was because it integrates port injectors directly into the manifold. The typical N54 port injection method (which I currently have) involves a spacer between the engine and stock intake manifold that creates an additional surface for potential boost leaks. Not only that, but it looks awesome too!
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 N54 single turbo kit.
Once I decided to convert my N54 from twin turbos to a single turbo, I spend 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 saved my parts list and will share that below. With this complete list, I was able to safely make 749whp on the stock motor in my BMW 135i.
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.
All pulls done in 4th gear (manual transmission). DynoJet with STD correction set at 5.
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.
Walnut blasting is one of the most common maintenance tasks for the N54 engine to remove carbon buildup from the intake valves. Some shops or dealerships charge an arm and a leg for this service, but it can be done at home for much less!
After “sending it” at 30psi for a couple hundred miles, I developed a misfire. I narrowed it down to cylinder 3, but wasn’t sure if it was plugs, coils, injectors, etc. I swapped all accessories between cylinders, but nothing would follow. That’s when I started to get worried.
Without wasting any more time, I busted out the compression tester. The results were disappointing.
I’m not sure what exactly caused the problem, but adding a tablespoon of oil down the cylinder boosted compression back up. 99% sure it is a cracked ring or a chipped ringland. If I had to guess, the car developed a misfire but I was too greedy and stayed on the throttle while it was a misfiring for a couple pulls. Or maybe it just randomly gave up… I’ll never know why. The logs looked good before the misfire, but I knew I was playing with fire at this power level.
After saving up for a few months, I bought a used motor from a junkyard. It came out of a 2008 335i 6MT with 91,223 miles. The car was hit pretty hard on the driver’s side, so I’m not worried about flood damage or anything like that. It was also modified, so I’m hoping it was taken care of by an enthusiast.