If you’re a diehard N54 enthusiast, you know that there are very few aftermarket intake manifolds available for us. Lucky for us, the Doc Race Intake Manifold is a great option!
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 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.
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.
After installing my new fuel system and turning up the boost on my MMP Stage 3 turbos, I started to notice some really bad heat soak in my logs. Guessing that the car is around 600-650whp at 28PSI, I could see that my standard VRSF 7″ Street intercooler was no longer keeping up. It did a great job on my stock turbos, but I needed something a little bigger.
After doing some research, I found the VRSF 7.5″ Race intercooler. Judging by its size and efficiency ratings, it seemed like the perfect intercooler for my power goal of 700whp. I ordered it right away to help cool things down a bit. Four days later it showed up, very nicely packaged.
After installing MMP Stage 3 turbos on my BMW 135i, I needed an upgraded fuel system to get the most power out of the car. I was filling up with an E40 mix of 93 and E85 , but my HPFP couldn’t keep up and my old stage 1 inline LPFP was inadequate. I needed something that could handle straight E85 fuel and not run out of pressure at 700+whp.
The products arrived quickly and were packaged nicely. I’ve always been satisfied with the quality from Precision Raceworks for the price. Upgraded fuel feed line not pictured.
The first step was to install the upgraded Stage 3+ bucket that had two Walbro 450s stuffed inside. Robert was nice enough to assemble the fuel pumps in a core bucket for me to swap out. Usually you have to modify your stock bucket while mounting and wiring up the pump yourself. I jumped in the back seat and got to work.