Bolt-On 600HP - Chris Armbruster’s E90 335xi

What do you buy if you’re on a budget, want accessible power, need to drive it year-round, and live with on a daily basis? Our Director of Personalization and resident track junkie, Chris Armbruster, says the E90 335xi is your only choice. While this isn’t his daily driver, this 335xi certainly could be. This week, we’re looking at why the N54-powered AWD sedan is such an appealing choice for anyone looking to get into blistering power for under ten grand and what it takes to reach that nearly 600 HP mark with Chris’ E90 as the template. Welcome to Turner Motorsport Weekly, this is bolting on 600HP. 

Unfortunately, before we can jump into the fun stuff, we have to address the several elephants in the room with the N54. Even when they were relatively new, the N54 showed as many problems as they did potential for power. Turbo failure, wastegate rattle, carbon buildup, injector failure, charge pipe failure, and water pump failure are all commonly reported problems the N54 suffer, but it isn’t something that should keep you away from one. While that list may seem fairly daunting and expensive, it isn’t an extreme amount of work to bulletproof your N54 for daily duty while you’re adding power at the same time. Chris did just that with his E90.

It’s important to start with a fresh slate when it comes to the N54. Since you’ll be nearly doubling the power, you need to take measures to protect your engine from all that added strain. Some of the upgrades you’ll make to get there will handle a few of the common concerns with the N54, but not all. Namely, the cooling system, walnut shell blasting, and oil leaks all need attention. 

The water pump on the N54 and most modern BMWs is electrically driven and can fail without warning. Since there isn’t anything to inspect from the outside, the only sign something isn’t right besides limp mode could be seeping coolant. Replace your water pump, thermostat, coolant hoses, and coolant before adding power so you know everything is new and ready to keep temperatures in check for a long time.

Walnut shell blasting was something novel when the N54 was released. Due to the direct injection fuel delivery, no fuel passes over the intake valves. This is all well and good, except that the suspended particles carried with the releasing pressure from the crankcase through the PCV system are no longer washed away by fuel and then burned up in combustion. With nothing to clean the valves, all those particles build up a crusty carbon layer that can, if left unattended, cause some serious issues after thousands of miles. With any N54, it’s a good idea to either confirm that walnut blasting service was completed recently or to perform the service yourself. It isn’t terribly difficult to do, but does involve quite a bit of disassembly to perform and some special tools. This service is a must to make all the power you want to make. It’s also a good idea to add a Turner Motorsport Baffled Oil Catch Can to prevent future carbon buildup so you don’t have to perform that walnut blasting service again in a few thousand miles. 

N54s also commonly leak oil from the oil filter housing gasket, valve cover gasket, and rear main seal. Fortunately, two of those gaskets are easily replaced and the third is accessible when you’re upgrading your clutch to handle that 600 HP mark, so they’re worth doing while you’re in there upgrading things. Our Packaged by Turner Service Kits have everything you need to replace the oil filter housing gasket and valve cover / valve cover gasket, which we highly recommend before upgrading your N54. For the Rear Main Seal, do that when you do the clutch. 

With those services handled, you can finally start upgrading your N54 to make more power. Fortunately, that doesn’t involve much more than simple bolt-ons and software thanks to the inherent power potential from this platform. 

Intake

Like any good performance bolt-on build, Chris started with an intake. Specifically, the ECS Tuning Kohlefaser Luft-Technik intakes. Another appealing option is our Turbo- Side Intake System, which further improves the efficiency of your intake system and cleans up the engine bay. Both intakes are good for a few extra horsepower out of the box and are necessary for some of the other upgrades on this list. 

Charge Pipe / Inlet Pipe / Intercooler

For charge air cooling and delivery, Chris opted for the VRSF 5” Performance HD Intercooler Upgrade Kit and OEM location High-Flow Silicone Turbo Inlet kit. For the cold side charge pipe, a Vargas Turbo Tial/Turbosmart Raceport BOV Flange that accepts his TiAL Sport Q 50mm Blow Off Valve. This series of upgrades improves the efficiency of the boost system for more power and replaces the failure-prone plastic charge pipe and turbo inlet BMW used from the factory. That’s what we call a two-for-one special, there.  

HPFP/LPFP

With air delivery handled, Chris needed to tackle fuel as well. Yet another common problem with the N54 is the high pressure fuel pump, which is known to die and leave your car in limp mode or totally stranded. Chris both replaced his High Pressure Fuel Injection Pump with the most up-to-date BMW pump revision and upgraded his Low Pressure Fuel Pump to boot. With a Low Pressure Fuel Pump upgrade, like the Fuel-It! Bucketless E-Series pump he chose, and a set of Genuine BMW ID12 Injectors, Chris’ N54 has all the fuel it needs to reach high performance ceilings. 

Crank Hub Seal Guard

While it isn’t as common as some of the other issues that affect the N54, there is a possibility of severe catastrophe from serpentine belt failure that should be something you address. When the serpentine belt fails and shreds if it’s old and worn out, the belt can work its way around the harmonic balancer and into the crank hub seal. Naturally, you don’t want bits of belt sucked into your engine where they can cause further damage. ECS’s new Crank Hub Seal Guard is a simple enough solution to protect your N54 from experiencing this worst-case scenario and should be considered part of your bulletproofing on the road to 600hp. 

Turbos

Ah yes, the real heart of the N54’s performance, the turbos. Again, another common failure item, the twin turbos are not only known for their rattly wastegates but also for their low performance ceiling. If you want to break into the 500 and 600HP mark, you absolutely need Pure Stage 2 twin turbo upgrades. These stock location turbo upgrades, designed to work with the 2” high-flow turbo inlets, allow Chris to push much more boost and eliminate the failure-prone factory units altogether. 

Downpipes

We’ve covered the inlet side of the engine, now for the exhaust side. The upgraded turbos require upgraded high-flow downpipes to meet their full potential. Chris chose high-flow downpipes to both decrease restriction and increase the volume from his exhaust. These downpipes are necessary for the upgraded software he also uses to reach that mythical 600hp mark.

Sensors & Software

When turning up the boost, you also need to address a few electrical components so your DME can use all the extra capabilities of the upgraded parts. Namely, fresh pre-cat oxygen sensors, a new VANOS solenoid valve, MAP sensor, and Burger Motorsports TMAP & PNP adapters. Fresh sensors will ensure your ECU is reading correct data to adjust air/fuel mixtures while the JB4 3.5 bar plug-and-play TMAP adapters allow your engine to unlock all the boost available from your upgraded turbos.

Clutch / Flywheel

With all that power, suddenly the clutch becomes the weak point. This is a great opportunity to tackle both an upgrade and maintenance service, as you’ll have access to the rear main seal with the transmission removed. An upgraded clutch, like the DKM Stage 3 Performance Twin-Disc Clutch Kit and Single Mass Flywheel, will allow you to hold up to 650ft/lbs of torque. This critical upgrade is just what you need to put that power to the wheels without slipping or roasting the clutch, while the fresh rear main seal will give you added peace of mind that you won’t have to pull the transmission off again until it’s time for the next clutch job.

Wrapping Up
 

Thanks to all these upgrades, Chris’ E90 335xi is sitting comfortably just shy of 600hp and doing it safely. With the right parts, the right maintenance, and some bulletproofing, yours can too. For a daily-driven car that sees all types of weather, we can’t think of a much better option than a well sorted 335xi like Chris Armbruster’s. All that’s left now is for you to see if you can top his build! Do you have a high-horsepower, daily-driven, BMW? We’d love to hear about it! As always, we love to hear from you at [email protected]. Who knows, maybe your build will be in a future edition of Turner Motorsport Weekly?