 | Building The Ultimate F3X N55-Powered BMW
You know what, I’m just going to say it: we don’t talk about the F3X chassis enough. With the new G20 capturing our attention and the E9X still holding its special place in our hearts, the F3X seems to fall between the cracks. Well, this week, it’s all about the F3X for Turner Motorsport Weekly. Settle in for a few of our suggestions on how we’d make a well-rounded build come to life in the F3X 335i/435i. | | |  | Intake
The first step to unlocking more power from your N55 is reducing restriction at the intake. A cold air intake, like our Turner Motorsport Carbon Fiber Intake, serves multiple purposes. First, it reduces intake air temperatures to send colder, denser air to your turbo, where it’s compressed before passing through the intercooler and into your combustion chamber by way of the charge pipe and intake manifold. Additionally, it resists heat soak, a common cause of power loss, by separating the hot engine bay air from the intake air box. Finally, it’s able to send a higher volume of that air to your turbo, which allows your injectors to supply more fuel and stay in that critical Air Fuel Ratio for peak performance. Plus, they just look clean and sound incredible with some beautiful carbon under the hood and turbo induction noises every time you step on the throttle. | | | | | | | | |  | Intercooler
Between the turbo and the charge pipe sits your intercooler. The intercooler’s job is to bring intake air temperatures back down to a suitable temperature for bringing that density and volume back. Colder air is denser than warmer air, which means you can pack more of it into the engine. One side effect of compressing air is that the air molecules generate friction, which causes heat. The intercooler combats this, but the factory intercooler is also a point of restriction. Our F3X N55 Stepped Intercooler solves both the volume and restriction problem by providing a more efficient path for the charge air to flow and increasing the surface area of the intercooler to provide more effective cooling. This means you’ll be able to shove more air at a colder temperature to your engine, further improving power output. | | | | | | |  | Charge Pipes
The final piece of the air induction puzzle is the charge pipes. The charge pipes sit between the intercooler and the throttle body on the cold side, and the turbo to intercooler on the hot side. Their job is to take charged air from the turbo to the intercooler then to the engine, but the factory pipes are yet another source of restriction. Our in-house designed F3X N55 hot and cold charge pipe kit offers a direct path for better efficiency as well as a larger consistent diameter for the air to flow without restriction. Yet again, the whole point is to push as much air as possible at the coldest temperature to your engine so it can gulp down the maximum amount possible for turning up the power. | | | | | | |  | Turbo Inlet
When you’ve made the above improvements, you’ll be almost ready to turn up the boost with a software tune, but there’s one last future-proofing upgrade you need to make. The factory turbo inlet on the N55 is a known source of failure both from age-related plastic deterioration and from increased boost pressure. Our Turbo Inlet Upgrade Kit provides a heat-resistant, long-term, durable solution designed to both offer you a replacement for a failing factory inlet and hold up under increased performance. If you don’t want to blow your inlet on the street or track, our Silicone and Aluminum Turbo Inlet Upgrade Kit is a must. | | | | | | |  | Catch Can
Speaking of future-proofing, a known downside to direct injection engines is carbon buildup. With no fuel cleaning the intake ports and valves, you can experience crusty and restrictive carbon buildup that requires regular cleaning. A Catch Can Kit, like our baffled can, intercepts the cause of that buildup from its source in the crankcase and offers two huge benefits. First, your intake ports and valves will stay nice and clean with the catch can trapping particulates from the crankcase before they’re reintroduced to the intake air to be burned off during combustion. Second, with significantly fewer particulates from the crankcase entering your intake, you’re feeding clean air into the combustion chamber. This means of the total volume entering the combustion chamber, nearly all of it are the ingredients for combustion. | | | | | | |  | Exhaust
With those bolt-on upgrades to the cold side, you’re ready to de-restrict the hot side. The final source of air restriction comes from the factory exhaust. Both the factory catalytic converter and exhaust system post-cat are quiet and restrictive after the aforementioned upgrades are added, so they need to go in the bin. Our N55 High-Flow Catted Downpipe offers a much freer-flowing solution that maintains legality to keep our EPA friends happy while giving you a heartier sound and up to 26whp more to play with. From there, the Turner Motorsport Valved Cat-Back Exhaust frees up the rest of the system and allows you to control the volume of your BMW at the touch of a button. If you’re in the mood for a relaxed and quiet drive, simply keep the valves closed. When you want all the power and all the sound, open them up and you have a nearly straight-through system virtually free of restrictions designed to sound and perform at the limit of what your N55 can do. | | | | | | | | |  | Software
This is the bow that ties everything together. With the above modifications, you’ll need to let the ECU know it can work with much higher ceilings than before. Our in-house developed N55 software tunes, either Stage 1, Stage 2, or Stage 3 will give your engine those parameters that let it take full advantage of the upgrades. Stage 1+ is a hearty upgrade, freeing up 97HP and 127ft/lbs of torque (provided you have an intake and cat-back exhaust). Stage 2+ takes it even farther, adding the knowledge that you have an intercooler, you’ll have that power delivery available for much longer with consistently lower intake air temperatures and charge air temperatures. Finally, Stage 3 gives you a whopping 110hp increase and 174ft/lbs of torque, utterly transforming your N55 into an all-out weapon. You will need an upgraded clutch (MT) or Transmission Tune (AT) to have this setup hold out in the long term, but the option is always there when you want to move up to the next level if that isn’t in your budget quite yet.
Of course, there are some other added benefits of our software upgrades, like smoother boost delivery, removing the speed limiter, and improving the throttle response. Not only that, but this is an upgrade you can perform in your driveway in as little as a few minutes. We send you the cable and software, you load it up, and it’s good to go. Even if you take your BMW in for a service and the software is overwritten by the technician, you can always flash it right back in a few minutes. | | | | | | |  | Coilovers
After all that power, you’ll want a suspension setup that can handle it. Coilovers are the go-to upgrade for better handling in terms of lowering your center of gravity, giving you the adjustability you need to dial in your settings for the perfect feel, and reducing body roll. Our friends at ECS are hard at work developing a line of coilovers specifically for the F3X 335i/435i, but if you can’t wait, there are plenty of competitive options already available like KW, BC, Bilstein, H&R, and more. | | | | | | |  | Sway Bars
Again, it all comes down to adjustability with suspension. Sway bars help reduce body roll, but in high-performance driving situations, the factory sway bars just aren’t able to give you the benefits you need to feel a true difference. You might even notice the car plows (understeers) a bit more in the corners with more power or is too tail happy (oversteer) as you step on the throttle out of a corner. With Turner Motorsport adjustable front and rear sway bar upgrades, you can reduce or increase your under and oversteer to suit your needs while significantly reducing body roll for better traction and faster cornering. | | | | | | |  | Front Lip
With the performance upgrades handled, you can turn your attention to aesthetics. First up, ECS' M Performance style Carbon Fiber Front Lip gives a ground-hugging and aggressive visual improvement to the front of your F3X, mimicking our championship-winning BMWs’ look on the track. It isn’t functional in terms of downforce, but it certainly adds to the total package of ‘performance BMW’ that you can’t skip once you’re at that kind of performance level with your F3X. | | | | | | |  | Rear Spoiler
On the back end of the car, our Carbon Fiber Rear Spoiler sits right at home on your F3X. It gives a more streamlined and sporty appearance that helps hint at the performance that lies beneath the surface and differentiates it from your run-of-the-mill commuter BMWs. Again, it doesn’t serve a purpose beyond looking good, but does it really need to? | | | | | | |  | Shift Kit
Finally, the last big improvement for you manual transmission drivers, the Turner Motorsport Short Shift Kit gives you the perfect way to fine-tune your driving experience with shorter, more precise, and more engaging shifts from our complete kit. This setup allows you to run both push-on style OEM BMW shift knobs and thread-on aftermarket knobs, so you can have the exact shifting feel you want from your F3X. | | | | | | | Wrapping Up
We already know the N55 can be an absolute unit when it comes to performance. That’s why we’ve spent so much time and effort developing all these upgrades to let you unlock that hidden potential in your F3X, whether it’s just your daily or a dedicated track toy. Any F3X with the full complement listed above is a formidable car and something deserving of admiration. Why not make yours as good as it can be? | |
About the Author
Craig Daugherty is a die-hard BMW enthusiast with a particular taste for E30s, engine swaps, and manual transmissions. A graduate of Lipscomb University in his hometown of Nashville, TN, Craig holds an undergraduate BA in English alongside an MS in Renewable Energy. Before introducing Turner Motorsport Keys to Performance and Turner Motorsport Weekly in 2017, he was the co-owner and co-founder of Tennessee30 Garage in Nashville and an active member in the Old Hickory BMWCCA chapter. With more than a decade of BMW experience and as an amateur or professional automotive journalist, his interests are evident in each weekly article. He’s the man behind the keyboard and who many of you correspond with in response to each edition and the source for all things BMW news here at Turner Motorsport!
Thanks for reading!
Craig Daugherty | | | | |
