BMW’s S55 motor is one of the best motors a BMW Enthusiast can mod. Debuting in 2014 after replacing the S65, the S55 received a lot of backlash. Swapping from an NA V8 to a forced induction straight 6 upset a lot of people, and rightfully so, the S65 was an icon. The infighting of the BMW crowd was a spectacle to see considering the popularity of the N54 and N55 regardless of maintenance problems or turbo problems.
The early models of S55 came stock with 425 horsepower and as they were refined, later models made up to 495 horsepower. The S55 came in some of BMW’s more iconic cars like the F80 M3, F82 M4, and later the F87 M2 competition. Over time these cars have started to become more attainable and accessible for people to mod, specifically the F80 M3. And with more accessibility and better aftermarket support, the S55 has been essentially turned into a rocket ship. You can do a couple simple things to get 600+ horsepower or if you commit like a real man, the S55 can ever so gently kiss 900hp.
We’ve had our fair share of F8X’s at Vivid Racing over the years, so we decided to compile a list of the top 5 mods to give your S55 more power.
Upgrading the Crank Hub
I don’t want to beat around the bush so we’ll talk about the elephant in the room when it comes to the S55. To add more power, the engine actually has to run, and the S55’s fatal flaw is the stock crank hub. At this point, the S55 is old enough to where I feel like the crank hub has already been replaced on pretty much every engine out there whether that’s preemptive or because it offed itself.
Regardless, there’s always options to upgrade it, and you can go with a couple of different brands, but our choices are RK Autowerks, MMX, and a controversial brand for BMW owners, Vargas.
Make sure you’re getting a billet crank hub when doing this, anything less will expose you to the same fate as the OEM hub.
BMW S55 Tuning Upgrades
Now that that’s out of the way, let’s talk about actual power addition. We’ll start with the stereotypical BMW thing, and that is a tune and downpipes, kinda a 2 for 1. Is this a basic thing to do? Sure, but the reason it’s so “basic” is because it actually works, and it works incredibly well.
Both of these items can be a touchy subject, with the epa and carb cracking down, it can limit what is available for you to buy, unless you go looking in other places.
Let’s start with tunes. Because of carb and EPA crackdowns, there really is only 1 company that has broken through with a carb legal tune, and that is Weistec. Weistec’s W.1 tune improves your throttle response, and optimizes your air fuel ration as well as boost. The tune alone will give you 546 horsepower and 675 foot pounds of torque which is an increase of around 120 horsepower and around 270 foot pounds of torque. I think we can all agree that for being carb compliant, those are some incredible power gains.
BMW S55 Downpipes
Now let’s add in the downpipes. Again being carb and EPA compliant, there are still plenty of options you can get that will open up exhaust flow. There’s a couple very good brands that we have loved pairing up with S55’s in the past. Evolution Racewerks has some solid options for high-flow cats that can add up to 25 horsepower with the downpipes alone. Now pair that up with a tune, and you’re cooking.
You could also go with a brand like Active Autowerke that has a ton of aftermarket options for the S55. With the pairing of a tune and solid downpipes, you’re staring right down the barrel of 600 horsepower. We’ve done this plenty of times here at Vivid, and the results have always been consistent and effective.
The rest of the mods we’ll talk about can be paired with downpipes and a tune, or they can just be standalone. The great thing about the S55 is that it doesn’t take a lot to get some additional horsepower. Doing basically any power mod will yield you real results, not like a marginal 1-2 horsepower increase.
BMW S55 Exhaust Systems
Next on the list, I want to talk about exhaust systems. Obviously pairing up a system with downpipes and a tune, downpipes specifically, will give you the best results when wanting to increase horsepower. But if you’re wanting to only install an exhaust system after the cats, there are hundreds of brands to choose from. Some of our favorites are:
Sure, exhaust systems are for power, but opening up the sound of the S55, letting that sweet, sweet straight-six sing. Freeing up those turbos is why you buy a BMW. But, regardless of the sound, you can see some actual powergains with an exhaust system. There’s always been a debate online of if exhaust systems alone can add horsepower, but with the S55, you will absolutely add more power. There are dyno graphs to prove it, look it up!
On top of just straight power addition, an upgraded exhaust will also come in lighter than stock, which can create a peppier, more agile ride. There are some systems like Valvetronic Designs that will take as much as 50 pounds off your car. Even a mildly experienced driver will notice that difference. Weight-saving plus opening up exhaust flow can typically give you an extra 15-30 horsepower and 25-35 foot pounds of torque.
Intake Upgrade
The next mod is very basic but very necessary. It’s one of the first things you should do when adding any other power mods to your car. You have to upgrade the intakes.
It’s all an ecosystem, your car works in harmony with itself, so you can free up exhaust flow and do whatever else, but if you’re not letting enough air into your engine to accommodate for the other additions, you either won’t see really any gains, or you could throw a code because your AFR is wonky. Some of our favorite brands, and not just because they look sick or make cool induction noises, are AMS, Dinan, and VRSF.
The biggest thing to look for when upgrading is the size of the intake tubes. On the stock intakes, the intake tubes will taper down below 3 inches in diameter at the turbo inlet.
When upgrading, a 3 and a half inch diameter is pretty standard to allow for better airflow.
Two other things to consider when upgrading is the air filter box and the material that the intake kit is made out of. Adding a filter box will add an extra barrier between the dirt and your filter, as well as heat coming off of the engine. The same thing goes for the material the kit is built with. The stock plastic sucks and absorbs heat from everywhere, making the air entering the turbo hotter than it needs to be. But by upgrading to titanium or aluminum, or even carbon, you can be nice to your motor and give it cooler air.
Some intake kits brands claim to add an additional 20 horsepower, but you probably won’t get 20 horsepower without additional mods. You’ll get cool induction growls and maybe a little extra kick in horsepower, but to get anywhere close to 20 additional horsepower, you’ll have to pair the intake with other mods.
BMW S55 Turbos
The best mod that you can go to your S55, no matter what car it’s in, is upgrading your turbos. Turbo upgrades are obviously getting out of the OEM+ or stage 1 build, for example, Pure Turbo’s Stage 2 Turbo Kit can handle up to 900 horsepower. Social media and the internet has desensitized us to how much horsepower that actually is. 900 horsepower is a certified race car!
Regardless, upgrading your turbo is the biggest power mod you can do both power-wise and parts-wise. You really don’t have to touch this unless you are trying to push 700+ horsepower out of the S55, but again, we’re talking about power mods.
With a turbo upgrade you’ll get things like a billet compressor wheel, stronger housing, better bearing, machined inlets, the quality of material and construction is just better, and that’s why it can handle more than stock turbos. Sometimes, even just the sizing of the turbos is bigger depending on the brand. If you’re going for gold, a turbo upgrade will get you right.
When you push more horsepower out of the S55, you’ll have to upgrade surrounding pieces, like heat exchangers, oil coolers, stuff like that to make sure your valves don’t become shrapnel. We won’t get too in the weeds on those because those are mostly supporting mods for power gains, rather than directly increasing horsepower.
You can find out more about these and other mods by visiting our website. Contact our team with any questions you have about these mods, and make sure to follow us on social media and take a look at our blog for more news and updates.
