BMW M240i Build For Street/Track Use
This build started out innocent enough; a stock 2017 BMW M240i RWD 6-Speed with 42K miles. The rear wheel drive, manual trans options made this the perfect base car for a street/track build. This is a pretty capable car even in stock form but I knew it could be so much better.
This will be my first BMW M240i build. After tuning numerous BMW’s with both the N54 and N55 engines, it’s time to finally tune a B58. I recently tuned the S58 in my X3M Comp with a JB4, so this is a little backwards but I already knew the B58 has tons of potential. This time I wanted to try something other than a JB4 but I’ll get to that in a bit.
Mod# 1 – BMW M-Performance Limited Slip Differential
The stock rear differential is pitiful for a small car with this much power. The dynamic traction control works hard to get the power to the ground but this car really should have had a LSD from the factory. I bought one and had it installed by my local dealer. The BMW M-Performance LSD comes with a 2 year warranty on both the part and labor. Besides, the dealer only charged me 3 hours to install. No core on the differential as well, so I now have the stock open diff in case I put the car back to stock.
Mod# 2 – High-Flow Downpipe
Because this is a street/track build I went with a high flow DP. If I was building a track only car, the catless option would have made more sense but I need to pass emissions.
Mod# 3 – BMW B58 Bootmod3 Stage 2 Tune
I’ve installed and tuned so many cars using JB4’s that it was hard leaving the platform but it was time for a change. Stage 2 really woke the B58 up and added tons of noticeable HP and Torque. I decided to run an E30 blend and try out the Stage 2 E30 map. Bootmod3 says on their website that this map is 420-440 whp. I roasted the clutch on day 2 🙁 I really didn’t expect the stock clutch to survive this build but I didn’t think it would give up that quickly.
Mod# 4 – Spec Stage 2+ clutch
After talking with a rep at Spec, I decided to go with Stage 2+. He felt it would hold my ultimate power goals of 500+ HP and still have good drivability. He was right about the feel, it’s slightly firmer than stock but not much. Let’s hope he was right about it’s holding power as well.
Mod# 5 – High Pressure Fuel Pump (HPFP)
The early B58’s do not have strong enough HPFP’s to run a lot of boost. You have options for aftermarket upgrades but I decided to go with the BMW HPFP from the B58TU1 (B58 technical update.) You can buy these from your local BMW parts department or online. You will need to extend the stock wiring harness to connect the new pump as well. If you’re handy this is not a big deal. If you want an easier install you can buy a kit from Burger Tuning here.
Mod# 6 – Coilovers
The goal here is to lower the ride height and increase handling but not at the expense of ride quality. After driving both an M4 and X5M with KW coilovers it was clear I was going to go with KW’s. I decided to get the KW V3’s with EDC delete. We set the ride height and approx. 1.5″ lower than stock and left the dampening and rebound settings where they were out of the box. Lower stance looks awesome and ride quality is unbelievable! Having installed sport springs in the past in an effort to get the look but save some money, I will always go with KW’s in the future.
Take a look at my previous 2013 BMW X1 35i Project Sleeper.
I asked ChatGPT “what is the 2017 M240i like on the track?” This was the response:
The 2017 BMW M240i is a well-rounded sports coupe that can hold its own on the track. It is equipped with a turbocharged 3.0-liter inline-six engine that produces 320 horsepower and 330 lb-ft of torque, paired with either a six-speed manual or eight-speed automatic transmission. The M240i also comes with rear-wheel drive and a limited-slip differential, which enhances its handling and grip on the track. Additionally, its dynamic suspension tuning, brakes, and steering all provide a great deal of responsiveness and agility on the track.
That being said, it is still a relatively heavy car, weighing over 3,500 lbs, which can limit its agility compared to some lighter and more dedicated track vehicles. However, for a daily driver that can double as a weekend track car, the 2017 BMW M240i is a solid choice.
ChatGPT got the limited slip diff part wrong but overall I think it did a nice job for AI.
Thanks for checking out my BMW M240i Build progress 🙂