Recently, we had acquired a 2017 M2 from our friends at McKenna BMW. This 3 liter twin-scroll turbocharged I-6 makes 365 HP & 369 lb-ft of torque from factory and we had it optioned with a six-speed manual transmission.
Upon delivery of the M2 and after the first drive, we speculate it would be a challenge to make any drastic improvements on this platform. Although some improvements may be attainable, the M2 feels incredibly track oriented right out of the box.
We will be publishing data from our track testing & dyno sessions on this thread. All track testing will be done at Buttonwillow in the 13CW configuration while dyno testing will be done on D-Sport's DynoJet.
Stay tuned for more updates.
Update #1
Stock Track Testing
We drove the M2 from the Supreme Power shop in Fullerton all the ways to Buttonwillow Raceway for a Speed District track day. Our first test would serve as the baseline, with the car completely bone stock. Our driver and marketing guy, Cameron Parsons, would set the lap times and provide his analysis. His experience spans open wheel race cars, touring cars, and lots of data analysis and coaching, so we trusted him to put together a fast lap without breaking anything. While there were a lot of cars attending this track day, Speed District did an awesome job of keeping cars spaced out so that we could establish some reference laps.
The only change we made was a drop in tire pressure to keep the tires from overheating. We then sent Cameron out on track. The M2 immediately proved to be one of BMW’s most fun track cars in factory form. It felt nimble, was easy to control (and drift) around corners, and the twin scroll turbo maintained the fun factor on the straightaways. It even offered a bit of wheelspin when exiting some of the tighter corners. One of the biggest benefits is that the car takes care of its driver on the track, especially if you’re less experienced and running in Sport or Sport+ mode. If you just turn your head and look at your turn-in points, apexes, and track-out points, let your hands follow on the steering wheel and it feels like the M2 takes care of the rest for you. By the end of the day, the car turned consistent 2:02s with a best time of 2:02.06. There was likely another few tenths left in the car, but we at least found a baseline time that the car could repeat continuously.
Cameron noted that when the car was pushed closer to its limits, it still had a tendency to understeer on turn-in. A little extra trail-braking helped the car’s rotation on turn entry, but a better suspension and alignment setup would help even more so. It needed a little help with responsiveness and yaw rates, especially in quick left-right and right-left transitional spots like Cotton Corners. As for the brakes, the durability of the OEM braking system surprised us. They held up much better than expected, even for 20 straight minutes of hard driving. While the brakes never completely overheated and failed, they still showed signs of fading and reduced effectiveness in threshold braking corners. Plus, they looked pretty toasted by the end of the day. They likely would only last another day or two of this kind of abuse.
Despite these few shortcomings, the M2 felt about as made-for-the-track as an OE can make a car. This of course means that wringing out extra seconds would be a big challenge, but that’s what we’re setting out to do! The first items on our to-do list after this test are the braking and suspension, then it’s off to the track again.
Update #2
Suspension & Alignment
Saving power mods for later, we addressed the car’s suspension first. Ideally, this would help with the car’s responsiveness on turn-in, and to help it rotate through the corners. We installed the Ohlins Road and Track kit to hit this goal, without ruining the M2’s level of comfort on the street.
The shocks and springs are tuned specifically for the M2 platform, plus the kit allows for single adjustable damping (affecting both compression and rebound) as well as height. We took this opportunity to drop the car a few millimeters and corner balance it to 49.98% crossweight.
In order to get the alignment settings we wanted, we also mounted up some Ground Control camber plates, allowing for up to 30mm of camber adjustment. With this possible, we were able to get -2.5 degrees of camber on the front end and -2.0 degrees on the rear. More negative camber was available, but we wanted to start with this as a baseline. Onto the brakes next, and then back to the track!
Update #3
Brakes & Track Test
All too often, gearheads and auto enthusiasts ignore the car’s braking system. If you’ve driven a track day on the stock braking system, you’ve likely felt firsthand the frustrations of a sinking brake pedal as the components overheat. Our M2 weighs in at only about 3,400 pounds, but that’s still a lot of mass to stop for repeated laps at speed. To this end, we installed Brembo’s GT-R braking system with massive 380mm two-piece Type III floating rotors and RT RE10 pads. We flushed the system out and replaced the original brake fluid with Brembo’s LCF600. The final package for this braking system will of course improve the M2’s stopping ability, but more importantly helps the braking system remain consistent and reliable for entire tracking sessions. With brakes and suspension installed, we headed out to the track for a test. First, we’d run it on stock wheels and tires, then we’d mount up a set of BBS Motorsport E88 wheels and Toyo tire R888R rubber to unlock the full potential of these upgrades.
We once again tested at Buttonwillow Raceway Park’s 13CW configuration with Speed District. Overall, the car felt much better, but it actually saw little improvement in lap times compared to factory form. The Ohlins Road and Track suspension did wonders in reducing body roll and keeping the front end responsive, but the stock tires simply couldn’t keep up. We found more of the same in the braking zones. The Brembo GT-R braking system wanted to bring the car to a sudden halt in the hard braking areas, but the tires would slide and skip as the car reverted to the ABS system to manage deceleration. Our M2 turned a 2:01.93 around the track, only a tenth or two faster than what we managed with the car stock. But the tires were obviously the major limiting factor.
Tune back in soon to see what improvements we found with some fresh rubber on the car.
Update #4
BBS E88, Toyo R888 & BMW Motorsport Wing
We were hoping for more of a performance gain when testing out the new braking system and suspension, but in reality it was the stock wheels and tires that held the M2 back. We experimented with an uncommon order of upgrades for this test and learned our lesson, we’ll start with wheels and tires next time. With the brakes and suspension already installed on the M2, the car turned a best lap time of 2:01.93 on stock wheels and tires. Next, we swapped in a set of BBS E88 wheels and Toyo R888R tires. We ran a staggered setup of 19x9.5-inch wheels up front and 19x10.5-inch wheels in the rear. The tires came in 265/30R19 and 295/30R19 front and rear, respectively.
This quick change really woke up the car on track, as it enabled the brakes and suspension to work to their full ability. We started the tires at 28psi cold, and saw them rise up to about 34-35psi when hot. They came up to temperature quick and handled great on track, providing excellent response and overall grip. The increased grip characteristics did make the car a little more twitchy, or prone to snapping away, but it was still manageable enough to make some steering and pedal corrections without ever losing control of the car. Considering that the tires got up to temp so quickly, gripped so well, and showed little enough wear that they’d easily survive a few more track days, these tires are excellent for the track. Just be warned that if you try these out for daily driving, they will be very noisy. After a few laps of testing, we got the times down to 1:59.33, approximately 2 and a half seconds quicker than when it was on stock tires.
The big surprise came when we then added the BMW Motorsport rear wing. It’s carbon fiber and 3-position adjustable, offering effective aero and great looks. With the wing set to the middle position, so as not to create too much drag, the car stuck to the ground through Buttonwillow’s higher speed turns like the Bus Stop and Riverside. Speed differences in some areas were nearly 10MPH. Cameron, our driver, reported back to us that this was because the car simply felt way more comfortable and confidence-inspiring in these sections. Without fear of the car trying to oversteer, he could keep the throttle planted much heavier than before. With all of the other upgrades and the addition of the wing combined, the car got another second faster, turning a 1:58.01 best lap. While we found some great advantages in this rear wing, the only problem is that it almost felt too effective as the car started developing some understeer in some areas. We’re getting teased with the benefits of downforce, so instead of trimming off the rear wing angle, we’ll start looking into front aero to balance out the car’s grip. And then it’s time to add some more power!
Update #5
Weight Reduction, Safety, & More Power
Recaro Profi SPG Seats
Studio RSR 4-point Cage
Schroth SFI 16.5 Profi III-6 Harnesses
Safety first! Now that the car is getting notably quicker, we need to address items in the cabin to make it more track-oriented. We’ve enhanced the M2’s track capabilities with better handling and brakes, with additional power on the way. This will come in the form of a Capristo exhaust, Akrapovic down pipe, Dinan intercooler, & VF-Engineering Tune. Maybe a turbo a kit if we keep getting that itch for more speed down the straights.
In the interest of safety, we pulled out the stock seats to clear space for a Studio RSR 4-point roll cage. This half-cage is designed to meet NASA racing specs, while serving as a 100% bolt-in solution (it can even fit with the rear sits installed). It uses DOM steel 1.75”x.120-thick tubing, with steel brackets form-fitted to the M2 chassis. As we pieced the interior back together, a pair of Recaro Profi SPG seats sit in place of the factory chairs. The stock seats weighed in at 56 pounds, while the Recaros only came in at 22. That way, the 70-pound weight savings would better make up for the 29-pound cage. Plus we of course get the added benefits of FIA-Certified racing seats, complete with sliders so we can still swap drivers for street use. Finally, we threw in 6-point Schroth SFI 16.5 Profi II harnesses on both seats. These meet FIA safety regs, offering thick 2-inch thick belts on the lap for better fitment and safety, and 2-inch/3-inch shoulder belts to fit over HANS devices.
We’re just about set to test the car again, this time with more power under the hood and a better feel for the car thanks to some proper seats and harnesses.
