Having raced professionally 3 Series BMWs of every generation since the E36 of the late 1990s, BimmerWorld Racing knows a thing or two about how the cars are put together. Even so, the Virginia-based team got a pleasant surprise when it started working on its new F30 328i last spring. Stripping out the interior to weld in the requisite roll cage, BimmerWorld found a chassis with a distinct advantage over previous models.
“In E36s, the M cars had subframe reinforcements and non-M cars didn’t,” says team owner/driver James Clay. “We found that you really needed to weld those in for cars that were going on the track. In the E46s, BMW did a better job, but even the E46 M3s were tearing out subframes. In the E90s, BMW made them stiffer still, but on the race cars we pick up the cage points all the way down into the subframe to give it extra support. In the F30, it’s almost like they took that element of a race car and built it with support down to the rear subframe.”
That, of course, made the task of race-prepping the car easier. It bode well, too, for the car’s prospects in the Continental Tire SportsCar Challenge (CTSCC), where it would join BimmerWorld’s fleet of E90s in the ST class for the last few races of the 2013 season. The team was still coming to grips with the new N20 four-cylinder engine, but the #84 car was sufficiently developed to take tenth place at the CTSCC finale at Lime Rock Park in late September. It was only its third race ever, but its pace was less than half a second down on the times set by its well-sorted and reliable E90 stablemates, which finished second and third in the same event.
Lap times aside, we wondered how these two generations of BimmerWorld race cars compare from behind the wheel. To find out, we joined the team for a private test at Virginia International Raceway, where we had a chance to drive both cars back-to-back. The new F30 shows plenty of promise, but is it ready to take on the venerable E90? We shall see!
F30 race prep
The process of building a new race car began when Virginia-based BimmerWorld ordered a new F30 328i from United BMW in Roswell, Georgia. After a thorough inspection, the team started stripping out the interior in preparation for welding in the roll cage and swapping the stock suspension for something more race-worthy.
In 2013, the CTSCC required AST dampers, which BimmerWorld fitted to its E90 and F30 328i racers along with Hyperco springs. For 2014, teams will have freedom of choice where dampers are concerned, so BimmerWorld switched to Motion Control units (still with Hyperco springs). It’s a return to the familiar: Motion Control is run by engineers who were at Moton when BimmerWorld used that company’s shocks in Speed World Challenge (2002 to 2009).
Along with the appropriate shocks and springs, BimmerWorld also installed larger roll bars, which Clay says are crucial to handling. The team also replaced the stock rubber chassis bushings with stiffer items in either Delrin or hard polyurethane (Powerflex Black Series).
As mentioned earlier, BimmerWorld has been racing the 3 Series for more than a decade. During that time, the team has pioneered the racing development of new 3 Series models: BimmerWorld was the first team in a U.S. pro series to race the E90 when it began campaigning that car alongside its E46s in 2006. More recently, BimmerWorld’s E90 racers have played a vital role in winning the Street Tuner class manufacturers championship for BMW in each of the last two seasons.
BimmerWorld would also be first to race an F30 when it entered the car in three of the last four CTSCC events of 2013, but the latest generation of 3 Series proved difficult to make track ready despite its more suitable chassis. This time, the challenge would be found in the engine bay, where the turbocharged N20 four replaced the naturally aspirated sixes the team had been working with for over a decade.
As far as we can determine, BimmerWorld is the first team in the world to race an F30 powered by this new four, and getting it to work correctly under racing conditions has been tough. Most of the issues have revolved around the Bosch Motorsport ECU that replaces the stock part, as it does on this and the other BMWs racing in CTSCC.
“It took some time to see if we could use the factory ECU,” says Clay. “Obviously there are software tuners out there, but BMW doesn’t want people in their ECUs and they’ve made them difficult to get into. We explored that a little but then just decided to go with the Bosch Motorsport ECU instead of fighting to get the factory ECU working and then realize we should have gone with Bosch in the first place.”
To maintain a level playing field among the various marques and models, the CTSCC series keeps a tight rein on turbo boost. The Bosch Motorsport ECU can regulate boost much more precisely than the stock ECU—which is also made by Bosch, though to a different set of parameters than the Motorsport part. Getting the Bosch Motorsport ECU to work correctly thus requires extensive tuning on the dyno and a lot of trial and error. Clay has the impression that the group at Bosch responsible for the factory ECU doesn’t work with the engineers on the Motorsport side, which makes things even more challenging.
“The N20 is only the third engine that Bosch Motorsport has worked on for the series that has a direct injected motor and only the second that has a turbo, so there’s not a lot of data built up,” says Clay. “The N20 has variable cam timing with VANOS, injector timing, ignition timing and high-pressure fuel rails, which is another variable, and the fuel rail pressure, injector pulse timing and ignition timing all have to converge together at exactly the right spot.”
Beyond the ECU, the N20 needed improved cooling, so BimmerWorld fitted a more efficient C&R Racing radiator, a higher-volume water pump and an oil cooler in place of the stock F30 328i’s oil-to-coolant heat exchanger; CTSCC rules mandate retention of the stock intercooler. Clay figures the cooling upgrades reduce engine temperatures by 30-40°F compared to stock.
Besides the ongoing engine work, the limited slip differential in the F30 race car also presented some challenges in the build process, but it was nothing Diffsonline couldn’t handle.
“BMW hasn’t provided a limited slip in a non-M car for over a decade, so it’s always a challenge to put one in,” says Clay. “The ring gear on the F30 was welded to the carrier, the piece that we needed to substitute, and the required offset for the ring gear to run in the correct position had to be changed. The F30 also runs a new half-shaft in which the output flange is integrated versus staying in the differential. When adding a limited slip unit, the drive gears had to be modified to not only retain the axle in the differential but to also have enough clearance to not add lockup under suspension droop.”
If swapping ECUs and differentials wasn’t enough, BimmerWorld also removed the F30’s electrically assisted steering rack in favor of one with hydraulic assist. That may sound simple, but the boost levels in the F30’s electric rack are part of the engine control strategy and thus feed into the ECU. BimmerWorld’s use of the Bosch Motorsport ECU forced the team to use the hydraulic rack from the E90 3 Series, which had to be lengthened to fit into the F30.
The brakes were modified, as well, though here BimmerWorld was limited by CTSCC rules that require that brakes be within five percent of the stock size; interestingly, the rulemakers have allowed that to be defined on the basis of the rotor size from the 2006 E90 330i, which at 330mm is larger than that on either the E90 328i (312mm) or the F30 328i (also 312mm). BimmerWorld uses the stock calipers fitted with Performance Friction pads and rotors for both the F30 328i and the E90 328i.
Driving old and new at VIR
To find out how the 3 Series has evolved in the transition from E90 to F30, we met up with BimmerWorld Racing at Virginia International Raceway (VIR). A week earlier, both cars had raced in the final CTSCC event of 2013, and we’d have the opportunity to drive both generations in as-raced condition.
VIR is one of the best tracks in North America, with 3.27 miles of pavement offering fast corners, slow corners, a long straight, and a rip-roaring section known officially as the climbing esses, which are taken flat-out while bouncing over the curbs and making left-right-left-right transitions.
VIR wasn’t on the CTSCC schedule in either 2012 or 2013, but it remains BimmerWorld’s home track. From its headquarters in Dublin, Virginia, about 130 miles away, BimmerWorld brought two cars to VIR: the #84 F30 328i driven by Clay and John Capestro-Dubets and the #80 E90 328i driven by Connor Bloum and Greg Strelzoff to three podiums in 2013, including a third-place finish at Lime Rock.
I started off in the #80 E90, following Clay as he piloted the #84 F30 ahead of me. The #80 gave off the vibe that it had been through many hard-fought battles in the hotly contested ST class, but it still felt well built and solid, not to mention well developed. It’s been raced for years, and its handling has been honed to perfection. Sharp and predictable, it’s a perfect match for the car’s smooth and responsive power and strong brakes.
The stock pedals, stock transmission and an ideal seating position made it easy to drive fast in #80. Through the challenging climbing esses, I was lifting off the throttle only slightly on the entry before putting my foot to the floor, following Clay’s line as he rode the curbs and climbed the hill. I’ve driven a lot of race cars over the years, but few have felt as well balanced and predictable as BimmerWorld’s #80 328i. I’m pretty sure I hadn’t really gotten all that close to its limits; in my experience, the hardest thing to get used to in a race car is the level of grip you have from the racing slicks, not only in corners but also in braking. Needless to say, Clay was going a lot deeper into braking zones than I was.
After some laps in the #80, I switched seats with Clay and climbed into the #84 F30 328i, a roomier ride than the E90 in both race and street guise. Having raced just three times, the #84 still felt fresh, with Racetech seats that still looked new, an OMP steering wheel whose suede wasn’t yet worn off at the hand positions and unblemished paint on the floors and the roll cage. BimmerWorld doesn’t scrimp on the details in building race cars, and the F30 was beautifully made, with well laid-out switches and controls and custom carbon fiber panels on the dash, as well as a nicely integrated MoTec display in place of the stock gauges.
Climbing from the E90 straight into the F30, I noticed the difference in the engines right away. CTSCC rules require that engines remain nearly stock, and the naturally aspirated N52 inline six in the #80 E90 had great throttle response and linear power delivery while the N20 four in the #84 F30 had duller throttle response and turbo lag, just like the road car. Thanks to mandated restrictions, the N20 has less turbo boost to work with in the F30 race car than it does in the road car (around 11 psi vs. 18.9 psi), so it doesn’t feel significantly faster than the road car in a straight line even though it’s much lighter. Fully race prepped, the #84 weighs in at 2,850 lbs. where the road car tips the scales at 3,360 lbs.
The F30 didn’t feel quite as sharp in its handling transitions as the E90, which of course has the benefit of years of development. I was still going flat through the esses, but doing so felt edgier than in the E90. The F30 did feel a touch faster on the straightaway than its predecessor, but I was too busy paying attention to the track to compare top speeds. (Stock, the E90 328i puts out 230 hp/200 lb-ft compared to 240 hp/255 lb-ft for the F30 328i, while both cars have an identically restricted top speed of 130 mph that no longer applies once the cars are converted to track duty with the Bosch Motorsport ECU.)
After a couple of laps, I started feeling more comfortable. Clay later told me our last few laps were run at around seven-tenths of a race pace, but I never felt as fully at ease in the F30 as I did in the E90. It was still a lot of fun to drive, but I would go with the E90 if I were buying one of these cars for a personal track day machine.
Far from done with development, but a challenger looms
That said, the #84 F30 328i was still very much in development when I drove it, and it was just one week removed from its tenth-place finish at Lime Rock. That surprisingly strong result so early in the car’s career heralds great promise for the F30’s first full season in 2014, and Clay expects the #84 F30 to become more competitive as the season progresses and another F30 is added to the fleet.
“The F30 still requires more development, and we’ve been digging into that, especially with learning more about direct injection and how to control that properly,” says Clay. “Every time the car is out on track, we get better with it. We haven’t picked up chunks of power and haven’t gotten rid of the turbo lag, but we’ve polished off a lot of the rough edges. The biggest change this year is with the Motion Control dampers. It’s a significant change, and we have the right partner and the right resources to get an advantage with that. We’re also building a second F30, and the plan is to release it early in the season, whenever we’re comfortable with the competitiveness of the car.”
Having been the first to race both the E90 and the F30, it’s no surprise that BimmerWorld Racing is looking beyond the 3 Series to
the new 2 Series coupe set to arrive in the U.S. in 2014.
“We have one F30 and are building another, but if I feel comfortable about the changeover in the series [from Grand-Am to USCC] and investing further in it, our next two cars may be 2 Series cars,” says Clay. “The 2 Series may be more appropriate, as the 3 Series has just gotten so big. The F30 is absolutely the largest car in the field, and with the series regulating power and weights, they often don’t account for things like frontal area. Having the largest cars makes it easier for cars behind us to draft, and it’s harder for us to catch a draft from the smaller cars like the Mazda MX-5. At fast tracks like Daytona, a small car can be much more slippery.”
Whatever the future holds, BimmerWorld has proven to be one of the most competitive teams in CTSCC. In addition to its individual and team successes, BimmerWorld’s 3 Series racers have played a vital role in winning the CTSCC Street Tuner manufacturers championship for BMW in each of the last two seasons. And given the team’s track record as a pioneer in racing new BMW models, we won’t be surprised if BimmerWorld becomes the first pro team in the U.S. to race the 2 Series alongside the venerable 3 Series.