Project Car Diaries: How My BMW 128i Is Holding Up to a Summer of Track Days

After performing some simple yet crucial maintenance, not only has the sturdy N52 inline-six not leaked a drop of oil, but it's stayed amply cool during some of the hottest on-track sessions that I've ever driven through. Who knew “sturdy” could be used to describe any BMW component?

Despite a lot of travel and occasionally trying to live my life outside of anything car-related, I've had the opportunity to hit the track three whole times this summer. It's given me a chance to reflect on how far I've come with figuring out the chassis, as well as whether the modifications I've done were a good idea. Short answer: No complaints!

When I replaced my BMW 128i's oil filter housing gasket and lower coolant hose—common service items for its N52—I did a 70:30 mix of distilled water and OEM BMW coolant. For folks who live in America's warmer climates, having more distilled water in the system should allow it to pull more heat out of the engine, but I'd hesitate to run this much water if I were visiting any climate that sees near-freezing temperatures. You wouldn’t want anything in the car’s cooling plumbing to turn into ice, that could make for major engine problems.

Heat management is crucial for tracking all year round, but especially in summer when my local circuits' ambient temperatures often exceed 100 degrees. 

I'm glad I went with a 128i over its turbocharged sibling the 135i; not running entire sessions at whatever pace I'd want to due to the added heat of turbocharging would get annoying, fast. So far, danger-level water temperatures haven't popped up, including a recent visit to Buttonwillow Raceway Park where it was brutally hot outside all day. I feel bad for my colleague Chris Rosales, running in these same conditions in his toasty FK8 Civic Type R. The highest I saw during the hottest session was a brief bit of 221 degrees, but otherwise, it averaged 215 throughout the rest of the circuit. According to fellow N52-equipped BMW owners, this is safe territory.

That being said, I'm going to look into trying to keep an eye on oil temperatures as well. Unfortunately, the 128i's OBD II plug won't send this data to my Apex Pro II app, which I use to not only keep an eye on lap times but also give me live readings of coolant temps during sessions.

One of my initial goals with the 128's setup was to keep things simple. I didn't want to worry about cornering balancing or fine-tuning the ride height like I would with a set of coilovers. I simply wanted slightly stiffer spring rates, the ability to adjust the dampers' rebound, and to hopefully preserve the chassis' factory 50:50 weight distribution along the way. Going with Eibach Pro-Kit springs and Koni Sports has proven to be a solid move: The ride is enthusiast-centric-yet-comfortable in any environment, and body roll is nicely contained after playing with the shocks' rebound. Especially with all four corners set to level three, which is three half-turns … I'm pretty sure.

Thanks to BMW's Lego-like parts bin sharing, upgrading the front sway bar with an E93 M3's (meaning, the convertible one) is in order, which is the stiffest option that the Bavarian brand offered at the time and bolts right up to my car. Fellow enthusiasts report that a bigger rear bar isn't really necessary. Finally, how could I forget one of the best bang for one's buck mods, ever: installing rear subframe mount reinforcements was an immensely … solid … move, too.

The same goes for its brake package. The front-drilled Zimmermann 335i rotors, OEM 335i calipers, and Ferodo DS2500 pads have held up wonderfully. They have yet to overcook on track and the rotors show no sign of cracking. These pads are expensive, but have been a great dual-duty compound and still have a good amount of life left. However, after six events and plenty of street miles, I'm definitely due for a Castrol SRF brake bleed.

Patting myself on the back doesn't stop there: The 245/40/17 Kumho Ecsta V730 tires on each corner have performed admirably as well. They've got at least two events left in them, after a total of five events so far, plus around 2,000 miles of street driving.

They aren't the grippiest compound, but break away very progressively, are very communicative, and don't seem to overheat much mounted up to the sort-of-svelte 128i over the course of a session.

Thanks to all this, plus getting a decent amount of seat time over the past year-and-a-half, I recently achieved second place in the B5 class in Speed Ventures' CSF Bimmer Challenge. It wasn't based on my best lap of the whole day, or anywhere near my personal best, but I'll take it!

Again, I'm quite stoked on how things have been going with my dear BMW 128i as it's proving to be an excellent dual-duty track car, and will hopefully continue to be plenty dependable. As long as I keep a close eye on things.

There are a few things that need remedying before my next visit to the track: New inner and outer tie rods, a refreshed alignment, and I need to remedy an issue with one of the swaybar mounts: While trying to track down a faint clunking, I snapped one of the studs that holds the front sway bar to the front subframe. It's mildly annoying, but I bought a suitable replacement and just have to drill the old one out. Without drilling into the (very close by) radiator … please pray for me.

Add all of this up, and I'm really excited for tracking in the final months of 2023. In addition to participating in as much CSF Bimmer Challenge as much as I can, I'm also taking part in GridLife Time Attack when it comes to Laguna Seca over the weekend of October 20-22. I'll share more about my plans for this epic event in a future blog, but I'm so stoked to both compete in this legendary series, as well as rip laps on such an immensely fun circuit.