Executive Action – 2012-2018 BMW F1X M5/M6 Performance Oil Cooler R&D, Part 1 – Concept and Design

The big BMW M’s, like the F1X M5 and M6, are the young executives of the automotive world. They’re powerful yet hungry for more. They’re decisive and maneuver with precision, but most importantly, they’re cool under pressure. Sometimes though, they can lose their cool, and for the M5s and M6s of this era, the oil cooler tends to be the source of their undoing. Luckily, we’ve already started on our plan to help the F1X’s keep climbing the performance ladder. 

Before we dig into our plans to improve the M5’s oil cooler, let’s take a look at the OEM cooler. BMW engineers are masters of packaging. Effective use of space is the name of the game, and when it comes to fitting the array of coolers on the front of their powerhouse sedans. In the case of the oil cooler, the engineers mounted this heat exchanger horizontal and right at the edge of the M5’s big-mouthed fascia and perpendicular with the rest of the cooling stack. This mounting method means that the cooler effectively utilizes the vehicle’s aerodynamics to maintain proper oil temperatures in this location. 

This oil cooler mounting method is also found on the F8X M3/M4 and follows the same concept. Essentially, the undertray creates a low-pressure zone behind the underside of the cooler. Basic laws of physics determine that high pressure wants to move to low-pressure zones, which draws some of the airflow from the front of the car—the downside to this method – parking barriers.

Just at a cursory glance, it seems that BMW was already expecting some hard knocks on their oil cooler. While a lightweight tube-and-fin core was used, the end tanks are clad in stamped aluminum, which is an upgrade from the typical plastic we find on OEM units. 

Even with the extra comfort-oriented amenities equipped to the M5 and M6, they are still low-slung GT sports sedans at heart and are designed to hug the pavement, even more so if you’ve lowered your M5, too. This concept enhances the daily driving experience, but it also puts your oil cooler directly in harm’s way. So, you have two options. You could give your M5 or M6 the proper safari treatment with a lift and body armor or just strengthen your oil cooler. We’ve already got the ball rolling on the rugged oil cooler option. 

Our oil cooler plan has two primary prongs. The first and most important is making sure that it can shrug off direct hits from parking barriers, curbs, road debris, or anything else that would cause your oil cooler to spring a leak. The second is maximizing the cooling potential. Luckily, most of our plans already combine these two goals.

First on the list is a more robust core. Tube-and-fin style heat exchangers are ideal for weight savings along with production costs, but there’s a better option out there. Instead, we plan to enlist the use of bar-and-plate core construction. Not only will this style of the core be better suited to glance incoming obstructions, but the heavy-duty bars and plates are more conducive to transferring heat. 

The core’s construction isn’t the only revision that we plan on making, and we are also opting to fill out some of the space we have available to us by adding to the core’s thickness. Adding more core volume in conjunction with the more robust core construction is the basic formula for improved cooling, which is now destined for our M5.

Since our new core design outgrew the OEM specifications, our engineer, Dan, needed to further solidify the oil cooler with a new pair of end tanks. Where the BMW design featured stamped aluminum tanks, we’re plotting on even tougher CNC-machined billet aluminum end tanks that will be securely fastened to the core via expert TIG-welding.

While our modeling and design software is precise, it never hurts to check your work. To ensure we’re not going to run into any unforeseen fitment issues, we typically produce a fitment prototype for real-world fitment tests. 

Executive decisions might only take a few seconds to declare, but in most cases, the proper implementation of those actions can take much longer. In the case of our M5 oil cooler defense strategy, even with the plans in place, the strengthening needs to be implemented appropriately. So make sure that you stay tuned for the first look at our new oil cooler coming soon!

Thanks for Reading!

-Nick

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