The Yost Autosport BMW M4: Part 3 – Feeding the Beast

The Yost Autosport BMW M4: Part 3 – Feeding the Beast

Words: Mike Bonanni
Photos: Garrett Wade

We know it’s been a little bit since we last updated you all on the initial build of the Yost Autosport BMW M4, and if you follow us outside of MotoIQ you’ll also know that between our last article and now, we have been extremely busy. Immediately following the SEMA Show where our car was displayed in the CSF Radiators booth, we went straight into final preparation and final testing for our big race. Then, it was off to the 25 Hours of Thunderhill and immediately into the PRI Show. Now I finally have some time to get you all caught up on the rest of the build! And we’re going to get into many people’s favorite part…horsepower!


Exhaust is a common power upgrade and for ours we turned things over to Gintani who made us a custom 3” dual turbo-back system, sans mufflers of course. Because race car!

While horsepower is great for any racecar, on an endurance racecar a big dyno number is further down the list of importance behind both reliability and fuel mileage. It’s counter productive to think of fuel mileage before performance in a racing situation but in a race as long as the 25 Hours of Thunderhill the more we can stay on the track and out of the pits the better! Especially when the pit lane delta for a fuel only stop is equal to about a lap at Thunderhill Raceway.

So when it comes to power adders we keep it pretty conservative on our racecars, but when you’re dealing with the new S55 twin-turbo inline six in the new M4 conservative is still awesome. To take on responsibility of the drivetrain on this car we handed things over to Gintani, a well-known name in the BMW community. We gave Gintani free range over power adders and tuning with the emphasis being on reliability, fuel mileage, and a restriction to 91 octane pump gas. I know what you’re thinking, why 91 octane? Well there were a few reasons, number one being that the initial goal of this build is to prove what is possible with quality parts and people in a way that is relatable to the consumer. When it came to the powertrain we wanted to prove the reliability and performance of this platform without using anything exotic. We want you to be able to look at our car and know that this is a combination of parts that you can buy for your own car and track as hard as you want worry-free.


Just behind the factory kidney grilles you can see our conical air filter elements on our custom made Gintani intake system. Since the 25 Hours of Thunderhill runs in December, these filters should be grabbing plenty of cool air.

When we picked our car back up from Gintani it was equipped with a muffler-less turbo-back 3” dual exhaust, a new intake system that puts the air filters in clean cool air just behind the factory kidney grilles, and a mild tune. Everything else was completely stock. Power wise, the car made 510whp and 550 lb. ft. of torque at the tire without breaking a sweat. Nothing impressive when there are guys out there making 700 horsepower on these engines but over 500 horsepower at the wheels, reliably, is nothing to sneeze at, especially when you consider the fact that our old E92 M3 was making 410whp and 365 ft. lbs. of torque and it took at lot more money to get that car to those numbers.


The CSF “Game Changer” charge cooler is named that for a reason! And it’s not just because it looks awesome. We of course had to customize the colors a little. Yours will come with a wrinkle black or raw finish.

This is the second piece of the charge cooler puzzle from CSF, the heat exchanger. This is a direct replacement of the factory heat exchanger and goes in front of the radiator. CSF even offers a replaceable mesh protector screen!

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