• Explained: Subaru BRZ’s 2.4-Liter Engine and Why It Doesn’t Need a Turbo

It might take a few viewings, but you’ll eventually understand the reasons behind the BRZ’s lack of turbochargers

A lot’s been made of the new Subaru BRZ and its naturally aspirated 2.4-liter four-cylinder boxer engine. The good news that came with the bigger engine — the first-gen BRZ was powered by a 2.0-liter four-cylinder boxer engine — was that it came with 23 more horsepower and 28 more pound-feet of torque. For power-starved fans of the BRZ, the new Subie’s output of 228 horsepower and 184 pound-feet of torque was a step in the right direction. Unfortunately, there is a caveat to the second-generation BRZ’s boxer engine. It’s still naturally aspirated, effectively squashing any and all dreams of seeing a turbocharged BRZ.

The Japanese automaker already explained that a turbocharged engine would come with a lot of complications, but for those who remain skeptical of Subie’s reasoning, this episode of Engineering Explained is must-see YouTube viewing. Host Jason Fenske is known for his deep dives on anything and everything related to automotive engineering. All the numbers might make your head spin as it did ours, but if you’re interested in understanding why the second-generation Subaru BRZ does not need a turbocharger, take some time out of your schedule and watch Fenske explain it in a way that we can (sort of) understand.

For what it’s worth, Subaru is right when it said that a turbocharged engine, while mighty appealing on the surface, compromises more than just the power and performance that you can get from the BRZ. Adding a turbocharger not only adds more weight to a car that probably doesn’t need it, but it also complicates the weight distribution, which, in turn, displaces the coupe’s center of gravity. Sure, forced induction generates more air, which in turn produces bigger pops in the combustion chamber that leads to improvements in horsepower and torque. All that is great, but is it great enough to justify dramatically changing the makeup of the BRZ?

Explained: Subaru BRZ's 2.4-Liter Engine and Why It Doesn't Need a Turbo
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We haven’t even gotten into the cost that comes with fitting a turbocharger into a model that wasn’t even a hot ticket item in Subaru’s catalog in the first place. Mind you, the 2020 BRZ starts at just under $30,000, and that’s without a turbocharger that, if in place, would raise the coupe’s price up to a presumably unreasonable amount. Putting yourselves in Subaru’s position provides some clarity on the matter, but there are also other mitigating — and scientific — factors that come into play to justify the rationale that the BRZ doesn’t actually need a turbocharger to be a fun and enjoyable ride.

Explained: Subaru BRZ's 2.4-Liter Engine and Why It Doesn't Need a Turbo
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Basically, Fenske compares the BRZ’s 2.4-liter boxer engine with the 2.4-liter turbocharged engine from the 2020 Subaru Ascent and determined that while the Ascent’s turbo-four packs more power and torque than the BRZ’s naturally aspirated 2.4-liter unit, the discrepancy isn’t as big as the catalogs might interpret it to be. That, according to Fenske, is a credit to the BRZ’s 7,500 rpm redline, which is high enough that you can use more aggressive gearing to reach the same vehicle speeds.

Explained: Subaru BRZ's 2.4-Liter Engine and Why It Doesn't Need a Turbo
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And while it is true that if Subaru put the Ascent’s turbocharged unit into the BRZ, the Subaru sports coupe would generate roughly 20 percent more torque than its current setup. But here’s the rub — and it goes back to Subaru’s own explanation why a turbocharged wasn’t in the cards for the BRZ. Would a 20 percent increase in torque justify the weight that a turbocharger would add to the BRZ? More importantly, would that same amount of performance gains — it’s really negligible if you think about it — justify the extra thousands of dollars that Subie would have to add to the BRZ’s price tag?

Probably not, right?

Kirby Garlitos
Kirby Garlitos
Automotive Aftermarket Expert - kirby@topspeed.com
Kirby’s first exposure into the world of automobiles happened when he caught Knight Rider on television as a five-year old boy. David Hasselhoff didn’t leave much of an impression on him (that happened later on in Baywatch), but KITT certainly did. To this day, Kirby remains convinced that he will one day own a car with the same ‘spirit’ as the original KITT (not the 2008 monstrosity). He doesn't know when that will be, but until then, he’s committed to expressing his love for KITT, and all cars for that matter, here at TopSpeed.  Read full bio
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