The infamous Subaru EJ boxer engine has been at the heart of WRX STI's for over 26 years now. But the brand new Subaru STI will receive a newly designed boxer engine which currently sits in the Subaru Ascent, a revised version of the Subaru FA24 boxer engine.
The upcoming Subaru WRX STI has been confirmed for 2022, and will produce over 400bhp at the wheels thanks to its newly designed FA24 engine.
So, how did Subaru get it right with the FA24? Well, the new engine features direct fuel injection, unlike the EJ which featured port injection. Port injection mixes the fuel and air in the intake manifold, which is not as consistent as direct fuel injection which delivers fuel directly into the cylinder.
The FA24 also features far thicker cylinder walls and support, which not only ensure the engine can withstand more power than the EJ, but will also disperse heat far more evenly as well.
The FA24 will also feature beehive valve springs. In the event that your valves are opening and closing so quickly, the springs themselves might not even have enough time to fully close before the next cycle, which puts severe stress and wear on the valve train. To solve this problem, Subaru has installed valve springs that are narrower at the top and bottom, which visually makes it look like a beehive (hence the name) to solve this problem.
Take a look at the video below by the YouTube channel, Donut Media, on Subaru's New Boxer Engine – The Science Explained...
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