One of the weakest links in Subarus are their flat-four boxer engines. They’re hard to work on, not that reliable, and don’t have the performance potential to justify their low center of gravity to everyone. But rather than swap one for a played-out Honda K-series, one 2004 Subaru Impreza WRX STI rally car driver is opting for a far more exotic swap: a Ferrari California’s flat-plane-crank V8.
The Prancing Horse-powered STI is being built by American rally driver and Dirtfish instructor Sam Albert, who tells me he originally bought the 2004 STI new as a road car. He turned it into a rally car in 2010, embarking on a racing career that took him to a North American Rally Cup win in 2018 (though in a different car).
After more than a decade in the sport, Albert was ready “to try something different” from his tried-and-true 2.5-liter turbo EJ25 flat-four engine. While reading the regulations for the American Rally Association’s Open 4WD class, he noted that naturally aspirated engines had a displacement limit of 4.5 liters. Some quick research showed the most powerful NA engine of this size to be the F136 V8 used in the Ferrari 458, where it makes 562 horsepower.
It was far beyond Albert’s budget, but the F136 is a big family of engines with more affordable options, including cross-plane versions used in Maseratis and—more promisingly—the flat-plane 4.3-liter from the California. Making 483 horsepower and 372 pound-feet of torque, it offered more power, a broader peak, and more drivability than the turbo 2.5-liter it was to replace, making the torque sacrifice worthwhile.
“Ultimately I think it will be more enjoyable to drive, have a slight performance improvement if I did my math right, and sound amazing in the forest,” Albert told me. “There was also a little bit of inspiration from Andy Burton and his Peugeot Cosworth that was ultimately banned from competition after he did so well with it.”
Albert says he did the swap almost entirely on his own, including designing the custom flywheel and adapter plate to mate it to his car’s six-speed sequential manual. Best of all, the V8 apparently improves the weight distribution by about 1% over the stock engine. Combined with some suspension geometry tweaks, Albert hopes for the best for the car’s competitive debut at Washington’s Olympus Rally in April.
But whether the Ferrari STI is a winner or not, it’ll probably be the best-sounding car at one of the most spectacular rallies on earth. Besides, the chance to wind it out through the forests of the Pacific Northwest will be a victory in its own right.
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