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The Mightiest Four-Cylinder Toyota Ever Made

This 2.1-liter mill won endurance and sprint prototype races, touring car races and hillclimbs.

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In the 1980s, Toyota began its most audacious push into the high-end side of the car world, racing V8 prototypes at the 24 Hours of Le Mans and designing V8 Lexus sedans to take over America. But while that was happening, the company was also working on a little four-cylinder that would become arguably its greatest engine.

From 1988 and on, Toyota’s top racing efforts focused on big, multi-cylinder engines. The R32 and R36 V8s (and 50-valve RV10) Group C engines nearly achieved their ultimate goal, too. In 1994, only a late-race transmission problem kept Toyota from taking overall victory and in 1999 the Toyota GT-One (running an updated Group C V8) only lost out from a final-hour tire failure. These V8s could have been Toyota’s crowning achievements in racing. But they weren’t.


The engine that did bring Toyota unmatched success was a tiny little 2.1-liter four-cylinder, twin cam, 16 valve, and turbocharged mill.


The name of the engine is a little difficult to pin down. Toyota calls it a 3S-G in an official history of its prototype cars, Wikipedia calls its a 3S-GTM as well as a 503E and racing expert Mulsanne’s Corner calls it a 503E as well. What you need to know is that this diminutive little twin cam ran anywhere from 500 to more than 850 horsepower in race trim, unbelievably reliably, and won endurance prototype races, sprint prototype races, touring car races and hillclimbs.

You probably know the engine best for powering Rod Millen’s Pikes Peak monsters, Celicas that set the fastest times when the most famous hillclimb in the world was still all dirt. These are the cars making horsepower in the high eights, torque over a thousand foot-pounds, as Speedhunters remembers. I assumed these engines blew up a ton, but the Millens barely ever touched them once they slotted into their chassis.

They are still hilariously quick today.

Or you may know it from powering Dan Gurney’s All American Racers Eagle IMSA GTP prototypes. The MkIII was one of the winningest race cars of all time, winning 21 of the 27 races it entered through 1992 and 1993, when America’s IMSA was like Group C in Europe only with more power and downforce.

I could watch this car all day.

I particularly love just how turbocharged it was. All you hear is the chirping and whooshing of the turbo, like the internal combustion side of the equation was only playing a supporting role. These were standard, off-the-shelf engine blocks, too, don’t forget.


The engine was so good, even, that Toyota ripped out the legendary 2JZ straight six in the mid-1990s Supra and stuck this little four-cylinder in when it took the Fast and Furious generation car racing in Japan’s touring car series, JGTC.

Toyota got serious about developing twin-cam engines as its corporate ethos at the start of the 1980s, sort of as a means of combatting Nissan’s big push to turbocharging. The strength of this 2.1-liter engine shows just how much development Toyota could throw at even the smallest engineering project back then in that Bubble Era, when pride was on the line and money was of little concern.