How the Engine From a Toyota Station Wagon Can Make an MR2 Nearly Perfect

The Toyota MR2 is, for this maligned journalist, the best car our species has ever created because it marks the point when there was no going back—no going back to stay-the-course, no-replacement-for-displacement domestics. The AW11 would out-turn anything but the most Olympic Steroid-ed wide-body Fox Mustang. Ethically sound and frugally-built, AW11’s stood at the parapet of new thinking.

Behind the MR2 were old and ugly Monte Carlos, upset at their own growing ineffectuality, and no matter how many friends-of-friends they forced to watch the “Left Behind” series, their glory days were not coming back—and in front of the MR2 AW11 was Freddie Mercury, thrusting on a day-lit stage with no costume, half a microphone stand and with that, unifying Wembley Stadium. That was the future the AW11 welcomed.

If only that crescendo-ing rock-and-roll late 80’s moment could be diluted and enjoyed longer. It can, at least in car-form. All it takes is one engine swap.

First, let’s look at what the AW11 was in its day.

From 1988 to 1989, the first generation MR2 (or AW11 if you want to sound cool) was offered with an optional supercharger boosting the 1.5L DOHC 4-cyl from 112hp to 145 hp. In the US, it was the only direct competitor to the Pontiac Fiero GT which made 135-140hp from a 2.8L V6.

The Fiero languished while the MR2 lived on for two generations. The supercharged AW11 is one of the rarer models of the midship linage, but it never quite caught on in the way the turbocharged second generation MR2 did. A wonderful suspension was always bored by the middle-of-the-road 4A-GE motor. Yes, the engine revved to 7000 but we are still talking about 80’s engine management. Plus, supercharging isn’t a very “Japanese” thing to do. Why did Toyota choose to supercharge the small 4A-GE motor instead of turbocharging it?

AND . . . Why did they choose a roots blower? Roots blowers are good for big American V8’s. Why did they engineer a tiny roots blower? Why didn’t they use an Paxton-style supercharger? Centrifugals would lower the complexity and build cost, especially for a small displacement engine.

AND . . . Why did Toyota make their supercharger act like a turbo? The roots blower on an AW11-SC has a little clutch (that’s not a clutch) that engages the supercharger. Under light driving, the AW11-SC is naturally aspirated. The supercharger’s clutch-that-is-not-really-a-clutch moves the blower only when the intake manifold vacuum reaches a specific value.

Toyota did this for fuel economy, so owners could run 87 gas if they wanted to. How? On all supercharged models of the AW11, there is button on the lower dash to toggle between regular and premium fuel. If you fill up with regular, you need to push the switch to the “regular” position, and if you fill up with 91-93 octane, you need to push the switch to the “premium” position.

Luke Habermel’s engine is not the stock 4A-GE, it is a Toyota Caldina engine. The Caldina is a station wagon that was never imported the US and looks like a cross between a Toyota Tercel wagon and an Eagle Summit. It’s a 2.0L twin-cam engine with four-valves and a turbocharger.

Snap. Bang. Woosh!

“There’s a company in New Jersey that specializes in MR2’s called ‘Prime Performance’,” said Habermel. “All they do is MR2’s. They specialize in this motor [turbo Caldina] and installation. They source the motor and do all the work. It’s great because you get a drive-able car. It’s a turn-key solution for the AW11.”

The engine makes at least 250 horsepower. BC Coilovers and poly bushings keeps the AW11’s body from moving too much under the new power.

Snap. Bang. Woosh!

The turbocharger is cooled by a water-to-air cooler that fooled me at first because it looked like some kind of aftermarket intake plenum.

“There’s a heat exchanger up front, and a water pump underneath…it cycles the water back. Put your hand on it,” says Habermel.

I put my hand on the intercooler, we were just driving the AW11. It was still cold even though the engine was still warm. Habermel walked me to the front of the MR2. The water-to-air overflow tank is the size of a Pop Tart box and the heat exchanger is the size of an iPad. Unless you were really looking, it doesn’t look like there is any difference in the AW11’s “frunk.”

“You use the regular green Prestone coolant, nothing special,” added Habermel.

The turbo takes no time to spool. At 1500rpm, it wants to go-go-go, like a overstimulated husky puppy, or a mess of elementary school kids who just learned that the cafeteria is giving out seconds.

“I’ve always liked superchargers because I hate to wait for turbos, but this set-up hardly has it [lag].” said Habermel.

Snap. Bang. Woosh!

There are still things to un-do from the previous owner of this AW11. A quad-speaker pod took up the rear center console. “Fast and the Furious was still going strong in 2007 when I bought this car. The whole inside was filled with neon lights,” said Habermel.

It was my turn to drive.

The clutch bit right away. That meant shove the pedal all the way though the floor; don’t be lazy.

Redline dropped from 7600 to 7000 with the Caldina motor. I bumped off the new rev-limiter because the Caldina’s turbo, mixed with a new ECU, shot the tach needle to the right before I was ready.

Snap. Bang. Woosh!

The Caldina swap puts the tubocharger right behind your head. I heard every fludder.

Maybe you think 250 is too much for the tiny and aged AW11 shell, it isn’t. Oh Lord, it isn’t! It is the perfect amount! The weight distribution remains the same, and best of all, the suspension has something to work with. The driving dynamics remain unchanged. It still feels like the light and happy AW11 it always was (the Calvin and Hobbes of cars)—but now you have an afterburner!

Snap. Bang. Woosh!

Modern automobiles, with their nanny-state computers are doing their best, but failing, to give an approximation of crazy—the untouchable sensation of being responsible for your own goddamn actions. The Fiesta ST, for all its accolades and Cobb tuning, will still clamp down with its front calipers before you nose the little sinner into oncoming traffic on an off-camber sweeper in the Coal Regions of this great Commonwealth. An AW11 had no dismissive HAL Computer, just a Tandy 1000 managing spark advance and fuel injection. Your judge traction control by the tightness of your asshole. If you lose it, well. . . that’s between you and your god.

Now, with a turbo, 400 more cubic centimeters, and 100 extra horsepower, the AW11 is on par with the second generation MR2 (SW20).  I can think of no more suitable words to end on than to paraphrase than 2004 Eisner Award winner, Mark Millar in “Superman, Red Son.”

“Go, little AW11! Take us back to those days. Be rejuvenated. Go back and bring a little light into our lives once more.”