How Do You Build Big Power With An MR2? Try A Two-Stage Fuel System.
Photography by John E. Thawley, III
David Lashbrook may not be lucky by magazine feature standards. When we finally found an envelope with John Thawley's photos of this 1993 turbo MR2, nearly 18 months had passed. We promptly set about rectifying our neglect, but Lashbrook wasn't too worried. As MR2 owners go, he's one of the fortunate.
He only recently learned of his car's rarity and hasn't confirmed the information independently, but from what he's gleaned via an MR2 owners club, Toyota only imported five MR2 hardtop turbos in 1993. Lashbrook says it's rare to find a non-T-top among the '91 and '92 model years, but apparently '93 was a particularly dry year for a car with minimal concessions to comfort.
"This car even has crank windows," Lashbrook says. "It was destined to be a race car."
He bought it sight unseen after a friend spotted an ad in the local classifieds: "Blown headgasket, leaking water pump. First $3000 takes it." The owner, Lashbrook says, was taking Blue Book price less $2000.
He snatched it up and promptly tried to make it overheat. He didn't care about the engine; he had another one lined up. But after "driving the hell out of it", he couldn't kill the engine. It was only as he went to remove it that he noticed the finish on the fuel tank was stripped, the result of a small coolant leak in the heater line.
He then put the story together. The headgasket was fine, the water pump undamaged. The Toyota dealers where the previous owner had taken it for repair had, says Lashbrook: "lied through their teeth." He felt bad for the guy, but the deal was done. The build was in motion, no turning back. Though Lashbrook can handle most chores himself (he did the wiring and tuning in this car, and the engine build in his other, daily-driven MR2), he wanted to go big this time. His goal: a nine-second quarter-mile run on street tires. So he sent the engine off to Chris Kattage at Engine Logics in Houston.
The engine build is anchored around a 5S-FE block with 87.5mm bores, modified to accept half-inch head studs. A balanced and chamfered 3S-GTE crank, with an 86mm stroke, spins custom rods attached to CP pistons. The ported 3S cylinder head uses 1mm oversize Ferrea valves. Engine Logics also fabricated an intake manifold to accept two sets of injectors, components of Lashbrook's dual-fuel system design.
"I decided to do [two fuel systems] when I realized I didn't want to pay for C16 just to drive the car everywhere," he says. "I want a streetable car, something I can drive to the track and race. It really wasn't that much work. I already had another fuel cell and the injectors floating around. I knew the computer could do it. What it really came down to was buying some fuel lines and another regulator."
It comes down to more than that of course, especially when engine management comes into play, but for the most part Lashbrook says it's an easy modification. The system, he says, works in a very linear fashion. He fills one tank with regular 87 octane and the other with C16. At around 4psi of boost, about 10 percent of the duty cycle shifts to the secondary 1600cc injectors, blending C16 with the regular octane.
"That turbo is so big that it doesn't spool fast, so there's a little bit of time for the injectors to work together," Lashbrook notes.