|12.9 @ 1/4-mile||282 hp @ wheels.|
For about a decade, the Mazda MX-5, known in the United States as Miata, has been the one and only truly affordable roadster on American soil. (For our purposes here, affordable will be defined as a car that can be acquired for less than $25,000). That all changed last year with the introduction of a totally revamped, open-topped MR2 from Japan's largest automaker.
Now in its second year of production, Toyota's MR2 Spyder comes well-equipped to do battle with the venerable Miata in the open-topped two seater arena, but truth be told, its overall performance is a far cry from that of the turbocharged and intercooled second-gen MR2. Like its predecessors, the new MR2 features a mid-engine, rear-wheel drive layout that lends the car favorable weight distribution, while advanced high-strength steel construction creates a rigid chassis and helps keep the convertible Spyder's curb weight down around a feathery 2200 pounds.
Mid-engined similarities aside, the new Spyder differs from its previous incarnations in two major areas. First is its styling-obviously, the lack of a hard top is a big factor here, and the very Porsche-esque head- and taillight assemblies and mid-engine configuration have helped the MR2 Spyder acquire the dubious nickname "Poor Man's Boxster."
The second area the new MR2 differs from the old is its powerplant and the lack of a forced-induction counterpart for its naturally aspirated base model. Motivation for the Spyder comes from Toyota's all-aluminum, high-compression 1ZZ-FE DOHC in-line four, the same engine found in the new Celica base model. In the MR2 application, this engine uses Toyota's VVT-i variable valve timing technology at its intake ports to produce 138 hp at 6,400 rpm, but that's where the fun ends.
Enter the visionaries at Axis Sport Tuning of Santa Fe Springs, Calif. For a company that purports to sell alloy wheels, Axis has recently been developing a reputation as a fairly prolific automotive tuning house. The company's latest project was the brainchild of Axis president James Chen. Having already tackled vehicles in the compact sedan arena, Chen wanted something different, something small and light coupled with ground-pounding engine output.
"Basically, I wanted a bad ass car that's light in weight," said Chen. "I wanted a Miata, but the Miata is played out."
The MR2 Spyder, on the other hand, is a different story. It's a brand new platform and, while a number of high-horsepower mods have cropped up for the Miata in the last decade, no one we know of has gone public with any such trickery with the Spyder. Until now, that is.
As we all know by now, there is but one route when planning to squeeze high horsepower numbers from a small displacement four-cylinder engine; it's spelled out in big letters on this magazine's cover. The task of developing a turbo system for the MR2's diminutive mill was handed over to Shaun Carlson of NuFormz.
"I've known James for many years," Carlson related. "He informed me that he was going to be getting an MR Spyder and that he wanted to turbocharge it." Actually, to hear Chen and Carlson talk about it, the task wasn't as hard as they imagined. Located immediately behind the cockpit, the Spyder's engine bay may appear to be pretty cramped at first glance, but Carlson and NuFormz managed to squeeze a custom straight-through exhaust manifold, custom exhaust, turbocharger and intercooler inside.
"When the stock muffler's out, there is a pretty good amount of room in the engine bay," Carlson assured us. That's good, because NuFormz needed the room in order to keep the header straight to reduce backpressure in what would soon be a volatile, high-compression, turbocharged engine. The tubular manifold and corresponding exhaust system is a nice piece of work, all constructed from 321 polished stainless steel with CNC cut flanges and heliarc-welded seams. The NuFormz manifold drives a single Garrett T28/T3 hybrid turbocharger with integral wastegate. An APEXi blow-off valve assists in maintaining proper boost pressure. From the collector, the charge passes through a Spearco liquid-to-air intercooler system via custom-bent plumbing (all provided by Spearco), then returns to the factory Toyota intake manifold, which has been fitted with modified Honda S2000 injectors to provide the increased fuel flow needed for boosted operation.
While Axis provided the car and NuFormz provided the forced induction, the actual engine tuning was carried out by another of Chen's associates, Loke Je-Kin; we'll call him Luke. Luke also handled the electronics and fuel supply side of the project, fitting the existing fuel system with the aforementioned S2000 injectors, which now produces 65 psi fuel pressure, a MSD in-line pump to feed the injectors and an SX regulator to ensure smooth operation. Additionally, at Luke's behest, an array of electronic monitoring equipment was installed in the car's cockpit to allow fine-tuning of the air/fuel ratio and boost from inside the vehicle. Two system-monitoring boxes from Split Second collaborate on supplying the correct air/fuel mixture. The Split Second ARC II fuel calibrator allows the larger injectors to be assimilated smoothly into the system and provides for comprehensive fuel mapping from idle to full throttle. Working in tandem with the ARC II, a Split Second ESC I (electronic signal conditioner) allows for the transition from naturally aspirated to positive boost conditions and fools the ECU into allowing open loop fuel mapping under boost. Rounding out the interior electronics are an APEXi turbo timer and AVC-R boost controller, the latter specially mounted inside the glove compartment along with an APEXi Peak/Hold boost gauge and a Split Second air/fuel ratio meter.
With phase one of Project MR2 Spyder under wraps, Chen and Axis turned their attention to the handling side of the performance equation. Fortunately, this is the one area where the mid-engined Spyder is brilliantly competent directly from the factory assembly line. While it's a fact that convertibles do tend to flex more than solid-topped coupes, word is the MR2 Spyder is as solid as they come. To put any potential problems to rest, a chassis brace kit from TRD, including upper strut braces and lower braces front and rear. APEXi World Sport coilover springs and strut assemblies drop the car above 17-inch Axis VPD five-spokes wrapped with Yokohama A520 rubber, sized 205/40-17. The Axis VPD wheels are the company's latest performance offering and incorporate high-quality alloy construction for great strength and incredibly light weight; the 17x7-inch wheels on the Spyder weigh in at a mere 16 lbs each. Axis also offers the VPD wheel in a 13-inch diameter for drag applications and you can bet the Spyder has a pair of slicks ready for when the time comes to hit the strip.
Which brings us to the Axis Spyder's overall performance. While on the phone with Chen, he threw out a few performance measurements gleaned from the car's track test day. Running 8 psi boost pressure, the topless Toyota vaulted down the quarter mile in 12.9 seconds-without the slicks-ran 0-60 mph in 4.5 seconds and clocked 73.9 mph through the slalom. More recently, the Spyder spun the Dynojet rollers at Swanson Performance in Torrance, Calif., to the tune of 282.5 hp; that's more than double the factory rating. Currently the car is under the knife again, and the motor is out; this time it's getting cracked open to see what can be altered within the block to allow for even more power. Chen said the 1ZZ-GE will probably benefit from new pistons, rods and possibly cylinder sleeving in order to bolster it against his ultimate dream of turning up the boost, while keeping the engine's compression ratio at the 10.0:1 factory setting. Given what has already been accomplished, it should be interesting to see what falls out of the Axis sleeve this time.