Power Pages: 1991 Toyota MR2

From an appearance standpoint, the second-generation MR-2 turbo (1991-'96) has withstood the test of time. Its smooth body lines and sports-car appeal makes the MR-2 a well sought after commodity. Combined with its high performance 3SGTE turbo engine, the Toy can easily outperform the current generation MR-2. Unfortunately, like many great sports cars, price hikes caused the eventual axing of the MR-2 in 1996, but on the brighter side there are still a number of virgin MR-2s for sale and ready for tweaking. The most commonly found MR-2 is the 1991 model, which usually prices around $7,500 to $8,500.

The Engine
Turbocharging has become an ever-so-popular upgrade among performance enthusiasts. Those that already own a factory turbocharged vehicle have a definite advantage over non-turbo owners. Vehicles already equipped with the turbocharged powerplant are often assembled with stronger internals to withstand the rigors of forced induction. One prime example of a strong factory turbocharged powerplant is the 3SGTE engine found in the MR-2 turbo and Celica All-Trac turbo. The 3SGTE engine's bottom-end features a cast-iron block with heavy-duty internal components. The factory rods, for instance, can withstand over 400 hp without any modifications. The compression ratio has also been kept to a minimum for turbocharging duty. From the factory, the 2.0-liter dohc powerplant pumps an already-potent 200 hp and 200 lb-ft of torque to the flywheel. One distinct advantage a turbo engine has over its naturally aspirated counterpart is the ease of increasing the power output. By adding a low restriction filter and free-flow exhaust, output can be easily increased by 10 to 15 hp.

Performance Components
When it comes to aftermarket parts availability, the 3SGTE engine has been well loved. From the simple air filter upgrade to the complete forged engine internals, you name it: it's available. One of the simplest upgrades you can perform on any vehicle is a high-flow exhaust system. On a turbo powerplant increased exhaust flow can easily increase power output. By installing a less-restrictive exhaust system, the turbocharger can spool faster, increasing airflow into the intake tract and, in turn, increasing performance. For our MR-2 test we elected to use the 5Zigen Fireball exhaust system. The Fireball system utilizes an N1-style canister, which exits the driver's side. Unlike many N1-style muffler systems available for the MR-2 which are terribly loud, the 5Zigen system also incorporates a silencer on the piping section to further reduce exhaust tone. With the system installed the MR-2 produces a nice rumble that is not too deafening on long trips.

Second on the list of modifications is installing a low-restriction filter system. Choosing the correct filter element is very important. You want to choose a low-restriction system but still need to keep foreign materials from entering the intake tract. Filtration is highly critical on forced induction engines, as foreign debris can damage the compressor blade of the induction unit impeding airflow. Our filter of choice was the A'PEXi Power intake. The A'PEXi unit features a dual-funnel, cotton-gauze design, which increases airflow while filtering all harmful elements from air entering the turbo. By utilizing a dual-funnel design, airflow turbulence within the filter is reduced, creating a smoother flow into the intake tract.

Dyno
Dyno testing is where a company earns its worth. Dynos don't lie; people do. It is hard to believe a sales person when the selling of the product puts money in his pocket. Our tester is a Spectra Blue Metallic MR-2 turbo outfitted with 18-inch 5Zigen Heidfeld aluminum. The 18-inch wheels really make a statement on the Toy. Providing the footprint of the "2" is Toyo Proxes rubber. The odometer on the Toyota recently clicked 90,000, so a tune-up was called for. Prior to the tune-up we performed a baseline run, which registered 157.1 hp and 172.9 lb-ft of torque. Our tune-up consisted of new spark plugs, cap, rotor, oil, oil filter and fuel filter. With the car back on the dyno, the newly revived MR-2's peak power checked in at 162.6 hp and 174.1 lbs-ft. We spent only $100 on parts for the tune-up and saw an improvement of 5.5 peak horsepower and 2.1 lb-ft of peak torque.

First of the performance upgrades to be installed was the 5Zigen Fireball exhaust system. Removing the factory exhaust system is not easy. The piping has to be removed in the correct sequence or it can't be removed at all. Fortunately, installing the 5Zigen system was a lot easier, taking us only 10 minutes to bolt up after the factory system was removed. The exhaust system made a great improvement on response, as the turbo now sings freely with each pounce of the throttle. On the dyno power figures were also increased dramatically, as peak power was pushed to 174.5 hp and 182.1 lb-ft of torque, an improvement of 11.9 hp!

The power upgrade was the A'PEXi Power Intake system. Removing the factory system was a breeze and installing the A'PEXi unit was equally as easy. By increasing the air flow to the turbocharger we were able to improve power levels by 3.7 horses and torque levels by 7.6 lb-ft. Peak power now checks in at 178.2 hp and 189.7 lbs-ft.

Conclusion
Despite the fact that we only performed two performance upgrades and a tune-up, we were able to increase power output by 21.1 hp and 16.8 lb-ft. You can immediately tell the difference in the overall power output of the vehicle by stomping on the gas pedal, as the MR-2 easily throws you to the back of the seat. In the next installment we will install some more power upgrades to see if we will be able to make 200-plus horses to the wheels. Stay tuned for more power infusion on the "2."