In Project MR6, we swapped a 1994 3.0-liter Toyota Camry 1MZ V6 into a 1991 mid-engine MR2 turbo. In various Toyota and Lexus platforms, this motor is good for 185-225 hp. With the new engine in place, we tuned and tested the vehicle with various power boosters, including: 1) a TRD supercharger system, 2) a custom Majestic-based turbo system, 3) both power adders compounded at once 4) naturally aspirated, with neither power booster installed.
We compared and contrasted the 2.0-liter MR2 turbo four-banger vs. a stock 3.0-liter 1MZ V6, the Majestic turbo vs. the TRD/Eaton positive-displacement blower, and the effect of both at once. We achieved our goal of 600 rwhp in Part 6.
In Part 7 we recap the project, test the engine compounded at high boost, bump the power to a new peak in the most optimal configurations, fill in a few holes in our knowledge of power levels at medium boost, dyno test the Random cat at high and medium boost, take stock of what we learned, and finally, complete a project that began nearly three years ago and first appeared a year and a half ago in Turbo.
For Part 7 dyno testing, we made a 400-mile round-trip from Austin to Dallas in record-setting 101-degree high-humidity Texas weather with the A/C working its heart out the whole way. Then we ripped off some high-boost turbo-only and compound turbo-supercharged dyno runs-which seemed to demonstrate fairly conclusively that this is a street car, not a dyno queen.
This car is something of a transformer robot: The modified TRD blower kit can be removed or replaced in less than an hour. The twin-entry turbocharger uninstalls in about 90 minutes with a "turbo-replacement pipe" plumbing from the twin-entry flange into the 3-inch exhaust turbine-out downpipe and muffler-and the car is a torquey, fun ride naturally aspirated. A Random Technology catalytic converter becomes an optional part of the exhaust upstream of the Borla muffler, installing or uninstalling in less than five minutes.
The Final Frontier-High-Boost Compound Turbo-SuperchargingFor the final test configuration, we started by backing away from the copper head gaskets. With good combustion chambers, great intercooling, an efficient turbo and race gasoline, we didn't encounter gasket-killing knock problems, but we were suffering from tenacious coolant leakages past the custom copper gaskets.
After Kotzur Racing verified the block deck and head surfaces were dead flat, we returned to stock gaskets, and removed the now useless inner wire O-rings. The outer O-rings fell at or just within the edge of the stock gasket's metal fire rings, which would increase clamping force and help prevent the head gasket's metal fire rings from being forced outward under extreme combustion pressures.
While the engine was apart, we replaced the main and rod bearings, repolished the crank, and disassembled and serviced the oil pump. Clutchmasters changed the multi-disc clutch facing to a new, experimental super-duty material that should improve torque-holding capability and make for excellent streetability.
Then we installed additional sensors. Fortunately, beside the standard engine temp and air temp inputs, the Motec M48 ECU is equipped with an auxiliary temp input, which thus far, we hadn't been using. We drilled and tapped the blower plenum downstream of the rotor assembly. Then we did the same for the air cooler inlet tank for the GM Delco 3500 Ohm air temp sensor.