Project MR6

With 12,000 miles of low-boost and naturally aspirated street and dyno testing on the transplanted Toyota 3.0-liter four-cam V6 powerplant in our compound-supercharged Project MR6, we were more than ready to stretch for some serious high-boost power in the 500-to-850-whp range.

But first, we'd have to open the engine and address the weak points so it will live long and prosper at big boost.

This project kicked off with the March 2003 Turbo documenting our efforts to experiment with twincharging a V6 '91 Toyota MR2-running both a supercharger and turbo system.

Alamo Autosports, Norwood Performance, and Toyota Racing Development pitched in to swap a Lexus 1MZ-FE V6 in place of the stock 3S-GTE 2.0-liter turbo-four.

We equipped the V6 with a slightly modified version of TRD's positive-displacement Eaton supercharger kit available for the 1MZ-FE powerplant used in the Camry, Solara, Sienna, and Lexus ES300. A MoTeC M48 was wired up, and for the April issue, we designed an intercooled custom turbo conversion package based on Majestic Turbo's 90-lb/min T76 compressor.

Unfortunately, by this time we'd already seen the stock 1MZ's heads begin to lift a bit on one runaway dyno pull at Norwood Autocraft. The powerplant belched a small breath of steam out the side of the aft cylinder head at the end of the run and the writing was on the wall. We needed to yank the 1MZ engine again, this time for internal refurbishing and performance and longevity upgrades.

In the midst of all this, we completed a long road trip from Texas through Arizona to California and back, uneventfully, with the exception of progressively reducing spark-plug gap from .030 down to .015 inches to keep the powerplant from misfiring under heavy loading.

Back in Texas, we contacted Ignition Solutions to obtain a set of six special microprocessor controlled, coil-on-plug, plasma-direct high-power coils that were several times as powerful (see sidebar).

Again, we were gearing up to test the new turbocharger configuration at 1 psi boost increments from normally aspirated to head-lifting boost levels, but in the meantime, the engine began making a faint, ominous tapping noise.

Clutch Masters was simultaneously anxious to get a look at the multi-disc Kevlar clutch we'd been alpha testing. We decided this was a good time to pull the engine for clutch examination and internal engine super-duty upgrades before moving to monstrous boost.

Analysis & Teardown: Toyota's 1MZ V6Alamo Autosports, builders of the MR6 turbo conversion, helped us remove and tear down the boosted 1MZ V6 powerplant. Later, we consulted with Dallas supertuner Bob Norwood, Houston cylinder head expert, Craig Gallant, and various performance equipment suppliers to meet the project's high-boost needs.

After removing the turbo and supercharger systems at Alamo's Arlington, Texas, shop, we ran the MR6 up on a lift and pulled the 1MZ V6 and MR2 transaxle as a unit. Then we separated the transaxle from the engine, and sent the multi-disk clutch and aluminum flywheel to Clutch Masters for forensic analysis. We also disconnected the engine wiring harness for evaluation and further fortification against the heat-soaked environment inside the MR6's "engine room."

With the 1MZ-FE engine mounted on a stand at Alamo Autosports, we yanked the cam covers and set them aside for sandblasting; this would be followed by welding permanent brackets to anchor the six Ignition Solutions coil-on-plug direct coils.

Next, we removed the lower intake manifold and set it aside for shipment with the heads to Gallant Technical Performance (GTP) in Houston. Surprisingly, the gaskets revealed the heads and intake and exhaust manifolds seemed poorly port-matched. Both head and intake appeared to have major potential for porting. GTP would have the final word on that.