Main Caps On Ground The 1MZ...
Main Caps On Ground
The 1MZ mains are fastened with four 12-point bolts and two cross-bolts at each main cap. This is a great system, but the bolts are undercut for even torquing with factory robots, and thicker main studs are definitely the way to go for serious high-boost engines.
"What we're not doing at this point," says Gallant, "is radically changing the valvetrain. We could certainly lighten the stock valvetrain, but with compound supercharging this motor is designed to make power with boost and airflow rather than rpm. We're not installing big valves, seats, bronze guides, and we're not using exotic materials like aluminum-ceramics in the valvetrain. We're not raising the roofs .200 because there's not enough material and we'd be at the casting limits."
The 1MZ has decent factory valves with good, thin stem Honda-type valves, says Gallant. GTP's Stage II 1MZ MR6 heads use 35mm intake and 27.4mm exhaust valves. Gallant assures us there's room for bigger valves should it come to that.
Stay tuned as we'll cover engine assembly and testing in the next Project MR6 installment.
Spark Solutions
Ignition Solutions Coil-On-Plug StrategyThe stock Toyota coils did not like the lengthy, 6-milli-sec dwell period we'd been feeding it to get the kind of ignition power needed to fire plugs through the vastly thicker mixtures of a compound-boosted powerplant.
After a long Texas-to-California road trip, we replaced the stock Toyota coil-on-plug units with super-duty coil-on-plug plasma-direct coils from Ignition Solutions. Ignition Solutions' Ulf Arens provided the following chart correlating dwell time (programmable in the MoTeC M48 engine management system) to current in spark energy. Arens decided we should run a dwell time of 2.5 milli-sec, which he computed would provide a vast increase in spark energy compared to stock Toyota coils.
| Coil Calculation |
| Dwell | Current | Energy |
| (msec) | (Ampere) | (Milli Joule) |
| 1.00 | 2.2 | 11.68 |
| 1.50 | 3.3 | 25.13 |
| 2.00 | 4.5 | 46.73 |
| 2.50 | 5.7 | 74.97 |
| 3.00 | 7.0 | 113.07 |
Says Arens, "The Plasma-Direct replacement ignition coil is built using Ignition Solutions' 'booster' technology to amplify secondary spark current by 100 percent (two times as much as OEM) and release about four times as much energy at the initial moment of spark.
"The Plasma-Direct coils are designed to provide a 100-percent secondary current (spark amperage) increase from 50mA to more than 100mA on most systems, with four times spark energy increase for the initial spark discharge (E=1/2*L*i*i). An added benefit is each coil's external LED that indicates power firing of the coil.
Block Heads Off 1MZ-FE short...
Block Heads Off
1MZ-FE short block, ready for further detail stripping. Note the OE detonation sensors on the inner side of each Vee bank. We've not used knock sensing thus far, but the MoTeC M48 EMS can log such data and initiate anti-detonation ignition retard strategies. We'll see.
Engine Fasteners - Stock Factory...
Engine Fasteners - Stock
Factory stock engine fasteners head 12-point, head Allen, main 12-point, main cross bolts, and flywheel bolts just before being sent to ARP to replace with upgrade studs and super-duty bolts. Note the undercut 12-point head and main bolts for even clamping force on a medium-power, normally aspirated powerplant. ARP studs are definitely the way to go for strength and clamping force, though the rear head may no longer be removable without pulling the engine.
Crank The 1MZ crankshaft is...
Crank
The 1MZ crankshaft is a high-strength forging, which should be adequate as we crank up the compound boost.
Bare Block upside-down on...
Bare Block upside-down on standToyota's 1MZ-FE block uses modern high-strength concepts, such as six-bolts, mains, structural upper oil pan, and deeply embedded crank. We saw no immediate need for modifications beyond honing the cast-iron liners for the one-over Wiseco forged pistons.
Bell Studs 2 Studs provide...
Bell Studs 2
Studs provide more accurate and consistent torque loading for clamping cylinder heads and main caps than bolts because when you use bolts to secure the head, the fastener is twisted while it's being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously.
Bell O-rings Techniques for...
Bell O-rings
Techniques for head gasket improvement. We've had reliable results with a simple O-ring in the block teamed with a special annealed-copper head gasket. illustration from Maximum Boost by Corky Bell
Oil Squirter Piston strength...
Oil Squirter
Piston strength and longevity can be increased greatly with cooler temperatures. Oil-squirting rods or oil squirters mounted below the cylinder will do the job, as will ceramic thermal coating of piston crowns. Our plan was for squirting and coating. Illustration from Supercharged! By Corky Bell
1MZ Parts on Ground Soon to...
1MZ Parts on Ground
Soon to be refurbished and reinforced with super-duty parts from ARP, GTP, Wiseco, Crower, Clark Copper Head Gaskets.
Wiseco Forging Wiseco pistons...
Wiseco Forging
Wiseco pistons are built from forged aluminum. Squeezing metal under high pressure can greatly increase the strength, and forged pistons will tolerate more abuse. They will still not tolerate a great deal of detonation.