Pans And Oil Pickup
The 1MZ-FE's aluminum block is designed for extreme rigidity, using modern concepts like the structural upper oil pan shown here for reinforcement. This block should have the rigidity to handle a lot of power without further low-end reinforcement.
Finally, we set out the internal engine parts for "before" photography and analysis, consulting in Dallas with Alamo owner Brice Yingling, Bob Norwood, and James Patterson of Norwood Performance, and then shipped the heads and manifolds to GTP in Houston.
The head gaskets headed to Clark Gasket in Minnesota, and FedEx carried away sample fasteners for ARP in Southern California. Prior to disassembly, we arranged for Crower Cams and Equipment to build a set of stock length, super-duty 1MZ connecting rods that were up to the task.
The Plan: Engine Prepping for High BoostWe concluded the following components were sufficiently strong to withstand a significant power boost to at least triple the stock 200 hp and 7000 rpm:* Forged crankshaft, six-bolt main caps, alloy block with structural upper oil pan and end plates, oil pump, and the cam-drive system.
Heads-off Gaskets On
With the heads gone, we got a look at the stock head gaskets. These composition gaskets are fine for a stock powerplant, but they can easily fail in high-boost applications if there's even a hint of detonation. We sent them to Clark Copper Head Gaskets to duplicate them in copper. Note the OE flat-top 10.4:1 pistons with intake valve reliefs almost ready for the scrap heap: We already had a set of Wiseco forgings one size over with extra-thick crowns capable of machining for reduced compression if required. Toyota permits one size overboring.
We Decided The Following Parts Required Upgrading
Cast pistons, connecting rods, composition head gaskets, block deck surface.The cylinder heads, camshafts, and valvetrain required further analysis at GTP. The goal was to increase maximum rpm and improve high-speed breathing without sacrificing torque at lower engine speeds.
"The modern trick with boosted engines is to go for efficiency," says Craig Gallant. "People used to say 'Let the turbo do the work,' but if you add more pressure, you add more heat, and heat promotes detonation.
"Our plan with the MR6 heads-whether normally aspirated or boosted-was to make CFM vs. boost-based power. The 1MZ head can be improved tremendously, but the trick is to produce efficient airflow. GTP-ported heads are efficient; they have maximum CFM at very high air speeds."
"Stock Toyota 1MZ heads," says Gallant, "flow very well for the runner volume they have. The stock low-lift and mid-lift airflow is phenomenal, and there is a lot of CFM potential in these heads. The Toyota 1MZ-FE 3.0-liter V6 uses a four-valve DOHC shim-over-bucket style valvetrain, capable of very high rpm with excellent stability. This system virtually eliminates valvetrain flex. The shim-over-bucket design has good geometry. The downfall is relatively high bucket and shim weight, which makes it harder to control valve float at high rpm."
Pistons
Pistons are probably the highest stressed items on a high-boost powerplant. Hypereutectic pressure-cast pistons are fine for low-to-moderate boost applications, but for serious boost, forgings are the way to go. Correct piston-to-cylinder clearance is critical, and the block should be bored or honed only when the machinist has the new forged pistons in hand. The stock 1MZ rods are a bit scary, and we'd already sent a new Toyota rod to Crower to have custom forgings built. Rpm is vastly harder on rods and rod fasteners than extra boost and combustion pressure, but cast or powder rods can suffer compression fracture in severe enough applications. Our engine had one bad rod cap and damaged bearing, though the crankshaft hadn't been damaged beyond polishing repair.
GTP can convert the 1MZ to a shim-under system with a 35-percent reduction in bucket weight and an 80-percent reduction in shim weight; with our relatively modest rpm-enhancement goals, we'll keep it simple for now with the stock valve-actuation system, including stock cams.
However, Gallant emphatically points out that raising the redline from 6250 to 7000 rpm requires stronger valve springs, particularly if you're planning to have 20 to 30 psi boost trying to push the intake valves open.
Stage II-type work, says Gallant, typically involves 1) aggressive media removal on both intake and exhaust ports and some combustion chamber work, 2) polishing with varying grit abrasives, 3) working the radius area to a desired finish, 4) flowing before and after, 5) checking the runner volumes, and 6) Rockin' 'n' Rollin'.
Prior to GTP's Stage II porting, intake airflow measured 264 CFM at .450 lift on the GTP flow bench, with exhaust at 147. After porting, GTP's flow bench found more than 301 CFM intake airflow at .450 lift and 185 exhaust.
In addition to the short-turn radius and bowl work, GTP removed a portion of the wall at the end of the twin exhaust ports coming out of each cylinder, improving the exhaust port exit and creating more room for a bigger exhaust header.
GTP techs moved the ridge bumps and blended with a lot of bowl work and short-turn work, streamlining the intake runners, working on the twist, and polishing the chambers.