THE H6 ENGINE
There are many things about this engine that are very cool. Just looking at the specs doesn't do it justice. 3.0L, 6 cylinders, DOHC, AVCS, AVLS, 250HP in stock form, aluminum block, forged steel crank, chain driven cams, and only .700" longer than an EJ20! Did I mention 3 point zero liters! Being familiar with the 4 bangers, the first thing that I was interested in seeing was how the Variable lift worked. The cams are the first strange thing you see as each valve has 3 lobes. One central lobe for the low lift and 2 outer ones for high lift, longer duration. The bucket is where the magic happens. There is an inner and outer piston that rubs on both cam lobes all time. When the solenoid allows oil pressure to shoot through the oil gallery, it locks the inner piston to the outer piston/bucket, and bam, new cam profile. I have to say this is probably the coolest part of the engine. Word is this is a co-developed technology from Porsche and Subaru, sure enough the parts are made in Germany.
Cutaway of EZ30R, aka H6
After getting the engine in hand a few other things that surprised us. The manifold is plastic, which sounds scary. But like other intake manifolds on cars, this is a glass-filled Nylon, which is good to 400+degrees and will hold high pressures at these temps. Plus the way these are manufactured, they allow for very smooth, very large internal diameters. Second surprise is the ports on the head. They are huge compared to the 4 cylinder ports. I was a little worried as since each runner is feeding smaller pistons they might be smaller than the 4 cylinder ports which feed larger pistons. But we were wrong. Another thing that we really liked was the throttle body. Yes its feeding a bigger engine, but it is feeding less power, so smaller throttle body??? Nope! Even better it was bigger! 3"OD vs. the WRX 2.75".
This build was a test of the basics of the H6, so drop in pistons were the answer we were looking for. We went to Supertech products and sent them an OEM piston set to build our custom pistons. Because this was a SEMA car, Willy at Supertech, was very excited about doing the H6 build as it was nothing he had seen before. This was a huge help in getting our pistons right away and getting the ball rolling with the build.