As many of you already know, we have been experimenting with the Subaru H6 motor applications in the Impreza platform. We put a ‘first stage’ H6 motor into Jeff Perrin’s 2006 STI just days before SEMA, which he successfully drove from Portland to Las Vegas and back. This car still serves as his daily driver. As of yet, we have not been able to get that car, or the other H6 platforms on the dyno. Since the installation of the Dynapak Dyno yesterday at our shop, we took quick opportunity to put Jeff’s car on the rack.
Before we delve into the results, I’ll provide some notes on the buildup, specifications, and future plans. This was by no means a tuning session, and the car still sits with a road tuned map that Jeff and Adam made over the last few months. Once some significant time is put into the map development, I suspect the pump gas lower boost numbers will improve significantly. The H6 motor in this car is a JDM 2003-2005 EZ30R motor, 3.0L displacement, AVCS variable valve intake cam timing, and two stage variable valve intake cam lift. This is the second generation EZ30 motor, which has the newer “3 port” exhaust head. It is used in a number of JDM H6 cars, the newer European H6 cars, and the 2004 and up US H6 cars.
We removed the heads from this motor, extracted the pistons, and installed a set of custom H6 low compression pistons we had built for us. These pistons run a 8.0:1 compression ratio, and come fully coated. They utilize the factory rings. This piston change was the only change to this particular motor. Rods, Heads, Cams, Gaskets, etc were all left stock. Jeff and Dustin built the exhaust manifold from stainless tubing, and adapted it to fit a standard T3 inlet flange and 4 bolt GT30/GT35 style outlet flange. For this particular setup, Jeff went with the GT35R turbocharger, identical to what I had on my 2.5L, and used by many here on Nasioc. This car also has a Aquamist water injection system is running the 2D setup with 6 injectors in the manifold runners. EM is the Hydra ECU built for us by Andrew. Jeff and I spent many hours getting the right info and oscilloscope plots for the cam and crank sensor interactions, and it starts and runs perfect. This Hydra also drivers the AVCS, Lift, and drive by wire.
Let’s take a look at the motor.
Here Jeff is taking off the front valve cover, which encloses the floating chain drive for the cam gears.
Once the front cover is removed, you can remove the chain assembly, remove the cam gears, and then the back cover.
Here you can see the chain mechanicals. Everything is floating in oil during operation.
With the chains removed, you can see the driver for the water pump and cam gears. Those cam gears are sharp!
As mentioned above, these new H6 motors have 3 exhaust ports, one per cylinder.
Intake ports are similar to the EJs, and look to have plenty of room for porting.
Here you can see how the intake cam has the two stage lift. The outer larger lobes are the low lift, and the inner lobe is the high lift, activated by pistons that come out of the valve buckets (controlled by oil pressure)
For the install into Jeff’s car, as mentioned above, we used 6 810cc modified blue injectors, some custom modifications of the stock fuel rails, a replacement coolant system (to fit the reduced front space), as well as a custom exhaust manifold, uppipe, and downpipe.
Here is an engine bay shot:
Let’s take a look at how it performs.