from wreck to warp-speed
Picked up as a damaged long-block out of a wrecked MY00 Outback, this EZ30D (early non-AVCS model) was in a sorry state and required substantial repairs even before any modifications were done! This didn’t slow down any planning, however, and the motor was torn down to assess the extent of the damage, and before long all the required components were sourced and the necessary remedial work carried out. New front and rear timing chain cases were obtained and the oil filter mounting and right-hand cylinder head welded before sending everything down to the machine shop for processing. A quick pass through the hot acid wash to remove all contaminants and a bore hone to ensure correct roundness and size completed the initial preparation stage of this build. Although it was more work than expected, a solid foundation from which to start was finally accomplished.
In order to survive the intended horsepower level demanded by the owner, tried and tested internal parts were the only viable solution. Supertech forged pistons, Pauter forged X-beam rods and 1mm oversized inlet and exhaust valves with double springs and titanium retainers, also from Supertech, were promptly ordered for this build and have been used successfully by Jeff Perrin and many other engine builders when adding forced induction to this originally naturally-aspirated engine. ARP head studs were also purchased along with genuine Subaru piston rings, new timing chains and rod & main bearings.
With the bare bones of the engine sorted it was time for the first of several dry builds to determine correct ring and bearing clearances, and to also plan out the routing of hoses and cables, etc, since all this was to be heavily modified and upgraded. All factory hose barbs were removed from the heads and oil pan casting, and replaced with NPT-AN fittings. The fuel rails were also modified with -6AN fittings brazed in at both ends, the oil pan drilled and tapped for the turbo oil drains and an adaptor made up to supply oil to the aforementioned turbochargers.
After media-blasting the outside of all the castings, the block halves were polished and the heads treated to a coat of hi-temp paint. The timing chain cover, inlet manifold and valve covers were painted with VHT wrinkle finish coatings, giving the desired factory-looking finish to an otherwise race-spec, high-horsepower installation. Add in the Aeroquip fuel, oil and coolant hoses and the initial stages of this build were complete.
In preparation for the next stage of this motor build, a billet flywheel and upgraded clutch are all that is needed now so that the entire rotating assembly can be balanced and polished. Then the final clearances will be set and the final assembly of the bottom end can commence. The connecting rods have already been balanced end-to-end and weight matched, and the same target will be aimed for with the piston/rings/pin groupings, to ensure the rotating mass is as balanced and smooth as possible. Being a 6-cylinder, it is important to maintain its inherent internal balance and enhance the rev-ability of the engine.
Supplying fuel to support the many horses under the hood is a critical element of any build and if you don’t want to run into top end fuel starvation or leaning-out conditions under boost then getting this system right is crucial. It is after all the lifeblood of any engine. Running a few quick calculations, the fuel requirements worked out to be less than 300lph at the top end and any decent aftermarket performance pump available today is capable of supplying this amount of fuel at conventional EFI pressure levels (40-60psi). This is good because it then comes down to choice and being able to physically fit inside the tank, noise, etc.
With pumps getting smaller for the same power and the eventual packaging considerations for what needed to be a factory-appearing installation, a twin pump, in-tank set-up was settled on, the ultimate in stealth. Since no circuit racing is intended, things like surge tanks and baffle plates are not required so the factory tank was retained and its pump cradle suitably modified to accept 2 standard pumps side-by-side. Their -6AN outlets connect to the -8AN supply line via a step-up Y-block and appropriate elbows and adaptors to fit it all into the limited space and out through the top of the tank.
It was first considered to control each pump separately, with the engine ECU switching the 2nd pump on as required, however this would have called for more changes to a wiring harness that was already complete and a few less than ideal working practices, so it was settled upon to simply run them in parallel. This method should be no more noisier or power-hungry (in terms of current draw) than a single pump since they are not having to work as hard. Plus there is the added redundancy; if one pump fails then there is still another able to supply enough fuel to keep running.