Subiesport Magazine - June/July 2008 - (Page 53)

2007 LEGACY GT PROJECT Tim Hadﬁeld from F.A.M.E. Automotive in Redmond, Wash., listens to the block and checks compression. Our fears were conﬁrmed: loss of compression on piston #4. (Below) ket specific to the Subaru 2.5-liter turbo engine. So far, it appears that these pistons are a universal fit for the EJ255 and EJ257 and will not alter the compression ratio for either as long as you are using a stock compression piston. We contacted Cosworth, which sent over a set of its 99.5mm stock bore pistons. (Note: this my be different for 2008 and newer EJ255 engines so make sure you consult with your parts supplier before ordering parts.) If you decide to reuse your old block, again you have options. Normally, a broken ring-land will not cause too much damage to the cylinder wall. If this is the case, and the crosshatch marks on the cylinder wall are in good condition, then you can probably install a set of forged stock-size pistons. If the bore is in poor condition then you will have to go to an overbore piston. Generally speaking, the first overbore size for the STI is 100mm, although you can bore further for more displacement. Normally, however, you don’t really want to push it much past this cylinder size. Also, if you are going to overbore, you will have to split the case and redo your bearings, which will add to the overall cost of your build. An additional note. Not all EJ257 blocks are created equally, and there is some variation in bore sizes. This is inherent in the manufacturing process. Fortunately, Subaru marks the blocks at the factory so that you can tell a tight block from a loose block. Blocks are marked with either a “B” or an “A” on the “Why am I doing this? What are my goals?” top. This refers to how loose or tight the bores are on a stock sized piston. “B” means the bore is tighter and “A” is looser. So a block marked “A B” on the passenger side means Cylinder 1 is looser and Cylinder 3 is tighter. Ideally for a drop-in piston setup, you would want to run a block that is marked “B” for all four cylinders. Looser bores are fine too, but you will probably have a bit of smoking on startup as oil will seep past the pistons in a looser bore. Our block was marked “BB” on both sides of the case, indicating tighter bores. In our case, the number 4 piston had fractured and was the cause of our excessive smoking and the low compression. Happily, the bores were still in good shape, so this shortblock can be used again and will find a home in the Dreadnought, with some slightly used CP forged pistons. Oddly enough, this case was also marked with “BB” on both case halves, so again, we should have a reasonably tight engine, despite not honing this used block. A final note: Dropping the coin for an engine build or a built engine can be a serious proposition, so ask yourself this question: Why am I doing this, and what are my goals? If you want a 700whp daily driver/drag car/track car exotic killer, etc., you may be in for a rough journey as it is very difficult and very expensive to execute this all-arounder effectively. Nor will a built engine be the end of the road. If you are looking for a streetable fast car that occasionally sees track time and just needs the extra insurance that forged internals offer, then your goals are more rooted in reality. To be sure, all things are possible, but those possibilities are closely tied to your budget and expertise. The following is a guide for building up a fresh shortblock using forged “drop-in” pistons. Hopefully these hints and tips can help you along if you do decide to do-it-yourself. In addition to the usual set of metric wrenches and ratchets, you will need some specialty tools. - An engine stand - An engine hoist (cherry picker) - Piston ring compressor - Extra long screwdriver (12-inch plus in length) - Piston ring grinder/gapper - High-quality torque wrench - Parts washer or a basin to wash parts in - Lots of brake cleaner - Fuji Bond (available at the Subaru parts counter) - Assembly lube SUBIESPORT MAGAZINE 53

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Subiesport Magazine - June/July 2008 Contents Editor Letters Readers’ Rides Subaru News Fresh Squeezed Hell's Legacy Under the Radar Project GT Rebuild New Engine AVO 420 Turbo Perrin Intercooler Rally Like a Rockstar Rally Jordan Adventure WRC Rally Argentina WRC Rally Jordan WRC Rally d’Italia Sardegna Where to buy Subiesport WRC2008 Debut Rally America: Olympus Ad Directory Rally America: Oregon Trail Spotted!

Subiesport Magazine - June/July 2008

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