Subiesport Magazine - June/July 2008 - (Page 52)

Smoke: not good. “We chose to go a middle road that is a solid and popular choice ” SO YOU HAVE copious amounts of smoke pouring from your tailpipe, you have that “thud” from the starter when you turn the key, and your car is making less power. Chances are, you have a blown engine. If you are going to swim in the performance tuning pool, you will have to at some point dive into the deep end, and that means rebuilding an injured engine. A fair amount of casual tuners will want to try to push their setups to the edge of what a stock block can take and then pray that something doesn’t go wrong. However, in a world of dodgy gas, high ambient temperatures and less-than-stellar tuning, the chances of some amount of knock causing engine failure are pretty good. Then there are those of us who, despite better judgment or sage advice, just want to “turn up the boost” past what is reasonable or safe. You know who you are. Knowing that at some point your engine will fail is a good place to start from. Having that knowledge in the back of your mind, and perhaps some rainyday cash set aside, will help ease the blow-by. Having done extensive modifications to our 2007 Legacy GT, and also having done some rather hardcore driving on and off the track with our car, it was only a matter of time before the stock EJ255 bottom end would give out. And so it did at our secret test track. After a hard day of lapping oil-smoke would billow from the tailpipe on startup. We also had the telltale “whump” 52 JULY 2008 on startup. Usually when you start your car, for those first few cranks before the engine fires, the engine will turn over smoothly and uniformly. On a car with a dead piston the engine will “thud” unevenly. Combined, these two symptoms should be enough to let you know something is amiss. The next step is a compression and leak-down test. Sure enough, we had 140psi of compression in three of four cylinders, with cylinder number 4 being the low man on the totem pole with only 75psi of compression. Once you know for certain that your engine is toast, you have several options. The first, and probably the easiest, method is to just buy a new STI shortblock from the dealer. These are relatively inexpensive at around $2,000 and are a direct replacement for all 2.5-liter turbo Imprezas, Foresters and Legacies. For 2.0-liter cars, you can use your WRX heads on top of the 2.5-liter block; however, you will need to use a thicker head gasket readily available from Cometic. The next easiest but a bit more expensive option is to buy an aftermarket shortblock. These are usually STI shortblocks with forged aluminum pistons in place of the stock units. Blocks like the Crawford S2 are a great way to bolster your engine without breaking the bank. Of course you can buy engines that take this much further, like blocks built by Cosworth. These engines, while quite expensive, feature upgraded rods, billet crank, race bearings and forged pistons. These engines are very durable and are made for extreme performance conditions; a bit overkill for a road car, but a very good option nonetheless. Then there is the build-it option. If you have never built an engine, we would recommend hiring a professional machine shop for this route. The upside here is that you get to choose exactly how you want your engine to be assembled and what components to use. The downside is that choosing the proper components, especially if you are going all out with rods and a new crank, etc., can be a bit daunting, but research and perhaps a guiding hand from your tuning shop of choice can ease that burden. We chose to go a middle road that is a solid and popular choice with Subaru tuners: the “drop-in” piston in a fresh STI shortblock. One of the virtues of the Subaru engine design is that the pistons can be removed without splitting the block or even removing the rods and crank. This means that you can purchase a factory-built shortblock and simply replace the pistons with forged stock bore-size units without having to re-torque the main and rod bearings. This makes building a solid and very stout Subaru engine very simple. Keep in mind this is specific to Subaru, and your buddy with the Evo will have to remove the bottom end to perform the same upgrade. There are currently several pistons on the mar-

Table of Contents Feed for the Digital Edition of Subiesport Magazine - June/July 2008

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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