Subaru EJ20 WRX engine short block assembly | Redline Updates - Hagerty Media
In this week’s episode of Redline Update, despite its best efforts to thwart our progress at every turn, our EJ20 Subaru WRX engine gets closer to completion. Davin figured out the issue with the main bearings (long story), so he sets out to get the short block assembled. He only hits one small snag in this episode but quickly remedies the situation with the help of a grinder and a sacrificed pair of needle-nose pliers!
The Subaru is unlike any of the other engines that have crossed the Redline Rebuild engine stand. The crankshaft is captured between the two case halves. Astute viewers are likely pointing out the Volkswagen engine from 2017, but you would only be partially correct. Indeed, the case halves are visually similar, but the Subaru has the crankshaft journals machined in a way that line boring them take special setup and tooling. That special process is not something that is in the cards for this particular engine.
Instead, Davin has mixed and matched from three sets of bearings to get the proper oil clearance across all the crankshaft journals. In addition to that, he is also switching from his initial plan to use ARP bolts to clamp the case halves together and is instead using the factory bolts. The ARP hardware required torque of 65 lb-ft, compared to the factory bolts needing just 35 lb-ft, which is a difference in clamping force that changes how much the block distorts significantly.
With the block halves together, it’s time for pistons. Getting the fresh pistons into the cylinder bores is the simple part, as the piston pins that connect the slugs to the connecting rods have to be inserted and retained through holes machined in the engine block. The No. 3 cylinder is especially annoying, as the depth of the hole requires a special tool to be made in order to install the snap ring that keeps the wrist pin in the piston. Building tools is one of Davin’s favorite hobbies though. See why we love him as our Redline Rebuild engine builder?
This motor should come together quickly with this step done, but not so quickly that it’ll be finished in this episode. To see the final steps and hear it run, you’ll have to subscribe to the Hagerty YouTube channel and come back each Monday for your high-octane engine content. In between, be sure to work on your own projects.
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