Subaru's EJ engine has been in use for more than 20 years and remains under the hood of Subaru's most sporty road car, the WRX STI. Vince Griffin is no stranger to these engines. In fact, they are all he has worked on for the past seven years. For nearly a full decade, Griffin has put together EJs for rally, drag racing, and street cars. Some of his engines have produced more than 1,000 horsepower—even Subaru Rally Team USA's Red Bull Global Rallycross cars only make around 600 HP.

Though newer Subarus, such as the WRX and BRZ, are switching to the newer FA engine, Griffin explains on this video of /ENGINEERED on /DRIVE the many advantages of the EJ and why he prefers it to the newer design. This may be why the older engine soldiers on in the WRX STI. Griffin covers numerous subjects, such as common problems and solutions, common build mistakes, what to watch out for in your build, and, of course, how much power an EJ engine can make.

Be sure to tune in next week for part two /ENGINEERED from Prime Motoring.