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Mitch Wright 06-09-2013 12:19 PM

02-05 2.0T or 06-07 2.5T WRX Engine & trans
I am doing research for a 818 Factory Five kit car I am interested in building. The doner car can be a 02-07 WRX. The car will only be used for track use and planning to keep the engine in stock form with a ECU flash and open exhaust.
I am leaning toward the 06-07 2.5T thinking the performance will be at a lower RPM range. Plus I have found cars with under 50,000 miles.

What are the Pro's and Con's of the 02-05 and 06-07 WRX engines and drivetrains?

Mitch Wright
Pittsburgh International Race Complex

Mitch Wright 06-10-2013 12:01 PM

Anybody have an opinion or comment on the benefits of the 2.0T WRX engine and trans over the 06-07 2.5T WRX engine and trans?

brfatal 06-10-2013 12:31 PM

The EJ255 is overall a more stout motor. You've already pointed out the main strong point: the extra low end. It is a stronger block and has stronger internals, but the 2.0L is happier in higher revs. It's something to consider.

The drivetrain on the 2.5Ls are unarguably better. Dual cone synchros were added to 1st gear in the +'06s where as the earlier ones had a 1st gear lockout. And they seem to handle more abuse.

Mitch Wright 06-10-2013 02:06 PM

Thanks, the type of information and insight I am looking for.

LW_Black4 06-10-2013 05:19 PM

2 Attachment(s)
Redline of the 2.5 L is 6700 rpm and the 2.0 L is 7000 rpm, likely to keep the max piston speed the same with the longer 79 mm stroke of the 2.5 L motor. [B]Both would be excellent choices for your application, as they have a fundamentally good design and are easy to tune. :)[/B]

Below are some power curves. The first is from the STI brochure, so it's stock and the other is COBB's tuned vs. stock comparison, probably for the 2.0L twin-cam turbo.

In general, "As you remove cats on the way to Stg 2, the spool improves and your torque peak moves earlier in the rev range. Most tunes also use more boost earlier in the rev range and taper to less. As Chris mentions, more power earlier, and it stays high for longer" [S.Deneka, SPDA auto Club co-founder]

Mitch Wright 06-16-2013 08:24 AM

Great, info thanks. My goal is a flat torque curve with around 270-280hp that will be durable. The car will weigh 1800-1900lb which will make it fun.

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