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#16 Old 01-11-2008, 10:21 PM
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Sorry I dont mean to jack the thread, but what exactly are the differences between the wrx 2.5l and the sti 2.5l engine? I know about the external differences like turbo, i/c, and the sti has avcs, but what else?
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#17 Old 01-11-2008, 10:46 PM
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Originally Posted by wrxman420 View Post
Sorry I dont mean to jack the thread, but what exactly are the differences between the wrx 2.5l and the sti 2.5l engine? I know about the external differences like turbo, i/c, and the sti has avcs, but what else?
STI short block is semi-closed (can withstand more boost), forged internals. Heads are bigger diameter intake ports and slightly more agressive camshafts. Essentially it is more fiendly to upgrades and will make more power at higher rpm's and modification levels than 2.5 wrx motor. And you mentioned AVCS on the intake cam making the off boost to on boost transition more street friendly.
In my opinion both motor should make about the same power untill a 18g sized turbocharger, after that the wrx motor will hit air supply bottle neck; and STI motor will be longer lasting with the same quality tune than wrx motor.

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#18 Old 01-12-2008, 07:09 AM
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Originally Posted by mosc View Post
They are not the same motor. They just are both Boxer-4 2.5L. They have quite a few differences.

You're absolutely right. What I meant was that they were both a 2.5 liter. Sorry for any of the confusion.
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#19 Old 01-12-2008, 05:52 PM
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very good summary b7g. Besides the internals though which you covered, the intake manifolds (headers) are different.

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