Which Subaru STI is better, the japanese or asian pacific version.?

Question

The japanese can reach 8000 rpm but it only has a 2.0L engine. Asian pacific has a 2.5L but can only reach 7000 rpm.

Answer 1

There are many reasons why the Japanese version is superior. The 2.0L motor utilizes a "closed deck" block. This basically means that there is a lot of reinforcement and less surface area where the weak head gasket can rupture.

This results in a dramatically stronger engine block. Since there is a stronger engine block, and stronger internal components the RPM limit is not the only thing that can be raised. Turbo boost pressure can also be higher because the engine is stronger.

The 2.5L "World" engine utilizes what people are calling a "Semi-Closed Deck" This is stronger than an open deck design (like the 2002-2005 WRX), but not as dramatically as a fully closed deck.

There are also numerous motor sports where a 2.0L Turbo engine is in a significantly lower class than anything above 2.0L, meaning the 2.0L engine is better because it is the maximum allowed displacement for the class, therefore can expect to be more competitive. Most professional rally circuits (the sport the STi was designed for) have a hard limit at 2.0L and 300 horsepower. Meaning the new 2.5L motors are immediately disqualified! Or bumped up to an unlimited class, where it is very expensive and difficult to be competitive.

Also in most countries (Japan and the UK for sure) 2.0L engines carry less taxes.

Answer 2

Aside from the racing points already mentioned the extra .5l makes a worlds difference for daily driving. The 2.5L has much better low end response, much less turbo lag(throttle response) and the turbo comes on at a much lower RPM. The only factory 2.0L I've seen with comparable power is spec C twinscroll setup, but that was severely limited in terms of upgrades. The 2.5L is no slouch by any means, and the 25% more displacement is more than enough to make up for the strength of the block. I'd much rather own a 500whp 2.5l than a 500whp 2.0l, for track or daily driving. With the EJ25, a decent stroker kit, some cams and springs, can get you close to 8k redline(I run 7800 soft limit with 8k hard limit, but that's a built blueprinted block) couple that with a nice fat turbo (like a 1.06AR GT35R) and you're golden.

The difference in torque between the 2.5l and 2.0l is enough that the 2.5l pulls from a stop quite a bit harder, regains full boost after a shift much faster, and while it doesn't rev as high the power band is much wider.

The only difference between the gear box is that 5th and 6th gears are a bit shorter on the JDM 6 speed, 1.062 versus 0.971 for 5th and 0.842 versus 0.756 for 6th. On the asian pacific version there is a pretty big gap between 4th and 5th which is meant for better fuel economy, whereas the JDM version maintains the close ratio all the way to 6th. The gap occasionally causes grinding on the 4th to 5th shift, but otherwise there is no difference in shifting or smoothness

Answer 3

japanese although the asian pacific has a bigger engine the jaanese will reach speedquick holding higher revs and better gear change

Answer 4

I think the Japanese version is better, but the best is an American Subaru!

Answer 5

agree.. the EJ20 (2.0L) motor is more reliable for street racer.. and alot quicker than the 2.5

Answer 6

Depends on what you define as better

Answer 7

buy an american one higher hp and tourqe numbers

Answer 8

neither, buy american