Most of the people here believe the new WRX has a semi-closed block like the Legacy GT and STI but does anyone know for sure? I mean really, the truth?

From cars101:
2.5L boxer DOHC, 4 cylinder, 16 valves
Active Valve System
Turbocharged
Hood scoop air intake with Intercooler
Block and heads, Aluminum alloy. open deck design, with
cast iron cylinder liners
Sequential multi-port fuel injection
Bore: 99.5x79mm, 3.92x3.11
Redline 7000 rpm

Since the 06 are being sold or will be soon, I was hoping some of you may have real answers.

I have no authority here, but from some of the reading I've done I infer that "open" is sometimes used as an overarching term for semi-closed and open--i.e. if it's not (fully) closed, it's "open." If someone could confirm or deny I'd appreciate it.

SOA's WRX spec sheet, http://vocuspr.vocus.com/VocusPR30/T...WRX_Specs2.pdf says "semi-closed deck cylinder block design".

They aren't going to use one block for the LGT, FXT, and STI, and then use a different one for the WRX... It's a semi-closed block.

The part number for the complete shortblock is different than the others, however, the part number for the cylinder block is the same (11008AA930) so it has to be a semi-closed deck design.

I am currently looking into the other part numbers to see what else changed to warrant the shorblock having a different part number.

The pistons for the 06 WRX AND 06 Forester XT are a different part number than the 04-05 Forester XT, 04-06 STI, and 05-06 Legacy GTs and XTs.

The piston part number for the STIs, 04-05 Foresters, and all the 05 and up Turbo Legacys is 12006AC390.

The part number for the 06 WRX and 06 Forester is 12006AD210.

List price on either piston is $85.42

Other than that, the crank, rods and cylinder block are the same between all the turbo 2.5 models.

How much cheaper are they than sti blocks?

List price on the STI block (10103AB440) is $1812.53

List price on the WRX block (10103AB630) is $1759.74 which is the same price the STI block was until July 1.

Most dealerships on NASIOC will sell them for quite a bit less than list...mine included.

Maybe the change in pistons (relative to the 2005 2.5L turbo engines) might account for some of the increase in compression ratio (now 8.4:1 was 8.2:1).

so its like 50 dollars for hypereuretic lol pistons? I was hoping for a bigger saving.

My guess is the pistons are still Hypereutectic, but have a different dish design. As John [inCT] mentioned, the compression ration is different on the 06 Forester.

does that mean the new wrx's have the same engine (almost) as the sti's, just detuned?

No, it means the new WRX has different pistons and different cylinder heads and different turbo and different intake manifold and different intercooler, etc.

This n00b gathers that you're talking complete shortblock pricing, right?

Correct, that pricing is for a complete shortblock, which is the cylinder block, crankshaft, connecting rods, pistons and all the necessary, bearings, rings, bolts, and clips.

So is an 06+ WRX swap into an older Subaru gonna be just as complicated as an STi swap now - AVCS, drive by wire, immobilizer, etc?

ss

Oh Yeah. Possibly more so if the secondary air pump is required and can't be bypassed easily.

That sucks but thanks for the info.

ss

Here are a few more very interesting things here. The headgaskets are a new part number wihich is different from the STI headgasket, 11044AA670 for the WRX and 11044AA642 for the STI). I don't think the headgasket difference alone is the reason for the variance in compression ratios, as the STI headgasket is already the thinnest head gasket Subaru offers. It could be a matter of pistons with a much higher compression ratio combined with thicker headgaskets to give a slightly higher value. It will be VERY interesting to see who cracks one of these new WRX blocks open first to do the research.

The only Open deck Subaru engines are the SOHC NA engines, right? The EJ251/2/3 are all Open, but the DOHC EJ22 is semi closed... Makes sense to me.

I thought the EJ22 blocks on the turbo legacy and the 22b were closed deck blocks...and don't forget that the old EJ205 block was also an open-deck design.

I'm not sure about the 22b, but the EJ22T is semi-closed deck.

After some researching, the EJ22T is a closed deck block.

http://forums.nasioc.com/forums/show...2t+closed+deck