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Old 01-26-2003, 04:35 AM   #1
Cusco
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99 ej25sett/TEC II
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Default Swapping MY99 EJ25 internals with sti EJ25 internals/head?

I was wondering what speculations there are when it comes to swapping parts with sti parts? I am running 10 psi with TEC II and am waiting for SOA to stock there warehouse with sti internals so that I can rebuild my engine for more power. my goal is to have a rebuilt MY99 EJ25 engine by next year with sti internals and head. I heard that the sti engine has forged internals and the compression is still 9.5:1 or 10:1, not sure. If this is so, theoretically all the sti 2.5 internals are interchangable with the RS EJ25. I am aware that the head on the sti is a DOHC and the MY99 are SOHC. If I was to change my MY99 to a DOHC by replacing the head and getting the ECU from the sti I would be able to run a MY99 block with sti head and manifold??? Wouldn't this be the ultimate engine? or is the block on the sti a better structurally design engine, I mean the sti engine itself is an ultimate engine (very strong), but trying to buy a brand new one of those would be a doosey. Im sure upgradinign internals one by one isnt any cheaper. after the parts are out and prices are set I will have to look further into the issue of cost.

Any info people can give me?
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Old 01-26-2003, 04:46 AM   #2
US2JDM
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Since no one has the specs of the engine dimensions yet, there is no guarantee ANY of the parts will be a direct swap w/ the N/A EJ25. Who even knows if SOA will let you order the STi parts without an STi VIN number and proof of ownership?

I think you'll have to wait a while till all the info is released.

Good luck.

-Milan
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Old 01-26-2003, 07:18 AM   #3
N/A
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I doubt SOA would be that strict on who buys the parts since all they seem to be concerned with is money so far. If they can make a buck then they will sell the parts. Especially if they can mark the price way up like the BBS rims.
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Old 01-26-2003, 12:02 PM   #4
Chav
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IIRC compression on the STI EJ25T is 8.2:1 and the block on the STI is semi-closed while ours is open.

With the STI ECU your also going to have to deal with that whole throttle by wire thing.

I think it will just be easier to buy STI pistons, pins, rods, and if you want it crank. For the stock heads, new cams and springs will help you move to a higher red-line.

-Chav
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Old 01-27-2003, 05:04 AM   #5
Cusco
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Default alternative?

CHav: If I am buying sti pistons,rods pins, springs springs and after market cams I am guyessing it will be a good 4k or so? If this is so and since the sti compresison is 8.2:1 wouldn't it be a better alternative to get a SOHC rebuilt head by COBB tuning which gives me a 8:1 compression as well as 2.5 displacement with turbo cams, springs, valves port and polished rebuilt head with a good strong redline of 8500?
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Old 01-27-2003, 10:24 AM   #6
8Complex

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I guarantee that you won't be able to buy internals or short blocks for at least 6 months without pulling teeth. Remember, this is a VERY limited model. If they released parts into the dealerships freely, they'll be opening the door to people buying the WRX, then swapping in an STi motor (long block), ECU, and turbo...
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Old 01-27-2003, 11:05 AM   #7
Chav
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Cusco, the Cobb heads reduce the compression ratio? It is my understanding that this method of reducing the compression ratio isnt the best because of the squish between the piston and head.

Are you saying to use the heads as an alternative to the bottom end build or to use those heads along with the bottom end build?

If you want to use it as an alternative you are still going to have to worry about the weak cast pistons. You will have the lower compression, but any detination that may occur will more likely destroy your engine without the forged internals.

I don't know the costs of the sti bits, but I can estimate the cost for you based on the prices for parts that are available now.

JE Pistons 8.5:1 650
Crower Rods 675
Cobb Valve springs, etc 495
Cam 499

You're looking at around 2.5 grand for parts and than the price of assembling the block.

-Chav
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Old 01-28-2003, 10:00 AM   #8
omahasubaru
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If short blocks become available from the dealer, that would be the way to go. However since the US is the only place with this car... I'm willing to bet that unless you have an STi (own one) you won't get parts for it. You'll have to find a wrecked one and then fight off not only the US market, but Japan and Europe to get your hands on it.

Don't worry there will be plenty of totaled STi's before this year is over.

Thanks - Jon
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