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Old 08-19-2003, 04:05 PM   #1
Crawford/I-Speed
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Default More 2.5 STI short block info...

More 2.5 STI short block info...

here is a link to more info
http://www.i-speed.us/news/sti_block...=ST;f=12;t=115

More Pics: http://www.i-speed.us/news/sti_parts.shtml

Also, we do not know if people are telling you this, but we have been told be several Subaru Reps and Subaru dealers that the 2.5 STI short block will ONLY work with the 2.5 STi heads. Well, that's not entirely true.
With the help of our engine builder, Crawford Performance, we can now get the new 2.5 STI block to work with USDM WRX heads! We keep the 2.5 STi turbo crank and rods and use special forged Crawford pistons. These Crawford pistons keep the proper compression ratios that the wrx heads need to operate effectively. Without specially designed pistons in place of the STI pistons…the 2.5 STI block will not work with the wrx heads.



Now, it's time to put that R/D on the street and then the DYNO

Chris
i-speedusa.com
cescamilla@i-speedusa.com
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Last edited by I-Speed USA; 08-20-2003 at 04:55 PM.
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Old 08-19-2003, 04:16 PM   #2
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Link isn't working.

Just out of morbid curiosity can you confirm that the picture above is your custom piston setup installed in a 2.5L sti block?

Those pistons look like they have quite a bit of dish in the picture (could just be picture quality). Do they have more or less dish than the standard UDSM pistons?

Any chance you are willing to reveal dish volume?
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Old 08-19-2003, 04:23 PM   #3
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Old 08-19-2003, 04:27 PM   #4
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nmyeti - yes it is our custom setup (2.5 STI block with Crawford custom pistons).
Yes, there is quite a bit of dish when compared to the stock STI pistons. And yes, we know the picture is not the greatest.
Sorry, not ready to divulge dish volume.


Chris
i-speedusa.com
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Old 08-19-2003, 08:54 PM   #5
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the 2.5 block will also work with the JDM STi heads as well btw
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Old 08-19-2003, 09:14 PM   #6
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Default heads won't work

Could you clarify the "stockUSDM wrx heads won't work" statement.

Do you mean that with the stock heads and no change in piston you have excessive compression, or you get valve to piston interference or both.


Do your custom pistons return the engine to the stock (for the 2.5 STi) compression ratio, or did you choose a slightly different compression ratio to make the heads work?

Thanks for the info and pic's!!

Larry
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Old 08-19-2003, 09:30 PM   #7
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Larry - Yes keeping the stock STI pistons with the USDM heads will get you "excessive compression". We also noted that you may have "valve to piston interference".
BTW: We did not test the interference theory. But other people are more than welcome to try it

"Do your custom pistons return the engine to the stock (for the 2.5 STi) compression ratio, or did you choose a slightly different compression ratio to make the heads work?"
We chose a different ratio

Chris
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Old 08-19-2003, 09:40 PM   #8
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So how much of an overbore is possible with this block? looks to be much more capible of mega displacement than the normal STi EJ20 block.
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Old 08-19-2003, 10:06 PM   #9
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Quote:
Originally posted by XT6Wagon
So how much of an overbore is possible with this block? looks to be much more capible of mega displacement than the normal STi EJ20 block.

how much more do you need? I speed already has a 2.8...
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Old 08-19-2003, 10:19 PM   #10
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Can't wait for testing results
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Old 08-19-2003, 11:33 PM   #11
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i thought the 2.5 STI blocks were closed deck? cuz it seems to me that, that looks open deck

or am i wrong in the defintion of what a closed deck is?

-thanks
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Old 08-19-2003, 11:36 PM   #12
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Quote:
Originally posted by BoostedAWD
i thought the 2.5 STI blocks were closed deck? cuz it seems to me that, that looks open deck

or am i wrong in the defintion of what a closed deck is?

-thanks
The new age sti blocks ej207/257 are not closed decks... they are reinforced decks. The older blocks ej20g,k? and the ej22t are semi closed decks. There are no closed decks from the factory
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Old 08-19-2003, 11:37 PM   #13
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Quote:
Originally posted by BoostedAWD
i thought the 2.5 STI blocks were closed deck? cuz it seems to me that, that looks open deck

or am i wrong in the defintion of what a closed deck is?

-thanks
The 2.5 STi block is "semi-closed".

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Old 08-19-2003, 11:55 PM   #14
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thanks for the info.
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Old 08-20-2003, 12:18 AM   #15
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Where can I get a set of those pistons? I need sety for a block I have sitting here.
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Old 08-20-2003, 12:37 AM   #16
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Are normal people now able to get ej257 shortblocks through normal channels?
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Old 08-20-2003, 12:37 AM   #17
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Let me say that i have personally dealt with Crawford Peformance and all i can say is that he knows alot. He knows his stuff. He also has been messing with subarus for years and lives and breathes motors. Anything from Crawford gets two thumbs up from me.
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Old 08-20-2003, 12:42 AM   #18
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Nice! Time for me to start saving my duckets.
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Old 08-20-2003, 12:44 AM   #19
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Not sure why you would want to waste your time running crap usdm wrx heads on a 2.5L block, unless you want a (small) stump puller that falls on its face at high rpm. If you want to do it, do it right the first time.
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Old 08-20-2003, 01:34 AM   #20
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I'm not trying to run 9's like Nick is... I'd be really happy sticking the new forrester engine in my car

Whatever is cheaper, cuz I'm poor

I guess I could just get a 2.5 sticker.
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Old 08-20-2003, 01:44 AM   #21
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“Where can I get a set of those pistons? I need sety for a block I have sitting here.”
We would need to know exactly (compression, material, size etc…) what you are looking for and the application you would be using them for. That would help us to help you better. Email me for details.

“Are normal people now able to get ej257 shortblocks through normal channels?”
I have no idea. Crawfords' Subaru connections run fairly deep. To be honest we all were surprised when we got what we asked for.

“Not sure why you would want to waste your time running crap usdm wrx heads on a 2.5L block, unless you want a (small) stump puller that falls on its face at high rpm. If you want to do it, do it right the first time.”
True the WRX heads may not be completely up to the 2.5 STi short block potential. However, getting the 2.5 STi short block to work with heads that most people seem to have is what we were after. In any case, this option now provides new avenues for people to mod their WRX. Where those people go from there is up to them and most often… their pocket book.

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Old 08-20-2003, 02:01 AM   #22
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Woops...forgot to answer this one

" So how much of an overbore is possible with this block? "
The overbore capability is 1mm. But in fact the overall thickness of the liner and casting is less than the 2.0.

Chris
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Old 08-20-2003, 02:45 AM   #23
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Well its just that some people seem to bore the EJ20 block out for 100mm pistons.... and since the inner AND outer diamiter of the "liners" is bigger in radius I figured that it could take a decent ammount of extra bore size.
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Old 08-20-2003, 03:12 AM   #24
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I dont want to turn this thread into a bitch fest as I think there could be useful information gained from it but...

... the pocket book argument is ****ing weak when it comes to building a proper 2.5L stroker. If you are in the market for something like this, please do yourself a favor and atleast get cams to stand up to the task at hand.
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Old 08-20-2003, 03:31 AM   #25
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I can't even afford brake pads, let alone cams right now.
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