List of differences between the JDM EJ20 and the USDM EJ25

27926 Views 13 Replies 5 Participants Last post by STi Addict, Oct 12, 2013

Widebody Spec C

Discussion Starter · Oct 5, 2013

What I would like is for the Subaru gurus and other well knowledgeable members to list, as much as possible, the differences between the two. I have been doing some research and I've found some differences but I'd like these differences to be in one place.

Please don't clutter the thread with off topic posts (start your own thread)

Please be as detailed as possible

Please include differences in electronics (ECU), gear ratios, etc. (Not just engine differences)

I hope this becomes a good thread.

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STi Addict

· #2 · Oct 5, 2013 (Edited)

Displacement.. JDM 2L / USDM 2.5L
Same gearing ratio
8k JDM redline / ~6750 USDM Red line
No TGV JDM / USDM has TGV
Forged JDM rods / non forged USDM rods
USDM nitrated crank (hardened instead of 2011+)
Twinscroll turbo JDM / Single scroll USDM
TS headers and up pipe JDM / UEL headers on USDM
JDM downpipe is optimized for performance / USDM is garbage and needs a bellmouth
JDM 08+ gets double din bezel / USDM gets wider-than double din deck bezel
02-07 gets red hazard button JDM / USDM gets the grey hazard button
JDM is closed deck block / USDM is semi closed deck

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Widebody Spec C

Discussion Starter · #3 · Oct 5, 2013

STi Addict said:
Displacement.. JDM 2L / USDM 2.5L
Same gearing ratio
8k JDM redline / ~6750 USDM Red line
No TGV JDM / USDM has TGV
Forged JDM rods / non forged USDM rods
USDM nitrated crank (hardened instead of 2011+)
Twinscroll turbo JDM / Single scroll USDM
TS headers and up pipe JDM / UEL headers on USDM
JDM downpipe is optimized for performance / USDM is garbage and needs a bellmouth
JDM 08+ gets double din bezel / USDM gets wider-than double din deck bezel
02-07 gets red hazard button JDM / USDM gets the grey hazard button

Wow, great info. Some of these stuff I already knew, alot i didnt.

Also, based on my readings, JDM has top feed injectors and USDM has side feed.

Anyone else has some differences?

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Widebody Spec C

Discussion Starter · #4 · Oct 5, 2013

I also know that Cobb Access Port dont work on JDM STi, only USDM. Anyone knows why? Is it because of different ECU pinout?

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STi Addict

· #5 · Oct 5, 2013

Widebody Spec C said:
Wow, great info. Some of these stuff I already knew, alot i didnt.

Also, based on my readings, JDM has top feed injectors and USDM has side feed.

Anyone else has some differences?

07+ USDM STi has top feed, 02+ USDM wrx is all topfeed

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Widebody Spec C

Discussion Starter · #6 · Oct 5, 2013

STi Addict said:
07+ USDM STi has top feed, 02+ USDM wrx is all topfeed

Ok, thx for the info....didnt know that.

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jam007

· #7 · Oct 6, 2013

STi Addict said:
Displacement.. JDM 2L / USDM 2.5L
Same gearing ratio
8k JDM redline / ~6750 USDM Red line
No TGV JDM / USDM has TGV
Forged JDM rods / non forged USDM rods
USDM nitrated crank (hardened instead of 2011+)
Twinscroll turbo JDM / Single scroll USDM
TS headers and up pipe JDM / UEL headers on USDM
JDM downpipe is optimized for performance / USDM is garbage and needs a bellmouth
JDM 08+ gets double din bezel / USDM gets wider-than double din deck bezel
02-07 gets red hazard button JDM / USDM gets the grey hazard button
JDM is closed deck block / USDM is semi closed deck

-Rods are the same P/N as USDM STI
-8,250RPM
-JDM STI Tuftrided Crankshaft/USDM Nitrided
-207 is Semi-closed Deck just thicker cylinder walls, essentially the same block as EJ257 without the bigger bore.
-V8 STI has big port heads (V7 RA as well)
-Cam pickups are different JDM Magentic (Sin Wave)/USDM hall effect (square wave)

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STIGR-Wagon-Dad

· #8 · Oct 6, 2013

Widebody Spec C said:
I also know that Cobb Access Port dont work on JDM STi, only USDM. Anyone knows why? Is it because of different ECU pinout?

Prova imports the accessport and does the programming. They are pretty much Cobb Japan.

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jam007

· #9 · Oct 6, 2013

There's a way you can make a AP work with your swap( i'm working on this as well) swap out JDM rear cam sensors, cams for USDM STI units and use a 16bit USDM STI ECU. I have read that there is some machining and or sleeve made to retrofit USDM sensor in JDM heads, have not concurred with this statement just yet.

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jam007

· #10 · Oct 6, 2013

Widebody Spec C said:
What I would like is for the Subaru gurus and other well knowledgeable members to list, as much as possible, the differences between the two. I have been doing some research and I've found some differences but I'd like these differences to be in one place.

Please don't clutter the thread with off topic posts (start your own thread)

Please be as detailed as possible

Please include differences in electronics (ECU), gear ratios, etc. (Not just engine differences)

I hope this becomes a good thread.

Here you go all the info you need for JDM:
Transmission ID Chart - NASIOC

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Widebody Spec C

Discussion Starter · #11 · Oct 12, 2013

Thx for the info guys. The reason for this post is to educate myself to know what will work on a JDM sti and what wont. I'm not swapping to a JDM engine, my car is already JDM. I'm from Jamaica and its mostly Japanese cars here. I have a widebody kitted 2006 Sti Spec C, which i would like to modify in the future.

Thx alot for the inputs so far.

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Widebody Spec C

Discussion Starter · #12 · Oct 12, 2013

jam007 said:
-Rods are the same P/N as USDM STI
-8,250RPM
-JDM STI Tuftrided Crankshaft/USDM Nitrided
-207 is Semi-closed Deck just thicker cylinder walls, essentially the same block as EJ257 without the bigger bore.
-V8 STI has big port heads (V7 RA as well)
-Cam pickups are different JDM Magentic (Sin Wave)/USDM hall effect (square wave)

So a USDM piston wouldn't fit a JDM block, correct?

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8cd03gro

· #13 · Oct 12, 2013

Widebody Spec C said:
So a USDM piston wouldn't fit a JDM block, correct?

Not without boring and it would be a horribly backward move. The USDM pistons are the suck.

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Reactions: 1

STi Addict

· #14 · Oct 12, 2013

Widebody Spec C said:
So a USDM piston wouldn't fit a JDM block, correct?

they won't because of the bore size.

Here's all you need to know on the EJ207 motors

EJ207 madness

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