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Old 03-29-2005, 04:55 PM   #1
e11ys
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Default Cold, hard numbers on USDM vs. JDM

In the argument about whether the US Sti or the JDM Sti engine is better, I have seen people on both sides claim one performs better than the other. However, a lot of the time neither cars are stock.

If a stock USDM car and a stock JDM car where taken to a track, how would they compare? Would the extra displacement of a US car make up for the lack of twin-scroll turbo? I'm not talking about the Spec C either, just a normal JDM Sti. I am planning to eventually swap an engine in my car, and I am just curious about the advantages of either one.

Oh, and I searched and didn't come up with anything conclusive.

Ellys
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Old 03-29-2005, 05:08 PM   #2
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Quote:
Originally Posted by wrx580
In the argument about whether the US Sti or the JDM Sti engine is better, I have seen people on both sides claim one performs better than the other. However, a lot of the time neither cars are stock.

If a stock USDM car and a stock JDM car where taken to a track, how would they compare? Would the extra displacement of a US car make up for the lack of twin-scroll turbo? I'm not talking about the Spec C either, just a normal JDM Sti. I am planning to eventually swap an engine in my car, and I am just curious about the advantages of either one.

Oh, and I searched and didn't come up with anything conclusive.

Ellys
Considering that our STi is mostly Spec-C (minus the shorter 5th and 6th and some other stuff), i would say the USDM STi would win. I think tires alone would make the difference, as the RE070 is the "Spec C" tire. IIRC the JDM STi comes with the RE040 (seen in the US as 350Z OEM tire), which is not as sticky as the RE070.
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Old 03-29-2005, 05:12 PM   #3
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What about the engines? If they had the same tires, would the USDM still be better?
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Old 03-29-2005, 08:14 PM   #4
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I'd always thought that the JDM was better until it occured to me that they both have AVCS. Now it is just a matter of torque and displacement. I would give it to the USDM anyday. Isn't bench racing fun!
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Old 03-29-2005, 08:26 PM   #5
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AFAIK the old style JDM STi used to be faster. Better power to weight ratio.
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Old 03-29-2005, 08:30 PM   #6
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If you are running USDM gas, I think the USDM STi would definitely be faster, as the JDM engine is tuned for the superior fuel available in Japan.
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Old 03-29-2005, 10:53 PM   #7
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My understanding is that the JDM handles better than the USDM due to less weight up front that the USDM has due to the larger displacement and supporting hardware.
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Old 03-30-2005, 11:05 AM   #8
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So basically a JDM can handle higher power levels if you plan to mod, but if you just want an STi engine, buying one here in the U.S. is much more cost effective. At least thats the conclusion I come to. I was looking at the V7 engine, but I think maybe I'll just get a US engine when the time comes. Thanks for all your input.
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Old 03-30-2005, 01:04 PM   #9
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Quote:
Originally Posted by cboggess
My understanding is that the JDM handles better than the USDM due to less weight up front that the USDM has due to the larger displacement and supporting hardware.
What supporting mods make the U.S. STi weight more due to the engine, same trannie, same engine block pretty much. If any thing the U.S. Sti engine should weight less becasue its bored out. The only thing that would make U.S. sti weight more is the bumper beam, and maybe some of the emmisions equitment.
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Old 03-30-2005, 01:12 PM   #10
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Quote:
Originally Posted by cboggess
My understanding is that the JDM handles better than the USDM due to less weight up front that the USDM has due to the larger displacement and supporting hardware.
How much more does the 2.5 liter weigh???

I have been toying with the idea of taking my WRX 2.0 and putting forged internals just to raise the redline. Then add as much boost as US Premium gas will allow.
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Old 03-30-2005, 01:18 PM   #11
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Quote:
Originally Posted by wrxsubaru
What supporting mods make the U.S. STi weight more due to the engine, same trannie, same engine block pretty much. If any thing the U.S. Sti engine should weight less becasue its bored out. The only thing that would make U.S. sti weight more is the bumper beam, and maybe some of the emmisions equitment.
And airbags....
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Old 03-30-2005, 01:36 PM   #12
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the JDM STi engine rev to 8k and are 2.0L. I'll take it over the USDM Sti anyday. And yes the JDM STi is lighter than the USDM STi.
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Old 03-30-2005, 01:38 PM   #13
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JDM Ver. 7 STi all the way, thats my plan and I'm stickin to it, better engine overall, better heads AVCS intake and exhaust and better short block, the list goes on and on...
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Old 03-30-2005, 02:01 PM   #14
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im much happier with our 2.5L, and since our USDM is the closest thing to a spec C out of japan, im pretty sure the JDM sti would lose.
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Old 03-30-2005, 02:05 PM   #15
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personaly i dont give a **** LOL!
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Old 03-30-2005, 05:54 PM   #16
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How about USDM 2.5L block with forged internals and v9 spec-c heads?

edit: and this thread is funny because not a single read # has been posted. Gotta love nasioc.
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Old 03-30-2005, 08:11 PM   #17
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JDM STI over USDM STI anyday ...

Jin
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Old 03-30-2005, 10:59 PM   #18
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Quote:
Originally Posted by Phil Jr.
How about USDM 2.5L block with forged internals and v9 spec-c heads?

edit: and this thread is funny because not a single read # has been posted. Gotta love nasioc.
Thats what i would do! "TYPE-25" IMPREZA says it all!
US 2.5 Block on v7 Head w/ more aggresive cams etc (+ twin scroll)
Type-25= fastest {in general} STi made (by litfield imports though)

may or may not be worth the $$ but seems like it may be cheaper if you can source the parts?
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