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Old 02-27-2005, 11:38 PM   #1
WSSBOARD18
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Default jdm sti v8 2.0l or usdm 2.5l shortblock?

I want to get a new short block for my wrx, should i get a v8 2.0l jdm sti or a usdm 2.5l? I can get either one brand new and for about the same price. Which one is going to be most reliable and hold the most horse power. At the moment i have a vf22 with suporting mods, in the future i want to get a gt30r kit to go with the new motor. I will keep my stock wrx heads but get them ported and I am looking into getting new cams, but might stay with my stocks for now. Which motor would you get for the best performance?
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Last edited by WSSBOARD18; 02-27-2005 at 11:47 PM.
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Old 02-27-2005, 11:49 PM   #2
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I would use the USDM 2.5 block. It'll make the VF22 and GT30 spool really nice, and with the WRX heads having a port and polish should flow decent. The real way to do it is to use forged pistons in the 2.5 block, and V7 or V8 heads. Thats a great frankenstein combo if thats what you're after.
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Old 02-28-2005, 07:38 AM   #3
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Ver 8 2L would be my choice...im a fan of the higher rev motors....plus the top end on a 2L is sick!......Also...the ribbings on the block are bigger on the JDM motors than the USDM sti motors.


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Old 02-28-2005, 08:39 AM   #4
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Quote:
Originally Posted by Scoobs2002
Ver 8 2L would be my choice...im a fan of the higher rev motors....plus the top end on a 2L is sick!......Also...the ribbings on the block are bigger on the JDM motors than the USDM sti motors.


Scoobs
he's only going to replace the short block. To be honest, the 2.5 shortblock is not that much weaker than the version 8 jdm 2.0 block, so i would just get the 2.5 shortblock for the added displacement.

If it were motors, I would get the version 8, hands down.
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Old 02-28-2005, 08:56 AM   #5
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Quote:
Originally Posted by Capt Crunch
he's only going to replace the short block. To be honest, the 2.5 shortblock is not that much weaker than the version 8 jdm 2.0 block, so i would just get the 2.5 shortblock for the added displacement.

If it were motors, I would get the version 8, hands down.
Werd....im just a fan of the 2l smoothness.
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Old 02-28-2005, 09:01 AM   #6
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the stock heads won't rev to 8,000.

get the 2.5 if your just doing the block.

-J
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Old 02-28-2005, 09:07 AM   #7
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dont flame me, but isnt the ver 7 stronger than the ver 8? the ver 7 has full forged internals and the ver 8 only has forged rods and crank and uses cast pistons. i'm just going by what i read.
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Old 02-28-2005, 09:07 AM   #8
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Quote:
Originally Posted by faylix
the stock heads won't rev to 8,000.

get the 2.5 if your just doing the block.

-J
^^^^^
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Old 02-28-2005, 09:14 AM   #9
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Quote:
Originally Posted by spoolinsuby
dont flame me, but isnt the ver 7 stronger than the ver 8? the ver 7 has full forged internals and the ver 8 only has forged rods and crank and uses cast pistons. i'm just going by what i read.
Yes you would be correct...the Ver 7 block is tougher than the Ver 8, but the Ver 8 heads flow a lil better than the Ver 7 heads....thats the trade off..Ideal would be Ver 7 block with Ver 8 heads.

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Old 02-28-2005, 09:41 AM   #10
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thats what i had gathered from what i read but i had'nt heard of people doing it.
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Old 02-28-2005, 11:30 AM   #11
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right now my wet dreams are 2.5 USDM Sti with Ver7 or 8 heads. Was thinking about keeping a set of WRX heads and just do the P/P, cams, springs, valves for the money but it would be getting close.
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Old 02-28-2005, 11:43 AM   #12
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Thanks for your guy's input.
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Old 02-28-2005, 01:36 PM   #13
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The ver7 motor is stronger if you have an improper tune and are detonating. If you do not detonate the Ver8 is mega strong.

Run a proper tune and do not detonate. Why would you get a motor and tune so you detonate? If that is your plan then get the forged pistons by all means. If you are no going to detonate then get the ver 8 motor. In terms of pressure, the Hyper-cast pistons can takes an abrurd amount of force. Subaru claims stronger than the forged variant. There is a huge upside to those pistons if tuned properly, they take heat better, short blocks can be built with closer tolerances, are lighter etc...

Now if you detonate that is a different thing. Again, why would you detonate if tuned properly?

The JDM short block is indeed stronger and not by such a little about either. However the 2.5 has greater displacement. The JDM block has stronger cylinder walls, much beefier pistons actually than the USDM variant and stronger wrist pins and some have reported on differences in connection rods in terms of the JDM being stronger. I think is may have been DEF can't remember.....

For pump fuel application,a USDM 2.5 short bolck with the rotating assembly balanced through 9-10K rpm woul dbe nice. The smoothness, or lack of it, is my biggest USDM 2.5 issue.

I can hit the same whp with JDM 2.0 or USDM 2.5 on pump gas for the most part. Out here in az, the 400whp mark is about what you get tops give or take 20whp. It is with the addition of racing gas theat the additional displacement becomes a real issue as well as the reduced lag with larger turbos.

For 300-375 whp cars, on pump gas I would do a JDM 2.0. That is 450-500 crank hp. I mean a real 300whp not my VF34/VF22 makes 300whp. A balanced 2.5 would be a real contender for me if it was available cheaply. That with my Ver8 top end would be superb. Otherwise, for the price, on pump gas, it just does not buy you that much. Putting forged pistons in the 2.5 is just not necessary for pump fuel cars.

Oh, a VF22 and GT30R are leagues apart in terms of power and size and application.
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Old 02-28-2005, 01:50 PM   #14
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Quote:
Originally Posted by ebeck
The ver7 motor is stronger if you have an improper tune and are detonating. If you do not detonate the Ver8 is mega strong.

Run a proper tune and do not detonate. Why would you get a motor and tune so you detonate? If that is your plan then get the forged pistons by all means. If you are no going to detonate then get the ver 8 motor. In terms of pressure, the Hyper-cast pistons can takes an abrurd amount of force. Subaru claims stronger than the forged variant. There is a huge upside to those pistons if tuned properly, they take heat better, short blocks can be built with closer tolerances, are lighter etc...

Now if you detonate that is a different thing. Again, why would you detonate if tuned properly?

The JDM short block is indeed stronger and not by such a little about either. However the 2.5 has greater displacement. The JDM block has stronger cylinder walls, much beefier pistons actually than the USDM variant and stronger wrist pins and some have reported on differences in connection rods in terms of the JDM being stronger. I think is may have been DEF can't remember.....

For pump fuel application,a USDM 2.5 short bolck with the rotating assembly balanced through 9-10K rpm woul dbe nice. The smoothness, or lack of it, is my biggest USDM 2.5 issue.

I can hit the same whp with JDM 2.0 or USDM 2.5 on pump gas for the most part. Out here in az, the 400whp mark is about what you get tops give or take 20whp. It is with the addition of racing gas theat the additional displacement becomes a real issue as well as the reduced lag with larger turbos.

For 300-375 whp cars, on pump gas I would do a JDM 2.0. That is 450-500 crank hp. I mean a real 300whp not my VF34/VF22 makes 300whp. A balanced 2.5 would be a real contender for me if it was available cheaply. That with my Ver8 top end would be superb. Otherwise, for the price, on pump gas, it just does not buy you that much. Putting forged pistons in the 2.5 is just not necessary for pump fuel cars.

Oh, a VF22 and GT30R are leagues apart in terms of power and size and application.
If i were jsut to swap out the shortblock which would you get to go with my vf22? The only other mod i would do would be to port my stock heads and maybe bigger injectors than my pinks if i needed too. Oh and i know that the gt30 and vf22 are worlds apart, It was jsut anohter option in the future for upgrading after i swap short blocks.

Last edited by WSSBOARD18; 02-28-2005 at 01:57 PM.
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Old 02-28-2005, 02:16 PM   #15
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I would not put the VF22 on either of those motors. But, if that is your power aspirations, then get a JDM 2.0 and be done with it. That is a small turbo. It will be smooth and strong as heck.

At that power level, with USDM heads, it is hard to make a case either way really. The 2.5 will make more power with that turbo on pump fuel, the JDM is a better motor. Just get what ever is cheapest.
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Old 02-28-2005, 03:34 PM   #16
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Quote:
Originally Posted by Capt Crunch
he's only going to replace the short block. To be honest, the 2.5 shortblock is not that much weaker than the version 8 jdm 2.0 block, so i would just get the 2.5 shortblock for the added displacement.

If it were motors, I would get the version 8, hands down.
agreed
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Old 02-28-2005, 09:28 PM   #17
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You have to remeber with the bigger displacement you will have increased torque. Then you will have to worry about drive train issues and having to beef that up too. With the JDM block you will have about the same, if not the same amount of torque. If I was you I would do either JDM blocks, V7 or V8.
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Old 03-01-2005, 12:19 AM   #18
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how much do you think it would cost.....JDM v7 shortblock and v7 or v8 heads, all with a tune?


This assuming you have a setup with upgraded turbo and supporting mods to?
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Old 03-01-2005, 12:26 AM   #19
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Old 03-01-2005, 02:01 AM   #20
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no i know that thread, i was thinking without the tranny
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Old 03-01-2005, 05:48 PM   #21
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ebeck?
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Old 03-01-2005, 05:50 PM   #22
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Sent you my phone number in a pm. Call me. It is easier.
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Old 03-01-2005, 07:54 PM   #23
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What do you guys think of a vf22 with the axis stage 2 2.5L motor?
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Old 03-01-2005, 08:35 PM   #24
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Quote:
right now my wet dreams are 2.5 USDM Sti with Ver7 or 8 heads
Thats what Ron at Axis is putting together for me. Except he's putting in balanced crank, rods, and pistons.
I wanted to have a balanced crank to work with the big port v8 JDM heads and keep it smooth!

Mitch
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Old 03-01-2005, 10:04 PM   #25
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Ebeck, i was suggesting that instead of buying a stage 4 kit, i would get a complete STI v7 Longblock swap from east cost scooby and leaving the tranny....

This is what i figure


v7 block with everything: 4,100 + about 300 shipping
ECUtek tune: 300
Sell my motor: -1,300

Total: $3,400



Is that all u need
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