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Old 05-10-2005, 08:22 PM   #1
rsti02
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Default JDM or USDM Sti Swap

compare the two

Pros and Cons
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Old 05-10-2005, 08:29 PM   #2
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USDM all the way! Bigger displacement
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Old 05-10-2005, 08:30 PM   #3
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US short block JDM heads
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Old 05-10-2005, 08:32 PM   #4
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jdm version 8 for me.
PROS: hypercast pistons, sick head and cam design, twin scroll, 8500 redline, silky smooth motor, same for the trans
CONS: ?????
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Old 05-10-2005, 08:33 PM   #5
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USDM

Can make it legal.

TORQUE, and minimal lag, both make for a better street car.

I don't know, but would figure you can make more power out of the 2.5 on pump gas because of the displacement.
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Old 05-10-2005, 08:54 PM   #6
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jdm > swap all the way. y swap a usdm motor when you could buy sti. I think if it exist in US, then choose that motor to swap other then displacement.
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Old 05-10-2005, 09:09 PM   #7
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A USDM swap will dramatically increase the resale value of the car, as well as maintain it as street legal. Plus its easier to find out the history of the motor/drivetrain you are purchasing.

HOWEVER, I bet you can pass inspections with JDM OEM STi turbo setups on the car
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Old 05-10-2005, 10:32 PM   #8
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HAHA another one of these posts. JDM all the way. USDM stuff is junk

Pros to a 2.5l USDM swap....none
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Old 05-11-2005, 12:12 AM   #9
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jdm version 8. bomb proof motor! automatic valve control system, twin scroll (NO turbo lag, is at full boost in under 2 seconds not five)8500 rmp redline. cant get any better. oh and it will waste a usdm sti. diplacement does matter (jdm is only 2.0) but according to most you can pull just as much power out of a jdm because rotaing mass is less. GO JDM!!!
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Old 05-11-2005, 12:37 AM   #10
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Yes, JDM is the greatest, it can run off straight nitroglycerin, and spool by -250 rpms, everyone keep hyping up JDM motors. Maybe that way I can get a lowly USDM one for cheap, I'll be satisified with that, I'm not greedy.
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Old 05-11-2005, 12:51 AM   #11
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i think that comment by Eby was totally uncalled for. we were asked OUR OPINION, so we are giving it......no reason to flip out and call people greedy when you dont even know anyof us. also one of the main reasons we (at least I) did a jdm swap is to save money. maybe if you did some research and came back you could say sorry for waisting space in this form.
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Old 05-11-2005, 02:28 AM   #12
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Dont talk trash about Eby, this is his USDM swaped L:

Why JDM swaps suck... IE Eby's USDM WRX swap in an L

Im sure he'd be glad to tell you what that car exactly had done to it, and its not much at all
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Old 05-11-2005, 02:37 AM   #13
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just for the record i was never talking trash....for anyone who might think so. i just think that comment was rude. now lets not turn this form into a place to argue, lets use it what it is made for......
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Old 05-11-2005, 02:56 AM   #14
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Quote:
Originally Posted by nate1654
just for the record i was never talking trash....for anyone who might think so. i just think that comment was rude. now lets not turn this form into a place to argue, lets use it what it is made for......
You totally overreacted man, go get some sleep and come back to the forums tommorow
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Old 05-11-2005, 03:29 AM   #15
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Do any of you know what you are talking about? Really?

To get the best set up for a dyno queen take a new US sti 2.5L block and add forged pistons. For heads get JDM Ver 8 STi. US sti heads pale in comparison to ver 7/8 JDM Sti heads in all aspects.

Total cost would be around $4500

However this is not the route Iíve gone withÖ (ver 7 bottom end with ver 8 heads)

It has also been proven that the JDM ver 7 ecu can pass OBD2 emissions

Hypereutectic pistons bomb proof? Just the opposite.
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Old 05-11-2005, 03:36 AM   #16
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Dyno queen vs. actual speed... You just dont need as massivly tuned of an engine to go fast with a swap

But ya, you are right, JDM Spec C heads = best, USDM STI block = best, and some crazy 500hp tuned massive turbo rig to go with it would be best too... for a dyno queen.

Then there are the folks who want daily drivers, just a faster non-n/a motor in their car with eyes other issues.

It all depends on the person and the situation, IMHO
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Old 05-11-2005, 04:00 AM   #17
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Quote:
Originally Posted by nate1654
i think that comment by Eby was totally uncalled for. we were asked OUR OPINION, so we are giving it......no reason to flip out and call people greedy when you dont even know anyof us. also one of the main reasons we (at least I) did a jdm swap is to save money. maybe if you did some research and came back you could say sorry for waisting space in this form.

lol, yea somebody here flipped out. I don't know, I figured with the nitroglycerin comment, and saying it spools the turbo at -250 rpm most people would get the sarcasm. Guess not.

Okay, my serious opinion. Anything I build right now is going to be mainly a street car. So basically that means no ultra hard suspension, no roll cages, no race gas, etc, etc, etc. Will it make 500 whp, no, will it pull the most G's around an autocross or roadcourse, no, does any of that really matter in a car I will 95% of the time drive on the street, no, not to me atleast.

So for a car that spends most of it's time on the street, why would I want an engine with less low end torque, more lag, less potential on pump, can't technically be legal anywhere(I know they can pass, but they aren't technically legal, you can be rat'd out, it's rare, but I know of 3 people that has happend to outside of the Subaru world, EPA is federal jurisdiction).

I'd be happy with the 300-350 whp I could make easily on a ej255/57 running pump gas. That should be good for mid to high 11's. No roll cage so no need to go any faster than that.
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Old 05-11-2005, 01:04 PM   #18
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300whp even in a light RS is really pushing it to hit 11's unless your using dyno dynamics numbers...

So your not a JDM fan boy? Neither am I... I could care less where the engine comes from but the fact is that:

#1 the Ver 7 bottom end is very tough and proven factory equipment. The new USDM sti bottom ends have frequent piston failures.

#2 JDM ver 7/8 heads VS worked WRX heads, you would need to spend up words of $2500 on the wrx heads to get the same results as the large port sti heads and still not have AVCS ( which is great for a street car, your primary concern)

#3 Stock VS Stock, a Ver 7/8 sti will take a USDM sti in the ľ mile.
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Old 05-11-2005, 01:15 PM   #19
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USDM STI=Best block? That is laughable..

You people are talking about power bands, etc.. Ok lets see vf30 on a usdm motor, full boost for this example lets say 2500, redline 6800(the turbo is be falling on its face far before then) JDM v7/8 motor vf30 full boost 2800-3k, redline 8200, boost may taper but no where near as hard as the USDM motor.. Seems like quite a big difference in power band to me..

I am not a fan of the usdm sti bottom end at all, and if i wanted any bump in displacement, i would opt for a 2.2 with pistons..

Eby- please show me examples of USDM 2.5's making more on pump then JDM sti motors... I have seen roughly the same numbers off both motors on pump..
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Old 05-11-2005, 01:37 PM   #20
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Well it all depends what you want. We all know the JDM heads are better and the JDM engine has higher quality internals.

That said we also know that the USDM can put out some very nice power on stock internals. How much power are you looking at trying to make?

I think a good setup, as other have said, would be a USDM block and the JDM heads. If you feel like you will be killing the stock internals, piston ring lands, you can also get forged internals from a couple places. Maybe I don't know enough about the USDM 2.5, but that is only major problem I consistantly hear about it. You can buy the bare block from rallispec for little over $800 or get a built block from a couple places. Axis power has a stock 2.5 for $2000 or you can buy forged pistons and rods from crawford performance for use in the stock block.

Price is also a consideration as you can typically get whole JDM drive trains for very good prices. IIRC, there were 3 V7 drive trains being sold in Canada for $8500. You don't typically see USDM drive trains going for sale, or at least I haven't. It's kind of odd considering that we are in the US and the 2.5 is used in 3 cars. You would figure there should be a good supply of inexpensive drive trains floating about. If somebody does know of a good source please let me know.

Apparently the JDM 6 speed is also better in that it has steel forks and better gearing. If you have a USDM 6 speed or a source for a cheap transmission then you could get a conversion kit from rallispec to swap 5th and 6th gears, cost is $340. Iím sure labor on something like that would be very expensive.

Last edited by silentbob343; 05-11-2005 at 02:07 PM.
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Old 05-11-2005, 01:38 PM   #21
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300whp is plenty for 11's. My last Impreza(99 L) was around 250 whp, and it was trapping 112 in the 1/4. That MPH alone is almost enough for 11's with an outstanding launch. I only did a few runs down the track and never got a good run out of it though, mid 12's was my best.

I never argued that the JDM motor isn't stronger for maximum power. In fact, I haven't been following what people have accomplished out of either of the motors for peak power. I don't really care, the US motor is strong enough for the power I want to make, it has a better low end, and it's legal. Simple as that.
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Old 05-11-2005, 01:59 PM   #22
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Both the V8 and USDM STi engines suffer from brittle pistons, strong yes, but not very knock proof. Both have ACVS and great heads. Twin scroll is useless to me, I'll go big and ball bearing when need be. Cyl wall deformation under boost on the semi closed deck hasn't been much of an issue it seems with the USDM.

If I had such a swap to do, it would be a USDM S3L from Crawford. Nice forged pistons and extra displacement.

I know the "USDM is crap" is just ribbing, but it gets old. Look at the blown USDM engines, mostly ring lands. Get some fuel in the ring lands, ignite and shatter. Just the same case with the JDM V8. What IS good about the USDM high silicon pistons, is low expansion under high thermal loads which means possible tighter clearances, less oil usage and a quieter engine (possibly).

EJ series is crap compared to the 4G63
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Old 05-11-2005, 02:14 PM   #23
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Screw the 6 speed. If you want to shift alot and go slow in the 1/4 get a 6mt. If you want to go fast get a non RA 5mt with 4.44. With the higher redline of a JDM engine you can still trap 125mph in 4th, try that with a USDM engine and 6mt.
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Old 05-11-2005, 02:28 PM   #24
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bump for the good info

whats the best set up for a jdm engine (6mt or 5mt)
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Old 05-11-2005, 03:15 PM   #25
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that depends on what you are looking for.
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