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Old 11-30-2012, 01:58 AM   #1
subiedrivaa
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Default Built EJ205 vs OEM EJ207??

Which would be a better route?
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Old 11-30-2012, 02:25 AM   #2
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This must be one of the most vague threads ever.
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Old 11-30-2012, 02:43 AM   #3
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207 for any reasonable amount of street level power. AVCS > anything an EJ205 can offer.

At the power levels you need a built engine vs. OEM EJ207, low end torque / lag becomes a serious issue, and you want AVCS even more.
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Old 11-30-2012, 03:15 AM   #4
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What do you want out of the setup?
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Old 11-30-2012, 10:31 AM   #5
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You will never beat the 207 heads, even with a great port and polish job on the 205 AVCS will make all the difference.
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Old 11-30-2012, 11:06 AM   #6
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By the time you build a ej205 up to be the same level of a ej207 you will have spent just as much if not more, unless you can do 100% of the labor yourself. Even then your looking at a solid week of tearing it all down and rebuilding it, and if your doing it yourself thats a week you could have done a ton to better the ej207

An out of the box ej207 even with 75k+ miles on it will be far more reliable then a ej205 thats been split and rebuilt with all the trimmings. The ej207 is just a better all around bottom end in terms of factory balancing, hence the +8200rpm red line. With a full spring/valve/ect head rebuild its a scooch over 9k rmp, and still mechanically reliable. The 207 breaths better and not just due to the AVCS. If you look down into the intake side of the heads the heads are a totally different casting and there are significant changes to flow direction, and just how "factory" smoother the runners are. There usually is a 20-25% increase in power on the same setup between a 205 vs 207 and the torque curve and HP are much further to the left on an ej207 in the same setup as a ej205.

If you have the money to build an ej205 or buy a ej207 no question about it. The ej207 is hands down the better platform to start with.
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Old 11-30-2012, 11:07 AM   #7
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If i were to get an EJ207 shortblock. Would using ej205 heads, intake, etc. be inefficient?
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Old 11-30-2012, 11:55 AM   #8
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In my opinion:

EJ205 < EJ207 < EJ205 2.1 stroker with v7/v8 heads with a mild cam < EJ207 2.1 stroker with v7/v8 heads with a mild cam

I didn't have an ej207 case available when I did mine but I did have good ej207 heads with Tomei's 256/264 AVCS cams and so I had working AVCS. The powerband and feel was awesome, went to 8k rpm multiple times every day and was trapping nearly 130 on an 8cm HTA Green on 100 octane.

I absolutely loved that engine and boy did it put up with some stupidity... 30-32 psi on a 93mm piston as my daily driven 100 octane tune.
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Old 11-30-2012, 12:01 PM   #9
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The EJ207 is a much better bottom end.

Inefficient .....?? The issue is your not comparing apples to apples.

-The ej207 heads will flow better even with out the AVCS working.
-Buying an ej207 short block and then swapping ( I assume your current ej205 heads ) heads will cost nearly as much. You will need head gaskets and for piece of mind a full timing kit. For that $500+ in parts and the cost of your 205 heads you could have gone to the ej207 long block.

Id figure a used under 50k if not near new EJ207 Longblock should run you $3000 shipped. A full ej207 Long block with all the other bits, basically ready to drop in $4000+, thats TMIC all the accessory's timed with exhaust manifold UP and maybe vf36 or vf37 turbo.

If your asking these questions because of money, then STOP. If you only have $1000-2000 the EJ207 is out of your reach, at best you can get a 207 bottom end and swap all your parts onto it. It will be a better platform then the 205, but with out the heads and the ECU to run them, your better off just tossing a used USDM WRX motor in and saving your penny's till you have the funds to do it right. There are other factors and parts and a retune you will have to pay for to get it all running. Yes!?! a retune if you go JDM AVCS ECU ( and you have to, to run the heads ) because of the high octane the car is normally runs on from the factory in Japan/AU, and its not the same as a USDM 04+ STI AVCS system, in terms of ecu talking to all the sensors.

Do some more research, in the guise that you are going full EJ207 long block with ECU and tune. Then you get a idea of what its going to cost.
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Old 11-30-2012, 12:47 PM   #10
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Quote:
Originally Posted by subiedrivaa View Post
If i were to get an EJ207 shortblock. Would using ej205 heads, intake, etc. be inefficient?

The heads are why people want a 207. AVCS means you get significantly more torque off boost and a wider powerband.

A 207 shortblock is better than an unbuilt 205 shortblock, but will require re-tuning for the different squish volume and will not give the low end torque that the AVCS on the 207 heads offer or the top end flow that the big port heads give.

The main differences in the block itself is the crank has slightly better oiling than the 02-03 EJ205 (but same as 04-05 as I recall), and the rods are beefier. From a butt-dyno standpoint, you're not going to notice any difference between the two unless you exceed the limit of the 205 rods... and EJ205 heads + turbo that exceeds the limit of 205 rods = no low end torque and not enough redline to make use of the big turbo, so you end up with a super lame powerband. In other words, I don't think it really provides anything useful to have a stock EJ207 SB instead of a stock EJ205 SB if you're using stock EJ205 heads. And building EJ205 heads to the point that they outflow stock EJ207 heads costs almost as much as a full EJ207 swap (cams + valve job + porting)... and you still don't get the extra off-boost and low end from the AVCS.
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Old 11-30-2012, 12:58 PM   #11
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Quote:
Originally Posted by Concillian View Post
The heads are why people want a 207. AVCS means you get significantly more torque off boost and a wider powerband.

A 207 shortblock is better than an unbuilt 205 shortblock, but will require re-tuning for the different squish volume and will not give the low end torque that the AVCS on the 207 heads offer or the top end flow that the big port heads give.

The main differences in the block itself is the crank has slightly better oiling than the 02-03 EJ205 (but same as 04-05 as I recall), and the rods are beefier. From a butt-dyno standpoint, you're not going to notice any difference between the two unless you exceed the limit of the 205 rods... and EJ205 heads + turbo that exceeds the limit of 205 rods = no low end torque and not enough redline to make use of the big turbo, so you end up with a super lame powerband. In other words, I don't think it really provides anything useful to have a stock EJ207 SB instead of a stock EJ205 SB if you're using stock EJ205 heads. And building EJ205 heads to the point that they outflow stock EJ207 heads costs almost as much as a full EJ207 swap (cams + valve job + porting)... and you still don't get the extra off-boost and low end from the AVCS.
The 207 has the semi closed deck cylinder supports like the 2.5s do without the bolt relief problems.

Edit:
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Old 12-01-2012, 01:19 AM   #12
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While true, it doesn't really matter since the 2.0L open deck sleeves will pretty much hold as much boost as you'd want to throw at it on a street car.

Back when there were really only 2.0L turbo engines and none in America, the Aussies were pushing massive boost through the 2.0L open deck blocks. 2.5L cylinders split even when semi-closed, but 2.0L open deck will hold boost more reliably. 2.0L semi-closed is overkill in most cases, but of course it doesn't hurt to have the added supports.

The OP never mentioned power levels, but it doesn't sound like he's talking about building a 500+ HP engine.
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Old 12-01-2012, 02:45 AM   #13
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Quote:
Originally Posted by Concillian View Post
While true, it doesn't really matter since the 2.0L open deck sleeves will pretty much hold as much boost as you'd want to throw at it on a street car.

Back when there were really only 2.0L turbo engines and none in America, the Aussies were pushing massive boost through the 2.0L open deck blocks. 2.5L cylinders split even when semi-closed, but 2.0L open deck will hold boost more reliably. 2.0L semi-closed is overkill in most cases, but of course it doesn't hurt to have the added supports.

The OP never mentioned power levels, but it doesn't sound like he's talking about building a 500+ HP engine.
Correct me if I'm wrong. But isn't the issue with open deck ej20 blocks that the top of the sleeve will flex/walk around at high power levels? I always thought the sleeves were plenty tough as far as splitting goes, they just added the extra metal in the semi closed blocks keep the top of the sleeves/bores aligned correctly?

My machinist added extra pieces of alloy to "semi close" my ej205 block when we rebuilt it.
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Old 12-02-2012, 08:10 AM   #14
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I've had a ej207 bottom end with ej205 heads. It was ok, certainly not great. The rpm was fun to play with. I absolutely 120% enjoyed my ej257 short block with my ej205 heads more. Both set ups had BC 272 cams, as well as extensive pnp work. The extra displacement of the 2.5 makes for a drastically more fun car, particularly on a largeish (for a Subaru anyway) turbo (50+ lb/min). Granted, I didn't run avcs on any setup, but adding avcs to the 2.5 would just make it that much better.

My vote, 2.5.
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Old 12-03-2012, 11:35 AM   #15
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Originally Posted by rexblake View Post
I've had a ej207 bottom end with ej205 heads. It was ok, certainly not great. The rpm was fun to play with. I absolutely 120% enjoyed my ej257 short block with my ej205 heads more. Both set ups had BC 272 cams, as well as extensive pnp work. The extra displacement of the 2.5 makes for a drastically more fun car, particularly on a largeish (for a Subaru anyway) turbo (50+ lb/min). Granted, I didn't run avcs on any setup, but adding avcs to the 2.5 would just make it that much better.

My vote, 2.5.
Yes! I'm thinking the 2.5 swap as well.
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Old 12-03-2012, 11:49 AM   #16
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Until the pistons break...
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Old 12-03-2012, 12:24 PM   #17
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The best setup would be a built 2.5 bottom end with v8 JDM STi AVCS heads that are machined for the 2.5L cylinder bore.
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Old 12-03-2012, 03:46 PM   #18
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Or a 2.1 stroker built with an EJ207 block and then the EJ207 heads. Not a torquey as the 2.5, but very rev happy and great driveability characteristics. My tuner has worked on hundreds of setups and cars and still says the 2.1 stroker was is favorite/most impressive to date. I think that says something.

Too many great setups, too little time and money.
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Old 12-03-2012, 03:50 PM   #19
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Quote:
Originally Posted by dangerousatom View Post
The best setup would be a built 2.5 bottom end with v8 JDM STi AVCS heads that are machined for the 2.5L cylinder bore.

I take that back....a full closed deck rebuilt 2.2 turbo bottom end


Quote:
Originally Posted by kpluiten View Post
Or a 2.1 stroker built with an EJ207 block and then the EJ207 heads. Not a torquey as the 2.5, but very rev happy and great driveability characteristics. My tuner has worked on hundreds of setups and cars and still says the 2.1 stroker was is favorite/most impressive to date. I think that says something.

Too many great setups, too little time and money.
......So true
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