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Old 02-24-2007, 06:13 PM   #1
2slofouru
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Default new ej22t closed deck shortblock or new 2.5 sti shortblock?

I am trying to decide on a new shortblock, one that will be durable through my process of upgrades, up until I get things running smoothly. My car is a 95 with obd1 and the ecu isn't very smart. It is running a 2.5 with 1.8 parameters. I want to start with these components and use my emanage and possibly a rrfpr to start:
-98 2.5 dohc heads
-stock 06 wrx turbo and tmic
-stock 06 wrx down and uppipes
-98 2.5 intake manifold?

I am sure the engine will run fairly well as long as the heads are compatible with either block. The ej22t shortblock with all gaskets is actually more expensive than the ej25 sti shortblock with all gaskets. Is the ej22t actually more desirable? I realize it is closed deck and may be helpful running higher boost, but starting out with .3liters more is already a plus, and aren't the 2.5 sti internals manufactured to better tolerances? Just trying to get things together.
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Old 02-24-2007, 06:21 PM   #2
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go with the 257 (sti shortblock) and install some better pistons before install... your right the extra displacement will help
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Old 02-24-2007, 06:36 PM   #3
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Originally Posted by Got Boost? View Post
... your right the extra displacement will help

rriiggghht, a whole .3 liters. it's been shown time and time again that the 2.0 liter can make just as much power as the 2.5. Just look at Rigoli's setup.
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Old 02-24-2007, 10:14 PM   #4
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the 2.5 is capable of 400hp easily. get a new shortblock. not a 13+year old (new) shorty. even tho your OBD1(dosen't matter really).

and the extra displacement WILL help regardless of what some people think. especially when you up the boost, or get a bigger snail.

ditch the old, go with the gold!

i have a JDM STI swapped L. and i wish it was as driveable in the low RPM's as the 2.5's are. if i toast my shorty, thats what i will do.

--keith
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Old 02-24-2007, 10:27 PM   #5
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Go for the 2.5

Odds are you'll never push the 40lbs or so of boost that would warrant a fully closed block.

The extra displacement WILL help in all situations. The only reason not to go with more displacement is if you cant afford it.


(and sure, rigoli can make ****loads of power out of a 2.0... but they do it at 10,000rpm, which you will never see)
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Old 02-24-2007, 11:17 PM   #6
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Quote:
Originally Posted by tooocool49723 View Post
Go for the 2.5
The only reason not to go with more displacement is if you cant afford it.

So by those standards we should all be using H6's. Man those honda guys are screwed i guess.
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Old 02-24-2007, 11:48 PM   #7
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build a used ej22t with forged internals. You can even use a 2.5L crank and have 2.35L closed deck with piston squirters. Your goals will always change. Better to over build now.
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Old 02-24-2007, 11:51 PM   #8
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the point i am trying to make is that displacement isnt the main thing. the reason why the ej22t doesnt make as much low end is because it has a lower compression ratio. displacement isnt much in our forced induction world. You can make just as much power with a 1.5 liter as you can with a 2.5. just as long as you build it right.
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Old 02-25-2007, 01:21 AM   #9
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funny to see 2.5 people acting like domestic owners.. hell even a 1.8T L made power.. that .3 liters will make very minimal gain to the point were it gets irrelevant(maybe a lil drivability differences) but to say the 2.5 is god and its always better is just ignorant. 2.2's can make as much power as 2.5's. if you wanted tq.. then u shouldnt be driving a subaru..
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Old 02-25-2007, 02:30 AM   #10
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Quote:
Originally Posted by xtian View Post
if you wanted tq.. then u shouldnt be driving a subaru..
Well, in all fairness, I guess that depends on what you consider a lot of torque.


OP: depends on what you want.
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Old 02-25-2007, 02:36 AM   #11
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from what I've read and seen in the subaru shop I worked at the internals on the 2.2t are stronger. Not only that but since there is less stroke there is also less stress on the reciprocating assembly. Either way you go you'll want to replace the pistons as I believe they are cast aluminum in both cases. I'm not sure the price but you could consider getting a crawford closed deck 2.5 if you want something bombproof, well bomb resistant. I have seen a 2.5 block with 25psi crack a cylinder because of stress on the open block.
the big question is are you going to have enough power for it to matter either way?unless it's a drag car I personally wouldn't want more than 300whp, but then again I'm cheap and like my stuff to last and be streetable.
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Old 02-25-2007, 06:06 AM   #12
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Get the ej257 block. It is GOD! I actually went from the ej22t to the ej257 short block on a stock head setup with a gt35r. Since it's my daily driver and has been for a while now, I have noticed quite the difference in drivability with the larger motor. Off boost torque is much better. In boost it is hard to notice a ton of difference but the extra displacement still makes a little difference.

i have done many many many four cylinder high horsepower engines and by car more displacement is always better if you plan on driving the motor. To make smaller displacement perform you have to rev the hell out of it. The down fall of Subarus is there crappy heads. Even built heads don't flow like an EVO or MR2 turbo. for smooth high revs you probably don't want the ej257 if you plan to build everything and race it. The ej22t motor with built wrx heads seems to be a good match. It makes for a nice smooth motor not the american STI style of driving.
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Old 02-25-2007, 10:21 AM   #13
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I don't think anyone has ever said anything bad about Subaru heads accept for the older 2.2 turbo heads found on the old turbo legacy.

Ive done a lot of research, comparison, and made the choice to fully build a 2.2t motor. My shortblock is finished and has a 2.5 Phase I crank, Pauter Phase I 2.5 Rods, and Wiseco .030 over pistons. It should be a stout 2.4 thats capable of withstanding 9000 rpm and well over 500 hp.

To be totally honest it was a very close decision between the STi 2.5 and the 2.2. The determining factor was that my goal is above 500hp and revs over 8000 rpm. If I was shooting for around the 450-500hp range I would have hands down gone for the 2.5.

Its way cheaper, easier, and less hastle to use the 2.5sti block which is fully capable of 450-500hp without touching the internals. The 2.5 block will cost you about $1500. I found a great deal on my 2.2 shortblock ($500 for the complete motor) but after the motor work and build parts its costing me $2200. Still a great deal when compared to the Axis line of shortblocks. I think a comparable motor setup to mine started at $4500 and went up from there.

If your curious my heads are Phase I 2.5 DOHC heads with TWE Stage III Cams, and their Shim Under Bucket kit that includes stiffer springs and titanium retainers. I'm going to see how this setup does without a valve job or port and polish. I really wanted to preserve as much low end response as I could while still reaching for big numbers up top.

When I get the motor together and my Legacy this Spring/Summer we'll see how it does.

What are your [realistic] power goals and what are you planning to [realistically] use the car for?

Brad
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Old 02-25-2007, 10:30 AM   #14
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257 sucks get the ej22t if its new, and if its not get it anyway and swap in new pistons, cheaper then a 257 and better for revs. .3 liters wont make a difference.
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Old 02-25-2007, 10:34 AM   #15
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Quote:
Originally Posted by Got Boost? View Post
go with the 257 (sti shortblock) and install some better pistons before install... your right the extra displacement will help
the extra displacement and low end grunt from the stroke will be appreciated a lot more unless you are making a high revving boost fed machine
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Old 02-25-2007, 10:35 AM   #16
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im rocking my 2.2 for a while longer and then I too will be getting a sti crank and pistons w/ correct pin offset for a stroker engine. I couldn't do that w/ a 2.5. And I'll take the stroke and revability over a 2.5 anyday.

I think Brad pretty much nailed it w/ his post.
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Old 02-25-2007, 11:18 AM   #17
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While it's true that you can make power with small displacement motors, there's some interesting math involved.

Power is produced by many things, but three major ones are:
-Displacement
-Boost
-Revs

You can replace one with the other, but you have to make compromises. Once you max out boost, you have to start looking at the others. High revs get quickly diminishing returns since it's harder & harder to get each additional 1k rpm... the stresses on the motor mount quickly.

Displacement is amazing. I have a spreadsheet that takes a bunch of variables, the above three, plus volumetric efficiency, fuel used, etc., and calculates potential horsepower. It's amazing what displacement does to the equation. That's why you can easily get 1000hp out of a boosted small block chevy.

Anyway, I'd start with reasonable displacement and then go for strength, boost and RPMs. In my case, I had a used EJ22T bored & sleeved to 2.5L with an RPM capability of 8,000. Lots of potential.

However, it can get pricey to do this sort of work, so if budget is a factor and your future goals don't reach much more than 450whp, starting with an STi block is just fine.

Russ
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Old 02-25-2007, 11:55 AM   #18
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Quote:
Originally Posted by rlavalle View Post
.

Power is produced by many things, but three major ones are:
-Displacement
-Boost
-Revs

Russ

I could have a ****load of displacement but without compression you're out of luck. You take an ej22t and step the compression up and it will have the low end that you want. There is a lot involved. First you have to look at the turbo you're using. If the turbo is say a twin scroll gt40r, I'd raise the CR a bit because you KNOW that the low end is gonna suck due to being off boost for so long. There are too many factors here to consider. .3 liters isnt going to give you that much of a difference unless your CR is also higher. btw....a chevy 350 is equal to 5.73 liters and they tend to be higher compression engines, my best friend has a 13.8:1 block in his monte carlo right no. Thats why they can make 1000hp easily, not just the displacement. You can't talk about one thing in a motor being the "draw back" without talking about everything else involved.
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Old 02-25-2007, 12:52 PM   #19
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As I said, there are compromises... Boost is similar to compression in that it gets more air into a designated space. You add compression, you get low end torque, but lose the amount of boost you can build and ultimate power. You can also raise the compression of a 2.5L block if you want.

High compression is why a Small Block Chevy can make 1000hp so easily?! Nope.
A turbo Chevy Small Block will certainly not have anything near 13.8 compression. You know they'd build it for a turbo, with much lower compression. In addition to little turbo motors, I'm also a big V8 kinda guy and subscribe to Hot Rod Magazine. They recently had an article on a daily driven 1000hp Small Block. Compression Ratio? 8.96:1.

Some folks like the JDM 2L motors for they're revability. If that's what you're into, more power to you. However, I wouldn't choose low displacement when there's not really a drawback to more. I guess gas mileage would be one. On the other hand, you gain quicker spool, more torque and more potential power, all else being somewhat equal.

Inaccurate example, but actual case: A buddy of mine had his 2.0L w/GT30R tuned by the same shop that tuned my 2.5L FP Green. He made the same power as I did at a higher RPM. A GT30R should have made 50hp more. Granted, there are a lot of variables there, but that's still quite a difference.

If anyone is interested in playing with numbers, the spreadsheet is located here:
Turbo Selection Spreadsheet.
It's built from equations found in the turbo info section of Garret's web site.
Yellow cells are parameters you can adjust depending on your motor needs.
Gray cells are less commonly adjusted parameters for innate motor characteristics.
Green cells are results.

Notice when you change the displacement, how the required boost changes. Example: At 8000rpm, a 2.2 Liter requires 33.1psi for 550hp. A 2.5 liter motor requires 27.3psi. Pretty significant.
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Old 02-25-2007, 02:21 PM   #20
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I never said high compression was the whole reason that they can achieve 1000hp and ive seen supercharged guys still running upawrds of 10:1. They have 5.7 liters or more, which is well over twice the displacement of a ej25.
So if you do the math. 5.7 small black is 3.2 liters more than an ej25. ej25 is .3 liters greater than the ej22. There's a huuuuuge difference.

2slofouru just go for whatever you think will be best for you. and by that i mean financially and also reliability. You can build great power and have good driveability with either block. One option for the ej22t is the stroker motor if you're looking for more torque. It all depends on if this is going to be a daily driver, a track car or whatnot.
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Old 02-25-2007, 10:50 PM   #21
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Quote:
Originally Posted by rlavalle View Post
They recently had an article on a daily driven 1000hp Small Block. Compression Ratio? 8.96:1...

...However, I wouldn't choose low displacement when there's not really a drawback to more. I guess gas mileage would be one.
.

ok so I'm also a big v8 fan and I found a couple things not exactly true. In most cases a larger motor, all else being equal most importantly hp#, will get better gas mileage. Also 8.96:1 seems to me pretty "high", at least for a 1000hp turbo small block, as they ran 8.5 without forced induction through most of the 70's and 80's from the factory.

One thing to improve low end response and torque is to have the seat cut at a lower angle. In a SBC stock valve seat angle is 45deg, if you lower this to 30deg at .050' lift the seat will be open .008" more. Doesn't seem like much but really makes a noticeable difference. Remember, all good engine builders agree that the most important detail to making power in an engine is cylinder head flow. So don't ponder too long on the block choice.

Ok now a question...anyone use the 2.2 crank in a 2.5 block? I've always liked big bore/small stroke combos as there is better revability with less valve shrouding.
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Old 02-26-2007, 12:31 AM   #22
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The whole point is moot anyway- there are no longer any new ej22t blocks available.
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Old 02-26-2007, 01:27 AM   #23
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Quote:
Originally Posted by stormsubaru View Post
Remember, all good engine builders agree that the most important detail to making power in an engine is cylinder head flow. So don't ponder too long on the block choice.
That makes for a nice quote.
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Old 02-26-2007, 02:21 AM   #24
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Quote:
Originally Posted by Drac9 View Post
The whole point is moot anyway- there are no longer any new ej22t blocks available.

/\Go to subaruproparts.com.


To everyone else, thanks for the replies. I am still as confused as ever but will eventually piece it together with your help. I understand the low end torque thing, I've had three turbo 280zx's and the low end torque was great, partly because of the inline six and 2.8 liter displacement. Ultimately overall horsepower is my goal, whether it takes higher rpms to get it isn't important to me, as long as I can mod my ecu for it, but that will surely add a lot to the cost of the project, and complicate tuning even more with my lame ecu. If I didn't live in the swamp, I'd get a used ej22t engine and do some upgrade work in the piston department and maybe overbore it to around 2.4, but the local builders are all domesticated. It would probably be an equally good idea to buy a used ej22t and upgrade pistons and displacement a little or buy a 2.5sti shorblock new, as far as cost is concerned in the long run. Wow, brain is smoking now..
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Old 02-26-2007, 03:03 AM   #25
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Quote:
Originally Posted by stormsubaru View Post
ok so I'm also a big v8 fan and I found a couple things not exactly true. In most cases a larger motor, all else being equal most importantly hp#, will get better gas mileage. Also 8.96:1 seems to me pretty "high", at least for a 1000hp turbo small block, as they ran 8.5 without forced induction through most of the 70's and 80's from the factory.

One thing to improve low end response and torque is to have the seat cut at a lower angle. In a SBC stock valve seat angle is 45deg, if you lower this to 30deg at .050' lift the seat will be open .008" more. Doesn't seem like much but really makes a noticeable difference. Remember, all good engine builders agree that the most important detail to making power in an engine is cylinder head flow. So don't ponder too long on the block choice.

Ok now a question...anyone use the 2.2 crank in a 2.5 block? I've always liked big bore/small stroke combos as there is better revability with less valve shrouding.
I beg to differ on a couple points here... A bigger motor may get better mileage than a smaller, horsepower being equal, if they are normally aspirated. You probably weren't talking about turbo motors though. The reason I say a smaller [turbo] motor will get better mileage, is because most of the time, you're off boost. A smaller motor cruising at 60mph will get better mileage than a big one in the same car cruising at 60. Once you open her up, all bets are off of course.

8.96 CR isn't that high for a 6.5 liter motor making 1000hp. Using the spreadsheet I posted the link to, you'd see that the car would need about 15lbs of boost to get there at 7000rpm... pretty mild and easily handled with a 9:1 CR. And besides... you can't really think of Power and the cars of the 70's and 80's together... those were the dead years and they were striving for economy. Look a bit earlier... to the 60's for motors with high compression ratios.

Regarding the availability of EJ22T's... there were quite a few early 90's Turbo Legacy's made... so lots used motors out there. That's where mine came from.
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