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Old 08-25-2004, 08:39 PM   #1
2.5rsDOHC
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Default 2.2l closed deck vs 2.5l STI semi-closed deck

Which would be a better choice the closed deck 2.2l or the 2.5l semi-closed STI shortblock on my98 2.5rs DOHC heads with a TD04 turbo powering it.
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Old 08-25-2004, 08:58 PM   #2
Wedge
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2.5 STi
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Old 08-25-2004, 09:30 PM   #3
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I chose the 2.5L STI (EJ257) for my DOHC, 98 RS Upgrade project. VROOOOM.
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Old 08-25-2004, 09:54 PM   #4
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I would go with the STi, 450-500 hp before it will break, Hell Yeah!
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Old 08-26-2004, 12:22 AM   #5
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Quote:
Originally Posted by impr25rs
I would go with the STi, 450-500 hp before it will break, Hell Yeah!
too bad you'll get a fraction of that with the TD04L.

...but I too vote for the 2.5L. hands down.
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Old 08-26-2004, 12:41 AM   #6
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hmmm, maybe I will be the only one to say 2.2L??? Assuming you can get the 2.2 a bit cheaper...

The 2.2L will end up giving you a better hp/tq ratio than the 2.5L. What I mean is that the 2.5L will generate alot more torque, which will be detrimental to your transmission.

Ive always been more "reliability oriented" ... which in the game of boost is almost impossible...

but lets face it... that .3L isnt gonna really make that much difference... and if im gonna push an engine to its limits, I would rather have a close deck, than an open, or semi open/closed deck...

But really, this is just splitting hairs... at this point, just get whatever you can get a better deal on.

-Jake

(really im not one to talk, im running 12 psi on an open deck block )
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Old 08-26-2004, 01:27 AM   #7
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if you never will build the block I say STI 2.5

if you will build the block in the future... EJ22T 4 life...
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Old 08-26-2004, 02:37 AM   #8
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EJ22T please.

-paK +1
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Old 08-26-2004, 05:04 AM   #9
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Why would you use the TD04? It is too small for the 2.0L.
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Old 08-26-2004, 10:49 AM   #10
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I presume he has a complete WRX take-off. header, crossmember, turbo, etc. but I wholeheartedly agree that the TD04L is too small for either a 2.2 or 2.5 making > 10psi. and I'm not even sure about that 10psi.
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Old 08-26-2004, 01:34 PM   #11
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Yes I know that the TD04 is very small but I practically got one for free and it boosts up to 14psi stock on the wrx thats all I'd ask for with a SAFC2 and J&S safegaurd being the only thing to regulate my engine management, I just cant bring my self to shell out $700 or more on a stand alone ecu.
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Old 08-27-2004, 04:17 AM   #12
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I think at this point both the Ej22-T and the EJ257 motors have proven themselves to be very potent powerplants.

If I can just point out a few differences. Being that the EJ22-T motor is only a 2.2L, versus the 2.5L, you have a higher threshold for revving the Ej22-T than you do with the EJ257. Lighter internal components, such as the pistons and rods, will allow you increased redline over the EJ257.

I am currently running the EJ257 in my RS, with a large Presision SC34 turbo. However, right now my redline is set to about 6900 RPM, whereas with the proper accompanying components, the EJ22-T could be taken higher without any fear of problems occurring (head work also has much to do with your rev capability, but in this sense we are discussing purely block issues).

This is not to say that the EJ257 has its limit at 7000 RPM, but most of the people running this motor as a swap or from the factory do not seem to be taking it much past the 7000 limit. Most of your smaller displacement guys (i.e. 2.0L and 2.2L) are running their motors with substantially higher rev limits, maybe upwards of 7500-8500 RPM.

Other than that, the fact is the EJ257 will be much more driveable around town. We are American's, and we love torque. The EJ257 produces lots of it, and you don't always have to be producing positive pressure to accelerate quickly. Of course, some of this has to do with what turbo you choose. If you stick with the TD04, which I DO NOT recommend if you choose either the EJ257 or the EJ22-T (both can make upwards of 400 BHP without any problems) as it is way undersized for making good power, then spoolup will not be a big problem.

Graham
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Old 08-27-2004, 09:06 AM   #13
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Closed deck EJ22T.
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Old 08-27-2004, 09:15 AM   #14
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Well, if you want torque, and a closed deck engine, build a 2.3L stroker.

Use JUST the phase I EJ25E crankshaft in a 2.2, (forged, yay!) will bump up the disp. to 2.3L and will have a longer stroke on it (79mm vs 75mm). After all, a 2.5L is just an overbored and stroked 2.2L. (which is why I think the first 2.5 had so much head problems... the overbore part)

If you ran the 2.2L like that with some EJ257 (or whichever DOHC 2.5L heads would work for you) you'd have the benefit of good flowing heads, and of course, a bigger dish in the heads vs. the 2.2 heads, which in turn lowers the comp. a bit. (good)

I figured out... an EJ20G stock, but with the EJ25 crank, and EJ25 DOHC (like yours) heads would be about 8.81:1 CR and of course now have a stroke of 79mm versus the 75 with the EJ18/20/22 series crank. Good for torque. But ever mm you increase in the crank's throw is one more mm adding itself to every rpm and in turn increasing the distance travelled by the piston. Every type of piston material has a different amount of distance/time measurement that it can withstand... so of course with everything else beign able to handle it, changing piston material allows you to increase your rpm... or of course, if your piston isn't the downfall, going with a shim under bucket kit and high pressure valve kit... ect. would rock.

</rant>
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Old 08-27-2004, 12:29 PM   #15
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just to add something to Graham talks..

I just completed my Ej22T buildup, and it's pretty torquey at low-revs off-boost. Nothing to compare with the 2.0l. At only 6psi i had a 14.68 1/4mile time with 97.8mph (launching very smoothly).

I'll do a post on my buildup and some details, it might be of interest.
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Old 08-27-2004, 12:32 PM   #16
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Quote:
Originally Posted by JonofScio
Use JUST the phase I EJ25E crankshaft in a 2.2, (forged, yay!) will bump up the disp. to 2.3L and will have a longer stroke on it (79mm vs 75mm). After all, a 2.5L is just an overbored and stroked 2.2L. (which is why I think the first 2.5 had so much head problems... the overbore part)
You'll have to get some custom pistons to do that, else the pistons will raise out of the block by 2.25mm ... conscidering the gasket is 1.51mm thick, you'll end up with big problems. (And we just experienced that last week, when a machine-shop mistakenly swapped our 2.2l crank with 2.5l crank... we discovered the prob after reassembling the shortlock )
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Old 08-27-2004, 12:43 PM   #17
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This 2.2l keeps sounding better especially with the EJ25 phase1 crank in it but has anyone actually done this before, what type of clearance issues would I be looking at. The only thing that makes me want to get the EJ257 is all the forged internals crank, rods, pistons does the EJ22T have any forged internals? How much is everyone paying for there EJ22T shortblock?
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Old 08-27-2004, 01:18 PM   #18
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The EJ257 does not have any forged internals.

It's the EJ22T the one that brings crank/rods, factory forged.
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Old 08-27-2004, 02:01 PM   #19
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Quote:
Originally Posted by Wedge
The EJ257 does not have any forged internals.
iirc, only the pistons are not forged in an EJ257. they are hyperutectic.
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Old 08-27-2004, 02:34 PM   #20
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My question is what is your budget for the block? How much power do you really want to make? Even a used STI shortblock is going to cost you some amount of money. Brand new they are the same price, which was raised about a month ago to around $1700. Used to be able to get them for around $1300. You can get a junkyard EJ22T and then spend the money on some new parts (pistons, rod bearings maybe).

For ultimate power and high (25+ psi) boost, a built EJ22T is going to be a better option.

The EJ257 has forged rods and a forged crank, the pistons are not forged, they are hyperutectic. The EJ257 off the shelf is probably going to be better than an off the shelf EJ22T even at moderate levels. The things it has going for it are possibly piston squirters and of course the fact it's closed deck. Most people do not use the stock EJ22T pistons though.

For a 300-350hp car I would never choose the EJ22T over the EJ257.
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Old 08-27-2004, 03:39 PM   #21
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does anyone know what the compression ratio would be on a 98rs DOHC heads with P&P on a EJ22t shortblock?
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Old 08-27-2004, 05:32 PM   #22
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Quote:
Originally Posted by 2.5rsDOHC
This 2.2l keeps sounding better especially with the EJ25 phase1 crank in it but has anyone actually done this before, what type of clearance issues would I be looking at.
Answer :
Quote:
Originally Posted by morgie
You'll have to get some custom pistons to do that, else the pistons will raise out of the block by 2.25mm ... conscidering the gasket is 1.51mm thick, you'll end up with big problems. (And we just experienced that last week, when a machine-shop mistakenly swapped our 2.2l crank with 2.5l crank... we discovered the prob after reassembling the shortlock )


Quote:
Originally Posted by 2.5rsDOHC
does anyone know what the compression ratio would be on a 98rs DOHC heads with P&P on a EJ22t shortblock?
around 7.3:1
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Old 08-27-2004, 08:14 PM   #23
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Quote:
Originally Posted by 2.5rsDOHC
Yes I know that the TD04 is very small but I practically got one for free and it boosts up to 14psi stock on the wrx thats all I'd ask for with a SAFC2 and J&S safegaurd being the only thing to regulate my engine management, I just cant bring my self to shell out $700 or more on a stand alone ecu.
If you're not willing to spend the money for your engine management, I don't think you'd want to go on with this project, whether you go for the ej22 or 2.5.
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Old 08-27-2004, 08:24 PM   #24
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Well what is your goal?

I have a 98RS with a 2.2T shortblock, and rallispec turbo kit@ 10psi its faster than a stock WRX, high 13s, just under 100 mph.

I can tell you that you wont be able to run much more than 11psi without a standalone.

I use an SAFC and J&S and with no control over timing, @ high RPMS, full boost, WOT, the egts get quite high at 11psi. I tried 14psi...and well yea...not a good Idea without timing control

If you never plan on getting EM, go with the ej257 and run lower boost on the smaller turbo, it will work better with the 6500 rpm redline you will be stuck with.

If you plan to eventually get EM, get th 2.2T cause once you get a standalone properly tuned the 2.2T can handle 20+ psi in stock form..

just my 2 cents.

my RS feels like an RS off boost, low end torque is there, but not being able to run to 7k, chokes the performance. But I plan to get EM in the near future.

my compression ratio is roughly 7.5:1 - 7.8:1 Heads where machinced when motor was assmbled so my comp ratio is slightly higher.

Jay
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Old 08-28-2004, 04:36 AM   #25
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I have just found a 93 legacy2.2 Turbo with 40k at the same place where my car is at with a spun rod bearing downside is having to wait till monday to to check it out, as for my decision the2.2T is definitly going to be my choice of block after compareing the two, I belive I'll be much happier in the end with the closed deck as for engine management im going to use the dastek unichip and shouldn't have to much trouble spooling up to 14psi(TD04)untill I can afford a fmI/C and a larger hampster wheel.

justin

btw...
McDade could you send me a list of mods to your car if you dont mind or at least tell me if you are using phase1DOHC heads off your 98 2.5rs & what type of head gasket?
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