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Old 05-25-2004, 10:22 PM   #1
Andursun0013
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Default Balanced Rotating Assembly Opinions

Hi all, I'm looking to finally build my EJ-22t block I have laying around. I'm planning on buying forged pistions that will get my 8.5:1 compression, billet rods (crawford pistons and rods) and using my 98 2.5 crank to get the 2.4l.

Being that my pistons and rods will be pretty well balanced, do you think it would pay to get the crank balanced as well?? Obvious benefits would be a smooth running engine that would be able to rev pretty high, the stock heads probably being the limiting factor on the redline. Any idea how high stock heads can rev??? What other benefits could be had from a fully balanced rotating assembly?? Also, is there a place to just buy a rebuild kit for a subaru (i.e all the bearings and gaskets) and if so would it come with new bolts for the block and head studs?

What kind of bearings and studs is everybody else using?

Thanks
Kyle

Oh yeah, any tips for a first time engine builder I'm pretty nervous about this process, but I want to do it myself. Don't be afraid to tell me what might seem completely obvious to you here, I want to make sure I have everything covered.
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Old 05-25-2004, 11:41 PM   #2
no-coast-punk
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How much power do you want to make? What type of powerband do you want? If you want something reliable with a stratospheric redline, the OEM EJ22t bottom end has been proven to be pretty reliable to an 8000 RPM redline.

The one thing you have to understand about stroking a motor out is that it will increase the sideloading on the cylinder walls. This means that you will not be able to run a very high redline, your piston velocities will also increase pretty dramatically, so this will further hurt your ability for a high redline. If you intend this car to be a straight line creature this is probably the route to take. You will have a peakier motor, but quite a bit of power. The lack of redline will probably put you in the middle of a few in-convenient shift points on tight road/auto-x courses and you'll have a powerband that isn't very great for this type of racing. The additional sideloading will also take quite a bit of life out of the motor before you start getting oil consumption and blow by.

If you are looking at building a motor properly, the crank MUST ABSOLUTELY be balanced to match your new rods and pistons. If you leave the counterweights on the crank (those big pie slice shaped things) alone, the counterweights on the crank will not be able to do it's job because it will be too light/heavy for your rods and pistons and you'll get lots of bearing eating vibration.

You didn't say which heads you were using, but I'm assuming the DOHC because you mentioned the '98 crank. You really don't want to push them much past 6500 RPM's on the stock springs and retainers. If I remember correctly, last time I worked it out, the stock heads stopped being able to flow much past 7000 RPM's or so regardless of cam choice. With the proper springs and retainers, matching the 8000 RPM redline of your bottom end won't be an issue. Definately look into head porting though. On the DOHC heads, cam choice isn't as important as with the SOHC heads, because the most important part of cam selection with forced induction motors is your valve overlap, and this can be adjusted on the DOHC heads. In terms of Aftermarket, COBB makes a cam that is the same duration as the OE cams, just with a higher lift and steeper ramp angle (valve opens and closes faster) however you might have to run some heinously high valve spring rates to keep from floating at high speeds with a cam like that.


As for the gaskets... I believe you can still get re-build parts for the EJ22T's at subaru dealerships, but not for much longer. Barring OEM pieces, cometic gaskets are very good, and so are ARP studs. There has been much debate on the topic of ARP fasteners alot of people swear by the OE Subaru stuff even for high power applications, just depends on personal preference. On the topic of bearings... they're all pretty much the same... My personal preference for bearings are Clevites.

Keep in mind what I said about the stroking/sideloading might be way off because I was going from memory off a chart I saw of rod/crank lengths quite a long time ago. If you can dig up some of these dimensions it would be easy to see what type of sideloading you'd be running up against. Dig up as many numbers as you can about your options and it's easy to show you what they all mean.

Keep in mind, the OEM EJ22t is a VERY incredible piece of engineering. Unless you plan on making over 400+ hp at the wheels, I'd just rebuild the thing to OE specs and be done.
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Old 05-26-2004, 10:16 PM   #3
Andursun0013
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Thanks for the nice reply, It was helpful. Honestly, my power goals are kinda to be determined. For right now...I'm trying for around 300-350 at the wheels but you know how that goes..its fun for now but then you want more. Thats why I just wanna get new pistons and rods, it might be overkill for now but I won't have to redo them over later.

I don't auto-x or anything like that right now, and do make an occasional trip to the dragstrip but most of my driving is on the twisties. After talking with Quirt from Crawfore Performance, I'm confident that 2.4l will be fine. He said that my setup should rev to 8400 RPM's with the proper cams and valvetrain obviously. He has built many many many subaru engines, and I trust his word.

He is sending me a slightly longer rod to use with the 2.5 crank to reduce the sideloading of the stroked engine. I'm pretty excited about the whole idea, it almost seems to good. I just need some big 'ol injectors and save some money for a bigger turbo. Then countless other things before I can crank the boost up that much. With the proper setup I could see 20+ psi daily and the motor not even sneeze at it

Kyle
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Old 05-27-2004, 08:51 PM   #4
no-coast-punk
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I see what you are saying... and I'm still not really seeing any reason for the built motor.... I do 22lbs daily on a bone stock shortblock/heads (dohc), so far the motor has like 30k on it, with no issues, not even a drop of oil consumption. Realisticly, with the strength of the motor you will be getting, 30 lbs daily is a very realistic number while still keeping enough reliablity for the motor to survive a very hard 150,000 miles.
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Old 05-27-2004, 10:58 PM   #5
Andursun0013
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Quote:
Originally posted by no-coast-punk
Realisticly, with the strength of the motor you will be getting, 30 lbs daily is a very realistic number while still keeping enough reliablity for the motor to survive a very hard 150,000 miles.
This is why, that kind of reliability is what i'm looking for. I want something I can learn on, this is my first turbo car, first engine assembly, and first tuning experience. I know the engine assembly can be screwed up just as easy, if not easier but the rest will be more reliable for me. I dont learn that well from reading stuff, I'm a hands on type of person and I don't like paying to have things done. Different strokes for different folks I guess...its worth it to me even tho your perfectly content with what you have

Kyle
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Old 05-28-2004, 12:07 AM   #6
no-coast-punk
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K.... sounds pretty sick, let us know how the build goes, and don't hesitates to ask about any assembly questions (plastigage is your friend).

I'm not trying to discourage you from what you're doing... just making sure you realize what you are getting yourself into, and that you use what you have to it's full potential. There are alot of guys out there that would build a motor like yours, run 15lbs daily and call it good... which is of course alot of wasted effort and money. Keep us updated, and like I said, don't hestitate to ask for help.

Oh yeah... I don't know if you ever checked out my calculator or not... but I seem to remember when I was playing around with it that 30lbs of boost with decent intercooling puts you in the mid-high 500hp range... something to keep in mind in case that viper at the light next to you starts making some growling noises
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Old 05-28-2004, 10:19 AM   #7
worry
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no-coast-punk,

Hi there. I have a couple of queries about your statements above, and I am sure you can help put my mind at rest.

The way I understand it, a stroked ej22t would be less peaky than the standard ej22t geometry?

The longer stroke increases cylinder capacity and improves the mechanical leverage afforded by the crank. The piston speeds increase for the same engine speed and consequently mixture gas velocities increase too. All of these factors will improve the potential for torque production throughout the engines operating range at the expense of having to limit the redline a little to keep average piston speeds within reason.

As I see it, this would make the 2.33l configuration less peaky than the 2.2l. this would make for better driveability and would potentially improve times on autocross tracks and suchlike.

Also, would the piston clearances you need to run on a motor built to handle 30psi boost on a regular basis not lead to accelerated ring/piston/bore wear and thus significantly reduced useful service life?

Cheers,

Worry
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Old 08-25-2004, 09:16 PM   #8
Chase Me
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i'm really sorry to ressurect a dead thread, but this has some very good information and i'm considering building an ej22t and would like to see the reply to worry's latest question
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