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Old 02-26-2010, 04:15 AM   #1
Audioexcels
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Default Best stock pistons produced in USDM/JDM engines and Comparison to Aftermarket pistons

Seeing so many USDM EJ257 blocks on the market with bad ringlands, I found this post by Clark (some I cut out to keep things simpler) to be interesting about the stock pistons used in various newer USDM and JDM engines:

"The old version 7 JDM pistons where very strong. The trouble with this is that the forged pistons expand alot at high temps. Cant run them with more clearance because the cold start emissions would be to high.

The Hyper cast piston can run tight and has very little blow by. So little that it was common for me to find V8 STI motors with 0! leak down.. NONE. Since they where small 2.0 pistons they where stronge enough.

The US 2.0 WRX was much lower power and the pistons being small where plenty strong. The rods are weaker then the pistons in the 205 engine.

When the US sti solution was the EJ257. They kept the Same Hyper cast style piston. Since this motor is stretched beyond its design limits (in my opinion) they ended up with a weak piston."

He proceeds on explaining how some of the mid-latter 04's had the better quality pistons which only became worst as the years went on.


My question deals with an attempt to compare what Clark is saying with the older Subaru blocks and the stock pistons (will get to aftermarket pistons later) in them vs. the ones found in the newer engines, particularly the 2.0 and 2.2's.

QUESTION:

Starting from old to new, how are the pistons in the engines listed below compared to those found in the V7/V8 and the USDM WRX? In other words, how would you rank the pistons in the blocks listed below vs. the ones found in the V7/V8 and USDM WRX engines and why?

1) EJ22 NA
2) EJ22T
3) VER1/VER2 WRX Pistons
4) VER1/VER2 STI Pistons
5) VER3/VER4 WRX Pistons
6) VER3/VER4 STI Pistons
7) EJ22 99+ NA Pistons


Question 2 deals with aftermarket pistons and use of them on older Suby blocks:

1) At what power level does one want to consider forged pistons and why?

2) What would make a forged piston more capable than a stock piston if one is using standard bore pistons and not using customized pistons for a custom/specific build?

3) Would an aftermarket piston still be considered an upgrade over the very best stock pistons Subaru used, those in the Ver8 included?


Thanks for your opinions on this subject!
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Old 02-26-2010, 10:07 AM   #2
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Since I've got some experience with all these pistons (had them all at hand at some stage in the past), I'll go first:

1) EJ22 NA - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
2) EJ22T - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
3) VER1/VER2 WRX Pistons - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
4) VER1/VER2 STI Pistons - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
5) VER3/VER4 WRX Pistons - short slipper skirt, skirts prone to breaking, not so good for high boost (about the same as USDM WRX pistons)
6) VER3/VER4 STI Pistons - forged but short slipper skirt, piston slap common, light so good for higher rpm's
7) EJ22 99+ NA Pistons - light, not suitable for (high) boost, nice n/a piston for high rpm usage but I would not risk using it on turbo engines

I'm sure others will chime in
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Old 02-26-2010, 02:34 PM   #3
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Thanks a lot Marnix. If you and other would not mind also stating the WHP you deem each of these pistons safe/reliable to, this would be greatly appreciated. I know the rods are an issue in Suby blocks at a certain power point, but from all I know and have read, the pistons seem to be able to take a decent beating before people decide to go aftermarket (though as mentioned, I've seen many aftermarket pistons get drilled and they aren't making that much more power than stock pistons can).


Thanks again for your input!
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Old 02-26-2010, 04:34 PM   #4
69subaru360
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I have run a stock EJ22E shortblock at 25 psi daily and a few oops to 30+ psi. It held up fine.

My EJ205 broke a rod bolt before a piston.

I should add that I was always on top of tuning both of those, making changes as needed, never letting it detonate and ran 93 all the time.

The material forged pistons are made of is more durable and less prone to cracking ringlands off the piston.
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Old 02-26-2010, 06:13 PM   #5
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Quote:
Originally Posted by 69subaru360 View Post
I have run a stock EJ22E shortblock at 25 psi daily and a few oops to 30+ psi. It held up fine.

My EJ205 broke a rod bolt before a piston.

I should add that I was always on top of tuning both of those, making changes as needed, never letting it detonate and ran 93 all the time.

The material forged pistons are made of is more durable and less prone to cracking ringlands off the piston.
That's absolutely insane! We hear about the closed deck being boosted at 23-25 for some willing to feel safe with that, but an open deck and with more boost...wow is all I can say!!! How long has or did that EJ22E last you and did you ever dyno that setup?
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Old 02-26-2010, 07:45 PM   #6
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Quote:
Originally Posted by Audioexcels View Post
That's absolutely insane! We hear about the closed deck being boosted at 23-25 for some willing to feel safe with that, but an open deck and with more boost...wow is all I can say!!! How long has or did that EJ22E last you and did you ever dyno that setup?
I had that about 6 months or so, close to 10,000 miles. I sold the car. It's still going as far as I know. The 02-05 wrx is an open deck block same as the EJ22. I never dyno cars, it seems like a waste, they all read different. It did run low 12's a few times. I could have went 11's but had clutch and traction issues.
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Old 02-26-2010, 07:57 PM   #7
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May I add that EG33 pistons(2.2 bore) are damn tough. Compared to a 22e, I'd say the 3.3 only suffers from a little worse dish design- but they are noninterference, so what can you expect.
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Old 02-26-2010, 08:46 PM   #8
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Originally Posted by eg33GC View Post
May I add that EG33 pistons(2.2 bore) are damn tough. Compared to a 22e, I'd say the 3.3 only suffers from a little worse dish design- but they are noninterference, so what can you expect.
Same pistons used in the EJ22T right?
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Old 02-26-2010, 08:50 PM   #9
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Originally Posted by Audioexcels View Post
Same pistons used in the EJ22T right?
no.. these are rougly 10.1:1. Different dish as well, these have MAJOR valve reliefs.
MY96 Eg33
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Old 02-26-2010, 09:12 PM   #10
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I'll be going to phil @ element tuning to tune my car mid march. I'll see how much boost I can crank up in stock EJ20G V2 with stock 16g
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Old 02-26-2010, 10:18 PM   #11
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Quote:
Originally Posted by eg33GC View Post
no.. these are rougly 10.1:1. Different dish as well, these have MAJOR valve reliefs.
MY96 Eg33
Ahhhh. I had seen many posts about people using EJ22T pistons in the 3.3L engine but maybe it's a different one I am thinking of? What you have is the one from the SVX correct?
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Old 02-27-2010, 12:56 AM   #12
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Quote:
Originally Posted by Audioexcels View Post
Ahhhh. I had seen many posts about people using EJ22T pistons in the 3.3L engine but maybe it's a different one I am thinking of? What you have is the one from the SVX correct?
yeah im the guy with the 3.3RS.. stock 92 longblock(for now)

will go custom CPs someday after undergrad..
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Old 03-01-2010, 12:10 AM   #13
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Quote:
Originally Posted by eg33GC View Post
yeah im the guy with the 3.3RS.. stock 92 longblock(for now)

will go custom CPs someday after undergrad..
That'll be awefully costly, but make your car what you really want it to be)

I wonder if anyone else has HP estimates on pistons like Marnix pointed out.
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Old 03-01-2010, 12:11 AM   #14
Audioexcels
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Quote:
Originally Posted by Marnix View Post
Since I've got some experience with all these pistons (had them all at hand at some stage in the past), I'll go first:

1) EJ22 NA - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
2) EJ22T - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
3) VER1/VER2 WRX Pistons - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
4) VER1/VER2 STI Pistons - a bit heavy but for that reason very tough (good heat dissipation) and long skirt so no piston slap issues
5) VER3/VER4 WRX Pistons - short slipper skirt, skirts prone to breaking, not so good for high boost (about the same as USDM WRX pistons)
6) VER3/VER4 STI Pistons - forged but short slipper skirt, piston slap common, light so good for higher rpm's
7) EJ22 99+ NA Pistons - light, not suitable for (high) boost, nice n/a piston for high rpm usage but I would not risk using it on turbo engines

I'm sure others will chime in
Thank you as always. Too bad no one else is speaking out about this one.
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