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Old 09-20-2018, 12:07 PM   #1
Chaudruc
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Default EJ257 “Best” Forged Pistons

I am in the current state of rebuilding my entire long block due to spun rod, and have purchased the IAG Stage 4+ Bare Closed Deck Block, and now am trying to stuff some great pistons in it. I intend to daily my 06 STI but put it to street race a few Saturdays and what not.

So with that said, i am looking into purchasing set of pistons i do intend to run E85 but also Pump Gas and +.25 bore it so the intent is to run a 99.75 Piston but there are soo many to choose from and im unfamiliar with the brands that are offered for the EJ257 my power goals are 700-800hp.
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Old 09-20-2018, 12:12 PM   #2
Chaudruc
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I also forum hunted down post and everything, i do not really know what piston slap is, i assume a audible sound created from the pistons going up or down, and i know that CP is the loudest due to their wrist pins or something.
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Old 09-20-2018, 12:15 PM   #3
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Piston slap is the piston skirt slapping the cylinder walls on the power stroke. Or all the time if it's bad enough...
Usually caused by warn parts, too loose tolerances, or too weak of piston metal being used with too much power.
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Old 09-20-2018, 12:34 PM   #4
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I am doing a similar build do you have a list on what your planning on building with? Just so i can cross reference it with mine and see where im standing. (Rods, rod and main bearings, machining services being done etc.) Personally im planning on going with:

Wiseco HD pistons 99.75mm with a 8.5:1 compression ratio so i can run more boost (planning on 27-30lbs)

What piston to wall clearances are you planning on running as well?
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Old 09-20-2018, 02:47 PM   #5
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So let me ask a few somewhat related questions to see where we stand here:

You are the one 'building' your engine, correct?
You don't know what piston slap is, even though Google exists?
You're building this motor to street race on Saturdays?
Why did you spin a rod bearing in the last block?
How are you going to clearance this new motor you're dropping major $$ on?

And back to you question about the pistons - surely you asked IAG before coming to the forum... what did they recommend?
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Old 09-20-2018, 04:05 PM   #6
Scuby04STi
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Quote:
Originally Posted by mrsaturn7085 View Post
So let me ask a few somewhat related questions to see where we stand here:

You are the one 'building' your engine, correct?
You don't know what piston slap is, even though Google exists?
You're building this motor to street race on Saturdays?
Why did you spin a rod bearing in the last block?
How are you going to clearance this new motor you're dropping major $$ on?

And back to you question about the pistons - surely you asked IAG before coming to the forum... what did they recommend?
LOL ^^^ "You want answers? . . . I want the truth . . . You can't handle the truth." LOL


So . . . I run a custom arise brand piston, very happy with how it has worked for me. I run clearances that kept it nice and quiet (zero slap) in the 500whp neighborhood on my car with a [email protected] That being said a 700hp DD out of a 4 banger Subaru will be a short lived experience and likely an expensive one at that. IMO pay now or pay later, for reference there is a local car in the 700whp range and it has eaten 2 transmissions and a rear diff in a few short months. So even if you do everything right on the engine the rest of the parts are going to take a beating.
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Old 09-20-2018, 04:08 PM   #7
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Quote:
Originally Posted by Scuby04STi View Post
That being said a 700hp DD out of a 4 banger Subaru will be a short lived experience and likely an expensive one at that.
Especially street racing. Light poles don't come cheap nowadays.
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Old 09-20-2018, 05:18 PM   #8
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Quote:
Originally Posted by mrsaturn7085 View Post
So let me ask a few somewhat related questions to see where we stand here:

You are the one 'building' your engine, correct?
You don't know what piston slap is, even though Google exists?
You're building this motor to street race on Saturdays?
Why did you spin a rod bearing in the last block?
How are you going to clearance this new motor you're dropping major $$ on?

And back to you question about the pistons - surely you asked IAG before coming to the forum... what did they recommend?
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Old 09-20-2018, 06:26 PM   #9
AliBenn
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ha ha ha ha

man I tell you, I have a cylinder down(97lbs MY05 STi).....getting close to my leak down test.
freakin daily driver also down(repairing that 1st) then will dig into the RSTi issue.

im going to be lurking here for few months b4 I post my questions!!!!!!

research research research
steven

hell im only 1/3 of the way thru reading stickys......

Last edited by AliBenn; 09-20-2018 at 06:43 PM.
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Old 09-20-2018, 08:28 PM   #10
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I don’t get what is is going on here did you buy and receive the engine just to toss pistons in? Or are IAG going to put them in your engine?
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Old 09-20-2018, 11:48 PM   #11
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Quote:
Originally Posted by Chaudruc View Post
I am in the current state of rebuilding my entire long block due to spun rod, and have purchased the IAG Stage 4+ Bare Closed Deck Block, and now am trying to stuff some great pistons in it. I intend to daily my 06 STI but put it to street race a few Saturdays and what not.

So with that said, i am looking into purchasing set of pistons i do intend to run E85 but also Pump Gas and +.25 bore it so the intent is to run a 99.75 Piston but there are soo many to choose from and im unfamiliar with the brands that are offered for the EJ257 my power goals are 700-800hp.
It seems 700-800whp is the new 450whp.
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Old 09-21-2018, 12:15 AM   #12
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Quote:
Originally Posted by slow.wagon View Post
It seems 700-800whp is the new 450whp.
Haha it really is... 15+ years of the EJ and its come such a long way. Cant wait to see what becomes of the FA motor in the next 5-10 years!
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Old 09-21-2018, 01:43 AM   #13
Chaudruc
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I think i may have confused some of you guys.. So IAG offers Closed Deck Blocks, without any internals. Thats what i have. I have the Stage 4+ with 1/2 inch head studs bare case halves. What i am trying to figure out is whats the most recommended piston, the block is unbored and at STD sizes. I am currently looking into getting 99.75 8.2:1 to 8:5.1 compression ratio pistons, i mentioned piston slap because many people say thats why they do not buy certain pistons or that one is better then the other for that reason.
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Old 09-21-2018, 11:09 AM   #14
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Quote:
Originally Posted by Chaudruc View Post
I think i may have confused some of you guys.. So IAG offers Closed Deck Blocks, without any internals. Thats what i have. I have the Stage 4+ with 1/2 inch head studs bare case halves. What i am trying to figure out is whats the most recommended piston, the block is unbored and at STD sizes. I am currently looking into getting 99.75 8.2:1 to 8:5.1 compression ratio pistons, i mentioned piston slap because many people say thats why they do not buy certain pistons or that one is better then the other for that reason.
Honestly, I would recommend a complete IAG shortblock. Even a Stage 2 is rated over 600hp. Then you have a warranty on tested components, optimized all by the same builder.
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Old 09-21-2018, 11:19 AM   #15
Chaudruc
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Quote:
Originally Posted by Dave D. View Post
Honestly, I would recommend a complete IAG shortblock. Even a Stage 2 is rated over 600hp. Then you have a warranty on tested components, optimized all by the same builder.


Yeah i thought about it to be honest but if you read the warranty it has its loop holes where it gets you. So i figured why not build and learn it
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Old 09-21-2018, 12:14 PM   #16
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Quote:
Originally Posted by Chaudruc View Post
i mentioned piston slap because many people say thats why they do not buy certain pistons or that one is better then the other for that reason.
dude, piston slap is from a piston material/construction having more thermal expansion than another, so when it's sized for it's bore (at temp of course) it's sloppy in there and slaps around when cold.
Wrist pins? If it were slopping on the pins that bad the thing would be history in two seconds.

This is super fundamental for someone getting ready to build a 400hp/liter engine, which is why you are getting a bit of push back.
Frankly I agree.
400hp/liter is EXPERT/Master level building
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Old 09-21-2018, 01:11 PM   #17
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Quote:
Originally Posted by Chaudruc View Post
I think i may have confused some of you guys.. So IAG offers Closed Deck Blocks, without any internals. Thats what i have. I have the Stage 4+ with 1/2 inch head studs bare case halves. What i am trying to figure out is whats the most recommended piston, the block is unbored and at STD sizes. I am currently looking into getting 99.75 8.2:1 to 8:5.1 compression ratio pistons, i mentioned piston slap because many people say thats why they do not buy certain pistons or that one is better then the other for that reason.
You didn't confuse me... I was just asking a few clarifying questions.

First off - if you are publicly stating you're building this motor to street race, you're a moron. While I would never wish ill will on anyone, if you do hurt or kill someone, I hope it ends up being you rather than innocent bystanders like the woman and baby down in Tampa this last May. Yes, we've probably all street raced... but most of us grew out of it before we turned 17 or 18 or so. Posting stupid **** like you did is the kind of thing that becomes evidence to a premeditated crime when you inevitably hurt someone... just sayin'.

You should be asking IAG for their recommendation on pistons, and you should budget a decent amount of money for either the tools to assemble your motor correctly or for a new motor when you don't.
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Old 09-21-2018, 02:30 PM   #18
Chaudruc
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Quote:
Originally Posted by mrsaturn7085 View Post
You didn't confuse me... I was just asking a few clarifying questions.

First off - if you are publicly stating you're building this motor to street race, you're a moron. While I would never wish ill will on anyone, if you do hurt or kill someone, I hope it ends up being you rather than innocent bystanders like the woman and baby down in Tampa this last May. Yes, we've probably all street raced... but most of us grew out of it before we turned 17 or 18 or so. Posting stupid **** like you did is the kind of thing that becomes evidence to a premeditated crime when you inevitably hurt someone... just sayin'.

You should be asking IAG for their recommendation on pistons, and you should budget a decent amount of money for either the tools to assemble your motor correctly or for a new motor when you don't.


I appreciate the concern and all, and i totally agree, it would be tracked every once in awhile, but i refrained from saying track and chose to say street race because i wasn’t looking for a track set up but i do not intend to street race and be all stupid crazy over the horsepower. But yeah IAG sent me specs and recommendations if i plan to have another shop assemble the short block etc
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Old 09-22-2018, 06:13 PM   #19
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You really should be having the block honed to suit the measured pistons individually. Unless IAG have left material in it to be honed you are on the wrong track
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Old 09-23-2018, 06:52 AM   #20
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Quote:
Originally Posted by ripman View Post
You really should be having the block honed to suit the measured pistons individually. Unless IAG have left material in it to be honed you are on the wrong track


This. Tossing pistons in a block isn’t the right way to do things especially if big power is the target. Pistons vary in size and weight and none of that is accounted for when you do something like this.
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