Piston slap?

Lachlan · 01-22-2006, 10:50 PM

Did all phase 1 engines have piston slap or is that just a usdm thing?

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HndaTch627 · 01-22-2006, 11:39 PM

subaru motors tend to be prone to piston slap due to its design however the phase 1 EJ25 suffered heavily from it due to the large bore and stroke of the piston

Lachlan · 01-22-2006, 11:58 PM

I was wondering because when I start up my ej20k if it's cold I hear some knocking noise from the engine, but it goes away when it gets warmer.

Hurley 2.5 WRS · 01-23-2006, 01:11 AM

yeah, thats cause the forged pistons expand more, so they have a larger tolerence when cold. common thing for forged pistons.

edit, 11:11.......

Lachlan · 01-23-2006, 01:14 AM

good to know, thanks. I did read somewhere on this board that forged pistons expand less, but I guess you can't trust everything you read here...

Related but ot: Did the JDM EJ20's pistons have skirts or no?

Hurley 2.5 WRS · 01-23-2006, 01:22 AM

yessir

HndaTch627 · 01-23-2006, 04:46 AM

Quote:

Originally Posted by Lachlan

good to know, thanks. I did read somewhere on this board that forged pistons expand less, but I guess you can't trust everything you read here...

Related but ot: Did the JDM EJ20's pistons have skirts or no?

forged pistons do expand less but they are still alumnium which means they are going to expand. Forged pistons usually are built with tighter clearances because of the fact that they won't swell like regular cast alumnium pistons. Sounds to me like you have normal piston slap, even my USDM wrx swap has a little bit on the very very cold mornings.

Matt Monson · 01-23-2006, 11:27 AM

Quote:

Originally Posted by Lachlan

good to know, thanks. I did read somewhere on this board that forged pistons expand less, but I guess you can't trust everything you read here...

Related but ot: Did the JDM EJ20's pistons have skirts or no?

I have both forged and non-forged Ej20G pistons. I will see if I can find my pictures...

Matt Monson · 01-23-2006, 11:29 AM

Forged EJ20G piston...

2slofouru · 01-24-2006, 02:36 AM

My ej25 phase 1 does that too, in the morning. I worry about it being a bearing or excessive piston slap, I hope it doesn't develop into anything soon. It does go away by the time the engine warms up though.

n2xlr8n · 01-24-2006, 11:10 AM

Quote:

Originally Posted by HndaTch627

forged pistons do expand MORE but they are still alumnium which means they are going to expand. Forged pistons usually are built with MORE clearance because of the fact that they will expand more than regular cast alumnium pistons. Sounds to me like you have normal piston slap, even my USDM wrx swap has a little bit on the very very cold mornings.

Fixed that for you.

Factory EJ clearances: <.001"

CP/JE/Ross/Wiseco 2618 forged piston-bore clearance: ~.0035 to .0055" depending on application.

HndaTch627 · 01-24-2006, 02:04 PM

Quote:

Originally Posted by n2xlr8n

Fixed that for you.

Factory EJ clearances: <.001"

CP/JE/Ross/Wiseco 2618 forged piston-bore clearance: ~.0035 to .0055" depending on application.

ah crap...you are right, i said that backwards

n2xlr8n · 01-24-2006, 02:16 PM

Quote:

Originally Posted by HndaTch627

ah crap...you are right, i said that backwards

I knew that you knew....that's why I didn't say "get your facts straight, you stinkin bastich"

S.

01-22-2006, 10:50 PM	#1
Lachlan Scooby Specialist Member#: 19470 Join Date: May 2002 Chapter/Region: SWIC Location: albuquerque, NM Vehicle: 1981 Brat GL Blue	Piston slap? Did all phase 1 engines have piston slap or is that just a usdm thing? * Registered users of the site do not see these ads.

01-23-2006, 01:11 AM	#4
Hurley 2.5 WRS Scooby Specialist Member#: 43916 Join Date: Sep 2003 Chapter/Region: RMIC Location: Old Town Vehicle: 2001 Impreza 4.7 Blue Ridge Pearl	yeah, thats cause the forged pistons expand more, so they have a larger tolerence when cold. common thing for forged pistons. edit, 11:11....... Last edited by Hurley 2.5 WRS; 01-23-2006 at 01:22 AM.

01-24-2006, 02:36 AM	#10
2slofouru NASIOC Supporter Member#: 90539 Join Date: Jul 2005 Chapter/Region: South East Location: somewhere east of CA Vehicle: 95 L with ej20k powa, Raven R6	not a turbo ej but My ej25 phase 1 does that too, in the morning. I worry about it being a bearing or excessive piston slap, I hope it doesn't develop into anything soon. It does go away by the time the engine warms up though.

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HndaTch627 Scooby Guru Member#: 6551 Join Date: May 2001 Chapter/Region: MWSOC Location: Carol Stream, IL Vehicle: '01 GC8 Dinged STM '09 Concours 14 ABS Black	subaru motors tend to be prone to piston slap due to its design however the phase 1 EJ25 suffered heavily from it due to the large bore and stroke of the piston

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Lachlan Scooby Specialist Member#: 19470 Join Date: May 2002 Chapter/Region: SWIC Location: albuquerque, NM Vehicle: 1981 Brat GL Blue	I was wondering because when I start up my ej20k if it's cold I hear some knocking noise from the engine, but it goes away when it gets warmer.

01-23-2006, 01:14 AM	#5
Lachlan Scooby Specialist Member#: 19470 Join Date: May 2002 Chapter/Region: SWIC Location: albuquerque, NM Vehicle: 1981 Brat GL Blue	good to know, thanks. I did read somewhere on this board that forged pistons expand less, but I guess you can't trust everything you read here... Related but ot: Did the JDM EJ20's pistons have skirts or no?

01-23-2006, 01:22 AM	#6
Hurley 2.5 WRS Scooby Specialist Member#: 43916 Join Date: Sep 2003 Chapter/Region: RMIC Location: Old Town Vehicle: 2001 Impreza 4.7 Blue Ridge Pearl	yessir

01-23-2006, 11:29 AM	#9
Matt Monson Scooby Guru Member#: 832 Join Date: Jan 2000 Chapter/Region: RMIC Location: Teh Ghetto Garage, CO Vehicle: 99 2.5RS, '85 911 '73 914 and 2012 BRZ	Forged EJ20G piston...