Welcome to the North American Subaru Impreza Owners Club Monday September 27, 2021
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo)

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 09-14-2021, 04:50 AM   #1
Hog Head
Scooby Newbie
 
Member#: 199810
Join Date: Jan 2009
Chapter/Region: International
Location: Chiangmai, Thailand
Vehicle:
72 VW Beetle
Ivory

Default EJ20K piston interchange

I have a JDM EJ20K - V4 engine and while I have the heads off for a re-seal, thinking of new pistons and rods
I already bought Cometic C4261-051 (1.4mm / .054") head gaskets

I see that Weisco has "pre 1998" pistons for my engine. Difference is compression height and volume, so I am guessing that it must be wrist pin location, and perhaps crown design.
Stock static compression with my 49cc heads is 7.8:1
Later EJ20 engines are 8.2:1

Or does this even apply to JDM engines?

Rod length seems the same as the later 2.0 engines at 130.5mm

Perhaps my search skills need improving, but surely I am not the first to run across this piston interchange. Must I buy pre 98 pistons, or will the later pistons give me a bit more compression?

Turbo is a VF-48
My goal is a reliable street engine with a bit more power
* Registered users of the site do not see these ads.

Last edited by Hog Head; 09-14-2021 at 06:27 AM.
Hog Head is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 09-14-2021, 10:09 AM   #2
benflynn
Scooby Specialist
 
Member#: 515308
Join Date: Jun 2020
Default

Id want 8.2 over 7.8, hell if u have E85 Id want 9.8
benflynn is online now   Reply With Quote
Old 09-14-2021, 10:58 AM   #3
Hog Head
Scooby Newbie
 
Member#: 199810
Join Date: Jan 2009
Chapter/Region: International
Location: Chiangmai, Thailand
Vehicle:
72 VW Beetle
Ivory

Default

Quote:
Originally Posted by benflynn View Post
I'd want 8.2 over 7.8, hell if u have E85 I'd want 9.8
Hence the question about late pistons in an early engine

We have E10, E20, and E85 in Thailand
Hog Head is offline   Reply With Quote
Old 09-14-2021, 11:11 PM   #4
Hog Head
Scooby Newbie
 
Member#: 199810
Join Date: Jan 2009
Chapter/Region: International
Location: Chiangmai, Thailand
Vehicle:
72 VW Beetle
Ivory

Default

I am now not so sure if my compression is 7.8 after doing more reading
I see specs ranging from 7.8 to 9.1???

My JDM engine is shim over bucket, TD04 turbo (I think this is stock), no variable valve timing, no wasted spark in the intake, bare aluminium intake
I "think" it is a EJ20K and defiantly is a JDM engine

Heads are off now so maybe time to measure head and cylinder volume
Hog Head is offline   Reply With Quote
Old 09-18-2021, 03:22 AM   #5
Hog Head
Scooby Newbie
 
Member#: 199810
Join Date: Jan 2009
Chapter/Region: International
Location: Chiangmai, Thailand
Vehicle:
72 VW Beetle
Ivory

Default

Valves are leaking so difficult to get an accurate volume until they are ground, but looks like 46-49cc
Piston dish is -7 cc per my measurement, but I have seen specs at 9cc so maybe my measurement technique and will try again with a plexi plate rather than the brimming bathtub method
Piston stick up is 0.3mm
I may well have the later post Oct 1998 EJ20K engine?

I will get a more accurate reading with good valves and a surfaced head, but the data in hand suggests 8.67 - 8.91:1 static

If the engine is post Oct 98 EJ20, I understand that all EJ20 pistons are compatible using my Cometic .054 head gasket - is this correct?

Last edited by Hog Head; 09-18-2021 at 11:30 AM.
Hog Head is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 02:57 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2021 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.