Welcome to the North American Subaru Impreza Owners Club Friday November 21, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated with bolt-on Forced Induction Powertrain

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.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 08-14-2006, 01:47 AM   #1
Leonardo
Consigliere
Super Moderator
 
Member#: 185
Join Date: Aug 1999
Chapter/Region: South East
Location: Orlando, Fl
Vehicle:
2009 Civic EX
Silver

Question Diference between 2.5RS and STi engine blocks?

As it asks above.

Looking to replace my block and the question came up.

TIA,
Leo
* Registered users of the site do not see these ads.
Leonardo is offline   Reply With Quote
Old 08-14-2006, 02:09 AM   #2
speed_freak27
Scooby Specialist
 
Member#: 30798
Join Date: Dec 2002
Location: kansas city ks
Vehicle:
2001 RS-T Hybrid
2.5>2.2T>257>2.35S

Default

Well the block itself, the diff is the sti is semi- closed deck and IIRC the sti block has an extra crankcase vent the rs is open deck. Internals are different as well.
speed_freak27 is offline   Reply With Quote
Old 08-14-2006, 02:12 AM   #3
Leonardo
Consigliere
Super Moderator
 
Member#: 185
Join Date: Aug 1999
Chapter/Region: South East
Location: Orlando, Fl
Vehicle:
2009 Civic EX
Silver

Default

Thanks but I have the STi internals so I don't want to know about that.

Just asking about the block itself.

might it withstand 400hp or a bit more?
Leonardo is offline   Reply With Quote
Old 08-14-2006, 02:19 AM   #4
ExecNav
Scooby Specialist
 
Member#: 30554
Join Date: Nov 2002
Chapter/Region: South East
Location: Ellijay, GA
Vehicle:
08 LGT Spec.B
01 Impreza RS-T

Default

Well he's right. The main difference is that the STi block is semi closed and has a little more support arount the cylinder walls. So the short answer is yes, it can handle 400hp. But so can a Phase II SOHC EJ253...

The EJ257 is almost a DIRECT bolton to everything EJ25...

There is a retarded amount of literature on this in the AFI forums, you know?

-Brett
ExecNav is offline   Reply With Quote
Old 08-14-2006, 03:15 PM   #5
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

Default

Quote:
Originally Posted by Leonardo
Thanks but I have the STi internals so I don't want to know about that.

Just asking about the block itself.

might it withstand 400hp or a bit more?
Before the Ej257 hit, Quirt Crawford built a large number of the Ej251/4 blocks for that kind of power. Many will argue that you want to do a closed deck modification to the block, but others will say it's fine as is, with the addition of turbo internals. Personally, I think if you limit is 400chp you can do it pretty easily. If you want to go past that, you will want to look at reinforcing the block, which quickly becomes very expensive and suggests just starting with an Ej257 case in the first place...
Matt Monson is offline   Reply With Quote
Old 08-14-2006, 08:20 PM   #6
Leonardo
Consigliere
Super Moderator
 
Member#: 185
Join Date: Aug 1999
Chapter/Region: South East
Location: Orlando, Fl
Vehicle:
2009 Civic EX
Silver

Default

thanks guys!
Leonardo is offline   Reply With Quote
Old 08-14-2006, 11:19 PM   #7
tmarcel
Scooby Specialist
 
Member#: 7555
Join Date: Jun 2001
Chapter/Region: South East
Location: Charlotte NC
Default

Quote:
Originally Posted by Matt Monson
Before the Ej257 hit, Quirt Crawford built a large number of the Ej251/4 blocks for that kind of power. Many will argue that you want to do a closed deck modification to the block, but others will say it's fine as is, with the addition of turbo internals. Personally, I think if you limit is 400chp you can do it pretty easily. If you want to go past that, you will want to look at reinforcing the block, which quickly becomes very expensive and suggests just starting with an Ej257 case in the first place...

Not to hijack the thread, but I just bought a 2002 Forester engine and am considering using it for the heads. However, I'm thinking of possibly using the crank as well. How does the crank compare to the 257 one? Is it forged (I'm assuming so) and are the journals the same size? I would want to re-use my 257 rods since they've already been balanced.

Oh yeah, got any idea of the original specs from the '02 Forester 2.5L as far as cams duration, lift, cyl head dish CC's, and of course the static CR? I found CR numbers from 9.7 to 10:1. My pistons are spec'd for 8.4:1 for a EJ257 using WRX 2L heads.
tmarcel 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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Differences between 2.5i and STi impreza2.5i2010 Newbies & FAQs 20 09-28-2009 04:13 PM
whats the difference between 2.5RS and WRX suspensions FromEvoToRS37 Brakes, Steering & Suspension 4 02-28-2007 05:45 PM
2.5rs and sti engine the same? shutupnshift04 Newbies & FAQs 21 12-03-2005 11:13 AM
Big diffrence in towing between 2.5RS and WRX? glockgod Newbies & FAQs 4 12-25-2004 12:52 AM
whats the difference between the 2.5Rs engine and STI engine? MaxPower STi Forum Archive 6 01-07-2003 09:15 PM


All times are GMT -4. The time now is 12:54 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.