Welcome to the North American Subaru Impreza Owners Club Saturday July 12, 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 General > Motorsports

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 01-19-2009, 11:43 AM   #1
T-WRX
Scooby Specialist
 
Member#: 2468
Join Date: Sep 2000
Chapter/Region: South East
Location: JAX
Vehicle:
08 RS4
05 STi

Default AutoX Gurus - Aftermarket pistons ok in BSP?

AutoX experts,

I ran my STi in BSP last season. In the off-season, I blew a ringland. Currently, my engine is dissassembled and receiving new aftermarket pistons. Does this change from stock to aftermarket kick me out of BSP?

The piston size is the same, but the material of construction and ringland design are different.

Thanks for your feedback!

Quote:
MAHLE PISTON
PART #: WRX209917I22
**INCLUDES PRECISION FITTING RINGS

APPLICATION: MAHLE Racing Pistons Subaru 2.5 Turbo WRX STI,Forester,Legacy EJ25/257
BORE: 99.50mm
STROKE: 79.0mm
ROD LENGTH: stock
PIN DIAMETER.: 23.0mm
COMP. HEIGHT: 30.70mm
DOME VOLUME: -22cc
WEIGHT: 399 grams
COMPRESSION RATIO: 8.5 to 1
* Registered users of the site do not see these ads.
T-WRX is offline   Reply With Quote
Old 01-19-2009, 11:48 AM   #2
KC
Scooby Guru
 
Member#: 442
Join Date: Oct 1999
Chapter/Region: NESIC
Location: SE Mass/RI
Vehicle:
2013 Crosstrek XV
00 Honda S2000

Default

Quote:
but the material of construction and ringland design are different.
15.10.R:
Quote:
R. Cylinders may be rebored to no more than .0472 in. over standard bore and the appropriate standard oversize piston may be substituted. This overbore dimension is an absolute limit; no additional tolerance is permitted to accommodate wear. Cast or forged, non-stock pistons of the same dimensions and configuration as original equipment pistons may be used. Additionally the replacement pistons must be of the same weight or greater as the original equipment pistons. Replacement pistons must match OE piston configuration exactly including quench area. The allowance for the use of aftermarket forgings vs. OE castings does not permit alternate piston dome designs. This allowance does not permit alternative ring configurations.
If the pistons meet that criteria bolded, you're good to go. As far as the rings, someone more knowledgable than I would have to answer that... I don't know what 'alternative ring configurations' means in SP context.

--kC
KC is offline   Reply With Quote
Old 01-19-2009, 12:29 PM   #3
Scooby South
Subtly Outspoken
Moderator
 
Member#: 238
Join Date: Sep 1999
Chapter/Region: MWSOC
Location: 2013 Limited SWP BRZ and a
Vehicle:
99 Ver6 Recreation
JDM Speedwagon 3 LSDs..:)

Default

Ha....learned something...

Last edited by Scooby South; 01-19-2009 at 02:58 PM.
Scooby South is offline   Reply With Quote
Old 01-19-2009, 12:38 PM   #4
espEVO
Scooby Newbie
 
Member#: 97610
Join Date: Oct 2005
Default

If the ringland is a different design then the rules state that it is NOT a legal piston for SP.

I see nothing wrong with alternate materials, that looks to be allowed.

John
espEVO is offline   Reply With Quote
Old 01-19-2009, 01:07 PM   #5
Storm
Scooby Guru
 
Member#: 5218
Join Date: Mar 2001
Chapter/Region: MWSOC
Location: SAUL'S Motorsports
Vehicle:
96L Most Over-
Developed Beater

Default

What's Doug Gill's email addy?

I'd send a letter to be sure......

Jay
Storm is offline   Reply With Quote
Old 01-19-2009, 02:34 PM   #6
cucamelsmd15
Scooby Specialist
 
Member#: 122980
Join Date: Aug 2006
Chapter/Region: South East
Location: Raleigh, NC
Vehicle:
2010 F150, 2013 CX-5
92 Miata 15 TTF/PTF/E3

Default

The way the rules are written, it doesnt look like youre going to stay BSP legal, as the stock compression is 8.2 and these pistons are 8.5.
cucamelsmd15 is offline   Reply With Quote
Old 01-19-2009, 02:50 PM   #7
CamaroFS34
Scooby Guru
 
Member#: 6850
Join Date: May 2001
Chapter/Region: MAIC
Location: SoBWI, MD
Vehicle:
Lots of ESP cars
'06 IAG WRX & LT1 Z28s :)

Default

Quote:
Originally Posted by Storm View Post
What's Doug Gill's email addy?
dgill@scca.com
CamaroFS34 is offline   Reply With Quote
Old 01-19-2009, 02:51 PM   #8
solo-x
Scooby Specialist
 
Member#: 37624
Join Date: May 2003
Chapter/Region: NESIC
Location: Doesn't drive a scooby....
Default

Compression ratio changed? = not legal for SP
Weight changed? = not legal for SP
Ring land configuration changed? = not legal for SP

In short, no, those pistons are not legal for SP.
solo-x is offline   Reply With Quote
Old 01-19-2009, 07:18 PM   #9
T-WRX
Scooby Specialist
 
Member#: 2468
Join Date: Sep 2000
Chapter/Region: South East
Location: JAX
Vehicle:
08 RS4
05 STi

Default

Thanks guys - very helpful information.

So it sounds like it may not be legal for SP. Drat.
T-WRX is offline   Reply With Quote
Old 01-19-2009, 07:36 PM   #10
dstan
Scooby Specialist
 
Member#: 120386
Join Date: Jul 2006
Chapter/Region: South East
Location: Asheville NC
Vehicle:
2000 BRP 2.5RS Coupe
Wow the 89 Civic is fast

Default

Quote:
Originally Posted by T-WRX View Post
Thanks guys - very helpful information.

So it sounds like it may not be legal for SP. Drat.
But you will have a Dependable car now
dstan is offline   Reply With Quote
Old 01-19-2009, 07:40 PM   #11
Mechie3
Scooby Guru
 
Member#: 120152
Join Date: Jul 2006
Chapter/Region: MWSOC
Location: Indy
Default

I looked into this a bit for ESP and it looked like staying stock was really the only way to assure you met all of the rules without getting some expensive custom deal.
Mechie3 is offline   Reply With Quote
Old 01-19-2009, 08:21 PM   #12
Patrick L
Scooby Specialist
 
Member#: 634
Join Date: Dec 1999
Chapter/Region: TXIC
Location: Tulsa, OK
Vehicle:
2000 Impreza 2.5RS
Becasue ITS racecar

Default

This is per the STI FSM
Cylinder Bore STD
(A) 99.505 — 99.515 mm (3.9175 — 3.9179 in)
(B) 99.495 — 99.505 mm (3.9171 — 3.9175 in)
Max over bore is 0.5 mm (0.020 in)

Subaru makes an STD A & B piston.
(A) 99.505 — 99.515 mm (3.9175 — 3.9179 in)
(B) 99.495 — 99.505 mm (3.9171 — 3.9175 in)
and an oversize piston.
0.25 mm (0.0098 in) OS / 99.745 — 99.765 mm (3.9270 — 3.9278 in)
0.50 mm (0.0197 in) OS / 99.995 — 100.015 mm (3.9368 — 3.9376 in)

This is the same as my 2.5RS.
I am assembling an SP motor for my DSP RS right now using the factory .5mm OS pistons. That is about all you can do to the bore and pistons.

There is also a surface grind limit on the head of .012" and .004 on the block for the STI in the FSM. It will give you a smal bump up in compression.

My RS FSM will only allow .004 on the head on block.
Patrick L 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
Best stock pistons produced in USDM/JDM engines and Comparison to Aftermarket pistons Audioexcels Pre-2002 Factory Turbo Powertrain 13 03-01-2010 12:11 AM
aftermarket forged piston/rods in ej207 ImprezaRSfan! Factory 2.0L Turbo Powertrain 37 08-02-2005 03:50 PM
Hey AutoX Gurus...should I... mykrrrr Mid West Subaru Owners Club Forum -- MWSOC 34 04-30-2004 10:11 AM
Autox gurus -- can you explain this? sdecker Motorsports 108 03-17-2004 05:24 PM
How do people like their aftermarket pedals? OK in the wet? Patrick Olsen Interior & Exterior Modification 12 01-26-2001 12:22 AM


All times are GMT -4. The time now is 05:49 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.