Welcome to the North American Subaru Impreza Owners Club Tuesday September 2, 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 > Built Motor Discussion

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 03-20-2006, 12:48 AM   #1
TypeC
Scooby Guru
 
Member#: 9794
Join Date: Aug 2001
Chapter/Region: TXIC
Location: Texas
Vehicle:
02 2.5LWRX-Retired
335i w/twins

Default Hybrid Phase II: Forged (Mahle piston install)

The good
After much debate on pistons, I decided on a set of Mahle 99.5mm forged. I liked the fact that you can run tighter clearances. They say .0020" is ok, but I went with .0026" with the bores individually honed to match to their respective pistons.

To my surprise, they sound like stock! The first ~15 seconds or so I hear a very SLIGHT slap (more like normal noise, but a tad more pronounced) but then it goes away. I couldn't hear it from in the car, but only when I had my head under the hood. Definately not any diesel sound.

The bad
I do have a complaint about the Mahle kit though. The main problem is the wrist pin retaining clips. Unlike the stock ones, they do not have tangs, so installing them is an extreme PITA. You have to work one end into the piston then walk the rest in. You can easily spend 20-30 mins working on a single clip (1 out of 8!). I found the best way to make this as quick as possible is to remove the #2 and #4 rods from the crank so you can put the clips on both sides of the piston while they are out of the block. Then push the rods through the block and bolt to the crank (just how you do normal, non-boxer motors). If you do it this way, then you only have 2 clips to install while the shortblock in assembled (#1 and #3).

I have to give BIG thanks to Dan and Jeff at Godspeed/Tuning Factory. They went beyond the sale and provided very good technical support.

The ugly
Some pics:

Stock vs Mahle:



Almost there:


All done:


The motor is done now. I decided to use the stock 257 rods as they more than meet my power goals. The only thing I didn't do that I would like to is to go to shimless buckets so I can use my launch control without having to worry about spitting a shim.

I had my injectors cleaned and flowed. They are a true 840cc now. I also added a Crucial Racing T-stat, which hopefully make a big difference as far as safety and det (I had a head crack in the past from heat). The cooling fans rarely even come on now with the T-stat.

Next step, GT30R (52lb), 6spd, and a beater.

More to come....
[Oh, setup is WRX heads milled .006", EJ257 shorty decked .003", 8.78:1 CR, UTEC, Tuna, TBE, FMIC, UP, modded injectors, fueling, plus normal bolt-ons/suspension, etc]
* Registered users of the site do not see these ads.

Last edited by TypeC; 03-21-2006 at 04:38 PM.
TypeC is offline   Reply With Quote
Old 03-20-2006, 03:09 PM   #2
dream
Scooby Specialist
 
Member#: 37003
Join Date: May 2003
Chapter/Region: MWSOC
Location: Twin Cities
Vehicle:
2006 WRX Wagon
Aspen White

Default

Very nice!!!
dream is offline   Reply With Quote
Old 03-20-2006, 07:27 PM   #3
Silverpike
Scooby Newbie
 
Member#: 92399
Join Date: Jul 2005
Location: San Jose, CA
Default

Quote:
Originally Posted by TypeC
The good
After much debate on pistons, I decided on a set of Mahle 99.5mm forged. I liked the fact that you can run tighter clearances. They say .0020" is ok, but I went with .0026" with the bores individually matched to their respective pistons.
Wow, you sure about that clearance? Clearance is largely based on the type of aluminum used in the forging. .0020" sounds kinda scary to me. Some of the best forgings I am aware of can't run below .0030" clearance.

BTW, piston companies also specify different measuring points for clearance. I know that Wiseco for instance specifies measuring near the bottom of the skirt (apparently most of the expansion happens there (?) ). Other specify at the wrist pin. I hope you had the right measuring point.
Silverpike is offline   Reply With Quote
Old 03-21-2006, 11:09 AM   #4
TypeC
Scooby Guru
 
Member#: 9794
Join Date: Aug 2001
Chapter/Region: TXIC
Location: Texas
Vehicle:
02 2.5LWRX-Retired
335i w/twins

Default

Quote:
Originally Posted by Silverpike
Wow, you sure about that clearance? Clearance is largely based on the type of aluminum used in the forging. .0020" sounds kinda scary to me. Some of the best forgings I am aware of can't run below .0030" clearance.

BTW, piston companies also specify different measuring points for clearance. I know that Wiseco for instance specifies measuring near the bottom of the skirt (apparently most of the expansion happens there (?) ). Other specify at the wrist pin. I hope you had the right measuring point.
Yes, the Mahle pistons are a bit harder than the CP's and are coated. Several people are running .0025" here. The Mahle's are tapered and the skirt is the widest point. I'm .0006" over the min spec. Thanks for the thoughts.
TypeC is offline   Reply With Quote
Old 03-21-2006, 01:40 PM   #5
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

Mahle recommends 0.0025, but does not specify a boost/HP level. There's always a game played with manfacturer's tolerences--how conservative are they? Regardless todays CNC-crafted forged pistons are not your father's forged pistons.

Mahle has a Grafel (lubricating, slick) coating on the skirts and the entire pistion has been phosphated.
bboy is offline   Reply With Quote
Old 03-21-2006, 02:37 PM   #6
jigga
Scooby Guru
 
Member#: 9960
Join Date: Sep 2001
Location: in bed...
Vehicle:
2002 Impreza WRX
WRBlue Perl

Default

pardon my ignorance, but what happened to the old block?

I understand you were running a 2.5 setup, and it looks like you lost a cylinder... So did you get a new 2.5 shortblock and just drop the pistons in? (I was under the impression that this is not a good idea to just drop pistons in...) Can you please enlighten me here?

again, please pardon my ignorance... I might be doing something similar in future and am trying to take in all i can here...
jigga is offline   Reply With Quote
Old 03-21-2006, 04:18 PM   #7
TypeC
Scooby Guru
 
Member#: 9794
Join Date: Aug 2001
Chapter/Region: TXIC
Location: Texas
Vehicle:
02 2.5LWRX-Retired
335i w/twins

Default

Quote:
Originally Posted by jigga
and just drop the pistons in? (I was under the impression that this is not a good idea to just drop pistons in...) Can you please enlighten me here?
-->
Quote:
Originally Posted by TypeC
I went with .0026" with the bores individually matched to their respective pistons.
I had the bores sized to fit the pistons.
TypeC is offline   Reply With Quote
Old 03-27-2006, 12:25 PM   #8
TypeC
Scooby Guru
 
Member#: 9794
Join Date: Aug 2001
Chapter/Region: TXIC
Location: Texas
Vehicle:
02 2.5LWRX-Retired
335i w/twins

Default

I finished the break in and did some prelim runs. To my surprize, I didn't need to relax the knock parameters at all.

I did a compression test and I was 170-170-170-185, with #4 being the high one. That is odd.

With the stock STi pistons, it was 180-180-180-185.

The bad part is that I didn't prime the turbo and it SCREAMS.
TypeC is offline   Reply With Quote
Old 03-27-2006, 12:44 PM   #9
Unabomber
Big Ron
Moderator
 
Member#: 18062
Join Date: Apr 2002
Chapter/Region: MAIC
Location: I can save you a ton of cash
Vehicle:
on car parts so PM
me b4 j00 buy

Default

Nice kill on the thermostat....many people overlook that very important piece. Best of luck.
Unabomber is offline   Reply With Quote
Old 03-27-2006, 01:43 PM   #10
InfamousDX
Scooby Guru
 
Member#: 25413
Join Date: Sep 2002
Chapter/Region: Tri-State
Location: North NJ
Default

Sounds like you have a great setup going for you. Glad to see that things are looknig up after your other scammer motor troubles.
InfamousDX is offline   Reply With Quote
Old 05-03-2006, 10:50 AM   #11
V5-STi
Scooby Newbie
 
Member#: 18058
Join Date: Apr 2002
Location: UK
Default

What gasket / thickness did you use to achieve your desired CR....I ask because the Mahle's are listed as 8.5:1 compared to the stck piston's 8.2:1......and with the WRX heads added - ????
V5-STi is offline   Reply With Quote
Old 05-03-2006, 11:52 AM   #12
ride5000
Scooby Guru
 
Member#: 32792
Join Date: Feb 2003
Chapter/Region: NESIC
Location: lincoln, ri
Vehicle:
2003 GGA MBP
12.9 / 105+

Default

Quote:
Originally Posted by TypeC
The bad part is that I didn't prime the turbo and it SCREAMS.
was this a new turbo, or the same old one?
ride5000 is offline   Reply With Quote
Old 05-05-2006, 05:50 PM   #13
TypeC
Scooby Guru
 
Member#: 9794
Join Date: Aug 2001
Chapter/Region: TXIC
Location: Texas
Vehicle:
02 2.5LWRX-Retired
335i w/twins

Default

Quote:
Originally Posted by V5-STi
What gasket / thickness did you use to achieve your desired CR....I ask because the Mahle's are listed as 8.5:1 compared to the stck piston's 8.2:1......and with the WRX heads added - ????
Stock STi gaskets, block decked .003", heads milled .006".

Quote:
Originally Posted by ride5000
was this a new turbo, or the same old one?
I had a tear in my turbo inlet hose, so I swapped that out and replaced my uppipe with a gutted stocker (I've swap back and forth sometimes).

The combination of the two made the sound go away. The turbo is fine, zero whine or shaft play.
TypeC 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
F.S. Forged Mahle PowerPak Piston Kit 99.5mm 06STi Engine/Power/Exhaust 10 02-25-2010 04:59 PM
Forged ACL pistons by MAHLE #4MKRY9620 col5555 Factory 2.0L Turbo Powertrain 0 05-18-2007 11:25 AM
Break in variations for forged Mahles? 2phless Built Motor Discussion 19 04-13-2006 01:18 PM
mahle pistons and oliver rods... 13secwrx Factory 2.5L Turbo Powertrain 12 08-12-2005 07:28 PM
Phase I Forged Internals on a Phase II Engine? latinskllz Normally Aspirated with bolt-on Forced Induction Powertrain 7 02-29-2004 01:55 AM


All times are GMT -4. The time now is 06:37 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.