Welcome to the North American Subaru Impreza Owners Club Sunday September 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 > 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 06-15-2008, 02:40 PM   #1
Acostafan
Scooby Specialist
 
Member#: 67398
Join Date: Aug 2004
Chapter/Region: South East
Location: Chattanooga, TN
Vehicle:
2002 Now with 100%
RDA of 2.5l Goodness!!!

Default Question about Hybrid compression numbers

I need some help here guys. I don't have the technical know how to figure what my compression numbers should be when I get ready to compression test my hybrid before going on the dyno. I'm running stock 2.0 heads, STI shortblock. I had about 7 thousandths milled off the heads and am running the OE STI HG. What is the acceptable range of cylinder pressures I should see after the compression test? Thanks so much!

John
* Registered users of the site do not see these ads.
Acostafan is offline   Reply With Quote
Old 06-16-2008, 07:42 PM   #2
Acostafan
Scooby Specialist
 
Member#: 67398
Join Date: Aug 2004
Chapter/Region: South East
Location: Chattanooga, TN
Vehicle:
2002 Now with 100%
RDA of 2.5l Goodness!!!

Default

Monday bump for some help!
Acostafan is offline   Reply With Quote
Old 06-17-2008, 01:57 PM   #3
bluescoobywagon
Scooby Specialist
 
Member#: 14911
Join Date: Feb 2002
Chapter/Region: MWSOC
Location: The land of E85
Vehicle:
Not A Wagon!
2011 WRX - 285s on 18x10s

Default

What's important isn't the compression number, but the consistancy. Compression testers vary as do testing methods. Go ahead and test and post the numbers.
bluescoobywagon is offline   Reply With Quote
Old 06-17-2008, 02:40 PM   #4
eastcoastbumps
Scooby Guru
 
Member#: 29201
Join Date: Nov 2002
Chapter/Region: NESIC
Location: Shrewsbury, MA
Vehicle:
BMW M3
Honda S2000x2

Default

Your compression numbers will be effected slightly by your increased compression ratio, but there are other things that will effect it more, such as gauge accuracy, cam timing (and overlap) as well as the engine temp.

I would only worry if you had one cylinder that was 15-20% less than the rest, or if all were less than 100psi.
eastcoastbumps is offline   Reply With Quote
Old 06-17-2008, 02:59 PM   #5
kellygnsd
Scooby Guru
 
Member#: 32669
Join Date: Feb 2003
Chapter/Region: SCIC
Location: Rancho C
Vehicle:
2007 2.34LR, EFR7670
LINK G4 hybrid STi

Default

I had a slightly higher than normal CR hybrid and I would get 155-160psig on a warm compression test. Now that I'm at 8.5:1 I'm getting 145 psig
kellygnsd is offline   Reply With Quote
Old 06-17-2008, 06:47 PM   #6
Acostafan
Scooby Specialist
 
Member#: 67398
Join Date: Aug 2004
Chapter/Region: South East
Location: Chattanooga, TN
Vehicle:
2002 Now with 100%
RDA of 2.5l Goodness!!!

Default

Cool. Thanks guys. I will post up numbers when I do the CR test next week. I'm just trying to cover all my bases before I go to Topspeed.
Acostafan is offline   Reply With Quote
Old 06-17-2008, 09:21 PM   #7
Turbo_Mike
Scooby Newbie
 
Member#: 130276
Join Date: Oct 2006
Chapter/Region: NESIC
Location: Dudley, MA
Vehicle:
2004 Pontiac GTO
LS1 T56 RWD

Default

Correct compression test by subaru standards...

Remove all coils and spark plugs.
Screw in compression tester, set throttle to 100% wide open.
Crank until gauge stabilizes at maximum.
Compression should be 131-175 (depends mainly on starter and battery)
Maximum difference between cylinders : 7 psi
Minimum allowable compression: 127 psi
Turbo_Mike is offline   Reply With Quote
Old 06-18-2008, 01:47 AM   #8
sleeperrex
Scooby Newbie
 
Member#: 19466
Join Date: May 2002
Location: san diego
Vehicle:
2002 wrx/hybrid
silver

Default

I also have a hybrid using the same head gasket.

I measured 180psi on all 4. Originally i was measuring 155 on my 2.0 heads and engine.
sleeperrex 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
question about hybrid engine foxtrott501 Factory 2.5L Turbo Powertrain 1 04-09-2010 07:21 AM
questions about hybrid swap wrxdrivr04 Built Motor Discussion 15 02-20-2009 01:43 AM
Question about doing compression test WrXwaBBit Service & Maintenance 6 07-10-2006 02:53 PM
question about mt compression test results kenlee Factory 2.5L Turbo Powertrain 11 05-13-2005 12:58 AM
Question about trim...part numbers?? jackacc Legacy Forum 4 02-25-2004 02:34 PM


All times are GMT -4. The time now is 10:18 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.