Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

LinkBack Thread Tools Display Modes
Old 07-19-2014, 08:31 PM   #1
Registered User
RayW's Avatar
Join Date: Jun 2014
Location: Chicago
Posts: 39
3 chain, 5 chain question

This may seem like a real stupid question, but I've seen conflicting info on this. I have a '98 base 2.5 do I have a 3 chain or a 5 chain engine.

RayW is offline   Reply With Quote
Old 07-19-2014, 09:02 PM   #2
Certified Boxster Addict
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,665
5-chain: Boxster thru 2002; 996 Carrera thru 2001
3-chain: Boxster 2003 and later; 996 Carrera 2002 and later
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
thstone is offline   Reply With Quote
Old 07-20-2014, 04:58 AM   #3
Registered User
RayW's Avatar
Join Date: Jun 2014
Location: Chicago
Posts: 39
Thanks, thats kind of what I thought, just needed clarification.
RayW is offline   Reply With Quote
Old 07-20-2014, 07:21 AM   #4
Registered User
Join Date: Jan 2014
Location: Charlotte, NC
Posts: 131
So, let me ask - what is the general consensus on reliability of the two? Major drawbacks/benefits of each?
Current: 2000 Boxster S....2012 Kia Soul+
Previous: '71 914 2.2 - TX license plate: "E-GO"....'73 914 1.7....'74 914 1.8....'73 914 2.0 - Saturn yellow with all original 2.0 options- R.I.P..... '74 914 1.8 with 916 body kit.... '72 914 1.7 - my very first car
Also: '09 Cooper Clubman....'90 Miata.... '80 MGB.... '76 TR-7
Ebell914 is offline   Reply With Quote
Old 07-20-2014, 10:22 AM   #5
Engine Surgeon
Join Date: Aug 2008
Location: Cleveland GA USA
Posts: 2,424
5 chain engines have more components to wear. They also do not have load sensitive variable valve timing, its a mere RPM switch.

There's a ton of benefits in 3 chain over 5 chain, it would be its own thread for sure.
Jake Raby/www.flat6innovations.com
IMS Solution/ Faultless Tool Inventor
US Patent 8,992,089 &
US Patent 9,416,697
Developer of The IMS Retrofit Procedure- M96/ M97 Specialist
Jake Raby is offline   Reply With Quote
Old 03-22-2018, 11:10 PM   #6
Registered User
Join Date: May 2016
Location: San Diego
Posts: 8
This is a good discussion. I was lead to believe that the 3-chain variants are more reliable. Is this a true statement, and are there other benefits of the 3-chain variant?
my1997golf is offline   Reply With Quote
Old 03-23-2018, 07:27 AM   #7
Registered User
Join Date: Feb 2017
Location: CO
Posts: 985
I thought the 3.2's were three chain?
Geof3 is offline   Reply With Quote
Old 03-23-2018, 08:30 AM   #8
Registered User
The Radium King's Avatar
Join Date: Apr 2010
Location: Canada
Posts: 2,987

so, here is a pic of a 5-chain engine:


chain joins driveshaft to intermediate shaft. chains from ims to heads, chains join intake and exhaust cams.

next step - understanding variable timing and cams. there are THREE systems, variocam, updated variocam, and variocam+.

variocam was on all 9x6 until 2002. in 2003 986 got updated variocam, while 996 got variocam+.


variocam uses an actuator that pushes on pads that tension the chains joining the intake and exhaust cams. this tension changes the timing (advances/retards). it is not gradual, but rather on/off based on rpm (and designed to interact with the resonance flapper on the intake). the pads will wear (hard dark brown plastic in the oil pan) on the chains and will eventually need replacing with the updated porsche part. the actuators can also fail, resulting in drastic (ie, -16 degree) cam deviation and often green rubber in the oil pan. the solenoids and cam position sensors are also a failure point.

updated variocam gets rid of the chains joining the intake and exhaust cams (ie the transition from 5-chain to 3-chain in 2003) and uses a 'vane cell adjuster' mechanism on the intake cam sprocket to provide infinitely adjustable timing. this is the reason for the bump in hp in the 2003 986 models. since more sophisticated ecu control is required for this (ie, no longer just an rpm-based on/off signal) the cars moved from the 7.2 to 7.8 dme and this is why putting a m96.2 engine in an early car is such a pain. it does, however, do away with many of the moving parts on the earlier engines and there are fewer failure modes.

finally, variocam+ incorporates the updated vane cell timing adjustment with variable valve lift height; 987 cars did not see this until just before the dfi engine came out.

otherwise, the three chain engines may have issues not directly related to the change in cam actuation; for example, the 996 moved from 3.4 to 3.6 displacement and the 3.6 engines tend to have piston slap issues (the increase in displacement was achieved by increasing stroke, which increased lateral force on piston walls and really brought to light the inadequacies of the cylinder liner material being used at the time) and, porsche also changed something with the ims in and around the same time.

Last edited by The Radium King; 03-23-2018 at 08:59 AM. Reason: note that i'm off on the 996 transition by a year.
The Radium King is offline   Reply With Quote

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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -8. The time now is 09:08 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page