Why are there 12 spark plugs in a 6 cyl ?
Thread Starter
Senior Member
Joined: Sep 2002
Posts: 352
Likes: 12
From: Worcester, MA
15' CLS400
Why are there 12 spark plugs in a 6 cyl ?
So I'm about to replace my spark plugs and saw the helpful threads regarding the DIY. I didn't see any threads addressing the topic of why MB is using two spark plugs per cylinder. Are there any MB tech's that can explain, from an engineering point of view, why MB designed it this way? Seems to me it only takes one spark to create combustion. 
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Benz used dual plugs on all M112/113 etc engines mainly to achieve LEV (low emission vehicle) status for cars so equipped in Europe. It is intended to burn every last ounce of fuel that gets into the combustion chamber even with detrimental AF ratio when running open loop.
As injection & ignition systems have improved & 3 Way Cats are fitted so they have become irrelevant.
The M112/113 engines blow squeaky clean tail pipes for the time.
As injection & ignition systems have improved & 3 Way Cats are fitted so they have become irrelevant.
The M112/113 engines blow squeaky clean tail pipes for the time.
Last edited by Glyn M Ruck; Apr 20, 2012 at 10:17 AM.
MBworld Guru
Joined: Dec 2009
Posts: 10,782
Likes: 1,011
NO LONGER ACTIVE
So I'm about to replace my spark plugs and saw the helpful threads regarding the DIY. I didn't see any threads addressing the topic of why MB is using two spark plugs per cylinder. Are there any MB tech's that can explain, from an engineering point of view, why MB designed it this way? Seems to me it only takes one spark to create combustion.
Thread Starter
Senior Member
Joined: Sep 2002
Posts: 352
Likes: 12
From: Worcester, MA
15' CLS400
Thanks a ton Rudeney! I should have done a bit more investigating. Good thing I didn't order 12 of them already. You the man!
Thank you Glyn for the very helpful info. May come in handy another day.
Thank you Glyn for the very helpful info. May come in handy another day.
