The C240/320 are fitted with twelve (two per cylinder) of either:

Bosch F 8 DPER,
Beru 14 FGH 8 DPUR X 2, or
NGK IFR 5 D 10
MB part number is 004 159 94 03

 

Twelve? Wow thats alot... Call me a moron but i thought v6 engines would use only 6 sparkplugs... Any benefits in using double the amount of plugs?

 

There are many engines that double up on plugs at one time or another, Nissan SX 240, Alfa Romeo, BMW motorcycles, Porsche 911 (previous gen I think). I also think that the Veyron doubled up on plugs. In the yesteryear when plugs were $3 for a twin pack it was no big deal but when plugs are $16+ each, it gets expensive to change them all

The major reason for two sparkplugs is the motor does not need as much advance ignition timing to complete the burn cycle, because the flame front has been started in two different areas of the combustion chamber and therefore the combustion process is completed more quickly. The need for less ignition timing means less chance of detonation. The flame front is not traveling any faster, there is just two flame fronts traveling the same speed but covering the combustion chamber more quickly.

Quench areas ( Squish Areas) promote cooling of the combustion chamber and true there is potentially more area for quench area in a larger bore diameter, however in the motor the third valve will take any of that extra room and then some, so I say, MB having put the third valve in the combustion chamber, reduced the quench area to the point that they needed some other way to reduce the probability of detonation, so that is when the second spark plug was added.

A little more clarification on detonation and shockwaves. Detonation occurs when the end gases (the last A/F mixture left to burn, to complete the combustion process) become to hot and ignite before they are supposed to and start another flame front which collides with the original flame front, causing a violent rise in peak cylinder pressure prematurly, which rattles the pistons back and forth in the cylinder bore as they are approaching TDC. This is not good especially on a turbo or supercharged motor. Even with the twin spark plugs MB still has to retard the hell out of the ignition timing to maintain safe operation of the motor.

 

Boom vang, that is an extremely detailed - almost scientific explanation, i thank you for that. I think i get what you mean about that, hence the double amount of spark plugs provides a more rounded and continuous burn as compared to single amount of spark plugs.

Hence, which of these plugs that will be best suited for tye c240 v6 engine? I usually take up on the ngk iridium spark plugs on my bmw, but i do take recommendations from avid benz owners..

 

I have only used Bosch plugs on my car because that's what it came with. NGK also make excellent plugs - I really don't think it matters.

In addition to the commentary above. MB used twin spark on the 112/113 engines because they were chasing LEV (Low Emissions Vehicle) status at the time these engines were designed & Cat converters were not as good as they are now. Especially the new 3 way Cats.

The Twinspark engines blow ultra clean exhausts.

 

I use to be a big proponent of non OEM replacement plugs but came to respect the motor design engineers' methodology more than my opinions. After market plugs claim to "surpass" heat range requirements of OEM plugs but they don't test them in every motor and rely on averages, not specifics. With the advent of electronic motor management the days of "reading" plugs are gone as long as you maintain standard tune. Now I say why take a chance? I haven't heard anyone complain about the NGK plugs yet but neither have I heard anything bad about the OEM plugs.

 

Yes with modern electronics & 100K plug life goals the humble spark plug has become very much part of the engine design process.

 

there is a reason why they spend a $billion++ in developing a car and its components, while some decisions come down to supplier costs and deals one has to assume that the engineers have tested all different combinations in determining the best compromise.

Of course this all falls apart when it comes to the decision of what kind of tires go on because usually the worst tires are the OEM. All I have to mention Michelin MXV4 and Pilot Primacy which were the darlings of the North American spec MB cars and perhaps the worst rubber I have ever drove

 

When is the best recommended time to replace spark plugs for best measure and preventive maintenance?

 

MB recommends 100K miles for your motor. My first 100K miles was ideal driving conditions for the motor....2 X 50 miles trips at 65 mph a day....where the motor came up to operating temp and stayed there. The plugs had great color with no deterioration and maintained the recommended gap. They looked like they could have done another 100K miles. If you do a lot of short trips or a lot of idling or you tend to punch it while cold I would suggest a shorter interval. Look at #1 cylinder if you're not sure but be sure to use anti seize if you return it.

 

I definitely dont punch it cold, but idling sounds more like it, traffic is more of a problem down here i live.. So im just hitting 40k miles, will replace them and see how it went at 60k miles..

 

Some of us with over boosted 4 bangers, have gone to cooler NGK iridium plugs.

 

I’ve owned three 2005 C230 Kompressor sedans and in all 3 Ive used these E3 spark plugs. I didn’t have any complaints whatsoever. They worked and worked really well. I’d definately use them in my wagon when it’s time to replace the ones in it now.

 

LOL this is a 10 year old thread.. I even replied to it back then! cool
Move on nothing to see here.. remain calm..

 

so what? we can’t reply for the people that never saw this? Just because it’s old does that mean what was said is the gospel? A comment like yours is why I can’t stand joining new groups. Always some bull$h!!. You’re right about there’s nothing here. Nothing positive that’s for sure. If it isn’t helpful, please refrain from commenting. I’d appreciate if you could do that.