eesjunin

So Ryan came by, C280AF, and he was going to chnage his spark plugs...now he has a 2006 c280 and i have 2002 c320...both 6 cylinders but mine had 12 plugs vs, a we found out, his had only 6...something for other to know
but how come did mb went this way? and what is the benefit of 12 vs 6?

TruTaing

M112 vs M272 - Old tech vs new tech

M112 (v6s before 2006) had two plugs per cylinder with 3 valves (two intake, one exhaust) - IIRC, the reasoning for two plugs per cyl were to create a cleaner burn for fuel efficiency.

M272 (v6s from 2006+) had only one plug per cylinder to make room for 4 valves.

eesjunin

ah...so which one is better for response, power , efficiency?

glocati

Exactly.

As far as efficiency, the m272 wins. Although a great engine, the m112 was not all that fuel efficient.

here's a good read on the differences:

http://www.mercedestechstore.com/pdf...2008-05-04.pdf

TruTaing

Whhatttt??? do all m272s come standard w/ the speed sensitive power steering?!

phister

Also the M272 engine was the first mb engine to have a constant variable valve timing controller. Or as Honda people call it Vtec and Toyota call VVTi. Mb somewhat caught up to Japan engine building IMO.

e1000

VTEC is a little different, it varies both valve timing and lift, which a lot of systems don't. It's also a phase system, essentially letting an engine swap between 2 cam profiles, one conservative and the other more agressive for high rpm performance.

I believe Mercedes was actually the first to develop simple variable valve timiing. Wayyyyyy before Honda or any other japanese manufacturer.

glocati

I do not know, John. The tech article certainly touts its availability, but not sure if that extends to all platforms that use the m272s?

phister

simple probably but not a continuous variable valve timing control.

c240DUDE

Interesting thread here.

eesjunin

Very interesting, although i find that a bit odd...that having 4 valves 1 spark plug vs 3 valves and spark plugs per cylinderwould make a more efficient...would the greater spark plugs give you a cleaner burn, hence higher efficiency, hence higher response...not an expert here

Silver C

Junin, *at that time*, twin plugs does provide better efficiency and cleaner burn etc etc. But as time goes by, MB redesigned the engine (thus a different engine code), and made out with better performance, with less plugs.

Norwichdelta06

or maybe more efficient plugs?