300 SEL 103.981 Engine MODS
 

I discovered that Mecedes also made a 3.2L inline six in the W140 cars. When my mill is ready for a rebuild I was wondering if any parts from the later engine are compatible with mine. Specifically I am interested in the 4 valve cylinder head and the rotating assembly. I was hoping that I could use the intake, exhaust, and fuel managment system off my car. My concerns are in the area of the timing chain mechanism and possible fuel system upgrades since the 3.2 had about 40 hp and 40 ft.lbs. of torque more than the 3.0 liter. Other data I would like for both engines includes cam specs in terms of valve event (IO,IC,EO,EC), bore, stroke, and connecting rod length.

Thanks,
Motorhead

Motor Head....
 

First of all, Im under the impression your a W140 owner? Im also an owner of a W140 300series, in wich the engine is labeled the M104. The badge on the rear of your car may say "300SE(L)", but the displacement is truly 3.2L in all Six cylinder gasoline W140s. MBUSA.com sais the M104 is a 3.2L DOHC 24-valve inline six. Net horsepower from 1992 till 1994 was: 228HP @ 5,800 RPMs. Net tourque for the same years was: 229Lbs @5,600RPMs. I think Mercedes made many inprovements in 1995, the most of which (engine wise) would be better Variable Valve Timing, so HP and Tourque stay the same, they just come at lower RPMs. I think this engine has just enough grunt to get by, but IMO its noticably more civilized than the 3.2L V-6, which makes close to the same numbers. I find it interesting Mercedes never put the V-6 in the W140? Was it because it wasnt civilized enough??????

The 300SEL was also a 6 cylinder M103 3.0L in the the W126.

Matt.

Benz_man600,

Thanks for the reply. Actually I own a W126 1990 300 SEL which has a 3.0 L inline six with 2 valves per cylinder. When it is in it's power band (3,000 rpm or more) the car is fairly responsive but this engine is lacking in low end torque. That is why I am interested in any mods that will improve engine performance in that region.

Motorhead

I'm thinking that the 24V 3.0L I-6 engine from the 300E/CE 24-Valve could fit in the W126 300SEL without much hassle.

Otherwise your option would be the V-8's namely the 5.6L or 4.2L