I noticed that the c320 has less horsepower than the e320 but they have the same engine. Then I noticed that this new 3.7liter engine in the ml350 only makes 10 more hp despite its significant increase in displacement. Why would MB want to hold back on a newly released engine? I can understand why the power may vary between the c320 and e320 to justify the difference in price but not the ml.

 

C320 and E320 power difference is because E has more room to use a more free flowing exhaust (dual setup), while on C it has room only for single setup exhaust.

 

good theory...but I just don't buy it.

it appears my exhaust system is a very free flow system...very much the equivalent of the E's more narrow twin piping.

 

I always wondered about this too.... i just figured it had to do with the exhaust system tuning. A little modification should be able to get us an extra 10hp.

 

Engines are much more sensitive to changes on the intake side than on the exhaust. If the cars have a different intake, that could explain the difference.

On the exhaust and the differences in pipe sizes between the two vehicles; the pipes are usually no where near the main contributor to overall restriction. Cats and mufflers are where the restriciton usually is: double up on them and see an improvement even if the pipes are a touch more restrictive in comparison.

Or, it very well could be as you suggested and they did it intentionally due to market position.

HP vs Displacement; Compare the torque curves of the 3.2 and 3.7 instead of the max HP number. Perhaps the intention of the 3.7 was to have a broader, stronger torque curve than the 3.2?

Depending on the application, adding more power to an engine may not be as desirable as having more torque. After all, how many ML drivers do you know that are reaching max rated rpm very often? They are all feeling low end torque each time they drive though... and it's how something feels pulling away from the light that most drivers are going to notice first.

So perhaps Mercedes wasn't holding back at all, they just had different goals than you?

 

Well actually, since the 3.2L V6's engine makes its torque peak (plateau) at 3000-4500 rpms, it is quite easy to spend some time in that range when climbing hills. Yes, the 3.7L V6 is tuned for light truck duty, which means a wider torque curve at lower revs, rather than more horses.

 

A new intake/filter and a new exhaust. The coupe got 3-5 hp if I remember correctly from what Buell dynoed. The exhuast should be good for another 5 or so.

 

Is the 3.7 just a 3.2 with a longer stroke or is it a completely different engine?

 

There are many, many variables in tuning an engine. The exhaust is just one of them. So MB can tune any engine to how they want it for that particular model, even though the displacement may be the same for those two models.

They could tune them to make a lot more horsepower if they wanted to. But they have to make a compromise between power, emissions, and fuel economy among others.

That being said, the differences in MB engines are usually very small. So it probably comes down to intake and exhaust. They have to use different parts depending on the space they have to work with. For example, the new twin turbo V12 in the S600 is the same as the one in the Maybach, but there is not as much room for the exhaust, and the the Maybach supposedly has a freer flowing exhaust. Although I don't know if that accounts for the entire power difference. Even if it wasn't the exhaust, I still think they would keep the S600 less powerful than the Maybach.

 

Exactly. But how often does anyone spend much time at peak (rated) HP?

 

My guess is this isn't the case, otherwise I'd imagine that they would have bumped up the power on the CLK320 for the same reason (although the CLK does have 8 more lb-ft of torque for some reason).

Cheers, BT

 

as often as possible