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Beyond the torque curve...

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zak
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What happens when the rpm's go above the peak power level?
I presume there is no damage to the engine to run rpm's up that high.
But what really occurs?
Is the perfect mix of fuel and air altered, or something?
I remember Marshall commenting that it was counter intuitive, but he read that running at high rpm's would improve fuel and engine efficiency.
Is the peak touque being adjusted downward purposely- for fuel savings and anti pollution reasons?
Is each succeeding diesel engine models - from the 220D to CDI- lowering the peak torque?
Just some wacky ponderings....

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zak
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I was out of town for a few days and unable to answer...
I guess I was asking about the ramifications of reving the engine above the level of maximum torque.

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Marshall Booth wrote:
In most Mercedes autodiesels maximum torque is delivered at relatively low rpm (~2500 rpm) while peak POWER is delivered at about 4500 rpm.

Maybe on the engine stand....

My torque peak is about 3300rpm. (Ignore the red arrow)

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Revving the engine above max. torque (2500 RPM) happens all the time, and athe consequence is the engine develops its potential horsepower.

Mercedes injection pump has an RPM governor which starves the engine of fuel when red line is exceeded, which will limit max. RPMs if the engine is not driven above the redline by the drivetrain.

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pch2021's picture
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2900-3100 rpms tends to be peak efficiency for most Mercedes diesel engines.

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I guess that would imply best fuel economy but there are some variables. These measurements are made with accelarator floored, i.e. maximum fuel delivery.

In practice, one can vary the fuel delivered by pressing accelerator. Therefore, best fuel economy is likely to be achieved with lower engine speeds than 2500. It does not take much HP to keep a Benz crusing at 60 mph, perhaps about 12 hp.

The curves forced induction shows have way too much power.They could only be relevant on hill cllimbing on top gear.

W115nut

pch2021 wrote:
2900-3100 rpms tends to be peak efficiency for most Mercedes diesel engines.

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