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Premium Member 2000 SLK230 Over 100,000 miles!!!
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Discussion Starter #1
I am mechanically challanged and have wondered how the kompressor works.

Is it always working or does it kick in at certain RPM's?

Thanks
 

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Premium Member 2000 SLK230 Over 100,000 miles!!!
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Discussion Starter #3
ok, thanks for the link.
So it is constantly working.

So there is no "boost" per say when I give it a lot more acceleration from it engaging?

Just solid flow of air at all times. right?
 

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Let me give a practical example on the m271 kompressor engine of the slk200.

With turbocharged engines that work with variable boost, you usually press the throttle hard enough ,revs increase along with the exhaust gases running the turbocharger, you get a momentary overboost of say 0,8 bar and then a steady boost of say 0,6 until the end of the engine's revs (the boost may decline in the end, it depends on the mapping of the engine etc ..). Whatever the scenario the turbocharger can be made to work harder or less so and deliver various amounts of boost.

With a kompressor engine, i.e the M271, the kompressor has a steady boost of 0,6, with the maximum torque of the engine being ata 4500 revs and maximum power at 5500. No matter the throtle position the eaton type kompressor produces the same amount of boost.

There is a steady flow of air at all times but as the revs of the engine increase, the supercharger must work harder in order to provide the increased volume of compressed air necessary for the engine to work. When tuning a supercharger we make it work harder by using a pulley that will allow for more revs of the supercharger,and thus increased volume of air delivered per engine revolution.


The major difference between turbochargers and kompressors, are that the first utilise exhaust gases to spin the turbocharger and thus increase the power input of the engine, while the kompressor is driven by using a belt driven by the engine itself.

The kompressor thus has the added advantage of having no lag in spining up since
it is directly related to the revs of the engine and does not need the exhaust gases to spool up
its internals and help compress air. It also does not need the more intricate cooling solutions of the turbocharger that has to deal with the hot exhaust gases.

The main disadvantage of the supercharger is that it is more parasitic to the engine than the turbo, i.e consumes more power from the engine in order to work. Advanced design and manufacturing nowadays has helped a lot in that regard.

For me the biggest advantage of the supercharger is its abilty to provide instant power with a partial throttle and power that is more linear as relating to the engine's revs, for that all important positioning of the car in a corner through drifting,power-sliding etc :).....


Then again a 450 bhp turbo rally car is a brutal thing of beauty :)

Please correct me with any inaccuracies. I have been typing too fast
 

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Founding Member #2 2008 SLK55 AMG
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That was a GREAT explanation ierax. Thanks a bunch. (BTW, only about 20 days left from delivery :) )
 

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Premium Member 2000 SLK230 Over 100,000 miles!!!
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Discussion Starter #6
Gotchya! Very understandable. Thanks for the info.
I now know what I am dealing with.

So that all ties into a larger pulley, right?

Is it the larger pulley turns the kompressor faster making more air flow resulting in more power?
 

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Great link dsb Thanks!!!

etyu my friend..Yes it is only 20 days :bannana::bannana::bannana:.... I hope that my precious will come on time..This bremen factory shutdown due to holidays, has me a bit worried, but my car is set for production as we speak..so fingers crossed.

slkman, it ties to a different pulley as far as the revolutions of the eaton type compresor is concerned.You will have noticed in the first link the two counter-rotating lobes that spin towards each other.

Nevertheless,it goes without saying that once you maximise the amount of air going into the combustion chamber you need the necessary amount of fuel, and the exact timing to detonate it....
Sometimes the standard ecu can compensate for that (in the case of the m271, mercs come with an 143,an 163 and an 193 hp variant of the same engine.
You will see tuners like carlsson, that tune the standard engine from 163 to 195 hp,only provide what amounts to a pulley kit, leaving the stock ecu to compensate).

If you are going to tune the engine further and until a point where you are sure that your internals (pistons, conrods etc) will hold, then you will need a differently mapped ecu,or a parallel ecu.

The ease of going from 163 to 195 without ecu intervention,just with pulley ancillaries, is something typical of eaton type kompressors who are more efficient in the lower rev band,providing more torque etc.

By changing the pulley, you fill up the upper rev band,but parasitic losses are higher...
You may encounter the eaton kompressor referenced as a modified roots type kompressor.

Root was a copatriot of yours :usa:, and a root kompressor was not a forced induction device as the turbocharger or the eaton kompressor, since it did not produce any vacuum (in layman's terms boost)...

I believe roots was initailly invented as an air pump to circulate air in furnaces :D
 

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Interesting reading!
First: the standard boost level is as I understand 0.6 bar and with a pulley kit 0.8 bar. Is it possible to get say 1.0 bar with or without lowering the initial compression ratio of 9.5? The higher boost, more power or?

Second: is there any known gauges that one could use monitoring the actual boost level just to confirm that everything is running as expected? Perhaps one that shows 0 - 1.0 or 0 - 1.5 bar.
 

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i know you can buy aftermarket boost gauges which read from anywhere from 0 to 2 bar of boost.
i would recommend 'autogauge' for quality and very well priced.
 

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Registered 1999 SLK230
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As far as guages go, in the early days of turbo's we were able to get vacum/pressure gauges that we just tapped into the intake manifold.

So i would assume that they would still be around in any good auto shop

The reason for a vacum/pressure guage is that a normal engine has to Suck in air/fuel hence the vacum, and once the turbo kicked in you would then transition from the engine having to suck to the turbo forcing the air\fuel in hence the pressure side of the guage.

And a big difference with a turbo was the faster you went the higher the pressure of the air/fuel untill the engine would exceed it's ability to remain in one piece.

This self distructive aspects of turbos was solved by either limiting exhust/input size or a waste gate which dumps pressure.

So as was stated before a supercharger uses more power as you go faster, so in a way limits the top speed of the engine by creating load, a turbo has no such restriction.

Sorry for going off course there but what i was going to ask is that i thought that the early SLK engines had a cutin pully similar to the aircon?

Will need to look that up, (or someone else might know) i know that its not relevant to original post but might be of interest to other readers.

Cheers
 
S

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That roots supercharger was also used on early model 2 cycle Detroit series truck engines - such as the 318 Detroit. The 2 cycle made a blower almost mandatory to push fresh air into the cylinder as the piston was in compression stage. Those engines had no valves as with a 4 cycle, but only oval ports to allow inlet and exhaust.

Google 2 cycle Detroit engines for more info.

Detroit used those engines for a long time. They were fuel hungry as a lot of wasted unburnt fresh diesel was blown out the exhaust ports. Detroit compensated with the 90 or 92 series engines that attached a turbocharge to the roots blown 2 cycle to increase the HP.

Cummins and Cat engines were 4 cycle - plus cummins added a turbo and had more HP plus fuel MPG efficiency over Detroit. Detroit finally saw the end of the 2 cycle - and converted to a 4 cycle for their OTR truck engines.

There are still some applications that use the 2 cycle Detroit in Marine/Boats and other odd areas.
 

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The stock ECU will only allow additional air volume passed (boost pressure will stay the same) as long as the MAF does not register more than 4.9 volts. Anything over 4.9 and the ECU will open the divertor valve and any additional volume will go straight back into the airbox. The ECU will need to be fooled into the MAF supplying less than 5 volts or the MAF voltage will need to be "clamped" to 4.9 by a zenor diode in series
 

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Registered 1999 SLK230
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That roots supercharger was also used on early model 2 cycle Detroit series truck engines - such as the 318 Detroit. ..........

There are still some applications that use the 2 cycle Detroit in Marine/Boats and other odd areas.
We stil come across a few of these runing standby power supplies in older industy/hospital etc..

Cheers from down under
 
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