The old VW 1.8 / 1.8T were the same.
A relevant comparison though to clarify the 1.8 T is turbo.
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I see, Kompressor is the German for Supercharger!
That means we can finally say there is now replacement for displacements :)
Why it is better than having a bigger engine (i.e. more torque) in the first place?
Edited by movilogo on 20/02/2008 at 13:03
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A smaller displacement engine should be lighter. I was also told (but am willing to be corrected) that a forced induction engine (whether by turbo or supercharger) will generally be more efficient for a given power output than a normally aspirated one.
Of course the downside is increased mechanical complexity, with intercoolers, additional drives and higher pressures all taking their toll.
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My understanding of a compressor (when used in a vehicle engine) is that its effect is linear throughout the rev range.
No doubt someone will put me right...:-)
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The forced induction gives optimum cylinder filling at a far wider range of rpm compared with a normal "suction" engine, which will only give a decent lungfull at medium to high rpm.
More air in = more fuel So you can get a bigger bang at lower rpm = more work being done = more torque.
A supercharger **can** give a more linear boost, however latest-generation variable-nozzle turbos and twin-scroll turbos have levelled the playing field somewhat ... and they are easier to install and maintain than a supercharger.
As an example my old Volvo V40 2.0T (with a Mitsubishi twin-scroll turbo) gave 170ft-lb from 1900 to 4700rpm. Cracking engine, that was.
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AFAIK the Merc Kompressor engines use an Eaton M-62 blower, which is a Roots-type supercharger - based on the same design as the ones used on pre-war Mercs and Bentleys. (Mini Cooper S uses an Eaton M-45 - theres one on ebay now for £1.20!).
Some of the AMG Mercs use a supercharger with a more modern rotor design which is more efficient and develops more boost.
The blower is driven by the engine so produces boost from idle and so does not suffer the low-rev lag of a traditional turbo (but which is all but eliminated by modern turbo designs as described by Craig).
The downside is that a supercharger uses up some engine power to drive it.
Not much on road cars but the big superchargers on top fuel dragster engines need around 400bhp to drive them at high revs, but the net gain in power makes it worthwhile.
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My understanding of a compressor (when used in a vehicle engine) is that its effect is linear throughout the rev range. No doubt someone will put me right...:-)
Positive displacement blowers ( Roots-type for example) do give more or less linear output of boost with speed: centrifugal blowers, as used on the 1950's BRM 1 1/2 litre cars, gave boost which was almost square-law related to revs making the early cars very difficult to drive. (double revs = four times power, so tricky accelerating through a corner or even on a straight)
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I remember when in my teens being driven in an Austin 1100 fitted with a supercharger driven from belt from the crankshaft. Smooth , quiet, lots of pull an dit went like stink.
Iirc it was a Shorrocks supercharger available at the time as a kit for BMC A series engines.
I understand, however, the gearbox could not really cope with the torque and he went through front tyres, driveshafts and couplings like brake pads:-)
It was a superb Q car and was very quiet:-)
Edited by madf on 20/02/2008 at 21:21
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When I was young!! I used to secretly put a Peco booster on the end of the exhaust pipe of my late father's Austin A40. It gave a fraction more top speed so I thought!!
Seriously I truly love Mercedes cars.Ever since the later 1950s they have been my favourite car. The Kompressors amaze me. They change the output so much. I remember five years ago, a pupil's father had one of the more powerful petrol E Classes, his father raved about the engine.
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