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Supercharger & Turbo


navygm
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both supply compressed air to the engine - because the compressed air contains more O2 particles than normal, this means when ignited with fuel, you get a bigger, more powerful explosion.

A turbocharger works by the exhaust gasses, which spins up the impeller, which in turn, compresses the air, which is then fed into the engine.

As such, as you accelerate, a turbo has to build up momentum before it is up to speed, and capable of delivering the compressed air into the engine.

As I said, a supercharger is exactly the same, but it is driven via a pully from the engine - this means the charger is constantly running, and the impeller speed is directly relavent to the engine speed (generally 2 or 3x rpm) and as such, gives a much more progressive increase in compressed air...

Because a supercharger is more linear, you do not get the same 'all at once' boost sensation that you get from a turbo - but the performance increase is much more spread over the rev range.

Each method has its advantages, depending on the car and what you want..

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Correct. The limit for engine power is how much air you can get into the engine (volumetric efficiency) the reason being that you need oxygen to burn fuel.

In a perfect world you have a stochiometric mixture. Simply correct volume of fuel to air. example.

Methane+Oxygen => Carbon Dioxide+Water+Heat

or

CH4 + 2 x O2 = CO2 + 2 x H2O + Heat

This the simplest but essentially the same combustion calculation that any fuel burning uses. Petrol is far more complex than Methane (and is a liquid) hence it is very easy to force through injectors into the engine. Air is a gas and therefore far more difficult

This means you make the air flow into the engine as easy as possible, add excess oxygen (ntrous oxide) or compress the gas (super-charging)

Superchargers came along first and the compressor section is driven by a pulley off the crankshaft. Advantage is immediate response as the compressor is linked directly to the engine so it picks up straight away. disadvantage is you are mechanically driving a pump by the engine and the friction losses increase the faster the engine runs. This means they draw off an awful lot of power at high revs. This means thay're most suitable for engines where you want to get good initial pick up and good acceleration (such as dragsters)

Turbo-chargers (actually they're Turbine powered superchargers) utilise the exhaust gas to drive the pump. This removes the direct connection to engine so stops the draw off of power at the top end. Traditionally however the lower velocity gas at low RPM stops the turbine spinning properly. This causes a pressure increase of exhaust gas behind the turbine stifling the engine resulting in turbo lag. This made them tricky to drive smoothly since all the power arrives in a sudden burst. More recently though variable geometry turbo-chargers have alleviated this problem a lot (allows the turbine to be optimised across the entire rev rage rather than being compromised to have to work across the entire rev-range)

There is another type called the pressure wave supercharger. It's a kind of hybrid of the two. Essentially the pumping work is performed by the gas but the unit is powered by the crank. Imagine a barrel filled with lots of very narrow tubes. The engine causes the barrel to rotate with one end of the tubes mating to the exhaust and the other to the intake. The pulse of gas from the exhaust slams into the air from the intake driving the charge into the engine (the narrowness of the tubes essentially stops exhaust gasses mixing and hence maintains power). Because the engine isn't doing the pumping it doesn't lose top end power but because the unit is powered by the engine it doesn't suffer lag. The BIG disadvantage of this type of unit is it's the same principle that air raid sirens run on so the noise is horrific and makes them unsuitable for most applications

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super charged are run by belts,and takes in more air into the engine from ethier and intercooler or air filter. you will get instant responce from the engine as soon as you put your foot down to the floor. but with super chargers you can only do so much it will never be as much bhp as a turbo. with a turbo theres much more fun when u pushing hard your waiting for it to spool up over 3000rpm theirs more g force and bigger the turbo you have the more power and lag, myself i wud perfer a turbo over supercharge system

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Correct. The limit for engine power is how much air you can get into the engine (volumetric efficiency) the reason being that you need oxygen to burn fuel.

In a perfect world you have a stochiometric mixture. Simply correct volume of fuel to air. example.

Methane+Oxygen => Carbon Dioxide+Water+Heat

or

CH4 + 2 x O2 =  CO2 + 2 x H2O + Heat

(and the rest)

Thats a bigger word count than in my asseys from uni days! :thumbsup:

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Great info guys. I never knew that Turbocharger was a contraction of Turbine powered supercharger. Makes sense though.

Like the idea of the 'pressure wave supercharger'; where can I get one?

I know what you mean Fidgits, but I'd question whether superchargers are 'constantly running'; the MR2 Mk1 supercharger was connected via a centrifugal clutch so that it only ran when required and I think that's true of other Toyota superchargers.

I find it strange that Turbos are so popular, when in many ways the Supercharger seems to be a superior technology.

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You'd need understanding neighbours if you did use one. Remember hearing one years ago belting down the straight at a race track (can't remember where though) and it was painful it was so loud.

You can probably find one by searching on the web for Comprex or pressure wave supercharging (or something similar)

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Great info guys.  I never knew that Turbocharger was a contraction of Turbine powered supercharger.  Makes sense though.

Like the idea of the 'pressure wave supercharger'; where can I get one?

I know what you mean Fidgits, but I'd question whether superchargers are 'constantly running'; the MR2 Mk1 supercharger was connected via a centrifugal clutch so that it only ran when required and I think that's true of other Toyota superchargers.

I find it strange that Turbos are so popular, when in many ways the Supercharger seems to be a superior technology.

well yes, i know Mercs have a clutch system for the s/c - but thats really to stop it running on idle.

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first of all thanks very much for the info!!

so can I find a supercharger for a Vitz 1.0lt ?? and is it recomanded to do it? anyone has got?

now I'm trying to find one over the internet...

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