[iraghava]

Originally Posted by RedMM340

Superchargers on large V8 motors can chew up 60+ horsepower at 5000+ rpm, so are just not that efficient at high rpm.

That was partly the reason Mercedes discontinued their 5.5L Supercharged engine. It was apparently robbing them of 100 bhp at peak rpm.

[v1p3r]

The whole loss factor is a bit overstated. You lose 100 hp but then you're gaining a lot more from the boost. It's not so much a loss in itself, as much as it is a deduction from the power increase.

If superchargers were so inefficient, top fuel dragsters wouldn't be using them.

[Mpower]

Originally Posted by RedMM340

Plus the SC has a much high cost and as far as I know there are no SC production cars here in India. With the possible exception of Mercedes? So in an extremely price sensitive market like India, Superchargers will not proliferate. Even in the U.S., SCs have just a fraction of the marketshare of turbos

Yes. Merc offers the C200K and E200K in India and no problems with dust have been reported so far. Audi A6 for 2009 will have supercharger standard on their V6s.

With any kind of compressor clearance between impeller and housing is critical. Even in turbo's compressor the goal is to minimize the clearance between the impeller and the housing for better efficiency. In fact Nissan once designed an abradable impeller that they would artificially wear to get the absolute minimum clearance.

[Dante]

Well many of them must be knowing this but for some who don't know, stick around.

Turbocharger VS Supercharger

Let's start with the similarities. Both and superchargers are called forced induction systems. They compress the air flowing into the engine*. The advantage of compressing the air is that it lets the engine stuff more air into a cylinder. More air means that more fuel can be stuffed in, too, so you get more power from each explosion in each cylinder. A turbo/supercharged engine produces more power overall than the same engine without the charging.*
*The typical boost provided by either a turbocharger or a supercharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50-percent more air into the engine. Therefore, you would expect to get 50-percent more power. It's not perfectly efficient, though, so you might get a 30-percent to 40-percent improvement instead.

*The key difference between a turbocharger and a supercharger is its. Something has to supply the power to run the air compressor. In a supercharger, there is a that connects directly to the engine. It gets its power the same way that the water pump or alternator does. A turbocharger, on the other hand, gets its power from the exhaust stream. The exhaust runs through a turbine, which in turn spins the compressor. There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs. Superchargers are easier to install but tend to be more expensive.

Note from the Team-BHP Support Staff : Do make sure that you provide the references/original source for every piece of material that has been taken from another website/publication, to give credit to the original author.

Source - HowStuffWorks "What is the difference between a turbocharger and a supercharger on a car's engine?"

[Technocrat]

For more definitions on both check This Thread

[Gany]

There are engines that have both - at low speed supercharger works & once enough boost is created turbo comes into picture when a clutch disengages the drive!
The only problem with turbo is 'lag', going in for low inertia turbo decreases the turbo lag, but then increases the boost at high rpms beyond the limit. This is where wastegated turbocharger comes into picture. Here at high rpms/boost the exahust is let off directly to the exhaust instead of passing through turbo. VGT's are newest entries where the boost is controlled at different speeds making the turbo to be effective through most of the operating regions!

[PRADEEP KUMAR]

Folks,
Somehow i have got a feel that the Turbo in my Scorpio CRDE 2.6 is not performing optimally.
How do we check its performance? does the regular A s s set ups have some equipment to handle it?

tnx

[iceman91]

the Golf has a supercharger and turbo charged engine.

Pradeep wrong thread but yes you can get it checked at an A S S

[Kappa]

Hello! I was wondering on this for quite a long time. The challenges we face today, regarding turbochargers in our cars (like turbo-lag etc.) are something which give the petrol cars an edge over the turbocharged diesel ones, and also make the petrol motors the better choice for us petrolheads.

But wait, what if we use an air-compressor(air pump) for the purpose of forced induction, instead of the traditional exhaust gas driven turbine-based turbocharger? The compressor could be fitted at the air intake of the vehicle, attached to a dedicated micro-computer which monitors and adjusts the power of the compressor in real time, based on the requirement of air by the engine, which would further depend on the throttle input by the driver. And regarding the problem of the energy that could be used up by the compressor, regenerative braking could help us here. The energy wasted by the vehicle could be saved and be made available for use, which shall be used exclusively by the compressor, thus freeing up the engine from any extra loads. This can greatly benefit us during city traffic conditions as we tend to brake a lot while under heavy traffic.

This way, the problems like low rpm turbo-lag can be solved, and will make the turbo'd diesel engines quite versatile - torquey, fuel efficient, plus no turbo lags!
And yes, this idea should work not only for the diesel engines, but also for the modern turbocharged petrol engines like the Ford Ecoboost, VWAG's TSI engines etc.

So, what do you think ?

[a4anurag]

Originally Posted by Kappa

But wait, what if we use an air-compressor (air pump) for the purpose of forced induction, instead of the traditional exhaust gas driven turbine-based turbocharger?

Just a thought - Will the 'Air Pump' be able to hold on to the boost in power that will be generated?! Varying load condition? heat generated? sustained high RPM's?

Originally Posted by Kappa

This way, the problems like low rpm turbo-lag can be solved, and will make the turbo'd diesel engines quite versatile - torquey, fuel efficient, plus no turbo lags!

If the low-end driving is the issue, add another smaller capacity turbo for lower RPM effectiveness and for regular highway ones keep the regular turbo in place. 2 turbo's will do it!

Why not a Super charger?!

[CrAzY dRiVeR]

What you are talking about is essentially a super charger. And you have mentioned the disadvantage yourself - it saps energy.

Regenerative braking might give you back some of that energy but it doesn't prevent the wastage of energy and pushes the costs higher up, now doesn't it?

Also- turbo lag can be enjoyable as well, depending on the tuning. Cars like the original Swift DDiS, Cruze VCDi were all known to be more enjoyable when they had turbo lag followed by a grin inducing boost. Not the case for cars like Corolla D4D, original Renault Fluence etc where the boost is actually required to get the car moving, forget having fun with it.

PS- In my personal opinion, I think NA petrols have lost the edge they once had over diesels. Modern diesels are not only fast, but very efficient as well compared to their NA petrol counterparts. Also, if the diesel suffers from turbo lag- the NA petrol suffers from weak low end torque. However, give me a turbo petrol like the 1.4 TJet or the 1.8 TSi- then we are talking!

[rajeev k]

Turbochargers are also, sort of air compressors. The centrifugal air compressors are exactly the same. These also runs at much higher rpm and are highly efficient and consumes much lesser power.

Today almost all major industries are going in for centrifugal compressors to meet their compressed air requirement.

Centrifugal gas compressors were used since a long time in Fertilizer and Petrochemical industries for compressing syn-gas and other gases.
Air and Gas compressors are multistage and quite big, whereas Turbochargers are smaller.

[dhanushs]

Originally Posted by Kappa

This way, the problems like low rpm turbo-lag can be solved, and will make the turbo'd diesel engines quite versatile - torquey, fuel efficient, plus no turbo lags!
And yes, this idea should work not only for the diesel engines, but also for the modern turbocharged petrol engines like the Ford Ecoboost, VWAG's TSI engines etc.

So, what do you think ?

The turbo lag problem was solved as soon as it was implemented, AFAIK (Twin turbo, VGT etc. etc.) . However, the issue was to implement it in common, day to day use cars, which needed cost effectiveness and fuel efficiency.

The Air Pump that you mention here, is basically a electrically driven supercharger. Usually, which are belt driven by the crank pulley.

Google Superchargers Vs Turbochargers to get more info regarding this topic.

[rpunwani]

The speed of a supercharger which is engine driven or a turbocharger which is driven by the exhaust gas varies with the speed of the engine. With an air pump, it will be extremely difficult to control the amount of air being supplied to the engine intake. Needless to say, the exhaust emission will vary significantly and most probably not comply with BS IV or later versions.

Even if you can accurately vary the flow of air into the intake depending on engine speed, you will utilize a fair amount of power (and therefore fuel) for operating the air pump.

One crazy idea is to have a compressed air tank and connect a line to the engine intake through a valve, the opening of which can be connected to the throttle/accelerator pedal

[.anshuman]

Audi is working on such a system. The RS5 TDI prototype with 3.0 TDI engine gets a 48v electrically driven Supercharger, which provides initial boost till the Turbocharger spools up and takes over from there on.



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