Why aren't more cars supercharged?

[dan5oclocksmith]

Forced induction these days usually means a turbocharger on production models. There was a time when Jag and Merc had supercharged models, and VW were using super- and turbochargers (they may still, I'm not sure).

So why is supercharging less popular than turbocharging? I'd assume that emissions and consumption are worse, but I'm just guessing really.

So people, factoid me up.

[LawrenceF]

Parasitic loss.

[RobCrezz]

Turbochargers are more efficient. Driven by the waste exhaust gasses, rather than sapping engine power by being driven by a belt.

[Changedmyname]

RobCrezz said:

Turbochargers are more efficient. Driven by the waste exhaust gasses, rather than sapping engine power by being driven by a belt.

A good enough answer for me.^^

[richardxjr]

Both is even better. For example, the Volvo D6 diesel marine engine: Supercharged up to 2300rpm then the turbos take over.
Lag free.
Don't some trucks use this as well?

[dan5oclocksmith]

Yep, seems reasonable!

My ropey old XJR is the first FI car I've had, and the noise of the supercharger is fantastically addictive, as is the smoothness of the power delivery.

The trips to the pumps not so much, but hey, it's a reasonable trade-off in my eyes.

[dan5oclocksmith]

richardxjr said:

Both is even better. For example, the Volvo D6 diesel marine engine: Supercharged up to 2300rpm then the turbos take over.
Lag free.
Don't some trucks use this as well?

VW Golf (and Polo?) GT was the car I was thinking of that has both - a 1.4 from memory.

[SystemParanoia]

http://www.autocar.co.uk/CarReviews/FirstDrives/Ni...

[dan5oclocksmith]

Perhaps you guys can educate me then - I assume that as a turbocharger works off exhaust gases, the point at which the turbo "cuts in" is dictated by the point in the rev range where the volume of exhaust gas is enough to spin the vanes of the turbo at sufficient rate to compress the air and provide boost?

In which case, I assume a supercharger is always spinning, but only generates boost above a certain engine RPM too?

I know nuffink

[shibby!]

I think HKS used to do a tuning kit that was twin charged. But i only remmeber it being used on a few Toyota engines.

Been around for quite a while.... i remmeber some mentalist had it on a 1990 Corlla Gti.

Also think the old Delta rally car was twin charged.

[Ramses]

Seem to remember a story that a (certain) supercharged car was estimated to lose 70bhp to drive the supercharger, therefore the supercharger needed to add twice that to make any material gain....with the fuel consumption that came with it.

Same article stated that that issue alone would be the death of supercharging.

[jagnet]

Presumably there are still losses associated with spinning up a turbo though - I struggle to believe that exhaust gas extraction from the cylinder isn't slowed by being put to work powering the turbo.

I'm guessing that for a small econobox box engine, you get the best of both worlds with a turbo. Off boost economy isn't going to be much worse than an equivalent sized normally aspirated engine, whereas a supercharger operates at all rpms.

I can also imagine that the noise of a supercharger wouldn't go down well with many drivers. In the right car however...

[Rovinghawk]

dan5oclocksmith said:

I assume a supercharger is always spinning

Older SLKs worked a clutch system to the supercharger drive pulley- only cut in over about 2500rpm iirc.

RH

[worsy]

dan5oclocksmith said:

richardxjr said:

Both is even better. For example, the Volvo D6 diesel marine engine: Supercharged up to 2300rpm then the turbos take over.
Lag free.
Don't some trucks use this as well?

VW Golf (and Polo?) GT was the car I was thinking of that has both - a 1.4 from memory.

And the B8 Audi S4 is s'charged.

[CO2000]

This Evo 5 uses both to great effect

http://www.youtube.com/user/evomadmac#p/u/0/8oqlPg...

http://www.youtube.com/user/evomadmac#p/u/23/Px41X...

[RB Will]

jagnet said:

I can also imagine that the noise of a supercharger wouldn't go down well with many drivers. In the right car however...

or this

http://www.youtube.com/watch?v=2lQX3cOAbes

[KevSeymour]

dan5oclocksmith said:

Perhaps you guys can educate me then - I assume that as a turbocharger works off exhaust gases, the point at which the turbo "cuts in" is dictated by the point in the rev range where the volume of exhaust gas is enough to spin the vanes of the turbo at sufficient rate to compress the air and provide boost?

In which case, I assume a supercharger is always spinning, but only generates boost above a certain engine RPM too?

I know nuffink

I'm no expert but from my understanding the SC would generate boost throughout the rev range, they're just not always very obvious at low revs and don't generate as much boost at higher revs as a TC.

I'm hypothesising here but i imagine on the VW 1.4 they rely on the SC up to somewhere in the 2.5-4k range at which point the TC comes in to add to the total available boost - being described as 'twin' charged suggests that both the SC and TC work simultaneously.

[RobCrezz]

dan5oclocksmith said:

Perhaps you guys can educate me then - I assume that as a turbocharger works off exhaust gases, the point at which the turbo "cuts in" is dictated by the point in the rev range where the volume of exhaust gas is enough to spin the vanes of the turbo at sufficient rate to compress the air and provide boost?

In which case, I assume a supercharger is always spinning, but only generates boost above a certain engine RPM too?

I know nuffink

The turbo will produce boost when: There is enough load on the engine, the throttle is open enough and the revs are high enough to (boost threshold) to get the turbo spinning. These amounts are different for different turbos as there are hundreds of different types.

Essentially a turbo is just a supercharger (compressor) with a shaft attached to a turbine which is driven by exhaust gasses. It then uses a wastegate, which opens and closes to reach and maintain the desired boost (and avoid over boosting).

Additionally there are a few different types of supercharger. Centrifugal superchargers are essentially the same as a turbocharger, but instead of the exhaust turbine section, this is a belt drive from the engine. Positive displacement superchargers are different again...

http://en.wikipedia.org/wiki/Supercharger

[Chicane-UK]

I'm pretty sure I wasn't dreaming when I saw a TV commercial yesterday that said the new Nissan Micra was supercharged....

Ah - Google answers all! --> http://www.which.co.uk/news/2011/02/nissan-announc...

Nearly 100BHP and free from road tax and congestion charging! Schweet!

I used to own a Corrado G60 which was 1.8 8v with a supercharger.. made a very unusual sound. Mine had some tuning work done to it to give it over 200BHP and it was quite a giggle - but utterly appalling on fuel consumption, especially when in traffic.

[cptsideways]

The current Golf TFSI engine is twin charged