Why do we not see switchable superchargers?

[OwenK]

Just a thought - why do we not see Mad Max style switchable superchargers for economy and big power when you want it? Yes obviously many people will say the a turbo does vaguely the same thing if driven properly, but I personally don't get on with turbo power delivery - hate the lack of grunt in my ZT if I put my foot down at the wrong RPM, or pulling away at junctions for example.

I always was under the impression that a clutch mechanism to disable the SC would be too complex, but on reflection air con compressors are belt driven by a switchable magnetic clutch, so what's the problem?

[jason s4]

I think there are some that operate via hydraulics and a clutch?

[XitUp]

Don't the VW twin charged engines have this?

[Liquid Knight]

Some of the Merc' Kompressors have it as well.

[cml]

Good question - I have wondered too - I wanty a big toggle switch marked 'supercharger' on the dash.

[Ozzie Osmond]

OwenK said:

air con compressors are belt driven by a switchable magnetic clutch, so what's the problem?

The only thing I can think of is the a/c belt/clutch doesn't have very much work to do. I think that driving a supercharger can require up to 100 bhp from the engine so the belt and any other mechanism needs to be pretty beefy.

I also thought the whole point of a supercharger is that it works right from low rpm.

[RobM77]

Ozzie Osmond said:

I also thought the whole point of a supercharger is that it works right from low rpm.

So, for example, a car could have 200bhp be default and good emissioms to satisfy the EU, and then at the flick of a switch, when you turn off the motorway or out of town, it could have 275bhp and the driveability a s/c gives.

[OwenK]

Anybody know how the VW and Merc systems work, then? I do hope it's not an RPM based thing, thus defeating the object of the SC?

I too want a big red Supercharger button (if not available, "Go baby go" would suffice).

Low down poke of a supercharger or big engine (or both!) really appeals - what's got me onto the subject is the poor mileage we're getting to the MG's tank & I'd really like the option to "switch off" the turbo for cruising at any RPM I fancy, plus the abilty to not have to thrash the life out of bloody thing to get onto roundabouts etc from a dead stop.

Edited by OwenK on Sunday 5th June 11:27

Edited by OwenK on Sunday 5th June 11:29

[davepoth]

That was why Mad Max had the switch anyway. I intend to fit one to my car...

[the-photographer]

OwenK said:

Anybody know how the VW and Merc systems work, then?

I too want a big red Supercharger button (if not available, "Go baby go" would suffice)

If want to build your own one, you can look how VW did it here;

http://www.volkspage.net/technik/ssp/ssp/SSP_359.p...

However, the VW implementation only works at low RPM because the turbo takes over beyond 3500rpm.

[P I Staker]

The Mercedes Kompressor cars use a super charger with an electro magnetic clutch, i know some one who has put one on his Land Rover fitted with a switch, on road he runs it just on the original turbo and offroad he presses the button and it runs on both the super charger and the turbo.

[XitUp]

RobM77 said:

Ozzie Osmond said:

I also thought the whole point of a supercharger is that it works right from low rpm.

So, for example, a car could have 200bhp be default and good emissioms to satisfy the EU, and then at the flick of a switch, when you turn off the motorway or out of town, it could have 275bhp and the driveability a s/c gives.

Could you not have it activated via a sensor on the throttle? So it only engages at say, 2/3 throttle? Or would that lead to lag? Someone make one and let me test it.

[davepoth]

XitUp said:

Could you not have it activated via a sensor on the throttle? So it only engages at say, 2/3 throttle? Or would that lead to lag? Someone make one and let me test it.

Mercedes did that with their cars.

[gamefreaks]

But surely, FI cars need to have lower compression ratios, so a good FI engine with a low compression ratio is going to be pretty lousy without the SC/Turbo.

[attym3]

Only ''the last of the interceptors'' have this.

Mark

[MikeyBe]

As far as I know, the clutch on the Merc SLK kompressor engages at 1500rpm. It isn't used for economy, but to disengage the kompressor at low rpm and help maintain a stable idle/emissions.

Just what I've been told, mind.

[mattmoxon]

It can (and has iirc) be done but to use the engine to it's full potential without the SC rotating you would need a second intake that bypasses the SC (Y pipes before and after the SC that directs the air around the SC). I would imagine it is not done because of the cost and complexity it would add to the car, it would be easiest on a car with a centrifugal SC, but imagine trying to do it with a roots or twin screw type SC!!

Plus I agree with what Swerni said, most people that fit aftermarket SC systems to Mustangs (roots and centrifugal types) seem to see very little (if any) reduction in fuel economy.

Edited by mattmoxon on Sunday 5th June 13:45

[aeropilot]

OwenK said:

but I personally don't get on with turbo power delivery - hate the lack of grunt in my ZT if I put my foot down at the wrong RPM, or pulling away at junctions for example.

You just need to drive a decent turbo'd engine

[M5 Russ]

cml said:

Good question - I have wondered too - I wanty a big toggle switch marked 'supercharger' on the dash.

I want a pull switch on the gear stick