HIGHSURVEY

Pardon my ignorance on the subject but from what I have been able to gather supercharging an engine seems like a more efficient way to substatially boost HP. It seems to do the same/similar thing as a turbocharged system w/o the lag that seems to accompany the turbo system. As such I am wondering why Porsche remains loyal to this system to the exclusion of trying something new. I see that independent suppliers are producing superchargers for installation on 911 engines. I also have not heard many reports on satisfaction (or not) with these new systems. Obviously strapping on a non stock component will cause all sorts of problems vis a vis warranty (read void) but I wonder why Porsche has never tried it themselves.

Dr_KarlB

Im no expert also, but putting on my Scientist/engineer hat i would guess:

Super charger takes power away as it is driven of the crankshaft directly. It has a parasitic effect.
Turbo uses the gas thats blown out the back anyway.

Supercharger boost will be linked to the engine revs...
Turbo boost is linked to the gas you give the engine... (well approx anyway)

But i could be totally wrong too :-)

911Dave

Supercharging is very effective, but much less efficient than turbocharging. Aftermarket companies offer supercharging kits not because it's better, but because it's relatively easy to supercharge an engine through modification. It's far more difficult and expensive to add a turbocharger.

HIGHSURVEY

I agree with you Karlb about the "parasitic" effect of the supercharger as a result of being driven by (and off of) the crankshaft, however it's my impression that whatever negligible power is seeped from this arrangement the gains are so significant that the end justifies the means. And 911Dave I also agree with you that it is much more difficult and expensive to "turbo" than to "super" - hence we return to my original question - why doesn't Porsche "super"? Myself I would love to feel the effects of possibly increasing the horses by a factor of 1/3 (and I understand it can be done for less than $20K) (but then again the thought of having no warranty returns me back to terra firma again!). Oh well............

dstrimbu

I think Porsche's reluctance to supercharge is based on 1.) history and 2.) emissions.

The 911 Turbo has been "The Turbo" for what... 32 years? There's your history.

With a 'super, the parasitic losses are worst at low power settings, and I'd think this would affect emissions negatively... just MHO, I'm not an engine designer.

But hey, Ruf and others have stepped up, so you can have a 'super 997 for around $20k USD.

That would be a hoot, wouldn't it? <g>

Moogle

A supercharger also adds quite a bit of heat in the engine compartment, either way, adding forced induction to an engine that was not designed to be may very well reduce reliablity.

Neither is the "better" solution

Fahrer

Actually VW is developing a small engine that uses a turbocharger and supercharger. The relatively small turbocharger spools up quickly with basically no lag. Such a small turbine runs out of steam as rpms get relatively high and this is where/when the supercharger kicks in. Mercedes has been using superchargers for years in their gasoline cars in Europe but I think they are moving more to turbos. As stated previously, supercharger boost is tied mainly to rpms while turbo boost is tied mainly to airflow ( load).