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Porsche Crest Supercharged Porsche....

Why doesn't Porsche supercharge any of their cars? With so many other lower priced cars nipping at their heels and some flat out cleaning their clocks (new Vette Z06), supercharging must have been discussed. No? How about a V-8 version of the CGT's V-10 engine? In todays horsepower wars 400 horse ain't what it used to be.

What are your thoughts........
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Old 01-10-2005, 09:57 PM
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Because with the progression of turbo technology that's leading to quicker spooling and more responsive engines, superchargers are pretty much obsolete on high-end cars.
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Old 01-10-2005, 10:00 PM
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turbos are also "free" horsepower. blowers are belt driven usually and cause drag=less hp. also, blowers are often times heavier than a turbo as well and for longevity usually need an oil line plumbed to it for lube, as if a Porsche doens't have enough oil lines on it! besides, I don't think there is alot of room to bolt on a supercharger onto a 911.
Old 01-10-2005, 10:20 PM
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Quote:
Originally posted by gmiles
turbos are also "free" horsepower. blowers are belt driven usually and cause drag=less hp. also, blowers are often times heavier than a turbo as well and for longevity usually need an oil line plumbed to it for lube, as if a Porsche doens't have enough oil lines on it! besides, I don't think there is alot of room to bolt on a supercharger onto a 911.
Turbochargers obstruct the exhaust flow and cause backpressure which is a parasitic loss similar to the drag caused by the belt on a supercharger. Turbos are also oil fed.
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Old 01-10-2005, 10:27 PM
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I'll take it from a marketing standpoint. When I was a kid, my dad told me the car to have was the TURBO Carrera. It was always "TURBO" this or "TURBO" that.

TURBO is what the very high-end Porsche is associated with. The added bonus for Porsche is the Turbo has also won races.

Has a supercharged Bentley won races? I dunno.
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Old 01-10-2005, 10:31 PM
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Here we go again.

There are heaos if discussions like this lurking in archives. I won't pull all that again but it all boils down to superchargin being the worse method of raising power.

Less dependable, less efficient, costs more money etc.
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Old 01-11-2005, 03:30 AM
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I don't know why a supercharger would be less dependable, there is typically much less complexity than for a turbo. They are less efficient from a power standpoint but adding a supercharger is definintely cheaper and easier than adding a turbo. So I guess it all depends on what your definition of "efficient" is.

I'll have to blame the marketing too. I think some of us might feel a little let down if Porsche went to superchargers. We'd like to think Porsche spares no expence to build the best car possible and the use of superchargers does not build that impression. IMO
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Old 01-11-2005, 04:03 AM
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Old 01-11-2005, 06:26 AM
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Speaking form a non-emotional standpoint....both forms are supercharging.

Turbocharging is supercharging with a compressor wheel driven by a turbine in the exhaust stream. ( "Turbo-compressor" pairing).Supercharging is simply the compressor mechanically driven.

The compressor doesn't care ( or know) what's on the other side of the shaft that drives it ( in simple terms).

Porsche ( the elder) did supercharging for Mercedes-Benz street and racing cars as early as the twenties. There is a strong history by Porsche ( the man and the company) for both types.

Basically....Turbos seem better matched for ultimate high end hp ( like tunneling down Mulsanne at LeMans) and Superchargers are better for immediate low speed response out of corners.

Both work...both have positive and negative aspects that can be largely overcome....

Wil
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Old 01-11-2005, 06:27 AM
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No. Turbocharger has only one moving part -> the turbocharger shaft. It spins on oil-film bearings that actually don't wear as long as there is oil pressure. There are no rubber belts that transfer tens of horsepowers, no mechanical gearboxes (for centrifugal superchargers), no big moving assemblies that require fine tolerances (roots, Lysholm), no need for inefficient recirculaten valves that are just wisping the air around when driving on half-throttle (all superchargers).

This is a no-brainer and all manufacturers knew this for decades. That's why you'll find avery few production cars fitted with supercharger. It's heavy, it's expensive to fit and produce, it's less reliable.

Turbocharger has only piping,one moving shaft and wastegate. Supercharger has to steal power from the crank and either transport it trough rubber belt (10's of HP's trough rubber-belt, what about reliability?) then pipe that power into big cumbersome spinning thing that needs tight tolerances (=expensive) or into "half of turbocharger (=precision gears to make it spin >60k revs).

Turbocharger produces back-pressure for the engine but also uses some of thermal energy stored in exhaust gases. Typically, turbocharged car will have better efficency than supercharged one, despite "backpressure".

And yes, I know there will be fifteen V8:driving good old boys telling you how easy and cheap it is to fit supercharger on the motor but this should be looked up from a wider perspective.

Yes...I know that some of you had _________ (fill in some turbocharged car) that had turbocharger failure and that you had _________ (fill in some pony car name) with supercharger that you think work great but in reality, that is only anecdotal evidence. In long run, superchargers are a bad solution. I believe there are lot's of "good old boys" that had experimented with superchargers, which subconciously makes them believe superchargers are best thing since sliced bread.

Reality is something else. Superchargers only benefit (instand boost response) is outweighted by it's numerous drawbacks in most applications bare niche cars (MErcedes AMG etc.) or heavily regulated sports (dragracing where NHRA "locked" technology on 50's level).

There might be few DIY applications where supercharger might be easier and cheaper to install (especially if person doing installation is acustomed to superchargers) but on bigger scale it's inferior solution.

It's 2005, remember? Cars are no longer equipped with carbed V8's and turbochargers are not exotic pieces anymore. They are cheap and readily available. Technology is constantly developing so sometimes it's hard to constantly re-learn and change opinions and preferences.

Who knows, I might be hanging on this board in twenty years, teaching youngsters that turbochargers are really the best thing around...and that their tuned 500hp hydrogen hybrid vehicles are bad.
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Old 01-11-2005, 06:41 AM
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Beepbeep:

Tell me precisely what you're answering "no" to....

I stand by the fact both forms are considered "compressed intake" charging systems. Porsche used Turbos because of the link to racing and the rules in effect at the time...also for the demands put onto them for where the hp was needed. Plug it into the equation and the answer was Turbocharging.

If the need ( or rules) demanded instantaneous power response, especially down low...then supercharging would be the better answer. I didn't specifically want to go tit-for-tat on a unit-by-unit comparison...but turbo lag ( as a negative) can be reduced by using smaller, faster spinning turbos ( in addition to a host of other things that can be done) and parasitic losses on Supes can be reduced by combinations of recirc, and clutch type systems ( like A/C).......and yet other things, too.

In both cases , a compressor of some sort is driven by some means. One way to drive it is via exhaust gas ( also not "free" ,...to counter your point that "rubber belts that transfer tens of hp"..)..and the other way is to drive it mechanically. The compressor doesn't care, in simplest terms.

No question....if you use ineffecient components in one case....and compare it to efficient set ups in the other case....a skewed comparison results. You can't compare the engineering behind a factory set up ( in either case) relative to a badly done home brew of the other.

I also won't argue your ( or known others') direct experience on this topic. Regardless...it doesn't mean you've encountered all the possible ways/means to do any one type of system.

Both can work if properly designed and executed. Both have drawbacks and strengths that are generally exclusive ( high end vs low end power).

Wil
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Old 01-11-2005, 07:01 AM
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Quote:
Originally posted by jfpound
... but adding a supercharger is definintely cheaper and easier than adding a turbo.
(NOTE: im not bashing jfpound or putting him down just playing around and its all in good fun. )

I think you are wrong there, Turbos are about as cheap as power comes for $ per horse. The 928 supercharger kit that tsuter is showing cost nearly 5 grand for the base kit. So you are now saying "but a turbo cost just as much", right but a turbo you can increase boost pressure much cheaper and start making power faster. Your next response, " but you will need an intercooler" okay lets up the game the 928 supercharger kit with an intercooler is nearly 7k. Now think of all the turbo bits you can get. Also superchargering has its limits of boost, maybe say max of a heavily modified system, maybe 10psi on the street do to rotating mass and such. Turbos on the proper engine (which the set up is very similar to a heavy supercharged engine) can come out pushing 2bar, like 32psi. There are consiquences for this but still for $ per horse turbos are a bargain that cannot be beat.

Also turbos are just plain more fun, people love the feeling of lag. Its that burst of speed that throws you back in your seat. A supercharger making the same power is much more linear, the power increases with rpm so there is no lag and you really dont "feel" the power.

btw someone is most likely gonna come and prove me entirly wrong but thats just my 2cents and what ive gathered over time.

btw2 Tsuter ya goof the supercharger is in the front, that thing in the back of the pick is the air to water intercooler! but i bet you knew that...When do I get a ride in your turbo SC?!
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Old 01-11-2005, 07:16 AM
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Re: Supercharged Porsche....

Quote:
Originally posted by jorian
Why doesn't Porsche supercharge any of their cars? With so many other lower priced cars nipping at their heels and some flat out cleaning their clocks (new Vette Z06), supercharging must have been discussed. No? How about a V-8 version of the CGT's V-10 engine? In todays horsepower wars 400 horse ain't what it used to be.

What are your thoughts........
More gains can be realized by the flexibility of a turbo system.

Also, FWIU, Porsche pioneered use of the turbo in their later 917s. Tested by Mark Donahue, the 1000 hp monsters had nasty lag and the turbo systems were described as on-off switches, resulting in a very difficult (read dangerous) car to race. Through refinement Porsche was the first to introduce a production turbo car with the 930. This may explain the commitment to the technology.
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Old 01-11-2005, 07:30 AM
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Corvair had a turbo charged road car in the early 60's....predating Porsche by at least 10-15 years..

Ferdinand Porsche did a "2-stage" supercharger for the no-cost-limit Mercedes-Benz Grand Prix cars of the later 1930's that topped 200 mph..

I'm not necessarily a supe fan....just trying to present a balanced viewpoint....

Wil
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Old 01-11-2005, 07:36 AM
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Hmmm...

http://www.google.com/search?hl=en&q=supercharged+porsche+911&btnG=Google+Search
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Old 01-11-2005, 09:09 AM
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Quote:
Originally posted by Wil Ferch
Beepbeep:

Tell me precisely what you're answering "no" to....
It was answer to jfpound. It took me so long time to type it that few posts got inbetween!

Quote:
I didn't specifically want to go tit-for-tat on a unit-by-unit comparison...but turbo lag ( as a negative) can be reduced by using smaller, faster spinning turbos ( in addition to a host of other things that can be done)
Well it's not so easy...small turbochargers that spin up fast usually produce lot's of backpressure or must be made lighter with ball bearings -> more expensive. Good thing with turbochargers is that there is a wastegate...if backpressure is too high or turbocharger is starting to pump hot air, ECU opens the wastegate and let the gases go around. that's one of main reasons why production cars have "tapered" boost curves. They use small turbochargers to minimize lag but they also get overburdened/inefficient at higher revs. Acoustic knock control usually gets deaf at higher revs as well but that's improved nowadays.

Quote:
and parasitic losses on Supes can be reduced by combinations of recirc, and clutch type systems ( like A/C).......and yet other things, too.
Yupp, but I've sen very few sucessfull clutch-systems...it all gets little cumbersome and expensive if you start to involve even more parts that can fail. Recirculation valves, clutches, bypas valves (so engine can suck "around" supercharger)...it all costs money and is raising complexity even further.

Quote:
In both cases , a compressor of some sort is driven by some means. One way to drive it is via exhaust gas ( also not "free" ,...to counter your point that "rubber belts that transfer tens of hp"..)..and the other way is to drive it mechanically. The compressor doesn't care, in simplest terms.
This is common misconception...that turbocharger and supercharger tap engine power equally, but in different ways. It doesn't work that way. If you measure EGT before and after turbocharger, you'll notice that there is a drop of few hundreds degrees C. This "entalpi" (dunno the english word for it) is what went into spinning the turbocharger and heating up the turbine housing.

With other words, of two engines producing 100hp, one turbocharged and other supercharged, the turbocharged one will use less fuel.

With other words, some of heat wasted trough exhaust gases is reused in turbocharger. Some of that is negated by higher backpressure but net result is still positive. These measurments were demonstrated decades ago, when supercharging was used on piston aircraft engines. highest efficiency can be achieved by using power-recovery turbines (turbo-compound) but it's probably overkill and too costly for car engines. to date, it's only big rig diesel trucks that use both turbocharger and turbo-compound (with 5% lower gas consumption).

to make it simple, it all boils down to this:

If turbocharger is not needed, you can open the wastegate (simple device) and let gases bypass the turbine, lowering backpressure. If needed, it will re-use some of heat in exhaust gases with good efficiency. It only has one moving part, the shaft, and is likely to last the lifetime of the engine.

If supercharger is not needed it still spins unless fitted with magnetic clutch (almost none). Spinning those big lobes (roots) or compressor (centrifugal) just wisps the air around and heats it up, using crank power for nothing. It has at least three moving parts, it's physically bigger than turbocharger but still needs high tolerances (=expensive). it doesn't muffle or reuses heat in exhaust gases either. As a pure air pump, all supercharger designs have lower efficiency than turbochargers except centrifugal design (which itself is as efficient but has gear drive which is inefficient itself).

Quote:
No question....if you use ineffecient components in one case....and compare it to efficient set ups in the other case....a skewed comparison results. You can't compare the engineering behind a factory set up ( in either case) relative to a badly done home brew of the other.
Any way you choose it, if you use efficient designs on both sides turbocharger will win on most points, especially prise/performance and reliability -> main reason of it's OEM use.


Quote:
I also won't argue your ( or known others') direct experience on this topic. Regardless...it doesn't mean you've encountered all the possible ways/means to do any one type of system.
Hope, I haven't. Actually, there are many things that I haven't encountered

Quote:
Both can work if properly designed and executed. Both have drawbacks and strengths that are generally exclusive ( high end vs low end power).

Wil [/B]
Absolutely. Don't get me wrong...I love superchargers and would really like to own blown V8 car. Actually, I'm a secret lover of muscle cars :-) But I would never go to to GM managment and say: "hey, let's make supercharged car. It will be cheaper, more powerfull and more reliable than turbocharged one". And that was maybe what I thread starter was arguing about.
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Old 01-11-2005, 09:13 AM
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There were many a supercharged air cooled engine defending our grandparents butts... fighters , bombers, etc...


PS : I LOVE MY SUPERCHARGER









..
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Old 01-11-2005, 09:32 AM
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Goran:

This dialogue can go on forever, and I don't really want to take sides on this issue, but you're putting words into my mouth ....for example , when you paraphrase me by saying ..."This is common misconception...that turbocharger and supercharger tap engine power equally.."

I never said "equally". What I *did* say is that the core element of the system is the compressor that makes for "compressed intake charge". How that compressor is driven is moot ( as far as the *compressor* itself goes)...it doesn't care if its spinning because there is a turbine at the other end of the shaft...or if there is a pulley that gets its power from the crank of an engine. I never said "equally". All sorts of things come into play including the compressor efficiency and operating range, etc.... tro know which one consumes more hp.

Let me agree with this:
- with most of pieces available today...it seems you can get a Turbo with greater inherent efficiency ( core basis and installed basis), but with technology constantly changing.. I wouldn't take the position that turbos are always better or more efficient for all modes of operation. The number of parts a system has must be accounted for in the design and execution...but "by itself" also means nothing. A good V-12 engine can be more reliable than bad inline four engine...for example.....

Wil
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Old 01-11-2005, 09:44 AM
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Ok, so you young pups know all the theory.......but what is the application of the thing laying on the bench and what is the application of the other thing in my hand???

Be specific in your response.....we know it will "charge air"....

Muhahahahaha!!

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Old 01-11-2005, 09:56 AM
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The Oldsmobile Jetfire Turbo Rocket was the first turbocharged production car. It appeared in 1962, before the turbo corvair.
Old 01-11-2005, 09:59 AM
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