****how does supercharger work anyways? close to turbo right?
05-30-2002, 10:18 AM
#61
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I do believe i said that...
Im actually not anti-SC. I firmly belive they are good solutions for many cars, and give a very stock, instant power added feel.
the SC is the only choice for many engines, and its a fine choice. But given a choice, a turbocharger kit is a preferred option.
Yes, a SC WILL have a constant parasitic loss on an engine. Yes, a SC will have exponentially higher parasitic drain as the engine climbs RPM. That does not make them un-worthwhile, they are still terrific bang for the buck.
While your SC is making extremely high power at high RPM, a significant portion of that power is not getting to the wheels due to losses.
This parasitic loss can be mitigated by advanced timing due to excellent computer management, but its a fact of life as much as low RPM turbo lag is for a 1.8T. Each kit has a plus and minus, its that simple. Either anemic pre-boost power for a turbo, or high RPM parasitic losses for a SC.
I have some exposure to the JRSC kit for the Miata, and while its clearly not the quality of PES's kit, it shows the weaknesses more apparently...still, there will be a JRSC in my Miata in time, because its a nice simple 50hp shot to the car, some more if i get an IC and some assorted pulleys what not to run at 10psi.
If i really wanted a V6, i would gladly get a SC (eventually) for it. As you said, its an alternative.
the SC is the only choice for many engines, and its a fine choice. But given a choice, a turbocharger kit is a preferred option.
Yes, a SC WILL have a constant parasitic loss on an engine. Yes, a SC will have exponentially higher parasitic drain as the engine climbs RPM. That does not make them un-worthwhile, they are still terrific bang for the buck.
While your SC is making extremely high power at high RPM, a significant portion of that power is not getting to the wheels due to losses.
This parasitic loss can be mitigated by advanced timing due to excellent computer management, but its a fact of life as much as low RPM turbo lag is for a 1.8T. Each kit has a plus and minus, its that simple. Either anemic pre-boost power for a turbo, or high RPM parasitic losses for a SC.
I have some exposure to the JRSC kit for the Miata, and while its clearly not the quality of PES's kit, it shows the weaknesses more apparently...still, there will be a JRSC in my Miata in time, because its a nice simple 50hp shot to the car, some more if i get an IC and some assorted pulleys what not to run at 10psi.
If i really wanted a V6, i would gladly get a SC (eventually) for it. As you said, its an alternative.
05-30-2002, 06:07 PM
#63
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Wht's funny is, at high rpm's, my SC is out of control fast!!! Full boost through the band!
The other thing is. I want to know where it states that a supercharger robs the engine of so much power. It's turning a pulley attached to a free flowing, sealed bearing. Shoot, removing the fan throttle driven pulley would be enough to compensate! Plus, MB offer SC on every V-6 they build. Check it out. Even the C-320 6 cyl now has a Kompressor option, why? Is it because a company that has patents in nearly every car produced on earth knows superchargers add a ton of hp without destroying the engine? Japanese cars use turbo's for two reasons: Marketing to Americans and creating disposable cars that have to be replaced every three to four years! It makes sense!
05-30-2002, 07:00 PM
#65
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You're talking differen't cars, so what's your point?
I said SAME car, SAME gearing, SAME engine, SC vs. Turbo, the turbo will have the slight advantage. Why are you trying to argue with facts? Besides, the E36 M3 was infamous for having the SC blow the head.
Mike
Mike
05-30-2002, 07:42 PM
#66
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Corky Bell: Maximum Boost, Ch.1, P. 5...
"That an air pump always heats air it compresses is a thermodynamic fact which we are stuck. Different kinds of air pumps heat air different amounts for the same flow rates and pressure ratios. These differences are due largely to different efficiencies of various types of pumps. The classic Roots-type supercharger usually rates efficiencies of about 50% wheras the turbo runs efficiencies in the mid-70s. The higher the efficiency the less the heating effect on the air. Efficiency is of paramount importance to the real power enthusiast, since heat in the intake charge is the enemy of performance. The density of an intake charge is less as the temperature rises, this, an engine actually consumes less air at the higher temperature even if the pressures are the same. A second problem is that higher temperatures promote detonation of the air/fuel mixture. Engines cannot withstand the thermal and pressure shocks of detonation for more than very short periods."
I forgot where I read this percentage, but the engine will lose roughly 5% from SC drag.
Why does Mercedes use SC instead of turbo? Marketing more than anything. The same reasons why they use a 5.5L engine while Audi is using 4.2 and BMW with 4.9. The Mercedes owners are very specific people, that would never stand for turbo lag. You obviously know nothing about turbos if you think they destroy engines. Saab has been turbocharging cars for decades, there are MANY high mileage cars out there. <a href="http://www.saabnet.com/tsn/faq/miles/All.html">High Mileage Saabs</a>. Which Japanese cars are disposable? The Toyota 2JZ-GTE and Nissan RB26DETT and SR20DETT are VERY reliable engines, two have been known to support 500WHP without internals. Volvo, Porsche, Lotus and many other manufacturers have been turbocharging for years. BMW's Turbo F1 engine from the 80's produced about 1,500HP from 1.5L, this is an estimate since they cannot measure over 1000HP. Why do you think Audi went turbo in the R8? Is there a perfect way to achieve power? No, each comes with it's own limitations. Just don't spout off mis-information to further your own agenda and make yourself feel better about the choice you made.
Mike
I forgot where I read this percentage, but the engine will lose roughly 5% from SC drag.
Why does Mercedes use SC instead of turbo? Marketing more than anything. The same reasons why they use a 5.5L engine while Audi is using 4.2 and BMW with 4.9. The Mercedes owners are very specific people, that would never stand for turbo lag. You obviously know nothing about turbos if you think they destroy engines. Saab has been turbocharging cars for decades, there are MANY high mileage cars out there. <a href="http://www.saabnet.com/tsn/faq/miles/All.html">High Mileage Saabs</a>. Which Japanese cars are disposable? The Toyota 2JZ-GTE and Nissan RB26DETT and SR20DETT are VERY reliable engines, two have been known to support 500WHP without internals. Volvo, Porsche, Lotus and many other manufacturers have been turbocharging for years. BMW's Turbo F1 engine from the 80's produced about 1,500HP from 1.5L, this is an estimate since they cannot measure over 1000HP. Why do you think Audi went turbo in the R8? Is there a perfect way to achieve power? No, each comes with it's own limitations. Just don't spout off mis-information to further your own agenda and make yourself feel better about the choice you made.
Mike
05-31-2002, 07:01 AM
#67
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The sleeve bearing or a BB bearing of a turbo charger is also free spinning...
but the resistance created by trying to compress air is the load that the SC places on the engine. Not too different that when you try to blow up a balloon; a 2 year old with small lungs (small engine) would have a tougher time than an adult (larger engine) to fill the same balloon. It's not the components that add the resistance to the engine, it's the function of the unit. Since the SC is DIRECTLY tied to the crank, either in a roots or a centrifugal (VERY similar to a turbo btw - HIGH RPMS), it is NOT making full boost until redline. A turbo is spinning near full rpm at a lower rpm by nature of design - there is no point of contention here; refusing to agree with that basic understanding of the workings means that this arguement is pointless until we can begin with a common set objective, factual information.
