supercharger or turbo?
08-09-2001, 08:46 AM
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supercharger or turbo?
i was browsing some tuning sites and i saw some advertised superchargers... are there ne real advantages to a charger? (just dreamin/thinkin til i get one of my own... can't have too much info 
08-09-2001, 08:59 AM
#3
Re: supercharger or turbo?..not really..turbos are better..
Read Maximum Boost, superchargers use up to 10-15 % of the power to drive its compressors while a turbo uses heat already being generated by the engine exhaust to drive the turbine. Turbos are much more efficient than superchargers and with proper selection turbo lag is almost non-existant.
08-09-2001, 09:02 AM
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In the spirit of "can't have too much info", there are a couple of downsides...
Theoretically, it's possible to make more power w/ a turbocharger because there isn't any drag on the engine. For the same reason, a turbo'd car will get better gas mileage than a blown car making the same power.
08-09-2001, 09:24 AM
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Like it or not - there is lag (the R8s last weekend lost because of that)
Supercharger has more torque at lower rpms - makes for a more driveable car. I think a turbo is more complicated but don't have any real facts on that.
My personal preference would be SC
Reggie
98.5 2.8QMS
My personal preference would be SC
Reggie
98.5 2.8QMS
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08-09-2001, 10:38 AM
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Technically speaking all forced induction is supercharging...
Turbo-charged cars are actually fitted with turbo-superchargers, though almost no-one outside of a thermodynamics course will actually use this terminology.
In layman's terms supercharging refers to forced induction by means of a mechanically driven compressor and turbocharging refers to the use of an exhaust powered turbine driven compressor.
From a thermodynamics standpoint the turbo is more efficient since it makes use of energy that would otherwise be wasted (energy in the form of the hot, pressurized exhaust stream). However there's no such thing as a free lunch, the turbo obstructs the exhaust path raising back pressure slightly and sapping some of the engine's NA output because of this. Turbine compressors tend to be small and produce high pressures at very high RPMs (50 - 100k RPM) to make up for their small size. Boost pressure is highly dependent on engine speed and the size of the turbo (really it's mass and rotational moments) determine the length of the response time (lag), another reason why the compressors are smaller.
Superchargers are driven directly, usually by a belt off of an accessory drive pulley. Most superchargers are underdriven, meaning they operate at a slower rotational speed than the engine. The compressor in a supercharger is larger than in a turbo (because it operates at much lower rotational speeds). Also because a supercharger is mechanically driven boost is produced immediately upon application of power.
Again, there's no such thing as a free lunch, the supercharger takes some power to operate since it is being driven by the engine itself. The enourmous superchargers on top fuel dragsters use approximately 350 horsepower, though the total output from such an engine is at least 7,000 horsepower (which is an estimate... there's no way to actually measure that).
Generally smaller engines are turbocharged and larger engines are supercharged. Small engines, particularly in-line configurations (such as 4 cylinders and some straight sixes) are particularly suited to being turbo charged. The exhaust stream from an inline engine is easily combined to preserve the thermal efficiency that makes turbos so effective. Split cylinder engines such as V-6s and V-8s divide their exhaust streams reducing the efficiency of a turbocharger greatly on such a car. SAAB's 9-5 has an asymettrically turbocharged engine because of this.
Larger split cylinder engines are better suited to providing enough power to deal with the parasitic loses imposed by a supercharger than their smaller in-line cousins.
Engines can make use of both types of forced induction systems. This was particuarly popular on high performance piston engine aircraft. In these applications it was important to have a full range of power available at all speeds and (importantly) altitudes.
Superchargers are well suited to providing low speed power and provide enough air pressure to keep an engine going even at high altitudes. Turbochargers make use of otherwise wasted energy and are well suited to high speed operations. Also they can compensate for the parasitic loses from the supercharger at higher speeds. The Rolls-Royce Merlin V-12 (of P-51 fame) made use of both forms of forced induction, and it used a two stage sequential supercharger as well. This made the Merlin a very complicated engine but at the same time at something like 25 liters it could easily produce 1500 horsepower and up to 2500 horsepower under emergency conditions. Because of the induction system this power was available across the entire operating range of the engine, and at very high altitudes, making the P-51 an excellent bomber escort.
In layman's terms supercharging refers to forced induction by means of a mechanically driven compressor and turbocharging refers to the use of an exhaust powered turbine driven compressor.
From a thermodynamics standpoint the turbo is more efficient since it makes use of energy that would otherwise be wasted (energy in the form of the hot, pressurized exhaust stream). However there's no such thing as a free lunch, the turbo obstructs the exhaust path raising back pressure slightly and sapping some of the engine's NA output because of this. Turbine compressors tend to be small and produce high pressures at very high RPMs (50 - 100k RPM) to make up for their small size. Boost pressure is highly dependent on engine speed and the size of the turbo (really it's mass and rotational moments) determine the length of the response time (lag), another reason why the compressors are smaller.
Superchargers are driven directly, usually by a belt off of an accessory drive pulley. Most superchargers are underdriven, meaning they operate at a slower rotational speed than the engine. The compressor in a supercharger is larger than in a turbo (because it operates at much lower rotational speeds). Also because a supercharger is mechanically driven boost is produced immediately upon application of power.
Again, there's no such thing as a free lunch, the supercharger takes some power to operate since it is being driven by the engine itself. The enourmous superchargers on top fuel dragsters use approximately 350 horsepower, though the total output from such an engine is at least 7,000 horsepower (which is an estimate... there's no way to actually measure that).
Generally smaller engines are turbocharged and larger engines are supercharged. Small engines, particularly in-line configurations (such as 4 cylinders and some straight sixes) are particularly suited to being turbo charged. The exhaust stream from an inline engine is easily combined to preserve the thermal efficiency that makes turbos so effective. Split cylinder engines such as V-6s and V-8s divide their exhaust streams reducing the efficiency of a turbocharger greatly on such a car. SAAB's 9-5 has an asymettrically turbocharged engine because of this.
Larger split cylinder engines are better suited to providing enough power to deal with the parasitic loses imposed by a supercharger than their smaller in-line cousins.
Engines can make use of both types of forced induction systems. This was particuarly popular on high performance piston engine aircraft. In these applications it was important to have a full range of power available at all speeds and (importantly) altitudes.
Superchargers are well suited to providing low speed power and provide enough air pressure to keep an engine going even at high altitudes. Turbochargers make use of otherwise wasted energy and are well suited to high speed operations. Also they can compensate for the parasitic loses from the supercharger at higher speeds. The Rolls-Royce Merlin V-12 (of P-51 fame) made use of both forms of forced induction, and it used a two stage sequential supercharger as well. This made the Merlin a very complicated engine but at the same time at something like 25 liters it could easily produce 1500 horsepower and up to 2500 horsepower under emergency conditions. Because of the induction system this power was available across the entire operating range of the engine, and at very high altitudes, making the P-51 an excellent bomber escort.