Supercharger
07-25-2004, 06:01 PM
#33
It came soon after the engine
Forced induction was devised within a few years of the invention of the internal combustion engine, and actually predates the advent of automobiles. Gottlieb Daimler received a German patent for supercharging in 1885, specifying an external fan, pump, or compressor to push the increased air into the engine.
In 1908 Lee Chadwick in Pottstown, Pennsylvania built a supercharged Vanderbilt Cup racer, which ran at 100 mph, using a fan driven by a leather belt to spin at five times crankshaft speed. Louis Renault had patented this centrifugal supercharger concept in France in 1902.
Another Frenchman, Auguste Rateau, in 1916 tested turbocharging an aircraft, and in 1918 General Electric produced a gain in horsepower with a turbocharged Liberty aircraft engine on the top of Pike's Peak - delivering 356 hp at high altitude compared with the engine's stock output at sea level of 346 hp, which formerly would drop to 222 hp at this altitude.
The pump was already there
The principles of positive displacement had long before been turned into working pumps by the Roots brothers, beginning in 1859 to develop a better water wheel, and discovering instead a very effective air mover. They formed the Roots Blower Company, but the name is used generically to describe the positive displacement type of blower. The blower has since been used for deep mine ventilation, pneumatic carrying systems, and countless industrial applications including refrigeration and air conditioning.
During the early twenties Mercedes innovatively developed a Roots type blower instead of the earlier centrifugal compressors. Over the next two decades interest was intense in both turbocharging and supercharging, in America and Europe, and across several industries. By World War II almost all military aircraft intended for high altitudes were supercharged.
Forced induction was devised within a few years of the invention of the internal combustion engine, and actually predates the advent of automobiles. Gottlieb Daimler received a German patent for supercharging in 1885, specifying an external fan, pump, or compressor to push the increased air into the engine.
In 1908 Lee Chadwick in Pottstown, Pennsylvania built a supercharged Vanderbilt Cup racer, which ran at 100 mph, using a fan driven by a leather belt to spin at five times crankshaft speed. Louis Renault had patented this centrifugal supercharger concept in France in 1902.
Another Frenchman, Auguste Rateau, in 1916 tested turbocharging an aircraft, and in 1918 General Electric produced a gain in horsepower with a turbocharged Liberty aircraft engine on the top of Pike's Peak - delivering 356 hp at high altitude compared with the engine's stock output at sea level of 346 hp, which formerly would drop to 222 hp at this altitude.
The pump was already there
The principles of positive displacement had long before been turned into working pumps by the Roots brothers, beginning in 1859 to develop a better water wheel, and discovering instead a very effective air mover. They formed the Roots Blower Company, but the name is used generically to describe the positive displacement type of blower. The blower has since been used for deep mine ventilation, pneumatic carrying systems, and countless industrial applications including refrigeration and air conditioning.
During the early twenties Mercedes innovatively developed a Roots type blower instead of the earlier centrifugal compressors. Over the next two decades interest was intense in both turbocharging and supercharging, in America and Europe, and across several industries. By World War II almost all military aircraft intended for high altitudes were supercharged.
07-25-2004, 06:06 PM
#34
Roots Blower - positive displacement air mover
The roots-type supercharger is a positive displacement system referred to as a blower since it doesn't compress air directly, but simply moves it quickly. It employs 2 or 3 counter-rotating lobes to scoop a fixed amount of air from the outside and deliver it into the intake manifold. Unlike the compressors of the turbocharger and the centrifugal supercharger, which deliver exponentially greater boost with increased rpm and which are not designed to perform at lower rpm, a positive displacement supercharger pumps a fixed amount of air for every revolution, and delivers instant boost even at low rpm.
Since positive displacement superchargers are both continually under drive and also delivering boost at all rpm an intake bypass system is used in street applications to divert airflow and prevent overboosting.
The roots type supercharger is based on the very efficient air moving principles of positive displacement, but loses supercharging efficiency for several reasons, and primarily because it doesn't compress the air directly.
High heat from turbulence
The blower delivers more and more air rapidly into the intake manifold, where it compresses from the addition of increasingly more air. The turbulence of uncompressed air entering the compressed environment - with associated backflows - creates heat, the great negative factor of supercharging.
The adiabatic efficiency of a roots type supercharger is only in the 40%-60% range. Furthermore, while the other compressors tend to gain efficiencies at higher rpm, the roots tends to experience decreased efficiencies as boost levels rise or for sustained maximum output periods.
A positive displacement supercharger has great advantages in lower end delivery - more power at lower rpm equals less strain on the engine.
The roots type blower is inherently noisy, largely from the gearing required to run the rotors. It is a very simple supercharger, and moves a great volume of air very easily. The roots blower has always been very popular, but is now yielding some ground to the twin screw.
The roots-type supercharger is a positive displacement system referred to as a blower since it doesn't compress air directly, but simply moves it quickly. It employs 2 or 3 counter-rotating lobes to scoop a fixed amount of air from the outside and deliver it into the intake manifold. Unlike the compressors of the turbocharger and the centrifugal supercharger, which deliver exponentially greater boost with increased rpm and which are not designed to perform at lower rpm, a positive displacement supercharger pumps a fixed amount of air for every revolution, and delivers instant boost even at low rpm.
Since positive displacement superchargers are both continually under drive and also delivering boost at all rpm an intake bypass system is used in street applications to divert airflow and prevent overboosting.
The roots type supercharger is based on the very efficient air moving principles of positive displacement, but loses supercharging efficiency for several reasons, and primarily because it doesn't compress the air directly.
High heat from turbulence
The blower delivers more and more air rapidly into the intake manifold, where it compresses from the addition of increasingly more air. The turbulence of uncompressed air entering the compressed environment - with associated backflows - creates heat, the great negative factor of supercharging.
The adiabatic efficiency of a roots type supercharger is only in the 40%-60% range. Furthermore, while the other compressors tend to gain efficiencies at higher rpm, the roots tends to experience decreased efficiencies as boost levels rise or for sustained maximum output periods.
A positive displacement supercharger has great advantages in lower end delivery - more power at lower rpm equals less strain on the engine.
The roots type blower is inherently noisy, largely from the gearing required to run the rotors. It is a very simple supercharger, and moves a great volume of air very easily. The roots blower has always been very popular, but is now yielding some ground to the twin screw.
07-25-2004, 06:07 PM
#35
Twin Screw Supercharger - a positive displacement compressor
The twin screw supercharger is a positive displacement air mover, in that it moves fixed amounts of air per revolution, like the roots type blower. Unlike the roots however, which is only an air delivery system, the twin screw supercharger is also a compressor. The counter rotating lobes and chambers of the twin screw are designed for a screw-like tapering effect which runs its intake air into a smaller space for output, thus compressing it. The rotors have very close tolerances yet never touch. Compressed air is delivered into the compression environment of the intake manifold with very little leakage or energy loss.
Because of the increased mechanical efficiencies of the superior design, the output air temperatures of the twin screw positive displacement supercharger are radically improved from the roots type. The Whipple twin screw quotes adiabatic efficiency of 70%-80% range across the whole powerband.
As with the roots, since the supercharger is under continual drive, and since it delivers boost practically from idle, overboosting is prevented by the use of an intake bypass system, which allows the engine to breathe normally at cruising or idle: the bypass closes on throttle use, delivering full boost.
Full boost by 2000 rpm
The twin screw supercharger creates boost the instant the throttle is touched, and generally reaches full boost by 2000 to 2400 rpm. Full boost is then available all the way to redline. A positive displacement compressor is ideal for street performance cars or trucks and suv's, and automatic transmissions.
Vehicles used for towing remain very responsive with positive control using this type of supercharger. The instant torque for accelerating, passing, and hill-climbing diminishes the strain on the engine and increases the safety factor. The twin screw compressor is especially useful at high altitude, where physics dictates that all engines lose power, and where our American geography dictates we often take the family vehicle on vacation towing a trailer in heavy traffic.
The twin screw supercharger is essentially silent, producing discernible sound no greater than whisper strength. It has a low profile and generally requires no hood modification. Of all the forced induction systems, the twin screw compressor supercharger is the most obvious for the bootlegger's car, the sleeper, and this is timely in an age where supercharging is no longer just for speed enthusiasts, but for all drivers who have needs for extra power and performance during fairly standard driving conditions.
The twin screw supercharger is a positive displacement air mover, in that it moves fixed amounts of air per revolution, like the roots type blower. Unlike the roots however, which is only an air delivery system, the twin screw supercharger is also a compressor. The counter rotating lobes and chambers of the twin screw are designed for a screw-like tapering effect which runs its intake air into a smaller space for output, thus compressing it. The rotors have very close tolerances yet never touch. Compressed air is delivered into the compression environment of the intake manifold with very little leakage or energy loss.
Because of the increased mechanical efficiencies of the superior design, the output air temperatures of the twin screw positive displacement supercharger are radically improved from the roots type. The Whipple twin screw quotes adiabatic efficiency of 70%-80% range across the whole powerband.
As with the roots, since the supercharger is under continual drive, and since it delivers boost practically from idle, overboosting is prevented by the use of an intake bypass system, which allows the engine to breathe normally at cruising or idle: the bypass closes on throttle use, delivering full boost.
Full boost by 2000 rpm
The twin screw supercharger creates boost the instant the throttle is touched, and generally reaches full boost by 2000 to 2400 rpm. Full boost is then available all the way to redline. A positive displacement compressor is ideal for street performance cars or trucks and suv's, and automatic transmissions.
Vehicles used for towing remain very responsive with positive control using this type of supercharger. The instant torque for accelerating, passing, and hill-climbing diminishes the strain on the engine and increases the safety factor. The twin screw compressor is especially useful at high altitude, where physics dictates that all engines lose power, and where our American geography dictates we often take the family vehicle on vacation towing a trailer in heavy traffic.
The twin screw supercharger is essentially silent, producing discernible sound no greater than whisper strength. It has a low profile and generally requires no hood modification. Of all the forced induction systems, the twin screw compressor supercharger is the most obvious for the bootlegger's car, the sleeper, and this is timely in an age where supercharging is no longer just for speed enthusiasts, but for all drivers who have needs for extra power and performance during fairly standard driving conditions.
07-25-2004, 06:08 PM
#36
Heat is not good and compressing air produces heat
Forced induction compresses air, and as a law of physics the temperature of the air increases as a direct counterpart to its compression. A lot of engineering goes into trying to compensate for this fact in supercharging and turbocharging design.
The word "adiabatic" describes a process in which no heat is gained or lost - 100% adiabatic efficiency would be the perfect forced induction device, creating no heat gain whatsoever, probably impossible to achieve ever. And the closest anyone can come yet is around 80% efficiency.
The problem with heat is it defeats the original purpose - the hotter the air, the lower the density possible, and the extra power comes from dense air. Another problem from heat is ignition - the hotter the inlet air, the more tendency the engine will have towards detonation and pre-ignition (knock and ping), which damages the engine, besides diminishing performance. Drivers of blown vehicles tend to keep an eye on the temperature gauge.
The goal of efficient charging is to compress the air and to keep it cool, for maximum power. The cooler the intake charge, the denser the air and the more horsepower produced.
The greater the adiabatic efficiency with which a supercharger compresses air, the less the heat that gets added to the intake manifold. Efficiency is measured by the discharge air temperature at a given pressure. For 6 pounds of boost, a supercharger with intake air temperature of 185 degrees is more efficient than another at 190 degrees. Boost itself is only the measure of pressure the intake air is under, not an indication of the power produced as horsepower.
Which has greatest adiabatic efficiency
The Roots blower has the lowest adiabatic efficiency of all the forced induction designs (including the turbocharger, which has to start off with hot exhaust gases to deal with) - generally around 50 percent. The roots type is so inefficient because it doesn't compress the air directly, but delivers uncompressed air which wells into the intake manifold, becoming more compressed, but with additional heat gain from the turbulence and reverse flows of air mixing. Centrifugal superchargers can vary from 60% up to perhaps approaching 80% efficiency, as can turbochargers; both are more efficient at higher rpm, which is another way of calling them more inefficient at lower rpm. The twin screw supercharger normally delivers lower output temperatures, for adiabatic efficiencies of 70-80% across the whole rpm range.
Cooling the air before it goes into the engine has a major effect on performance. Intercoolers are the physical means of cooling the compressed air, radiator-like systems using air or water for cooling. Inter cooling reduces temperature, but reduces boost (pressure) too because of flow restriction as the air circulates through cooling, and also as a direct result of the temperature change itself - again that law of physics. But the net result is compressed (dense) air at a cooler temperature. Cooler air at lower boost will give more power than hotter air at higher boost, because cooler air can be denser than hotter air no matter how much boost you throw at it. Drag racers often use cold water and ice in the intercooler for tremendous power over the short term.
Intercoolers come as air cooled systems and as water cooled systems. Very often the efficiencies of modern chargers permit running without an intercooler especially in street or OEM applications, but for performance uses, in general optimal performance comes from intercooling.
Forced induction compresses air, and as a law of physics the temperature of the air increases as a direct counterpart to its compression. A lot of engineering goes into trying to compensate for this fact in supercharging and turbocharging design.
The word "adiabatic" describes a process in which no heat is gained or lost - 100% adiabatic efficiency would be the perfect forced induction device, creating no heat gain whatsoever, probably impossible to achieve ever. And the closest anyone can come yet is around 80% efficiency.
The problem with heat is it defeats the original purpose - the hotter the air, the lower the density possible, and the extra power comes from dense air. Another problem from heat is ignition - the hotter the inlet air, the more tendency the engine will have towards detonation and pre-ignition (knock and ping), which damages the engine, besides diminishing performance. Drivers of blown vehicles tend to keep an eye on the temperature gauge.
The goal of efficient charging is to compress the air and to keep it cool, for maximum power. The cooler the intake charge, the denser the air and the more horsepower produced.
The greater the adiabatic efficiency with which a supercharger compresses air, the less the heat that gets added to the intake manifold. Efficiency is measured by the discharge air temperature at a given pressure. For 6 pounds of boost, a supercharger with intake air temperature of 185 degrees is more efficient than another at 190 degrees. Boost itself is only the measure of pressure the intake air is under, not an indication of the power produced as horsepower.
Which has greatest adiabatic efficiency
The Roots blower has the lowest adiabatic efficiency of all the forced induction designs (including the turbocharger, which has to start off with hot exhaust gases to deal with) - generally around 50 percent. The roots type is so inefficient because it doesn't compress the air directly, but delivers uncompressed air which wells into the intake manifold, becoming more compressed, but with additional heat gain from the turbulence and reverse flows of air mixing. Centrifugal superchargers can vary from 60% up to perhaps approaching 80% efficiency, as can turbochargers; both are more efficient at higher rpm, which is another way of calling them more inefficient at lower rpm. The twin screw supercharger normally delivers lower output temperatures, for adiabatic efficiencies of 70-80% across the whole rpm range.
Cooling the air before it goes into the engine has a major effect on performance. Intercoolers are the physical means of cooling the compressed air, radiator-like systems using air or water for cooling. Inter cooling reduces temperature, but reduces boost (pressure) too because of flow restriction as the air circulates through cooling, and also as a direct result of the temperature change itself - again that law of physics. But the net result is compressed (dense) air at a cooler temperature. Cooler air at lower boost will give more power than hotter air at higher boost, because cooler air can be denser than hotter air no matter how much boost you throw at it. Drag racers often use cold water and ice in the intercooler for tremendous power over the short term.
Intercoolers come as air cooled systems and as water cooled systems. Very often the efficiencies of modern chargers permit running without an intercooler especially in street or OEM applications, but for performance uses, in general optimal performance comes from intercooling.
07-25-2004, 07:02 PM
#37
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Lets see.... who do we think is right here... 
Someone obviously not happy with their radix and BITCHING all day long, or someone who actually does radix INSTALLS all day long. You seem to be the only one with such low numbers. What have you done to insure the quality of your engine? Im sure nothing because its easier for you to blame the Radix than look otherplaces.
I have no loyalties, Ive bitched out brian before, but quit crying Naked, its no ones fault that your engine produced less hp.
If you work that engine like you drive the canyons IM NOT SUPRISED.
And it seems to me your calling Blownchevy a liar. He told you the facts, gave you numbers and now you wont believe without scanned dynos? Common man whats next? You want god to come down and personally tell you the gains?
Someone obviously not happy with their radix and BITCHING all day long, or someone who actually does radix INSTALLS all day long. You seem to be the only one with such low numbers. What have you done to insure the quality of your engine? Im sure nothing because its easier for you to blame the Radix than look otherplaces.
I have no loyalties, Ive bitched out brian before, but quit crying Naked, its no ones fault that your engine produced less hp.
If you work that engine like you drive the canyons IM NOT SUPRISED.
And it seems to me your calling Blownchevy a liar. He told you the facts, gave you numbers and now you wont believe without scanned dynos? Common man whats next? You want god to come down and personally tell you the gains?
07-25-2004, 07:44 PM
#38
TECH Veteran
The guy who started the thread was asking about superchargers and I told him he could get a Radix for around $4500 but that he should look at the Whipple and Kenne Bell also. Any bitching there? No.
Then Brian comes in and tries to start something (as per usual) and manages to succeed. If anyone out there thinks the MP112 is more efficient than a twin screw, you get a free ride in the short bus. Any bitching there? No.
Then Brian invites a challenge and I give it to him. Promises to be of benefit all on the LS1Tech board. He says he will deliver. I hope he does. Any bitching there? Nope, just anxious anticipation.
As a matter of fact, there has been relatively little bitching until your punk *** showed up. You are hereby invited to find another place to be a whiner.
Then Brian comes in and tries to start something (as per usual) and manages to succeed. If anyone out there thinks the MP112 is more efficient than a twin screw, you get a free ride in the short bus. Any bitching there? No.
Then Brian invites a challenge and I give it to him. Promises to be of benefit all on the LS1Tech board. He says he will deliver. I hope he does. Any bitching there? Nope, just anxious anticipation.
As a matter of fact, there has been relatively little bitching until your punk *** showed up. You are hereby invited to find another place to be a whiner.
07-25-2004, 08:04 PM
#39
Originally Posted by Naked AV
then Brian comes in and tries to start something (as per usual) and manages to succeed. If anyone out there thinks the MP112 is more efficient than a twin screw, you get a free ride in the short bus.
07-25-2004, 08:06 PM
#40
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Originally Posted by Naked AV
As a matter of fact, there has been relatively little bitching until your punk *** showed up. You are hereby invited to find another place to be a whiner.
And quit acting all innocent, you were bitching like alittle school girl who just got her milk stolen at lunch. Quote what you want, I know bitching when I hear it.
Another person who says things online they would NEVER say to someones face. Dude I dare you to prove me wrong
