Supercharger vs. Turbo ????
08-14-2001, 04:06 PM
#2
Banned
Join Date: Jan 2001
Location: Somewhere between here and there, yet neither.
Posts: 9,151
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by WI CL TypeS:
<STRONG>Okay this is a newbie type question. I know a little about turbo's and superchargers but could someone explain the differences in the to me or point me to a good resource that does?
Thanks,
Brenden</STRONG>
<STRONG>Okay this is a newbie type question. I know a little about turbo's and superchargers but could someone explain the differences in the to me or point me to a good resource that does?
Thanks,
Brenden</STRONG>
A supercharger is a belt-driven turbine...that increases the amount of air pushed into the engine...and a turbo is exhaust driven.
08-14-2001, 04:08 PM
#3
Instructor
Join Date: Aug 2001
Location: Shepherdstown, WV
Posts: 226
Likes: 0
Received 0 Likes
on
0 Posts
Read this, if you dare. (quiz on Monday) 
Supercharged!
"The Wild World Of Belt-Driven Bliss"
By Dave Coleman
Supercharged! The very word conjures up images of burning rubber, low E.T.s and performance that will make you sweat testosterone. Unless you're normal, that is. The word supercharged has been so spread through our vocabulary that normal people apply it to anything from batteries to herbal supplements. But those of us who really understand the term know that supercharging an herbal supplement will get you nothing but an expensive cloud of plant extracts.
Supercharging--real supercharging--is actually a relatively simple concept. The amount of power an engine can make is proportional to the amount of air and fuel it can ingest and burn. Supercharging is the simple act of putting an air pump in front of the engine to cram in more air and fuel than it would normally be able to ingest on its own. For such a simple concept, the variety of methods for supercharging an engine are staggering.
The reason for the variety is the sheer number of air pumps and drive mechanisms available for the supercharging task. The most basic requirement of a supercharger is that it pump air faster than the engine it is attached to, but there is more to supercharger design than that. A supercharger also has to operate over the same wide range of rpm as the engine it is attached to, and it has to pump air as efficiently as possible without excessively heating it or absorbing too much power.
Technically, turbo-charging is just another form of supercharging--turbochargers are just centrifugal superchargers that happen to be driven by exhaust gasses, rather than the crank--but in the popular car-guy vernacular, the term supercharged is reserved for those installations where the air pump is mechanically driven off the crankshaft. The seemingly minor detail of how the supercharger is driven has a profound effect on how the car drives.
Since the turbocharger relies on exhaust gasses for its power, there is a slight delay or "turbo lag" when the throttle is opened, air is ingested, burned and finally expelled into the turbine to drive the turbo. Depending on the design and sizing of the turbo, this lag can be anywhere from a few agonizing seconds, to a barely noticeable fraction of a second. In contrast, a mechanically driven supercharger should be trying to pump air even before the throttle is opened, resulting in nearly instantaneous boost. Another fundamental difference between turbochargers and superchargers is how each regulates boost. Turbos use a wastegate to bleed off the exhaust gasses driving the turbo when the desired boost level is reached. What this means is that turbos run a fixed boost level, at least in theory.
In a perfect world, a turbo system with the wastegate set at 6 psi would make 6 psi of boost under all wide-open-throttle conditions. A supercharger, by contrast, runs a fixed speed relative to the engine. If a supercharger is geared to pump 1.5 times more air than the car breathes naturally aspirated, the boost will be different at different rpm. In the parts of the rev range where the engine doesn't breathe well, the supercharger's insistence on pumping air will cause air to pile up in the manifold, increasing more pressure. In areas where the engine does breathe well, there will be less of a back-up, and less boost. The end result is that turbochargers tend to simply magnify the stock power band of the engine they are attached to, while superchargers are more likely to totally change the power band to reflect the characteristics of the supercharger.
One thing turbos and superchargers do have in common is the need for intercooling. It is a common myth that turbos need intercooling and superchargers don't. There is no truth to this statement. Compressing air makes it hot; this is an inescapable fact of nature. The more efficient the compressor, the less it heats the air, but the heating still occurs and it is still significant. Cooling that air before it goes into the engine can have a profound effect on performance. In general, turbo compressors are more efficient than supercharger compressors, but this obviously depends on the particular turbo and supercharger you are comparing. The end result is the same: Superchargers stand to benefit from intercooling as much as turbos do.
But enough generalities. All the supercharged cars we gathered this month use one of only two different styles of superchargers, so let's take a look at the superchargers themselves.
Roots Blowers
Both the Dodge Neon SRT and the TRD Solara use Roots blowers made by Eaton. The Roots concept is quite simple. In its plainest form, a Roots blower has two rotors with either two or three lobes each. Like giant gear teeth, the lobes on these rotors intermesh inside a tight-fitting, peanut-shaped housing. If air is allowed to enter the waist of the peanut, or the narrow portion right where the lobes are un-meshing, the air will be drawn into the gap between lobes on each rotor. As the rotors turn, chambers are formed between two adjacent teeth of each rotor and the wall of the rotor housing. Air is simply carried around both sides of the supercharger in these chambers until the lobes try to mesh again at the other end. Here, an open discharge port allows the air somewhere to go as the meshing lobes take up all the space in the chamber. A Roots blower, then, has a discharge port that pulsates as pockets of air are expelled one by one. Eaton put a twist on the Roots design by twisting the rotors and moving the intake port from the top to the rear. Air is still carried around the sides of the blower, but the twisted rotors help the intake and discharge ports move air more smoothly and thereby the whole unit operates more quietly.
The Roots blower is the most prominent in a family of positive-displacement superchargers. A positive-displacement supercharger, by its nature, pumps an essentially fixed amount of air for every revolution. The Eaton blower in the Neon SRT, for example, pumps 45 cubic inches of air for every revolution, and the one in the Solara pumps 62 cubic inches per revolution. Because of their very linear pumping qualities, engines using positive-displacement superchargers tend to have very linear power bands and excellent, low-rpm response.
You'll notice the Roots design is referred to as a blower, while a centrifugal supercharger or the pumping side of a turbo is referred to as a compressor. The reason is simple. A Roots blower doesn't actually compress air, it simply picks it up and moves it. This is one of the main reasons most Roots blowers are less efficient than most centrifugal compressors. All the compression of the discharge air happens when the air is first exposed to the backup of air waiting to get into the engine. The high-pressure air in the manifold will rush into the back of the blower until the air in the blower is at the same pressure as the air in the manifold; then, as the lobes turn, they will push the air back out of the blower again. This turbulent airflow hurts efficiency, though some creative discharge port design on the Eaton blowers helps minimize this turbulence.
Centrifugal Superchargers
A centrifugal supercharger is basically the same type of pump as the compressor side of a turbocharger. That explanation, of course, is of no help at all if you don't know how the compressor side of a turbocharger works. Let's try again: It's just a radial fan. No? OK, look at the shape of the compressor wheel on the cut-away Vortech supercharger and visualize the air that is trapped between those blades. As the compressor spins, the air trapped near the edge of the wheel gets flung off and the air closer to the center slides in to take its place. Remember centrifugal force? Here it is in action.
The air that gets flung off the end of the wheel is collected in the snail-shaped compressor housing and delivered to the engine. Because the air trapped between each set of blades travels down a progressively smaller path as it nears the edge of the wheel, the air is actually compressed as it is pumped. This, and the inherently smooth nature of the air's journey through the compressor, led to relatively high efficiency. Where the Eaton blower runs at about 65-percent adiabatic efficiency (meaning the air is heated 35 percent more than the laws of physics demand) the Vortech V5 centrifugal supercharger used on the Civic Si runs at up to 73-percent efficiency.
To pump effectively, the compressor wheel has to be spinning extremely fast. Where an Eaton supercharger starts running out of steam around 12,000 to 14,000 rpm, the Vortech V5 centrifugal supercharger used on the Civic Si is barely starting to work at 30,000 rpm, and can run all the way to 60,000 rpm. The smaller centrifugal compressors on turbochagers can run over 100,000 rpm. The high speed of the centrifugal supercharger means some sort of secondary gearbox is needed to spin the supercharger up to 10 times faster than the engine. On the Vortech supercharger, a small, sealed gearbox lubricated by the engine's oil supply does the job. On the Z-Engineering supercharger, the speed multiplication is handled by a secondary belt drive.
While the higher efficiency of the centrifugal supercharger is appealing, the design does have its downside. At low speeds, a centrifugal compressor can hardly pump at all, meaning there is very little boost at low rpm. This can be solved by spinning the supercharger faster, relative to the engine, but overdo it and you end up with too much boost at high rpm. This is where a turbocharger has an advantage. A turbo can be spooled at low rpm, and the wastegate used to keep it from over-boosting at high rpm.
The end result of the centrifugal supercharger's high-rpm nature is a very peaky powerband. The Vortech Civic Si made an astounding 272 hp at the wheels, but the power curve is nearly exponential in shape, meaning that most of the time the car makes far less than peak power. As always, it pays to look at the whole powerband. So there you have it, a crash course in forced induction. Now read on and relish the visceral rewards of air pumps chasing air pumps, and never, ever try to supercharge a supplement.
[ 08-14-2001: Message edited by: technoid ]
Supercharged!
"The Wild World Of Belt-Driven Bliss"
By Dave Coleman
Supercharged! The very word conjures up images of burning rubber, low E.T.s and performance that will make you sweat testosterone. Unless you're normal, that is. The word supercharged has been so spread through our vocabulary that normal people apply it to anything from batteries to herbal supplements. But those of us who really understand the term know that supercharging an herbal supplement will get you nothing but an expensive cloud of plant extracts.
Supercharging--real supercharging--is actually a relatively simple concept. The amount of power an engine can make is proportional to the amount of air and fuel it can ingest and burn. Supercharging is the simple act of putting an air pump in front of the engine to cram in more air and fuel than it would normally be able to ingest on its own. For such a simple concept, the variety of methods for supercharging an engine are staggering.
The reason for the variety is the sheer number of air pumps and drive mechanisms available for the supercharging task. The most basic requirement of a supercharger is that it pump air faster than the engine it is attached to, but there is more to supercharger design than that. A supercharger also has to operate over the same wide range of rpm as the engine it is attached to, and it has to pump air as efficiently as possible without excessively heating it or absorbing too much power.
Technically, turbo-charging is just another form of supercharging--turbochargers are just centrifugal superchargers that happen to be driven by exhaust gasses, rather than the crank--but in the popular car-guy vernacular, the term supercharged is reserved for those installations where the air pump is mechanically driven off the crankshaft. The seemingly minor detail of how the supercharger is driven has a profound effect on how the car drives.
Since the turbocharger relies on exhaust gasses for its power, there is a slight delay or "turbo lag" when the throttle is opened, air is ingested, burned and finally expelled into the turbine to drive the turbo. Depending on the design and sizing of the turbo, this lag can be anywhere from a few agonizing seconds, to a barely noticeable fraction of a second. In contrast, a mechanically driven supercharger should be trying to pump air even before the throttle is opened, resulting in nearly instantaneous boost. Another fundamental difference between turbochargers and superchargers is how each regulates boost. Turbos use a wastegate to bleed off the exhaust gasses driving the turbo when the desired boost level is reached. What this means is that turbos run a fixed boost level, at least in theory.
In a perfect world, a turbo system with the wastegate set at 6 psi would make 6 psi of boost under all wide-open-throttle conditions. A supercharger, by contrast, runs a fixed speed relative to the engine. If a supercharger is geared to pump 1.5 times more air than the car breathes naturally aspirated, the boost will be different at different rpm. In the parts of the rev range where the engine doesn't breathe well, the supercharger's insistence on pumping air will cause air to pile up in the manifold, increasing more pressure. In areas where the engine does breathe well, there will be less of a back-up, and less boost. The end result is that turbochargers tend to simply magnify the stock power band of the engine they are attached to, while superchargers are more likely to totally change the power band to reflect the characteristics of the supercharger.
One thing turbos and superchargers do have in common is the need for intercooling. It is a common myth that turbos need intercooling and superchargers don't. There is no truth to this statement. Compressing air makes it hot; this is an inescapable fact of nature. The more efficient the compressor, the less it heats the air, but the heating still occurs and it is still significant. Cooling that air before it goes into the engine can have a profound effect on performance. In general, turbo compressors are more efficient than supercharger compressors, but this obviously depends on the particular turbo and supercharger you are comparing. The end result is the same: Superchargers stand to benefit from intercooling as much as turbos do.
But enough generalities. All the supercharged cars we gathered this month use one of only two different styles of superchargers, so let's take a look at the superchargers themselves.
Roots Blowers
Both the Dodge Neon SRT and the TRD Solara use Roots blowers made by Eaton. The Roots concept is quite simple. In its plainest form, a Roots blower has two rotors with either two or three lobes each. Like giant gear teeth, the lobes on these rotors intermesh inside a tight-fitting, peanut-shaped housing. If air is allowed to enter the waist of the peanut, or the narrow portion right where the lobes are un-meshing, the air will be drawn into the gap between lobes on each rotor. As the rotors turn, chambers are formed between two adjacent teeth of each rotor and the wall of the rotor housing. Air is simply carried around both sides of the supercharger in these chambers until the lobes try to mesh again at the other end. Here, an open discharge port allows the air somewhere to go as the meshing lobes take up all the space in the chamber. A Roots blower, then, has a discharge port that pulsates as pockets of air are expelled one by one. Eaton put a twist on the Roots design by twisting the rotors and moving the intake port from the top to the rear. Air is still carried around the sides of the blower, but the twisted rotors help the intake and discharge ports move air more smoothly and thereby the whole unit operates more quietly.
The Roots blower is the most prominent in a family of positive-displacement superchargers. A positive-displacement supercharger, by its nature, pumps an essentially fixed amount of air for every revolution. The Eaton blower in the Neon SRT, for example, pumps 45 cubic inches of air for every revolution, and the one in the Solara pumps 62 cubic inches per revolution. Because of their very linear pumping qualities, engines using positive-displacement superchargers tend to have very linear power bands and excellent, low-rpm response.
You'll notice the Roots design is referred to as a blower, while a centrifugal supercharger or the pumping side of a turbo is referred to as a compressor. The reason is simple. A Roots blower doesn't actually compress air, it simply picks it up and moves it. This is one of the main reasons most Roots blowers are less efficient than most centrifugal compressors. All the compression of the discharge air happens when the air is first exposed to the backup of air waiting to get into the engine. The high-pressure air in the manifold will rush into the back of the blower until the air in the blower is at the same pressure as the air in the manifold; then, as the lobes turn, they will push the air back out of the blower again. This turbulent airflow hurts efficiency, though some creative discharge port design on the Eaton blowers helps minimize this turbulence.
Centrifugal Superchargers
A centrifugal supercharger is basically the same type of pump as the compressor side of a turbocharger. That explanation, of course, is of no help at all if you don't know how the compressor side of a turbocharger works. Let's try again: It's just a radial fan. No? OK, look at the shape of the compressor wheel on the cut-away Vortech supercharger and visualize the air that is trapped between those blades. As the compressor spins, the air trapped near the edge of the wheel gets flung off and the air closer to the center slides in to take its place. Remember centrifugal force? Here it is in action.
The air that gets flung off the end of the wheel is collected in the snail-shaped compressor housing and delivered to the engine. Because the air trapped between each set of blades travels down a progressively smaller path as it nears the edge of the wheel, the air is actually compressed as it is pumped. This, and the inherently smooth nature of the air's journey through the compressor, led to relatively high efficiency. Where the Eaton blower runs at about 65-percent adiabatic efficiency (meaning the air is heated 35 percent more than the laws of physics demand) the Vortech V5 centrifugal supercharger used on the Civic Si runs at up to 73-percent efficiency.
To pump effectively, the compressor wheel has to be spinning extremely fast. Where an Eaton supercharger starts running out of steam around 12,000 to 14,000 rpm, the Vortech V5 centrifugal supercharger used on the Civic Si is barely starting to work at 30,000 rpm, and can run all the way to 60,000 rpm. The smaller centrifugal compressors on turbochagers can run over 100,000 rpm. The high speed of the centrifugal supercharger means some sort of secondary gearbox is needed to spin the supercharger up to 10 times faster than the engine. On the Vortech supercharger, a small, sealed gearbox lubricated by the engine's oil supply does the job. On the Z-Engineering supercharger, the speed multiplication is handled by a secondary belt drive.
While the higher efficiency of the centrifugal supercharger is appealing, the design does have its downside. At low speeds, a centrifugal compressor can hardly pump at all, meaning there is very little boost at low rpm. This can be solved by spinning the supercharger faster, relative to the engine, but overdo it and you end up with too much boost at high rpm. This is where a turbocharger has an advantage. A turbo can be spooled at low rpm, and the wastegate used to keep it from over-boosting at high rpm.
The end result of the centrifugal supercharger's high-rpm nature is a very peaky powerband. The Vortech Civic Si made an astounding 272 hp at the wheels, but the power curve is nearly exponential in shape, meaning that most of the time the car makes far less than peak power. As always, it pays to look at the whole powerband. So there you have it, a crash course in forced induction. Now read on and relish the visceral rewards of air pumps chasing air pumps, and never, ever try to supercharge a supplement.
[ 08-14-2001: Message edited by: technoid ]
08-14-2001, 06:12 PM
#5
Racer
Join Date: Jul 2001
Location: Ohio
Posts: 362
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by technoid:
<STRONG>Read this, if you dare. (quiz on Monday
[ 08-14-2001: Message edited by: technoid ]</STRONG>
<STRONG>Read this, if you dare. (quiz on Monday
[ 08-14-2001: Message edited by: technoid ]</STRONG>
A Supercharger is a belt driven forced-induction device that is tied directly to engine RPM and driven by the crank. This means that forced induction is available right from idle.
A Turbocharger is forced induction driven by exhaust gasses. The famed turbo lag is the wait for engine RPM to rise to the point that the turbo produces meaningfull forced induction. Intercoolers are used to cool the turbo, as exhaust gasses are EXTREMELY hot (grab the header after a long drive, then proceede directly to the ER).
Both provide forced induction, just through different methods.
My supertoroturbocharger in the TL:
[ 08-14-2001: Message edited by: jdl75 ]
03-31-2003, 01:49 PM
#7
1 Dog, 2 Cats and a G-Pig
Join Date: Nov 2002
Location: Crap Arbor
Age: 44
Posts: 938
Likes: 0
Received 0 Likes
on
0 Posts
So where does nitrous fit into all this?
Also, can you super/turbo charge an auto? Do they make super/turbo charges for our cars, and do they damage the car?
Also, can you super/turbo charge an auto? Do they make super/turbo charges for our cars, and do they damage the car?
Trending Topics
03-31-2003, 02:20 PM
#8
im back
Join Date: Apr 2002
Location: New York
Age: 39
Posts: 2,153
Likes: 0
Received 0 Likes
on
0 Posts
you can super/turbo charge anything with a motor. Auto, stick, smg whatever you want. Comptech makes a supercharger. A turbo on our car is custom(like allmotor did) They do put extra wear on the motor.
04-01-2003, 12:24 PM
#10
VOTE OUT THE BUSH REGIME
Join Date: Mar 2002
Location: PHX
Posts: 2,207
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by jdl75
My supertoroturbocharger in the TL:
[ 08-14-2001: Message edited by: jdl75 ] [/B]
My supertoroturbocharger in the TL:
[ 08-14-2001: Message edited by: jdl75 ] [/B]
04-01-2003, 02:44 PM
#12
Banned
Join Date: Jan 2001
Location: Somewhere between here and there, yet neither.
Posts: 9,151
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by mrateb
Stupid question then, but if turbo is powered by the exhaust, and super is powered by the crank, can you put both in?
Stupid question then, but if turbo is powered by the exhaust, and super is powered by the crank, can you put both in?
Basically, both parties have solved this problem to a degree.
The turbo camp has developed hybrid turbos with ball bearings to enable quick spool up coupled with good high end. The previous way to fix this problem was by using a sequential twin turbo...a small one and then a big one.
The Supercharger camp has introduced the Lysholm twin-screw as used on Mercedes AMGs. This offers the low end instant power of a Roots with a more efficient twin screw design v. single screw design of Roots...which means more air is forced in with less heat association. Also, the centrifugal sc (Vortech) has introduced the belt driven turbo....to offer a higher degree of reliability associated with SCs, but with the benefit of a turbo.
04-01-2003, 07:12 PM
#13
Grammar Police
Join Date: Feb 2002
Location: SF Bay Area
Posts: 196
Likes: 0
Received 0 Likes
on
0 Posts
An awsome reference for everything scientific and technological is HowStuffWorks.com.
Check out the answer to your question:
"What is the difference between a Turbo and a Supercharger?"
http://auto.howstuffworks.com/question122.htm
And also, take a look at their awsome article on Turbos:
http://auto.howstuffworks.com/turbo.htm
Check out the answer to your question:
"What is the difference between a Turbo and a Supercharger?"
http://auto.howstuffworks.com/question122.htm
And also, take a look at their awsome article on Turbos:
http://auto.howstuffworks.com/turbo.htm
Thread
Thread Starter
Forum
Replies
Last Post
joflewbyu2
5G TLX (2015-2020)
139
10-08-2015 11:16 AM
Joe Avesyan
3G TL Performance Parts & Modifications
9
09-29-2015 03:57 PM
81brettkeith
3G TL (2004-2008)
34
09-15-2015 06:04 PM
203, acurazine, centrifugal, dinan, higher, lysholm, mercedes, roots, rpm, rush, supercharger, turbo, twincharging, vortech, vs
