Supercharging the Z06
Sep 14, 2004 | 09:56 PM
#22
Thread Starter
Teching In
Joined: Sep 2004
Posts: 30
Likes: 0
From: Texas
How do these things pull outta the hole? I mean right now I have a 5.7L with an ATI. It runs 13.2 through the quarter. It's hard to get much more outta that Vortec. It starts pullin good around 2300 and really kicks in about 3400. I heard these twin screws pull hard all the way through. By the way, how the hell do ya get your trucks to bite?
Sep 14, 2004 | 10:39 PM
#26
Holla, if ya hear me.....
Radix:
A common, but perhaps more correct, term for a Roots supercharger is "blower. One defining characteristic of a Roots is that charge air compression occurs outside the supercharger, in the space between it and the intake valves. In effect, it blows air into the intake manifold where it becomes compressed due to the system's pushing more air in than can flow out.
The Roots blower was patented in 1860 by two brothers, Philander and Francis Roots, as a ventilating device for blast furnaces, grain elevators and coal mines. In the last half of the 19th century they were quite common in those applications and that ancestry is key to understanding that a Roots is a device which moves air rather than compresses it.
In the early part of the 20th Century, engineers perfected supercharging in motorsports and aircraft applications using primarily centrifugal superchargers. In the '30s, Roots blowers gained acceptance in Grand Prix and Indianapolis racing and on some expensive, high-performance sports cars of the period. Starting in the late-'30s, General Motors began using large Roots blowers on the diesels it built for its GMC heavy-duty trucks, its marine customers and its Electromotive Division locomotives. In the 1950s, drag racers and Bonneville Salt Flats competitors adapted GMC blowers to racing engines. Today, Roots blowers are still quite common in motorsports, especially drag racing.
The Magnuson "Radix" supercharger in GM, Vortec truck engine trim. Magnuson makes both the intake manifold and the blower case. The drive and the guts of the blower are Eaton parts used in Eaton's model-M112 supercharger, the largest unit Eaton makes for O.E.s.
Later, the Roots idea transferred to the street high-performance aftermarket and the Eaton Corporation developed a small, compact Roots blower for original equipment use on some performance cars, luxury sedans and, yes, pick-up trucks. Buick, Pontiac, Ford, Lincoln, Jaguar and Mercedes Benz are just a few brands using the Eaton blower, the design of which is now in its fifth-generation.
These are the rotors from the fifth-generation Eaton supercharger. The frosty-looking, matte-black color is the APC with partially-abrades away during break-in leaving an enhanced lobe-to-lobe seal. The lobes mesh as they turn and that pulls the air through the supercharger.
There are some concerns with blowers and one is cost. A properly developed, aftermarket supercharger kit runs several thousand dollars. Add installation labor and you're past five large pretty quick. Because a supercharger increases both the engine's cylinder pressure and charge air temperature, two causes of detonation or "knock", blowers mandate use of at least 91-octane fuel which may increase operating cost. A "boosted" engine produces a higher volume of exhaust gases, so engines equipped with superchargers usually need a low-restriction exhaust system.
With aftermarket superchargers on computer-controlled engines, the "calibration" in the computer, software which tells the computer how to set the fuel curve, spark curve, emissions controls operation and a host of other operational parameters, can be a significant development issue. In fact, proper engine controls calibration of a aftermarket supercharger system requires almost as much work as developing the supercharger hardware, itself, so a key factor in the difference between a good aftermarket blower kit and a bad one is, often, calibration. Lastly, don't be surprised if there is a reduction in fuel economy. How much depends on how the engine is driven. If boosted operation is infrequent and the blower has a bypass (which we'll discuss momentarily), fuel mileage will be close to stock. If you're "on boost" regularly, expect a noticeable decrease in mileage.
Let's take a closer look at some features of the Magnuson Radix Supercharger. The word "Radix" is Latin for "root" or "origin," an appropriate name, indeed. Radix are based upon Eaton, fifth-generation, M112 superchargers but they're not simply "rebadged" Eatons. Magnuson uses many of Eaton's internal pieces but manufactures its own supercharger case, intake manifold, charge air cooler and drive system.
What actually moves the air through a Roots blower is a pair of contrarotating, tri-lobe rotors which mesh as they turn. The tighter the fit of the lobes, the more efficient the blower is, however, there must be some clearance or the rotors won't turn. If the clearance is too great, the supercharger is inefficient because of leakage past the lobe edges. If the clearance is too tight, there is a high level of resistance to rotation. To both tighten rotor clearance and reduce friction, one trick Eaton began using with its fifth-generation Roots is to coat each rotor with an abradable powder coating or (APC). During the break-in period, in the first few hundred miles of operation, a small portion of this coating abrades away, leaving the contact areas at the tips of the rotor lobes perfectly matched to each other and able to run extremely close. This is Magnuson's Radix case. At top left, just inside the blower inlet is the bypass valve butter fly. At lower right, on the side of the blower case if the vacuum motor that operates the valve.
Eaton rotors are twisted 60 degrees. Helical rotors, along with specially designed inlet and outlet port geometry in the blower case, help to reduce pressure variations resulting in a smooth discharge of air and a lower level of noise during operation. This arrangement, also, improves efficiency. With helical rotors, the supercharger can run at up to 14,000 rpm, making for a small blower for a given boost and air flow output. The Eaton's axial intake further reduces package size.
Another "secret of the Radix" its bypass valve. This small valve, between the the throttle body and the intake manifold, increases fuel economy and reduces parasitic power loss. The bypass is operated by a vacuum actuator and is normally closed. When manifold pressure is low (high vacuum typical of light throttle operation) the actuator opens the valve, allowing charge air to flow from the throttle body directly into the intake manifold, bypassing the blower and equalizing pressure in the system. The bypass valve open at low manifold pressure eliminates parasitic loss in a practical sense. Magnuson superchargers running with an open bypass consume only about one horsepower. When the supercharger begins to make boost, the bypass valve snaps closed, allowing pressure to build in the intake ports.
All Radix have a "charge air cooler" which some call an intercooler. During compression, charge air temperature rises. Because a temperature increase reduces air density, negating some of the effect of compression, and makes the engine more prone to detonation; there is an advantage in cooling the air after it exits the blower but before it goes into the cylinders. The Radix charge air cooler is built into the intake manifold.
Radix:
A common, but perhaps more correct, term for a Roots supercharger is "blower. One defining characteristic of a Roots is that charge air compression occurs outside the supercharger, in the space between it and the intake valves. In effect, it blows air into the intake manifold where it becomes compressed due to the system's pushing more air in than can flow out.
The Roots blower was patented in 1860 by two brothers, Philander and Francis Roots, as a ventilating device for blast furnaces, grain elevators and coal mines. In the last half of the 19th century they were quite common in those applications and that ancestry is key to understanding that a Roots is a device which moves air rather than compresses it.
In the early part of the 20th Century, engineers perfected supercharging in motorsports and aircraft applications using primarily centrifugal superchargers. In the '30s, Roots blowers gained acceptance in Grand Prix and Indianapolis racing and on some expensive, high-performance sports cars of the period. Starting in the late-'30s, General Motors began using large Roots blowers on the diesels it built for its GMC heavy-duty trucks, its marine customers and its Electromotive Division locomotives. In the 1950s, drag racers and Bonneville Salt Flats competitors adapted GMC blowers to racing engines. Today, Roots blowers are still quite common in motorsports, especially drag racing.
The Magnuson "Radix" supercharger in GM, Vortec truck engine trim. Magnuson makes both the intake manifold and the blower case. The drive and the guts of the blower are Eaton parts used in Eaton's model-M112 supercharger, the largest unit Eaton makes for O.E.s.
Later, the Roots idea transferred to the street high-performance aftermarket and the Eaton Corporation developed a small, compact Roots blower for original equipment use on some performance cars, luxury sedans and, yes, pick-up trucks. Buick, Pontiac, Ford, Lincoln, Jaguar and Mercedes Benz are just a few brands using the Eaton blower, the design of which is now in its fifth-generation.
These are the rotors from the fifth-generation Eaton supercharger. The frosty-looking, matte-black color is the APC with partially-abrades away during break-in leaving an enhanced lobe-to-lobe seal. The lobes mesh as they turn and that pulls the air through the supercharger.
There are some concerns with blowers and one is cost. A properly developed, aftermarket supercharger kit runs several thousand dollars. Add installation labor and you're past five large pretty quick. Because a supercharger increases both the engine's cylinder pressure and charge air temperature, two causes of detonation or "knock", blowers mandate use of at least 91-octane fuel which may increase operating cost. A "boosted" engine produces a higher volume of exhaust gases, so engines equipped with superchargers usually need a low-restriction exhaust system.
With aftermarket superchargers on computer-controlled engines, the "calibration" in the computer, software which tells the computer how to set the fuel curve, spark curve, emissions controls operation and a host of other operational parameters, can be a significant development issue. In fact, proper engine controls calibration of a aftermarket supercharger system requires almost as much work as developing the supercharger hardware, itself, so a key factor in the difference between a good aftermarket blower kit and a bad one is, often, calibration. Lastly, don't be surprised if there is a reduction in fuel economy. How much depends on how the engine is driven. If boosted operation is infrequent and the blower has a bypass (which we'll discuss momentarily), fuel mileage will be close to stock. If you're "on boost" regularly, expect a noticeable decrease in mileage.
Let's take a closer look at some features of the Magnuson Radix Supercharger. The word "Radix" is Latin for "root" or "origin," an appropriate name, indeed. Radix are based upon Eaton, fifth-generation, M112 superchargers but they're not simply "rebadged" Eatons. Magnuson uses many of Eaton's internal pieces but manufactures its own supercharger case, intake manifold, charge air cooler and drive system.
What actually moves the air through a Roots blower is a pair of contrarotating, tri-lobe rotors which mesh as they turn. The tighter the fit of the lobes, the more efficient the blower is, however, there must be some clearance or the rotors won't turn. If the clearance is too great, the supercharger is inefficient because of leakage past the lobe edges. If the clearance is too tight, there is a high level of resistance to rotation. To both tighten rotor clearance and reduce friction, one trick Eaton began using with its fifth-generation Roots is to coat each rotor with an abradable powder coating or (APC). During the break-in period, in the first few hundred miles of operation, a small portion of this coating abrades away, leaving the contact areas at the tips of the rotor lobes perfectly matched to each other and able to run extremely close. This is Magnuson's Radix case. At top left, just inside the blower inlet is the bypass valve butter fly. At lower right, on the side of the blower case if the vacuum motor that operates the valve.
Eaton rotors are twisted 60 degrees. Helical rotors, along with specially designed inlet and outlet port geometry in the blower case, help to reduce pressure variations resulting in a smooth discharge of air and a lower level of noise during operation. This arrangement, also, improves efficiency. With helical rotors, the supercharger can run at up to 14,000 rpm, making for a small blower for a given boost and air flow output. The Eaton's axial intake further reduces package size.
Another "secret of the Radix" its bypass valve. This small valve, between the the throttle body and the intake manifold, increases fuel economy and reduces parasitic power loss. The bypass is operated by a vacuum actuator and is normally closed. When manifold pressure is low (high vacuum typical of light throttle operation) the actuator opens the valve, allowing charge air to flow from the throttle body directly into the intake manifold, bypassing the blower and equalizing pressure in the system. The bypass valve open at low manifold pressure eliminates parasitic loss in a practical sense. Magnuson superchargers running with an open bypass consume only about one horsepower. When the supercharger begins to make boost, the bypass valve snaps closed, allowing pressure to build in the intake ports.
All Radix have a "charge air cooler" which some call an intercooler. During compression, charge air temperature rises. Because a temperature increase reduces air density, negating some of the effect of compression, and makes the engine more prone to detonation; there is an advantage in cooling the air after it exits the blower but before it goes into the cylinders. The Radix charge air cooler is built into the intake manifold.
Sep 15, 2004 | 08:11 AM
#30
TECH Veteran
Joined: Sep 2003
Posts: 4,534
Likes: 3
From: Las Vegas, NV
no matter how much you want that to be a 2005 engine, it's not. it's also not brand new if it has over 2000 miles on it. the title of supercharging a Z06 when it's only an LS6 is amusing. as for putting a radix or some type of supercharger, it's been done many times and there are many examples of supercharged LS6's on this board if you search around.