One Blown Bat Outa Hell
The Tom Henry Racing Camaro's Supercharger System
Halverson, Content Director
Jeff Sable, of
Mars, Pennsylvania, is one of half-a-dozen
Tom Henry Racing Camaro owners so far who've
opted for the Edelbrock E-Force
Supercharger. Once it was installed, he knew
exactly what to do with an old pair of tires
he found in the garage...bolt
them on the back of his car, 2010 THR Camaro
#31 named "Bad Jewel", and smoke 'em with
the power of E-Force. Image: Jeff
Superchargers are the weapons of choice for
fifth-generation Camaro owners looking for big power
increases. With the car's real-world weight hovering
around 4100-lbs, hardcore owners of Chevrolet's iconic
sports coupe are looking for 150-or-so more horses
needed to show their tail lights to Corvettes.
Consequently, in the short period since Camaro returned
to the marketplace, the aftermarket has responded with
bunches of blowers.
Chevrolet is posed to jump on the boost band wagon with
a 5G Z28 which will use GM's LSA, a 6.2-liter,
supercharged V8, and that begs the question: why bother
with an aftermarket blower when GM will have its own?
upfitter, Tom Henry Racing, sees The Edelbrock E-Force
Supercharger is as the best solution to a Camaro buyer's
need for boost–better than other aftermarket systems
and, perhaps, better than GM's factory blower.
Consequently, the supercharger THR makes available on
its uniquely personalized Tom Henry Racing Camaros is
Image: CHpg Staff.
The LSA is
rated at 556-horsepower, SAE-corrected, and is topped
with a smaller version of the blower introduced in 2009
on the Corvette ZR1. The Camaro E-Force (PN 1597,
automatic trans; PN 1598, manual) uses the larger rotor
set from the LS9 and bumps the manual trans Camaro from
426- to 570-hp SAE. Edelbrock documentation rates an
E-Force supercharged LS3 even higher, at 599-hp, using
the "standard-correction" common to the performance
The E-Force increases
power to 599-hp (standard corrected).
Image: Edelbrock LLC.
attractive feature of the Edelbrock system is that, for
those wanting their hot rods to have a stealth look,
while GM's Z28 supercharger requires a specific hood
with more clearance, E-Force fits under the standard
Camaro hood so as not to giveaway your "supercharged
secret" until you pass a Corvette.
the great features of the E-Force system
Tom Henry Racing puts on its Camaros
(shown here is 2011 THRC #3) is there is
no special hood to tip-off observers
that there is anything "special" under
the hood of a supercharged THR Camaro.
Image: Tom Henry
Another big selling point? Right now, E-Force is the only Camaro
supercharger kit with California Air Resources Board (CARB)
Executive Order (EO) approval. This means E-Force is
street legal in all 50-States and will pass state
exhaust emissions inspections.
then We Drive.
Edelbrock, one of the oldest and most recognized brands
in the performance aftermarket, late to jump into the
aftermarket blower business? Last Spring, just before
the Camaro E-Force was introduced, CHpg visited
Edelbrock in California to get the answer, straight from
the guy who's name is on the building.
In an interview with the
Camaro Homepage, Vic Edelbrock told us
that his company's Roots supercharger,
".... is a way of gettin' horsepower
like no other." The 150-horsepower kick
a Camaro gets from his blower kit has us
Image: CHpg Staff.
been considering something like E-Force for a long
Edelbrock told us. "In the late-'90s, when we first
looked at the (GM Gen 3/4) engines, there was only so
much you could do with a set of heads and a camshaft and
it wasn't easy to make a manifold. You're lookin' at 40
horsepower, maybe. We needed something for the LS
engines we could put on and get an appreciable gain of
at centrifugal supercharging. We almost bought a maker
of centrifugal superchargers but that would have been a
mistake, in my opinion. A few years later, I talked to
Eaton, but they were thoroughly plugged-in with
Magnuson. At that time, unless a company doing OE that
had what you wanted, you were dead in the water because
superchargers were kinda hard to make.
knowing what we could do with boost in kept us looking
in that direction. A couple of years ago, when Eaton
gave us the opportunity to participate in their
supercharger) program, that energized us because
supercharging is a way of gettin' horsepower like no
day, Edelbrock's Vice President for Research and
Development, Rob Simons, and I went for a drive in the
company's 2010 Camaro development vehicle which, from a
duplicates a supercharged Tom Henry Racing Camaro except
it lacks THR's additional dyno-tuning work.
Image: CHpg Staff.
Many of the
company's test cars have a small fender script: "Edelbrock:
The FUN Team". Near the company's Torrance, California
headquarters, Crenshaw Boulevard runs for half a mile or
so alongside a giant Exxon-Mobil refinery. It was there
I had some "fun" in a demo of what Vic Edelbrock meant
about "...gettin' horsepower like no other."
From a first
gear roll, I punched it. The throttle response was just
about instantaneous–thanks, in part, to Edelbrock's very
good calibration work. A second later, as the engine
pulled into it's best torque range, the red Camaro was
spinning the tires. I pedaled it a bit and she hooked
so, I let it pull just about to the rev limiter. I got
second gear, whacked the throttle wide open, again.
Second is a hoot in this car! While a stock SS
accelerates sportingly, with stick-shift versions of
Chevy's sports coupe, the impact of E-Force on the
engine's torque makes the 5G Camaro a rocket ship. I
banged third and stayed on it until about 4500. Fun?! An
E-Force supercharged Camaro is a whole lota fun!
And...most blown THR Camaros will have 30-horsepower
more through headers and custom tuning, making for one
blown bat outa hell.
Image: Edelbrock, LLC.
At the core
of E-Force is Eaton's new, sixth-generation,
"Twin-Vortices Series" R2300 rotor set which was
developed in the late-'00s for the ZR-1's 638-hp LS9
engine and is manufactured in the U.S, at a plant in
Athens, Georgia. The "TVS" sets new standards for
supplies the rotor set, Edelbrock developed and
manufactures the rest of E-Force's major hardware,
including a large aluminum casting, poured at
Edelbrock's foundry at San Jacinto, California and
machined at the company's main facility in Torrance,
which serves as both the supercharger case and the
The start of an E-Force
Supercharger case at the Edelbrock
Foundry is the assembly of the cores.
Here, a foundry worker sets the
foot-long, runners in place. Image:
The mechanized crucible
at left scoops molten aluminum from the
melting furnace then transfers it to the
line of black boxes in the background.
Those are the core boxes on a conveyor
system and each holds one blower case.
The crucible fills one core box then
goes back for another load while the
conveyor moves the next box into
position for pouring. Image: Edelbrock,
In Edelbrock's Torrance
manufacturing facility, a blower case is
being removed from a pallet which holds
it during the CNC machining process.
Image: CHpg Staff.
Viewed from the rear, the
finished blower case before assembly.
The part is black-powder-coated prior to
machining. Image: CHpg Staff.
A Camaro E-Force
Supercharger ready for installation. It
is an amazingly compact package. The
E-Force is a front-drive design with a
front intake, slightly left and below
the drive rotor's shaft, and a top
exhaust. It needs neither a jackshaft,
used by some aftermarket superchargers,
nor complex intake ducting used on
others. Image: CHpg Staff
advancement is the R2300's increased displacement over
the largest fifth-generation Eaton blower, the M122,
which was the basis of a number of aftermarket
supercharger kits. Eaton categorizes blowers by the
volume of air they displace during one rotation of their
rotors. With the fifth gen, "M-series", the unit of
measure was cubic inches (M122 is 122 cubic inches or
1999 cc.) With the TVS line, it's cubic centimeters
(R2300 is 2300-cc.). About 300-cc more displacement and
other enhancements has the R2300 flowing about 20% more
air along with having a wider dynamic range than the
M122. It builds boost more quickly at low rpm and can
sustain it at higher speeds.
This is math art of rotor
sets from the Eaton M122 and R2300
superchargers. Big difference--four
lobes rather than three and a 100°
greater helix angle. Image: Eaton Corp.
does the TVS rotor set add performance, but it does so
without the characteristic loud whine typical of
"modified-Roots" superchargers previously used in
aftermarket blower kits. One enabler of that is a switch
from three to four lobe rotors and a significant
increase of the rotor helix angle from the Gen 5's
60-degrees to 160-degrees for TVS.
changes allow better "porting"–how the air gets to the
rotors through the supercharger intake. The more
tightly-twisted, four lobe rotors allowed Eaton to
enlarge the supercharger inlet which slows the air going
through it. That is a significant advancement over the
fifth-generation which, under some conditions, had air
flowing at sonic speed through the inlet but slowing
substantially as it filled the rotor cavity. Such a
large change in velocity increased both the power
required to drive the unit and noise radiated through
the case and out the throttle body.
more work on efficiency and noise reduction at the
supercharger outlet. "Backflow ports or 'slots' were
added to the 3rd generation, primarily to quiet the
sound of the supercharger," Eaton's Development
chief for the TVS, Mike Sitar, told us.
is the method of compression within a Roots device. Air
enters the inlet port, gets closed off by the rotor
faces, then transfers to the outlet at inlet pressure.
As it hits the outlet port, if you didn't have backflow
slots, the air would immediately rush backwards, through
the outlet port, to bring that cavity up to outlet
pressure, then the rotors would come into mesh and force
the air back the other way, through the outlet. That's a
full, air flow reversal in the outlet port.
This view of the outlet of an
M122 outlet shows one of the backflow slots Eaton used
in the Gen 3, 4 and 5 designs as a noise reduction
measure. Image: CHpg Staff.
reversal creates a high level of pulsation and noise.
Backflow slots allow the air from the outlet to begin
pressurizing that closed chamber before it moves to the
outlet port. They allow air flow, into the supercharger,
through those ports, then out the outlet port,
maintaining one-way flow through two different ports. We
took a percent, maybe a percent and half hit in
adiabatic efficiency, but it, also, allows a one to
three decibel decrease in noise. It does impact
efficiency of the supercharger, but our biggest goal was
does not have those backflow ports,"
continued. "Its backflow function depends on flow
from the outlet to the rotor bore. There's actually a
hole–we call it a "blowhole"–located within the rotor
mesh. When the rotors mesh, there's still an open area
that connects the rotors across the top of this cusp
within the supercharger. In TVS, backflow occurs within
the rotor set itself. The air is never moved to the
discharge port, then brought back in.
More math art explains the TVS
supercharger family's "blowhole" feature used to reduces
noise caused by backflow. Image: Eaton Corp.
blowhole exists continuously, it just moves forward all
the time. It starts in the rear, after the inlet closes,
and travels forward as the rotors mesh. It always exists
between the rotors, but its position changes all the
allows our backflow event to be more than twice as long
(than with the Gen 5), so before the rotor even opens
to the outlet; the air is almost completely pressurized
inside the supercharger.
still pressurizes the intake manifold through backflow,
which defines it as a Roots device, but when it goes to
the outlet port, it's primarily one-way flow. The TVS is
5-10 decibels quieter, compared to a fifth generation
supercharger, and a lot of that is because of backflow
The set of
56-tooth, blower drive gears in an M122 are
shown at left. The R2300 has 101-tooth
gears. The near-doubling in tooth-count
moves the gear noise to a higher,
less-objectionable frequency. Image: Author.
during LS9 development that noise radiated by the
supercharger was reduced by 10-dBA and it's a logical to
conclude that the noise reduction is similar with the
E-Force system on a Tom Henry Racing Camaro. By going from three to four lobes,
Eaton raised the frequency of what noise was left making
it less noticeable. Additional noise reduction came from
an increase in blower drive gear tooth count from 56 to
101 which raised the frequency of the gear noise to a
less annoying level. Bottom line: an Edelbrock blower
still makes noise, but it's not near as loud, because of
Eaton's work in controlling air flow, and less
objectionable, because of its higher frequency.
Some of the
engine's power is used to drive the supercharger.
Engineers call that "input power requirement" and
limiting it is important to both fuel economy and the
supercharger's ability to increase performance. For
better gas mileage, E-Force has a bypass valve which
opens during part-throttle operation. When manifold
absolute pressure drops below about 69 kPa (10 psi), the
bypass opens and intake air flows from the supercharger
outlet, through the valve and back into the blower
inlet. With the bypass open, the supercharger consumes
only about half-a-horsepower which has minimal effect on
In this image, the bypass is
closed. When it's open, the supercharger consumes about
half-a-horsepower and has minimal effect on fuel
economy. Image: Author.
reduced input power requirement of the blower when it's
on boost. At the engine's power peak, it dropped from
around 115 hp, for the M122, to about 75-hp for TVS.
This reduction came from the efficiency improvements
cited earlier and efforts in friction reduction, chiefly
with the rotor surfaces which mesh.
One reason the R2300 is the most
efficient modified-Roots superchargers on the market is
minimal clearance between the lobes of the rotors.
Image: GM Powertrain.
During the rotors' first turns,
part of the black coating abrades away, leaving lobe
contact areas better matched to each other and able to
run extremely close. All surfaces of each rotor except
the shafts are treated with the abradable powder
coating, however, it only abrades in the areas shown.
Image: CHpg Staff.
sealing is a double-edged sword. The tighter rotors
mesh, the better they seal and the less leakage the
blower sustains, however, a tight seal means more
friction and more power needed to turn the blower. The
TVS rotor set maintains a tight seal, but with less
friction due to:
tolerances Eaton uses during machining and assembly.
Because rotor clearance remains more consistent from
rotor set to rotor set, the minimum clearance can be
treated with a graphite-based, abradable powder coating
(APC). During the rotors' first few turns, part of the
coating abrades away, leaving rotor lobe contact areas
better matched to each other, able to run extremely
close and lubricated by the graphite. That provides
enhanced sealing with reduced friction.
A design that is
dimensionally-stable at outlet temperatures up to 300°F.
A rotor set that is dimensionally-stable at higher
operating temperatures means there is less rotor
expansion so clearance can be set tighter. For more
technical discussion of superchargers
intake air temperature makes the engine more prone to
detonation. The nature of supercharging is that, because
it compresses air going into the engine, it adds heat to
the charge air. Edelbrock attacks that problem on three
improvements discussed previously cut temperature rise
by 15% compared to the M122, so not only is the R2300
better performing, smaller and quieter; it adds less
typical of many superchargers used in high-performance
applications, the E-Force has an air-to-liquid, charge
air cooler. Some call this an "intercooler" but, if
we're going to be dead-nuts accurate, it's a "charge air
aftercooler" because it cools the intake charge after it
exits the supercharger.
system uses the wave tuning effect to further limit heat
At a glance,
Edelbrock's supercharger may seem a copy of GM's
hardware, but while Rob Simons' team was inspired by the
ZR1's blower; there are significant differences. Like GM
did with the LS9, Edelbrock
opted for two charge air cooler heat exchangers for
easier packaging, but key to E-Force fitting under a base Camaro
hood was putting those heat exchangers in a different
benchmarked the GM supercharger,"
Rob Simons told us, "and discovered
aspects we wanted to change. It wouldn't fit under a
Camaro hood. Ours had to be lower and we achieved that
by moving the intercoolers to the side. That gained
about two inches. In addition, the GM's intercoolers
overlap the supercharger outlet, so there's restriction.
Getting them away from the outlet improved air flow."
Image: CHpg Staff.
exchangers have a separate cooling system consisting of
an additional radiator mounted at the front of the
Camaro's cooling stack, an electric pump, a reservoir
and associated plumbing. The system holds a gallon or so
of coolant and is capable of cooling the intake charge
up to 70 degrees.
There are two of these heat exchangers
which sit either side of the blower
case. This is a significant difference
in packaging from how GM locates the
exchangers for the LS9 and LSA and gives Edelbrock's supercharger more space to use for the long
intake runners. Image: CHpg Staff.
Ample space in front of a 5G
Camaro's cooling stack allows a generously-sized
radiator for the E-Force charge air cooler. Image:
Charge air coolant is circulated
in the system by this Bosch electric coolant pump.
Image: CHpg Staff.
The charge air cooling system is
separate from the engine's cooling system, has its own
reservoir tank and uses the same type of coolant as the
engine. Image: CHpg Staff.
major feature differentiating E-Force from GM's and the
aftermarket's Roots blowers are long intake runners in
the bottom of the supercharger housing. "When air
flows down into the LSA's ports," Simons stated,
"it has to go around the injector which sits right above
the port. To not constrict the port entry, GM siamesed
the runners, so the port is shrouded by the injector and
there is no demarcation between runners.
Moving the heat exchangers to the
side not only lessens the space needed for hood
clearance but it allowed Edelbrock to put long runners
beneath the blower case. Couple a TVS with short runner
manifold then compare it to the same blower coupled with
a long runner manifold. Use the same engine, same pulley
ratio, same rpm and you'll get the same airflow, but the
pressure, from 2000 to 5000 rpm, can be as much as two
pounds lower. That makes for less temperature rise and
less parasitic loss. Image Edelbrock, LLC. Image:
of short, siamesed ports, we used space we gained moving
the intercoolers for individual runners underneath the
supercharger. We have 12-inch runners, which provide a
tuning effect. Each four runners go from below an
intercooler to the opposite cylinder head. In addition, the
injector doesn't impede flow. It's in the same location, if the air
goes down, it was in the way. When the air goes across, it's not."
"In a ZR1 supercharger, after
air flows horizontally though the intercoolers, it makes
an abrupt turn then goes down, into the heads. We
wanted the supercharger to flow more freely, so we don't
have the hard right turns," Simons told us. Image:
Few Roots or
screw blower systems go this route because of the
complex design and casting necessary but the advantage
is the effect resonant tuning has on the engine's
performance. In the critical 2000-5000 rpm range, you'll
observe enhanced mid-range torque when you compare an
E-Force to one of the other, Roots systems.
The individual runner manifold also
allows a more efficient spark schedule in Camaro's ECM
calibration and that further improves response and fuel
economy. For a more detailed discussion of long runner
read this sidebar on blower tech.
This is the E-Force reprogrammer.
The calibration for a stock Camaro is 50-state legal
with a California Air Resources Board "EO Number".
Image: Edelbrock, LLC.
drive in the Edelbrock Camaro on Torrance streets and
nearby I-405, I found that besides more power and less
noise, the E-Force system exhibits the outstanding
drivability one expects from a production engine,
something absent with some of the other Camaro blower
kits on the market. Doesn't matter how you drive it:
stop-and-go traffic, lugging in sixth, cruising the 'burbs
at 30-40 mph, part throttle high rpm in first, going for
high mileage on the highway at 55 mph or cruising at 90
on the Interstates out west–whatever. Edelbrock has its
calibration down pat and, because of that, E-Force is a
new drivability benchmark for aftermarket blower kits.
During development Edelbrock
determined that the stock Camaro air filter box posed a
restriction and needed to be enlarged. Every Camaro
E-Force comes with this larger air filter top and a
high-performance Green Filter. Image: CHpg Staff.
Edelbrock benchmarked competing
aftermarket superchargers and found that with some of
them belt slip was a problem. Because of that, design of
the blower drive and the drive belt selection received
much attention. Every E-Force comes with the Goodyear Gatorback belt which is the only belt Edelbrock
recommends. Image: CHpg Staff.
system comes with everything necessary for installation
on a stock Camaro L99 or LS3 including a handheld
reprogrammer containing the engine controls calibration.
Racing is a factory-approved Edelbrock E-Force
Installer. THR Camaro E-Force system prices start at
$8300.00 which includes the supercharger system,
installation, custom tuning and a 12-month, limited
warranty. In addition, Edelbrock offers three
extra-cost, extended warranties which offer coverage of
up to 5 years or 100,000 miles.
A lot of parts? You bet. This is
why installing the E-Force is best left to facilities
such as Tom Henry Racing which are trained and
experienced in supercharger work. Image: Edelbrock, LLC.
For more information on superchargers, read our sidebar
on blower tech.