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Blowin' in a Box

Vortech's F-body Centrifugal Supercharger Adds Some Punch--and Looks Good, to Boot!

Jun 27, 2003

Many performance enthusiasts believe the only way to make a centrifugal supercharger work is to install it on a fuel-injected engine. When it comes to carburetor-fed machines, the theory is forced induction is simply not tuneable when it's blown through a standard four-barrel fuel meter. While it's a fact that electronic fuel injection does have benefits when it comes to maintaining a more constant air/fuel ratio, there's no question that an equal amount of power can be tuned through a carb when you know what you're doing.

With companies like Vortech Engineering investing time, money and effort to produce an effective "blow-through" supercharger, the interest in throwing one of these power-adders onto classic machinery is growing by leaps and bounds. One of the more recent introductions is their setup for First-Gen Camaros (which also adapts to '64-72 Chevelles, '62-72 Novas, and '55-57 Tri-Fives). And since our own Classical Resurrection '68 F-body was available, the gurus at Vortech jumped at the chance to use it as a guinea pig.

With the popularity of their blow-through systems at an all-time high, they recognized the need for a Camaro unit. The basic kit began as one of their universal carbureted packages. Most enthusiasts can afford this kit and with a little creativity, basic mechanical aptitude, and some patience, it can be installed in a weekend.

As most readers know, the staff here at SUPER CHEVY prides itself on being ready to tackle almost anything the industry throws at us. And, as many may recall, the Classical Resurrection has been the recipient of many "firsts" throughout its maturing process. So what's one more experimental installation, we thought. Why not help out the guys at Vortech and see if we can finesse their F-body package?

To say that this kit is a bolt-on is an understatement. Aside from the well-crafted blower (and in our case, a polished one!), the setup includes a nice billet bracket arrangement (replete with belt idler pulley) that mounts the huffer up high on the left (driver's) cylinder head. It also comes with a crank pulley that includes the requisite ribbed-belt section and a V-belt arrangement for running other items such as an alternator and power steering pump. Of course there's the neat polished aluminum box where the carb resides, and all the necessary ducting that helps route the air into it.

What you don't get in the kit is the "other" half of the components that will make it work. We're talking about the intake manifold, carburetor and fuel system. The selection of parts we used, although approved by Vortech, are not the only ones that will work with this system. Our combination included an Edelbrock Victor Jr. intake (and aluminum water pump), a Demon 750cfm double-pumper carb and a way-cool Product Engineering fuel pump and boost-reference regulator. Other supporting components were a neat 6BTM boost retard ignition box plus a corresponding small-cap billet distributor and companion 8.5mm plug wires from MSD, March billet water pump pulley, Lokar throttle and kickdown cable assemblies, Granatelli sheetmetal valve covers, and a trick adjustable polished thermostat housing from Billet Specialties. Of course, there were also miles of cool plumbing (hose and fittings) from Russell to make it all come together.

The supercharger offered in this universal kit is Vortech's "standard" model. This blower can be tuned to put out more than 10 pounds of boost, though on street applications it is not recommended to run more than 6 pounds, which is enough to produce up to 140 hp, providing the tune-up is dialed-in properly (that means correct air/fuel ratio, timing, etc.).

The way that Vortech's system works is that it forces the boost into the aluminum box where the carb is completely sealed within. Once it enters the "box," the carb is essentially pressurized and with increased throttle position, the boost level rises and, voila, more power is produced. While it sounds simple enough, it's really a little more complicated than that, as the engine needs more fuel in proportion to the rise in boost. This is where the Product Engineering fuel pump and regulator play a major role.

At 310 gph, the Product Engineering street/strip bypass fuel pump is more than enough to feed this system. Coupled with their four-port billet aluminum boost-reference fuel regulator, controlling the fuel is a simple matter of setting the pressure at idle to between 6 to 7 pounds and attaching the vacuum line to the carb box. What happens is that the regulator senses the increase in boost and essentially ups the fuel pressure at a rate of 1 pound of pressure to 1 pound of boost. This is how the engine is prevented from running too lean. Theoretically, with this linear increase in fuel pressure, the air/fuel mixture stays ideal. Of course, part of the tuning is making sure that the carb jetting is on target, as well.

The other factor in getting the supercharger system to work up to par, is making sure that the ignition timing is within an acceptable range. It's widely known that when you add boost, you must take away timing. Therefore, initial setup requires that you back off of the optimum timing for a normally aspirated engine in the neighborhood of 4 to 6 degrees. So, if you'd normally place the advance at 34 total degrees, you'd back it down to 28 to 30 with the blower in place. The nice thing about MSD's 6BTM is that it includes a boost retard control that can be adjusted while you're driving the car from 0 degrees per pound of boost to 3 degrees per pound. This allows the engine to be run right up on the threshold of detonation for maximum power without allowing knocking to occur. Example if you set the dial at 2 degrees, that means for every one pound of boost the ignition box will remove 2 degrees of timing. So at max boost, or six pounds the ignition box will take out a total of 12 degrees of timing. In most cases saving the engine from detonating itself to death. Though this may sound like we're adding a bunch of exotic pieces to a high-dollar engine that already produces a ton of power, it isn't. For this project our base engine was a bone-stock, never been run before 300-horse, 350-inch crate engine. A perfect starting point for this supercharger setup, for sure.

The installation of the supercharger was fairly simple. Although Vortech didn't have a specific kit for a First-Gen Camaro, we picked up the ball, with the help of Jim Sleeper and Bob Vrbancic. Included in this phase was creating the fuel system, adapting brackets to mount all of the other front-of-the-engine components, and finally, getting it to run.

While the project has taken roughly a year to come to fruition, we feel that the finished system has the best combination of parts. And, although our initial trip to the dyno only netted us 80 hp (to the rear wheels), we can only say that was because we ran out of time and weren't able to make any jet changes. We also learned a few lessons about plumbing the boost reference regulator and getting the correct fuel pressure. With these lessons we'll move on to getting the car to run. Then we're planning to take it up to Vortech where they can add some of their expert tuning and show us how much power this First-Gen creation can really make. Stay tuned!


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Here are the basics of what we started with. The Classical Resurrection Camaro in the background is no stranger to being a guinea pig. So fitting Vortech's new centrifugal supercharger system was a natural. The Edelbrock Victor Jr. manifold and Demon 750cfm carburetor are not included in the Universal Small Block kit. However, these items are recommended by Vortech to be used with their system.

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The main pieces in the kit consist of the mounting brackets and the supercharger. This is how they will come from Vortech. The instruction manual you see sitting off to the side provides all the info needed to install the system. Once you have all the pieces sitting in front of you, you'll see how simple it all goes together.

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The first step is to mount the middle plate on the supercharger. All the holes are precisely drilled and will bolt directly in place. The oil feed line is also installed at this time. The feed line runs from a pressure source on the engine to the supercharger housing. A return line is also plumbed in and requires making a hole in the oil pan.

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The top plate bolts to the supercharger and to the middle plate with the use of the supplied spacers. You'll leave everything kind of loose at this stage, since there is still one more layer to go.

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Here's the last layer, which will go on the bottom. Some bolts from the top will go through everything to hold it all together tightly. If you look at this shot, it is easy to figure out how it goes together. The entire assembly bolts cleanly to the upper left side to the accessory holes in the end of the cylinder head.

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Here is what we originally started with: A 300hp GM crate engine that went from the crate right into the car. The Edelbrock manifold had to be machined a little bit on the top edge of the runners so it fit cleanly under the valve cover mounting pad on the late-model heads. Luckily the Victor Jr. is a "race" manifold and has added material for extensive port work. Also seen here are the Granatelli sheetmetal valve covers and Edelbrock long-style aluminum water pump. The perimeter-mount covers were mounted to the center-bolt heads with a set of adapter plates from GM Performance Parts.

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The supercharger and brackets mount directly onto the motor as one piece to the accessory holes in the front of the left (driver's) cylinder head.

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Here's the fitting supplied with the kit for the oil feed line. It is best to come from the pressure port just above the oil filter. When you plumb the pressure line from there, the oil is freshly filtered and under good pressure.

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With the supercharger in place, we were happy to find out there was no need to modify the inner fenderwell.

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The carb box was set atop the Edelbrock manifold's carb mounting surface. Extra long studs come with this kit because they have to go through the box and the carb.

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After the carb was installed in the box, the lid was positioned and we bolted on the intake elbow that will attach the supercharger to the box just to check its fit.

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If you look at where the supercharger outlet is compared to the elbow on the box, it is easy to see that it just won't work. You will have to pull the blower off again to "clock" the housing in relationship to its outlet.

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To do this, you need to loosen these clamps on the outer edge of the supercharger housing. When they are loose, you will be able to spin the case until the supercharger properly lines up with the carb box.

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When the blower is clocked correctly, it will look something like this. Ideally, the supercharger side is directly in the center of the intake tube of the carb box.

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Vortech's own lower crank pulley was tightly bolted to the balancer. We went for the double groove pulley to be able to run the power steering pump and A/C compressor. The alternator, which required fabricating a custom bracket, was destined to run off of the March billet water pump pulley.

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This tensioner is supplied with the kit and bolts directly to the top of the mounting bracket. It has a mounting dowel on the back and can only bolt on one way. Being spring-loaded, this idler will keep the 10-rib belt in place nice and tight.

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Installing the belt required using a 1/2-inch drive ratchet to pull back on the tensioner. The tensioner will spring back and keep the right amount of tension on the belt at all speeds.

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Here's Vortech's carb linkage and fuel lines that are provided for feeding the fuel and actuating the throttle inside the carb box. Not all of these lines are going to be used.

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This is the fitting that comes with the kit and is designed to be a bulkhead through the front of the box. It's purpose is to deliver fuel from the outside of the box to the fuel line inside. There is one port on each side of this fitting so that you can run a fuel pressure gauge.When plumbing our fuel system with Russell components, this fitting was replaced with a simple #8 bulkhead.

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With the carb sitting in the box, it was time to install the throttle linkage. We started by installing the main shaft and the inner linkage. Leave the bolt on the inner arm loose until further positioning.

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On the outside of the box, start by installing the stop for the throttle arm. The hole to the right is for tuning the air/fuel screws on the carb while it is the box. A brass screw-in plug closes the hole.

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It is easier to install the adjustable rod with its two small Heim joints while the carb is outside of the box.

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Once the carb was back in the box, the rod was installed onto the linkage arm on the inside. Some minor adjustment in length may be necessary and once finished, it is important to tighten both jamb nuts.

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The arm on the outside of the box looks just like the one on the inside. This is what it will look like from the outside with the Lokar return spring and throttle/kickdown cables in place. You may need to adjust the stop for the throttle arm once you get the car running.

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Since we worked on the carb/box assembly on the bench, we needed to put the whole thing back on the engine. You can do this without removing any of the linkage, and when it is in place tighten all the carb studs to secure both the carb and the box.

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When the supercharger is bolted on and the box is in place, it will look something like this. To our delight the top of the carb box just fit under the Classical Resurrection's cowl induction hood without any modifications.

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The fuel system was one of those things that went through some metamorphosis. Through it all, we used a variety of fuel fittings and a lot of hard aluminum and stainless steel braided line from Russell Performance. The Russell line of fluid transfer fittings helped us accomplish a fuel system that was completely free of cavitations and dead-on precise.

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This high-flow fuel pump was supplied by Product Engineering and offers some of the most beneficial features around. This pump is designed for constant-duty usage and is backed by a hefty warranty. Using our Russell fittings, we plumbed out of the tank and also our return using -8 steel braided line. The hose on the right is the fuel input from the tank. The line next to it is the pump's bypass, which essentially bleeds off excess fuel back to the tank. We used #8 stainless steel flex line to run from the tank to the pump and back.

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Then, another #8 hose goes from the outfeed side of the pump, through the trunk floor and connects to a 1/2-inch aluminum hard line. The hard line travels up the length of the rocker panels and heads up to the boost reference regulator.

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Using a Russell fuel pressure gauge attached to the Product Engineering four-port boost-reference regulator, we will start by setting the line pressure at about 6 pounds. As the supercharger starts coming on boost the reference line going to the top of the carb box will take a reading and allow more fuel pressure to run to the carb at a rate of 1 pound of fuel pressure for each 1 pound increase in boost.

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The fuel line from the regulator runs to a 180-degree fitting that attaches to bulkhead in the box. As you see from this picture, many other things have changed about this car. The amount of effort that has gone into this Camaro has been phenomenal, from the trick MSD ignition to the now functioning A/C, quick ratio power steering and even cruise control. The MSD 6-BTM ignition box also gets a boost reference from the back of the box and can pull timing out of the motor when under boost, all from a dial inside the car. With everything finally in place a day at the dyno is all that is left.

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With our ride running smoothly on the Primedia Tech Center Dynojet in-floor chassis dynamometer, carb and engine-tuning guru Bob Vrbancic offered his time and overwhelming experience with supercharged engines for a day to help us get this car somewhat correct. One of the more important aspects was the setting of the boost reference regulator. This gauge was precisely set at 6 pounds and will await until the presence of boost before raising the fuel pressure.

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Although the engine sounded and ran well during our short stint on the rollers, we weren't able to adequately "play" with the tuning and the results fell a little short of what they should have been. Not to fret, as we plan to take another stab at it with jets and timing light in hand and give you a true number of increased ponies from our long-standing Camaro project.

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We're pretty proud to have been able to help Vortech put together this blow-through supercharger package. We have to admit it looks pretty cool under the hood of this F-body. Just wait until we get it up to their dyno. Stay tuned for an update.


March Performance
Naples, FL 34110
Vortech Engineering
Oxnard, CA 93033
Russell Performance Plumbing
Torrance, CA
Vrbancic Brothers Racing
Sleeper Suspension Development
La Verne, CA
(909) 392-8886
Autotronics Controls Corportation
El Paso, TX 79936

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