Tech Review: Chassisworks CDS Gear Drive On Project BlownZ

Chris Alston’s Chassisworks, long one of the most recognizable and respected manufacturers in the aftermarket street and racing industry, has helped lead the charge in hardcore supercharging accessories with the development of the Component Drive System (henceforth referred to as the CDS). We recently got our hands on one of these unique and diverse kits for our Project BlownZ 275 Drag Radial Camaro to pair with our ProCharger F1-R blower, along with a new Billet Hex Drive fuel pump from the guys at Aeromotive and a new damper from ATI Performance Products designed to work with our new gear drive setup.

In this tech review, we’ll be taking an in-depth look at this trio of new additions to the business end of our Camaro as we upgrade our combo in our tireless quest for the sevens.

Driven by the sheer nature of engineering evolution and intense competition from other forms of power adding, the technology involved in the design of centrifugal superchargers has come a long way from the early days of heads-up street car racing. Today’s modern self-contained supercharger units are capable of producing obscene amounts of horsepower – enough to propel race cars equipped with such combinations into the record books time and again.

As we all know, superchargers place you one step back to move you five steps forward, requiring the use of horsepower to create more horsepower. As these units have become physically larger and the demands for more boost greater over the years, so too have the demands and stresses on the components used to drive the supercharger.

The complete CDS gear drive assembly that we'll be installing on our Camaro, designed for use with an LSX block. At the bottom of the frame is also the optional fuel pump drive accessory that we've chosen to use to drive our new Aeromotive hex drive pump.

The CDS operates through a set of gears (which are interchangeable) inside a gear casing. Chassisworks has a number of overdrive options available, depending upon the supercharger model and the customers' needs.

Centrifugal superchargers are traditionally driven by belts, although chains have been used with mixed results in years gone by. The best case scenario is to run as short of a belt as necessary by keeping the location of the supercharger as close to the crankshaft as possible, thereby reducing stress on the belt, the crankshaft, the mounting assembly, and the supercharger itself. With large blowers producing 2,000 horsepower and up, however, the undue demands placed on the snout of the crankshaft to turn the unit can be immeasurable. Thus, the bright minds in the racing industry searched for a solution, and that solution came in the form of the gear drive.

The supercharger side (left) and the crankshaft/damper end of the CDS gear drive unit.

Why Gear Drives?

Gear drives reduce much of the stress that's placed upon a supercharged engine during operation, largely upon the snout of the crankshaft, the belt, and the bracket assembly.

From roots to centrifugal, blower belts have always been the de facto method for driving a supercharger, and while belts are more than capable of doing the job (consider the loads that blower belts on nitro motors are under), the considerable side loads placed on the crankshaft and the entire blower and bracket assembly under a high-boost load can put a lot of wear and tear on parts. Aside from said stress on the crank, the belts can stretch and break, causing another obvious problem.

A gear drive, on the other hand, allows the crankshaft to turn the blower via a set of gears inside a gear casing that are directly in line with the crank. Rather than have a belt trying to yank to the snout of the crank off, the stresses are placed on the gear drive to do the grunt work.

The Component Drive System

Chris Jr. has spent most of his life in a machine shop and decided to make a gear drive himself, and it developed from there. – Lino Chestang

The CDS was the brainchild of Chris Alston Jr., the son of company founder Chris Sr. and a racer himself, who puts components through the ringer on his six-second, supercharged Chevrolet Nova in the PSCA ranks. Alston Jr. saw a need for an improved gear drive design, and he set out to produce it. However, it wasn’t a singular, one-size-fits-all product that he had in mind, but rather an entire ecosystem of gear drive designs and accompanying accessory drives for a number of different engines makes and accessory drive layouts. If it was a popular engine combination in drag racing (and even some that aren’t), Alston Jr. and the rest of the Chassisworks team were ready to provide. And for those intent on continuing to run a belt, the CDS would accommodate that, as well.

“Chris Jr. has spent most of his life in a machine shop and decided to make a gear drive himself, and it developed from there. It began as a single supercharger drive, followed by a dual unit, and from there they began adding the shaft-drive accessories,” explained Chassisworks’ Lino Chestang.

Component Drive System Accessory Drives

The Component Drive System is a robust ecosystem of accessory drive add-ons operated in conjunction with the gear drive casing. Chassisworks has or is currently developing billet aluminum drives for fuel pumps (single or dual), water pumps, alternators, distributors, and steering pump to work with the single-supercharger gear drive unit.

The CDS gear and belt drive systems are designed for use with Vortech, ProCharger, and Paxton superchargers, in either a single or dual blower configuration. In lieu of a supercharger belt, the gear drive models can include a broad selection of drive ratios using large 1-3/8″ quick change gear sets. Other features include built-in timing pointers, a built-in crank trigger pickup mount, high density urethane coupler bushings, an oil level sight glass, a two-piece case, stainless steel blower and crankshaft hubs, and scalloped mount plates to reduce weight.

“There are a lot of unique things about it as far as the gearing.” says Chestang. “There are ratios available from 40 to 75 percent overdrive, depending on the model. The faster you spin the supercharger, obviously the more boost you’re going to make, and some superchargers can only spin to a certain speed. We look at the limits of what RPM you’re turning and how quick you’re spinning the supercharger to come up with a number.”

One of the features that really sets the CDS system apart however, are the optional accessory drive add-ons, allowing the gear drive to become an all-in-one unit capable of turning your alternator, fuel pump, magnetos, and other crank or camshaft-driven components.

CDS systems come in single blower, dual blower, and accessory gear drive configurations, along with a single-blower belt drive system. Applications that the CDS system is currently compatible with include:

Chevrolet – Small Block, Big Block, LS Series (Stock, LSX, WarEagle, RHS, and Dart Billet Blocks)

Ford – Small Block, Big Block 429-460, Modular 4.6L and 5.4L

Pontiac – Aftermarket Pontiac Block

Studebaker – 289 V8

BAE – Hemi

Mopar – Small Block, Big Block

MBR – 8.3L Hemi

“We’ve worked to cover all of the popular engines combinations, but if someone is interested in a more custom setup, it’s just a matter of contacting [Chris Alston] Jr. and providing the dimensional information from the engine block or sending us the block, and we can built a bracket mount system for them,” says Chestang.

In the single blower configuration, Chassisworks has designed the gear casing in both a vertical and angled mount position, allowing the racer some options in terms of how to position their supercharger to take advantage of the space they have available in the engine bay. As you’ll read shortly, we had to get creative to make room for our gear drive.

Aeromotive’s Hex Drive Pump

Left: Aeromotive's Billet Hex Drive fuel pump mounted on the front side of the billet aluminum, belt-driven fuel pump accessory drive that runs off the secondary shaft of the CDS gear drive. At right is the accessory drive itself, with the belt exposed on the backside.

Because our switch to the gear drive allowed us the option to run our fuel pump as an accessory off the crank, we took full advantage of the opportunity to place less electrical draw on the system as compared to the large, electric pump that we were running previously. We’re not running an alternator and recently downgraded from two 16-volt batteries to one, so that reduction in draw is a must.

The Hex Drive pump is perfect for our application as it was designed for high horsepower, forced induction engines running on gasoline or methanol.

Aeromotive’s Billet Hex Drive fuel pump fit the bill for what we needed, delivering exceptional flow and performance with the convenience of a direct-drive configuration. Although we’ve mounted the pump off to the side of the block, operated via an accessory belt drive from the CDS, this pump can be driven from the back of an external oil pump or via the camshaft with a timing cover adapter.

The Hex Drive pump is designed for applications just like ours: high horsepower, EFI, and forced induction. It has a standard 3/8-inch hex driveshaft, with support for 3,500 horsepower on gas and 1,800 on alcohol, a durable CNC-machined billet aluminum body, and ORB-10 inlets and outlets – all in a very compact and robust package.

Our New ATI Damper

The CDS gear drive system, naturally, is driven right off the front of the damper, with the hub of the gear drive bolted to its face. Because of this, you’ll need a damper with a six bolt front to mate the engine to the gear drive. With space at a premium, a thinner damper is also required.

We turned once again to our friends at ATI Performance Products to create us a custom damper for our new configuration. What they came up with was a version of their lightweight Super Damper with a dual-keyway hub (a must when running a blower), a thinner physique, and a face with three extra bolts to create the mounting pattern for the gear drive.

From this angle, you can see the direct connection of the ATI damper to the flange of the gear drive.

ATI’s JC Beattie Jr. worked with us to develop a damper that suited our needs. The twin keyways on it were done in a step-key design, necessitated by the lack of enough wall thickness to do a 1/4-inch keyway. The step key measures 3/16-inch on one side and 1/4-inch on the other. According to Beattie, the dual keyways are pretty common in any application with over 12 pounds of boost. The damper itself is a crank trigger shell, with the magnets located inside the shell, eliminating the need for another crank pulley and the space it requires.

We made the damper a six-bolt Chevy front, so we drilled the holes through the shell and the damper and then drilled and tapped three extra holes in the damper shell itself so that you can bolt the gear drive to it. – JC Beattie Jr.

Said Beattie as he described the design of our damper, “We made the damper a six-bolt Chevy front, so we drilled the holes through the shell and the damper and then drilled and tapped three extra holes in the damper shell itself so that you can bolt the gear drive to it. It’s actually seven different part numbers involved in making this particular damper.”

Our Gear Drive Setup

We’ve paired our 388 LSX powerplant with one of the CDS accessory drive units designed for the LSX combo, which is what we’ll be taking a look at today. With the addition of the gear drive, we’re hoping to gain more consistency and reliability by doing away with all of the factors that belts can and do present.

Here's a more detailed look at the six-puck flange that connects the crankshaft and damper to the gear drive. This pair of six-puck flanges (one is for the crank end and the other for the supercharger side) utilize urethane bushings in between to cut down on harmonics.

Here you can a more detailed view of the mounting points to the engine block, as well as the standoffs for the gear drive casing and the blower.

The CDS gear drive on the Camaro is an angle mount configuration. Despite some very attractive accessory drive options, we’ve chosen to use only the fuel pump accessory drive, which is driven by a secondary gear drive shaft through a belt within a very sharp-looking machined aluminum housing.

The CDS is bolted directly to the motor plate using M10 allen head bolts, providing plenty of rigidity under some fairly extreme torque. The primary difference between the various engine configurations that the CDS is compatible with are the mounting plates and patterns, so the plates for a Small Block Mopar may look nothing like our LSX setup.

Due to the size (depth) of the gear drive unit, we had to remove our radiator entirely, replacing our cooling setup with a simple cooling box. A fair tradeoff, we like to think.

As alluded to earlier, the CDS connects to the crankshaft through the damper, using six bolts to connect the damper to the gear drive input shaft through a six-puck, urethane bushing clamp that helps to reduce vibration and harmonics to and from the engine. The front side of the gear casing, where the output shaft connects to the supercharger, also uses a hub containing the six-puck urethane bushings and flange.

The fuel pump accessory drive comes complete with belt and pulleys, with everything assembled other than the cog that you’ll attach to the output shaft on the front side of the gear drive casing. An aluminum bracket is supplied that mounts the fuel pump drive housing to the gear drive brackets. The opposing end of the accessory drive contains a hex drive designed for hex drive fuel pumps like the Aeromotive pump introduced above.

The male end of the hex drive is installed into the female end of the accessory drive, which is held in place by a compression ring. Interestingly, this accessory drive can operate the fuel pump on either side, and can even by set up to run dual fuel pumps. Ours is set up on the front side supercharger side) of the drive.

On the left is our Jesel belt drive setup that's neatly tucked behind the new ATI damper. The three remaining images provide a look at the CDS assembly in process, prior to mating the supercharger to the gear drive case.

Here's an up close and personal look at our finished product ready for a crack at the dyno. We'll be bringing you additional updates on our experiences with the gear drive after we get some testing hits on the new combo.

Set up and installation of the gear drive is a simple and straightforward process, although with anything of this nature that involves fitment of other components, some minor machining may be necessary. Liberties also have to be taken in terms of space; in our case we had to remove the radiator entirely to make room for the gear drive, made possible by the use of a cooling box. The gear drive worked flawlessly in our first hits on the dyno, where we made 1,132.4 rwhp at 22 lbs. of boost, although we did torch a head gasket that delayed us from being able to test it at the track. We do, however, have plans to test the car this winter for what we hope to be an even more successful sophomore season, and we’ll bring you an update on our experiences with the gear drive when that happens.

Article Sources

About the author

Andrew Wolf

Andrew has been involved in motorsports from a very young age. Over the years, he has photographed several major auto racing events, sports, news journalism, portraiture, and everything in between. After working with the Power Automedia staff for some time on a freelance basis, Andrew joined the team in 2010.
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