In part seven of our Cimtex Rods Super Cameo Buildup series,  we covered the installation of our Stainless Works four-tube ZR1 headers and Cimtex Rods-fabricated 3-inch custom exhaust system, as well as the fabrication and installation of our Cimtex Rods-constructed 22-gallon fuel tank and the accompanying MagnaFuel fuel system.

Now we’re going to cover the mockup of our Powerdyne BD-11A SilentDrive twin supercharger system. But first let’s digress and take a look at the big picture.

One of the key criterion in our Cimtex Rods Super Cameo buildup was to elicit that all-important “wow” factor throughout the entire series. When it came to the engine, we didn’t want to install just any old run-of-the-mill, multi-carbureted GM small or big block, much less a late-model GM crate engine straight out of the catalog. Going in we figured that the Cimtex Super Cameo powerplant should be something special.

 

The engines considered ran the gamut from a blown 426 Hemi to a Pro Stock-type Arias Hemi Chevrolet. However, the phenomenal cost of building either engine (at $25,000 plus) eventually ruled them out, and we also wanted this ride to be practical as a driver. At that point, Tim and Darrell Cimbanin came across an excellent deal on a 1996 Corvette ZR1 dyno engine originally used on the Mercury Marine “Wet Vette” project. In fact, the deal was so sweet that the seller prohibited us from publishing the actual sales price.

 

So now, with something affordable, albeit exotic, installed between our Super Cameo’s highly modified 1956 Chevrolet half-ton framerails, Tim and Darrell had to make the decision whether to leave the ZR1 stock and simply polish the heck out of it, or go a little more exotic by installing a turbocharger or supercharger. 

 

Of course, the first thing Team Cimtex did was check on the availability of an aftermarket supercharger and turbocharger kit for the Corvette ZR1 engine, and they came up with a big, fat zero! Suffice it to say that ­whatever aftermarket power adder they might enlist would require scratch building to their own ­specifications. 

 

“Early on, we decided that since this is a show truck, we didn’t want to run anything that would produce excessive heat buildup in the engine compartment, so that pretty much ruled out a turbocharger,” commented Darrell Cimbanin. “Space availability was likewise a prime consideration. We’ve already set the engine back within the chassis a total of 6 inches in order to provide adequate room for our custom-built Be Cool four-core aluminum radiator and twin electric fan setup. Clearing the Flat Out Engineering front crossmember and Corvette C4 rack-and-pinion steering assembly was yet another design challenge.”

 

Initially the Cimbanins considered using either a Kenne-Bell twin-screw or Eaton-Magnuson Roots-type street supercharger. However, in order to do the job right both required a custom-fabricated intake manifold, a costly proposition at best, not to mention that the job also required an entirely new fuel system, which meant messing with the ZR1’s tricky engine electronics—something neither Darrell nor Tim really wanted to do.

 

The next candidate was a centrifugal supercharger such as a Paxton, Vortech, ATI Pro Charger or Powerdyne, as all of these units are lightweight, compact and make plenty of horsepower. Furthermore, all of these blowers are available in either standard or reverse rotation, allowing them to be placed virtually anywhere at the front of the engine.

 

Ultimately, the Cimbanins settled on Powerdyne Automotive Products’ self-­contained, self-lubricating, BD-11A SilentDrive supercharger equipped with a space-age ceramic ball-bearing drive.

 

“We didn’t want to tap into the ZR1’s crankcase for lubrication, so the self-lubricating Powerdyne BD-11A proved the most logical choice. With the stock 3-1/4-inch pulley, these blowers are capable of safely producing six psi. With such a conservative boost rating, we also didn’t have to worry about changing the compression ratio of the engine.”

 

Due to space limitations, it was quickly determined that a reverse-rotation Powerdyne BD-11A centrifugal-drive supercharger was required. However, no matter where the Cimbanins attempted to place the BD-11A, the engine looked lopsided. So Tim and Darrell reasoned that if one Powerdyne BD-11A was good, then two would look even better. The Cimbanins contacted Powerdyne and arranged to have yet a second BD-11A RR core shipped down to their Jarrell, Texas, shop for ­prototyping.

 

“Initially we had intended on placing these blowers to the front of each rocker cover, off to the right and left side of the power steering pump and the alternator. But that took up a considerable amount of space and looked ungainly. There was also the question of how to successfully route the supercharger ducting around our custom-designed Be Cool radiator.”

 

Another design criteria was that the brothers Cimbanin wanted to retain the Corvette ZR1 single serpentine drive belt, not only to keep things simple but also to save space. As luck would have it, the ZR1 crank pulley was located directly over the Corvette C4 steering rack, leaving enough room to mount the BD-11A reverse-rotation superchargers on either side of the engine, low enough in the Cameo chassis to clear the new radiator and the dual electric fans. In order to accomplish this, the Cimtex crew designed a 1/4x30x10-inch steel template (or cradle) spanning the inner width of the Cameo chassis. With twin Powerdyne BD-11As mounted in the cradle, clocked at approximately 45 degrees left and right, allowing the discharge tubes to face outward, the supercharger ducting could be routed outward, or it could be routed perpendicular to a common junction converging at the ZR1 throttle body. The ducting would remain clear of the radiator and the electric cooling fans.

 

Part of this setup also included the relocation of the ZR1 serpentine belt idler pulley from the driver’s side of the ZR1 engine to the driver’s side of the new bracket, although now operating in reverse rotation. However, in order to maintain proper belt alignment, the pulley had to be spaced out from the bracket via a specially machined 3x3x2-inch aluminum spacer. 

 

Once proper belt alignment had been achieved, Team Cimtex constructed the actual (production) supercharger mounting bracket out of laser-cut 5/8-inch aluminum flat stock. Then a series of 2-, 1-1/2-inch and 3/4-inch holes were laser cut into the bracket to not only reduce weight, but also to dress up the bracket itself. You will note that the center hole in the bracket intersects with the crank bolt for ease in servicing. Actual mounting of the bracket to the Cameo’s front framerails was accomplished via a set of 3x2x3/8-inch mounting tabs made out of flat stock and welded to the inner framerails.

 

When it came to the supercharger ducting, the Cimbanins used a MagnaFlow 3-inch-diameter stainless steel 45-, 60- and 90-degree elbow kit, which provided the guys with enough varying bends to be shaped into a fully functional dual snorkel assembly or air discharge tract. With these pieces of tubing welded together as a unit, they converge on an oval-shape junction fashioned from a piece of formed and welded 15-gauge stainless steel strap. The entire snorkel assembly is then secured to the ZR1 throttle body via a neoprene rubber coupler and a pair of stainless steel hose clamps. 

 

Of course, no supercharger system would be complete without a supercharger bypass valve or, in this case, two of them. A pair of Vortech Engineering polished aluminum bypass valves (p/n 8D204-008) was placed on the bottom side of the air discharge tube(s), located directly below the ZR1 throttle body and set at 45-degree angles. These bypass valves are set to operate at 10 to 11 inches of vacuum. 

 

Next came the actual fabrication of the air intake tract itself. Since the ZR1 Corvette engine operates on speed density, use of the normally bulky mass airflow sensors was not necessary. However, our fabricators still had to worry about radiator clearance. Cimtex fabricator Darren Barker came up with a rather trick-looking “vacuum cleaner” cold air intake box, which is mounted directly to the 3-inch supercharger inlets, mounted down low in the chassis beneath the radiator. This aluminum box measures 23 inches in width, 11-1/2 inches at the back, 8-1/2 inches in depth and 2 inches at the intake opening (or air inlet). Inside you find a paid of K&N lifetime conical filters attached to the supercharger inlets.

 

“This box is 100-percent restriction free, and it can pass more air than the superchargers can actually handle. Furthermore, we’ve still got more than enough room to mount our radiator. It’s a real efficient system!” 

 

That pretty much concludes Project Cimtex Super Cameo’s chassis and fitup. In our next installment, we actually begin hanging sheetmetal and performing the tricky bodywork. Follow along with the guys at Cimtex as they show you how the Powerdyne BD-11A twin supercharger system was tailor made for our installation.