Whether or not the exotic-looking Silverback carburetor will be a disruptive force in the performance carburetor market has yet to be determined, but it is certainly drawing enough attention to stir up opinions and emotions. First, it was named Best New Racing Product at the SEMA Show. Then there was no shortage of onlookers, including some of the best-known tuners in the industry, checking out the new variable-cfm carb at Silverback’s booth in the PRI Show.
“When you buy a Silverback carb, it’s like buying 10 carbs in one,” says the Silverback’s inventor, Bruce Kahlhamer.
Besides variable cfm — which isn’t a new concept as the venerable Predator carburetor is still available — the Silverback boasts some two dozen features not found or described as superior to “traditional” carbs. EngineLabs has looked over the claims and found five significant talking points that deserve additional exploration.
“It can vaporize fuel better than most fuel injections, and I do that mechanically,” says Kalhamer. “That’s what makes it simple for the consumer. With traditional carbs, it looks as if you’re blowing fuel at the motor with a fire hose. With our carb, it looks like all fog. Our fuel comes out lighter. It turns corners much easier.”
The Silverback has four adjustable knobs on each side of the throat for fine tuning the air-fuel mixture. Each has detents so that settings can be recorded when making adjustments for different tracks and conditions. The knobs are knurled and slotted, so they can be adjusted by hand or with a screwdriver — eliminating the need for a box of jets and even tools at the track.
“The outside adjustments are used to supply the last five to 15 percent of fuel,” explains Kalhamer. “The main fuel load is off the needle system. I’m giving you a specific fuel supply for your power and torque levels. From there you have adjustments to fine tune the application.”
The Silverback doesn’t rely on the familiar butterfly or flapper valves to control airflow.
“We use a variable slide or guillotine. When it’s pulled completely to WOT, you’re looking at the bottom of the bottom of the motor instead of having a lot of things in the way,” says Kalhamer. “So, our airflow is much cleaner through intake tract.”
As the slide passes the eight power jets on the side of the throat, the fuel flow is initiated in those ports. The tuner can dial in stop points for the slide, effectively determining the exact cfm level desired. Two ranges are available: 600 to 850 cfm and 950 to 1,200 cfm for racing.
Floats and bowls
One of Kahlhamer’s top priorities was addressing issues with the float bowl. Off-camber driving for off-roaders and G-forces for drag and road racers often present fuel starvation and uneven performance.
“In a traditional float bowl, it’s half fuel and half air,” says Kahlhamer. “When you start bouncing them around and mixing them up, it causes inconsistencies and exposes the jets, which causes bogs. My solution is to clean the fuel on the way in using Mil-spec foam as it leaves the needle and seat. Once it’s in the bowl, we contain it. We don’t let it get airborne again. Also we have more foam in there to prevent slosh.”
Shaping the air
The billet-aluminum construction has some unique design features, including laminar flow “power bars” that help straighten the air and “vortex controllers” for additional flow management.
“We’re looking for total control in shaping the air,” adds Kahlhamer. “We spent four years getting the perfect shape. We have very good lofting and flow without any restrictions and flat spots.”
In addition, Silverback has designed an “air-speed enhancer” for use under the carb in an open-plenum-style intake manifold. And there’s a similar enhancer designed for the air cleaner.
There are numerous other features worth mentioning, such as full O-ring sealing and a tunable nitrous manifold. It’s also designed to handle different types of fuels, including methanol.
Kahlhamer says final design touches are being made and production units will go on sale soon. He also indicated a number of early carbs are going to engine shops where independent dyno tests will be conducted. Looking forward to the results!