Conventional four-barrel carbs are equipped with progressive linkage arrangements, allowing the primary two barrels to open to approximately 30 percent before the secondary barrels begin to open. The reason is throttle control, since this linkage arrangement allows more precise mechanical control of throttle area at lower throttle openings. Similarly, the Bad Man is equipped with a progressive mechanical linkage, however, the arrangement opens the first and third barrels simultaneously, with the linkage picking up the second and fourth barrels further in the travel. The "secondary" barrels open at an accelerated rate so all four barrels reach wide-open throttle at the same time. The slick linkage setup essentially uses every other barrel as a primary, with the alternate barrels as the secondaries. This spreads the mixture discharge over a broader length of the intake manifold compared to any conventional four-barrel, which improves mixture distribution to all the cylinders.
A notable Bad Man design element is the configuration of the major castings. Essentially, the carb comprises a main body, which incorporates integral float bowls, the venturis, and the throttle plates, with a separate air horn casting bolted on top of each primary/secondary pair. The air horn is highly contoured to direct airflow straight down the carb's barrels. Unlike conventional four-barrels with separate float bowls hung off each end, the Bad Man's integral bowl system contains all the casting's fuel, so the carb does not rely on any gaskets for sealing below the fuel level, a design that guards against fuel seepage or leaks.
The upper air horn assembly contains most of the tuning parts of the carb, including the air bleeds, emulsion tubes, accelerator pump squirters, the jets, the needle and seat assemblies, floats, and the enrichment circuit. Rather than draining the fuel in a catch can, unbolting the bowls, and pulling the metering blocks, a jet change on the Bad Man is a matter of just popping the air horn lid, and swapping the conventional jets screwed inside. The fuel stays captive in the bowls, preventing much of the mess and potentially torn gaskets normally associated with a jet change. Each barrel has a pair of air bleeds, one for the main or high-speed circuit, and one for the idle circuit. Again, these are familiar parts, with the same tuning process as any other Demon four-barrel.
You'll find regular needle and seat assemblies on the Bad Man's air horn, just like any other Demon carb, but this inline carb has a separate needle and seat assembly and fuel inlet for each barrel. This arrangement is capable of handling the mightiest race engine's fuel flow requirements, while providing precise fuel control suitable for a mild street driver. The floats are unique to this carb design, with paired floats swinging from a central yoke, though the adjustment procedure is the same as a regular Demon four-barrel, with Demon's excellent large sight glass giving a clear view of the bowls' fuel level.
Two items that are substantially different in the Bad Man are the accelerator pump system and the enrichment (power) circuit. Rather than using a diaphragm accelerator pump as found on the Demon carbs, the Bad Man uses a piston-style pump located in the main body. Piston-style accelerator pumps are a proven design, with a long history of use in OEM carburetors. The piston-style pump is a far more suitable design for the inline carb's layout and eliminates the diaphragm pump's potential seepage below the fuel level of the bowls. With the piston pump, the amount of pump shot can be adjusted by simply changing the linkage for more or less pump stroke. With the Bad Man's rocker-style pump linkage, there seem to be endless possibilities for fine tuning the accelerator pump delivery. The shooter size controls the accelerator pump discharge rate, just like with a conventional four-barrel carb. The pump shooters on the Bad Man look similar to those used on a Demon four-barrel, however, each has a single orifice, since there is a separate squirter at each barrel instead of just one splitting fuel flow to each pair of barrels.
Probably the biggest change to be found in the Bad Man's metering is the power enrichment circuit. Four-barrel Demon carbs have always used a power valve for this function, where a rubber diaphragm operates against an integral spring to open and close the enrichment circuit based on engine vacuum level. The Bad Man uses a power piston for this purpose, again a design proven in a multitude of OEM-style carbs. The power piston, like a power valve, operates against a spring, based upon the level of engine vacuum. The piston has the advantage of not being subject to rupturing or blow-out, as with a power valve, and tuning can be done by changing the spring instead of having to replace the entire assembly. The Bad Man's power piston is linked to a simple slide mechanism, which opens or closes an auxiliary fuel orifice at the main well via a Viton seal.
We took one look at the Bad Man, and immediately recognized the inline concept's value. Although the carb is radically different, on closer inspection it seemed imminently familiar. The regular tuning parts, Demon-style sight glass in the side, and even the linkage to the throttle plates, bear enough resemblance to the four-barrel carbs we are used to for us to feel right at home. One glance and you know how to adjust the idle speed, and the two idle mixture screws at the primary barrels promise easy dial-in. We can see the natural advantage to fuel distribution. According to testing at Demon, the setup accomplishes this goal so well it allows larger camshafts to operate at low engine speeds (as low as 450 rpm, according to Grant), improving vacuum and low-speed idle as well as part-throttle drivability and fuel consumption.
The plenum-ram-style Aero-Ram intake is exactly the correct arrangement to make the best use of the inline carb configuration, and we suspect the straight, direct runners are nearly ideal for unrestricted airflow while taking advantage of ram-tuning effect. Grant has the small-block Chevrolet version of this induction fully worked out, while the LS1 and big-block Chevrolet versions are following close behind. We're already putting the thumbscrews on Grant's people to get one over to us for serious dyno evaluation. With the inline Demon combined with Grant's Aero-ram Triple-D intake manifold, this induction looks hot.
 To the left of the main well...  To the left of the main well (central casting boss with the jet affixed at its end) is the tower for the power piston. The spring-loaded piston works against vacuum to operate a slide, which opens and closes an auxiliary metering orifice to the main well. |
 With the Bad Man mounted to...  With the Bad Man mounted to the matching Aero-ram intake, it is plain to see how the carb layout is a more appropriate fit compared to a conventional four-barrel. Look at the position of the ports below the carb. Flow is right down the center for a line-drive into the ports below. |
 While the Bad Man is quite...  While the Bad Man is quite an innovation, the Aero-ram from Grant's Triple-D manifold line is the perfect complement. A peek inside clearly spells out the concept of this plenum-ram manifold. |
 The runners shoot straight...  The runners shoot straight across the manifold, opening into the plenum at the other side. There are no curves, kinks, or bends in this design, just a straight shot aimed directly at the cylinder head ports. Production manifolds will have a radiused entry at the runner openings. |
 At the SEMA show, we photographed...  At the SEMA show, we photographed this prototype LS1 Bad Man system. After the traditional small-block Chevy is available sometime in 2007, Barry Grant plans on developing induction systems for all major engine families. As you can see, the LS1 won't be far behind the small-block. |
 Also in development is the...  Also in development is the big-block Bad Man. The system's modular design requires dedicated manifolding, which is good when you consider that the design can take maximum advantage of runner placement. You'll also note the camshaft-Barry Grant plans to offer each Bad Man induction system with a performance-tuned cam. With far better idle and vacuum characteristics than traditional four-barrels, the Bad Man can effectively use longer duration valve events on the street without the ill effects. The new cams will take advantage of this. |
 Here's the small-block Bad...  Here's the small-block Bad Man as seen from the passenger side. By now, you're wondering how much it's going to cost. Look for a street price of around $1,795 (bare-cast appearance) for the small-block unit, which includes the inline four-barrel Bad Man and the Aero-ram manifold seen here. That's a lot of dough, but not when compared to the cost of converting to electronic fuel injection. Compared to EFI, the Bad man avoids the hassle of laptop tuning, wiring, and fuel system conversion, while offering equal (or better) drivability and power. |