While the performances of today's Top Fuelers and Funny Cars are truly impressive, often the problems encountered have been solved by simply using a bigger hammer to pound the square peg in the round hole. Take the ever-present GMC 6-71 Rootes-type supercharger for example. Originally designed to operate at low rpm as a diesel exhaust extractor for buses and the like, it was pressed into service by drag racers when they found that it was commercially available at a tolerable cost. Where centrifugal superchargers, turbochargers and the like all had an undesirable lag in terms of throttle response and low-end boost, the 6-71 offered an immediate pressure boost.

But the 6-71 had a few shortcomings which drag racers, to this day, have either overlooked or not cared to admit. While the Rootes-type blower works on the positive-displacement principle, with lobes stuffing the air down into the engine, it is also "friction city." The heat of compression and friction caused by the impellers scraping against the inner case wall raises the temperature. Heat-sensing thermocouples mounted in the intake manifold of a 6-71 superchraged engine have recorded temperatures in excess of 250 degrees F.

We know that the amount of horsepower an engine creates is directly proportional to the amount of fuel/air mixture it burns per minute. It follows that if the fuel/air mixture is heated and expands before entering the combustion chamber, it becomes less dense, which means that the engine burns less fuel/air mixture. This, of course, means less horsepower.

Another discouraging aspect of the 6-71 blower is that it takes a lot of power to spin the rotors. Accurate estimates peg a 6-71 blower with 33% overdrive, mounted on an engine operating at 8000 rpm, as requiring between 250 to 300 horsepower to spin those rotors around. This power is sapped from the engine. And when you go to higher rpm ranges of the 6-71 blower, its efficiency takes a dump. In effect it requires more power to spin the blower than the blower is adding to the engine.

Detonation is still another bad feature of today's nitro-burning supercharged engines, although it doesn't necessarily have any connection with the 6-71 blower. For one reason or another the charge of fuel in the combustion chamber is ignited at some time prior to the instant the plug fires. This detonation literally plays havoc with the bearings, rods, rod bolts, wrist pins and pistons, generally messing up the otherwise smooth, ideal rotational operation of the engine.

So what would you say if we told you there was a way to provide a boost for the engine without creating heat, which eliminated detonation, and which didn't require one horsepower of the engine's output to operate? Well we wouldn't lead you down the primrose path if we didn't have some sort of punch line.

It seems that aerospace engineer Bob Keane of Keane Engineering in Fullerton, California, has been working for the past three years to develop a system of pressurized air bottles to replace the 6-71 blower. The idea is to supply all of the engine's air needs for a run from a number of scuba tanks filled with 2200 psi (pounds per square inch) of normal air. The tanks are secured in the chassis in a location where the weight is desired for additional traction or front-end ballast. The entire system, complete with bottles, doesn't weigh much more than a complete 6-71 blower setup. Each tank contains approximately 80 cubic feet of compressed air.

Since the desired boost on a blown fuel engine varies between 14 and 22 psi, you can see that in order to make the concept feasible, the pressure in the bottles must be reduced to match the needs of the engine. To accomplish this, the key component of the system is an air pressure regulator which controls the reduction of gas pressure from 2200 psi to 15 psi or so. This flow control valve was originally built for use in ground systems tank pressurization (fueling) of Titan and Saturn missiles, and was developed by Keane for that purpose. The pressure regulator keeps the outlet pressure at the desired preset level with an accuracy of plus or minus 1 psi, even though the inlet pressure is falling from 2200 psi to 200-300 psi as the air supply is depleted at the completion of the run.

Other components in the system in addition to the scuba bottles and the air pressure regulator include a special high pressure Enderle fuel injection "bugcatcher" unit (which also doubles as a plenum), an engine-driven fuel pump with 10% overdrive, and a fuel-control valve which was also developed by Keane for aerospace applications. Patents are pending on both of Keane's valves, as well as on the entire system. All of the components in the system are functioning below designed operating pressures and provide a maximum safety factor. As an example, the bottles are capable of containing pressures of 8000 psi, or four times the working pressure of Keane's system.

Initial testing of various forms of the system was done on three different dragsters and one of Mickey Thompson's Ford Funny Cars, but in all instances, no full quarter-mile runs were attempted. Recently, however, Keane got together with Mickey Thompson and, utilizing Thompson's exotic dyno facility in Long Beach, accomplished an exhaustive testing program. The results were phenomenal. Where a 6-71 blown Boss 429 Ford engine on 20% nitro had produced 1360 horsepower, the same type of engine equipped with the bottled air system in place of the Rootes blower, burning only straight alcohol, produced 2400 horsepower at 6000 rpm! On gasoline, the system made about 1550 horsepower. This success was not easily achieved, as in one week of testing, Thompson reportedly ran 150 gallons of alcohol through the dyno engine.

If those horsepower figures sound a little too incredible for you to believe, understand that there are several factors working in the bottled air system's favor. First is the fact that the 250-300 horsepower previously required to turn the 6-71 can now be put out at the flywheel for the driveline to use. Secondly, because the thermal characteristics of alcohol are better than those of nitromethane and the air fuel mixture is much cooler, detonation is reduced to the point where it is almost entirely eliminated, making for a smoother-running engine that produces more power.

Most important, however, is the fact that the engine will consume as much alcohol as a 6-71 blown engine would consume nitro (remember that business about horsepower being directly proportional to the amount of fuel/air mixture consumed). In a normal 6-71 engine, not nearly as much alcohol would be used as nitro during a quarter-mile run, but because the fuel/air mixture is considerably cooler with the bottled air system than with the 6-71, the charge is much more dense.

The reason the charge is cooler with the bottled air system is twofold. First, you don't have that firction-producing air pump to heat the air up to 256 degrees. The air in the bottles is at room temperature. Secondly, when the air is released from the bottles into the system and passed to the engine, it encounters such a steep pressure drop (from 2200 psi to 16 psi) in such a short period of time that the temperature of the air actually drops anywhere from 70 to 100 degrees below the ambient (room) temperature. So where the air coming out of a 6-71 is above 250 degrees F., the air from the bottles is anywhere from 0 to -30 degrees F. It is this densely packed charge of air/fuel mixture that provides most of the extra power.

There are several interesting aspects to the system which should be noted. When the engine is started and the car is driven to the line, it runs normally aspirated (unblown). Small flapper doors open and allow normal atmospheric pressure to supply the engine with air, even for the burnouts. But when the car is staged and the driver is ready to make his pass down the quarter mile, he presses the throttle "to the wood," activating a button which turns on the system. The instant-pressurization causes the flapper doors to slam shut tight. From then on, until the driver decides to stop using the system, the car runs entirely on the air contained in the scuba tanks.

If the tanks run out of air, the flapper doors open and the engine runs normally aspirated with no "lean out" explosions similar to those experienced with 6-71 blowers. If the driver lifts the throttle at any time, the system shuts off within .030 to .200 of a second, putting the engine back on a normally aspirated status. If at any time the driver shuts off the ignition, the engine stops running. When you go back to the pits, you just refill the bottles with more compressed air. Another clever feature of the system is that any predetermined amount of boost can be "dialed in." If you want anywhere from 8 to 50-psi boost, just set the gauge before you run and the engine will be constantly fed just that much boost.

You've probably surmised that fuel metering poses a tricky situation, which it does. A fuel pressure control valve (compensator) senses the air flow from the storage vessels to the engine manifold, and adjusts the fuel-flow rates as a function of the air-flow rate to the engine. And when the engine reaches higher rpm operation, the air flows out of the bottles at a faster rate to supply the need, thus causing an even greater rate of pressure drop and a denser charge as a result. The faster you use the air, the colder it gets . . . just the opposite of the situation with the 6-71, which gets hotter as it runs faster.

Despite the changing fuel/air mixture density, the fuel pressure control valve compensates with a response time of only .030 of a second. All fuel is injected into the engine through port nozzles in the manifold, and any preselected fuel/air ratio can be maintained (five units of air to every one unit of alcohol in this case). Interestingly enough, no matter what Thompson and Keane tried on the dyno, they couldn't get the engine to lean out. It always ran on the rich side, which means that the engine is always "safe." In all the dyno testing, they have not damaged one engine part, despite the fact that they performed 50 simulated "runs" on the dyno. And in all the testing, the engine's leakdown rate (compression sealing) didn't change at all!

The unit may be made commercially available, manufactured by Keane and marketed through Mickey Thompson, and should sell for only slightly more than the cost of a good 6-71, injection setup, blower drive and manifold (although your present 6-71 intake manifold and port nozzles can be used with the system). Considering the low fuel and air costs compared to the high price of nitro, a racer should be able to save enough money in fuel costs over a period of three months to pay for the unit. Another count in the bottle air system's favor is the fact that engine breakage should be reduced, as well as the possibility of a blower explosion/fire.

Just to make sure that some smart guy doesn't try to "cheat" with the bottled air system by "hopping up" (increasing) the oxygen content of the air in his bottles, Keane suggests that a small valve be included in the system so that officials can take a sample of the air and analyze it, as they currently do with gasoline, to see that the guy is playing it honest with "straight" air.

If drag strip testing of the system proves as successful as the dyno results indicate it might, the sport is going to undergo a vast changeover as far as equipment is concerned, since the 6-71 blower will go the way of the flatheads. But a need will arrive for gobs of clutch, drivetrain and tire development, as existing equipment will not begin to suit the demands of a 2500-horsepower Top Fueler or Funny Car.