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TMCNet:  THE BLACK BOX [National Dragster]

[April 05, 2014]

THE BLACK BOX [National Dragster]

(National Dragster Via Acquire Media NewsEdge) EVERYTHING YOU WANTED TO KNOW ABOUT TOP FUEL AND FUNNY CAR ELECTRONICS You see crew chiefs reaching for it all the time and drivers referencing their tuners being "in the box." The control system for the timers that activate changes to the clutch, fuel, and ignition systems during a Top Fuel and Funny Car run are located within a literal box made of sheet aluminum on a Funny Car or underneath the cowl of a dragster body. The functions in the timer box activate quickly to dictate the fuel, clutch, and ignition curves that take place in a run that lasts only 3.7 to 4 seconds.


By the time a dragster or Funny Car pulls into the water box to run in the next pair, it's too late to make a mechanical change, such as weight on the primary or secondary levers of the clutch, pulleys to change the blower overdrive, and certainly head-gasket thickness, one of the first final decisions a crew chief makes in the pits to determine a compression ratio that they must live with. The electronic and pneumatic timers and ignition graphs allow for last-minute adjustments that a tuner can make up until the car is fired or, in some cases, after the burnout.

We're going to look at an example of a socalled "black box" to identify the components and their function therein. Crew chiefs Richard Hogan (Steve Torrence) and Scott Graham (Pat Dakin) were helpful in explaining the process and functions and are quoted throughout. Members of the Antron Brown, Brittany Force, and Tim Wilkerson teams also contributed, and information was verified with publicly accessible diagrams and informational materials from Electrimotion.

COMMAND MODULE In this example, the Electrimotion 15 Channel Timer [1] and Electrimotion Timed Air Pressure Regulator [2] is used with the 15 Channel Timer dictating when the timers go off, and the Timed Air Pressure Regulator, which looks identical save for the red stripe, regulates the air pressure or, as Graham puts it, "how forcefully and how quickly it pushes it." The latest technology from Dave Leahy's Electrimotion features a single command module that determines all of the functions in up to 24 timed outputs and up to four timed air or clutch regulators, but the dual modules in the example essentially perform the same tasks. The command modules can be programmed or changed on the module itself, connected directly to a computer, or with an SD card.

The entire process begins with air pressure from the air bottle activating the box when the three-way Clippard valve releases it at wide-open throttle. The electric module is the brain that controls the pneumatic timers in the system, which has 14 channels in the example if you count the blue buttons on the Electric to Air Solenoid Logs on the right.

ELECTRIC TO AIR SOLENOID LOGS The Electric to Air Solenoid Logs [3] are activated by electric control from the command module with channels dedicated to each one. Air pressure of 0 to 160psi is released at a predetermined time and sent to a function of the fuel or clutch system. In the example, the first six channels (starting from the bottom) activate the six pods, which control the clutch system. The sixth channel simultaneously activates the first of two regulators for the slide valve [4].

"The slide valve controls the orifice of the fuel going in," said Graham. "The regulator determines the pressure on the plunger in the valve until it ultimately closes and all of the fuel goes directly into the motor. Some teams hit the regulators on the slide valve two or three times." In this example, there are two regulators for the slide valve, a high-speed regulator (activated by the sixth channel) and another regulator activated by the seventh channel that sends air to the fuel-enrichment valve, also known as the slide valve [5]. The slide valve in this example is made by AFT, and slide valves made by Alan Johnson Performance Engineering are also prevalent in the nitro ranks. The fuel pressure is regulated by a BDK valve, which is not pictured within the box.

WHITEY NEEDLE VALVES The Whitey Needle Valves [6] control when the clutch cannon is pulled back to release the levers of the clutch. In this example, they are activated by the first six channels. Beyond the command module telling the Electric to Air Solenoid Logs when air is released to each pod, there are dials [7] similar to micrometer handles that open or close the valves to determine the rate of speed at which they are opened.

Whitey Valves are made by Swagelok/Nupro, Electrimotion, and J.T. Stewart's Dynamic Machine, among others. A full turn of the dial may affect the valve a different amount depending on the manufacturer.

"Leahy's is a little more linear than a J.T.- style," said Hogan. "His needles are just a little more different profile. That's the main thing. Whether someone uses the latest thing available or something a little older, they all work. Dave makes the timers that make any of them function." The valves essentially work like a plunger that controls fluid that opens and closes the clutch cannon. The air pulse from the dedicated channel of the command module activates it at a preset time, and the dials dictate how quickly the plungers open beyond that. While some crew chiefs incorporate the dials into their tune-up process more or less than others, it is one of their last remaining options for changing when to apply horsepower. Some of the valves and timers have more impact than others.

"The stuffthat's critical is what happens in the early one-second range, 1.1 to 1.25," said Hogan. "Once it gets out in that 1.5-second range, the time isn't as critical." IGNITION BOX The MSD ignition box [8] controls the ignition-timing graph. This may also be one of the final changes a tuner makes before a run, and it's all done electronically. A tuner can connect through the box by plugging in a graph editor, on which they can modify existing ignition-timing charts or simply opt for one of many ignition-timing curves that has been saved onto it. SD cards can also be used.

"We plug it in right up there in the staging lanes," said Hogan. "We keep multiple files and can edit them pretty easy. Everything else is all sealed up when you can still make changes to the timing map. I'm sure some guys now have SD cards that have parameters with hard numbers for all our runs, like a Funny Car team that has a file labeled 4.10 or another one if they want to run 4.0- something." OTHER COMPONENTS The RacePak data recorder [9] doesn't control any functions. It records data from a run that crew chiefs are able to download and observe on its software afterwards. There are a couple of analog boxes [10 and 11] that serve as a junction block for the cables and a datacollector box [12]. The black, rectangular data-collector box collects data for mechanical functions, such as oil pressure, fuel pressure, blower boost, air bottle pressure, etc. The transducer reports the mechanical data to the RacePak box. In the example, a RacePak recording begins when the toggle switch [13] is turned on either before the car is started or when the body is lifted up after the burnout.

The accelerometer [14] monitors the G forces during the run and is connected to a cable that reports it to the RacePak. The encased battery [15] powers all of the electrical components in the black box. The bleeder screw [16] is in place to bleed air from the clutch controller system.

Funny Car tuner Mike Neffaccesses the black box for a run to open or close a clutch flow with the turn of a dial that determines when one of the Whitey Needle Valves sends an air pulse to the cylinder that pulls back the clutch cannon during a certain part of the run.

It all starts at the step of the throttle. At wide-open throttle, the pedal pushes the button of a normally closed Clippard MJV-3 three-way valve, which sends air from the bottle through an airline to the box and activates all of the timer systems, including ignitions, fuel, and clutch.

Top Fuel teams set up their timers and electronics under the cowl of the body. Not confined to a box, the layout varies more from team to team, but the components and functions are the same.

Top Fuel tuner Alan Johnson accesses the timers underneath the cowl of Shawn Langdon's dragster to make last-minute adjustments in the water box.

(c) 2014 National Hot Rod Association

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