Throttle position sensors...
Throttle position sensors can be mounted in the engine bay or in the driver's cockpit. TV crews tend to mount the sensor under the dashboard and run the cable down to the throttle pedal. Many race teams prefer to mount the sensor on the manifold in front of the carburetor or front bay bar and run the cable back to the carburetor linkage.
Data Acquisition Basics Relax-this is not going to be a lesson on how to build an atomic clock. But, just as you need to understand engine basics before you can set the timing, it is necessary to understand data system basics to see the incredible performance potential.
Data acquisition systems are not as complicated as you might expect. The basic concept is very simple and easy to understand. A data system has three basic functions: 1. sense or measure; 2. save; 3. replay.
Chances are you use machines that do this every day, but never thought to apply it to your racing. For example, an old-fashioned phone answering machine can be thought of as a data acquisition system. A microphone (sensor) is used to measure a voice message. The electric signal from the microphone is saved on a magnetic tape. Later, when you press play, an electric signal goes from the tape to the speaker, and you retrieve the message.
Racing data acquisition systems are much like phone answering machines. But instead of using a microphone, they use sensors to measure engine rpm, vehicle speed, pressure, or movement. The magnetic tape on the answering machine is replaced by a digital "data logger" on the race car. The main difference with a data system is the "replay" portion. Instead of the speaker in the tape recorder, the racing data stored in the logger is displayed via computer software.
This tiny sensor measures...
This tiny sensor measures g-force. It is best to mount the sensor to the rollcage and not the floorpan or other sheetmetal panels. A good location tends to be on the chassis centerline somewhere in the middle third of the wheelbase. The bar behind the driver seat (running from door to door) is a popular location for mounting this sensor.
The exciting aspect is that race car sensors are measuring "the real deal" on the racetrack, and the logger box is recording it all the way around the track, lap after lap. Problems that happen very quickly on the racetrack can be replayed back in the pits. You can replay it in slow motion or even freeze-frame to pinpoint something that happened in 11/450 second on the racetrack.
In addition to capturing events that happen quickly, many other events can be captured, too. Data that determines what the chassis, engine, and driver did on the racetrack is neatly saved for examination 15 minutes later, or when you get home, or even next week. This can be a great stress reliever because you don't have to digest the information at the racetrack when other priorities demand your attention. Another advantage is that you don't have to remember to write every detail in a notebook.
In our illustrations, you'll see a marker beside the device. This will give insight into the size of each particular item.
Data Sensors Sometimes the hardest part of using a data acquisition system is deciding what you want to measure. There are sensors to measure just about every aspect of your race car, especially for the chassis, engines, and even the driver.
Wheel Position Data Wheel position sensors are a typical part of a circle track data system. They look like a skinny little shock and are often called data shocks. Data shocks are mounted just like your regular shocks. One end is attached to the frame and the other to the rear axle or lower A frame in the front.
Without data acquisition, wheel travel is typically measured by the position of the rubber grommet on the shock absorber. This method only measures the maximum compression travel from the last time you reset the shock rubbers and requires the measurement be taken on a flat and level surface. The advantage of data shocks is the ability to continuously measure wheel travel all the way around the racetrack. Rebound and compression travel are recorded-not just the compression displacement of the old shock rubber. You will know the suspension travel at every point on the racetrack.
Here's where chassis people get excited. By having data shocks on all four wheels, the wheel position information can provide even more information. For example, comparing left and right wheel positions gives you the ability to measure body roll. You can tell if the chassis is rolling up or down and where that happens on the racetrack. Likewise, you can measure dive, squat, or ride heights at any point on the racetrack.