Early Warning System
A probe-style pyrometer can be linked to a surface sensor to do almost everything an infrared pyrometer will do; it is just more cumbersome and slower. Infrared pyrometers measure only surface temperatures, but they can measure them from a distance, so the samples can be taken faster.
"Let's say you are working on a brake problem," Butcher says. "You can measure rotor temperatures as soon as a car comes in and get a pretty good idea if it needs more or less rear brake bias. Something like that can be very important on a short track where the brakes are getting used a lot."
"I think a lot of teams are just beginning to realize the potential of infrared pyrometers," says Bruce Rhoe, who is in charge of the motorsports program for Intercomp, one of the nation's largest producers of the devices.
"It is one of the best tools going for preventative maintenance," he says. "You can shoot-read hubs to be sure you don't have a wheel bearing getting hot. You can do the same thing with universal joints. If you know what temperature they normally run, and all of a sudden you see it go up, that's a good indication of a part that could fail."
Many Uses
Rhoe recommends using an IR gun to check radiator flow, the area around the thermostat housing, engine block, cylinder heads, and oil and water-cooling lines. An infrared gun can be a valuable tool to help keep a driver cool by using it inside the car to discover where heat may be entering through holes that can't be easily seen, or through radiation. "A lot of times we find heat is coming in through places we never figured it would be a problem," Butcher says.
Pick up an engine miss? By checking each of the header pipes with an infrared unit, you can determine which one is misfiring. The faulty pipe will be cooler than the others. A pipe that shows hotter than the rest may indicate a cylinder is running lean. An infrared gun can also detect a part of a radiator or oil cooler that is running cooler than other portions because it is blocked or the flow is restricted.
"We discovered a while ago that we had one brake that was running cooler that the rest. It indicated we had a problem on one corner and the brake wasn't working as it should," Rhoe says.
Got a circuit breaker that keeps tripping? Use the IR pyrometer to trace the wires and find the hot spot.
Rhoe says he also uses his IR gun to check trailer axle bearings during coffee or refueling stops. "Drivers tend to ignore things like that. They also are great to check that all the trailer brakes are working," he says.
The most basic Intercomp IR gun sells for $79, but it is limited to 500 F degrees. The best buy for the money, Rhoe says, is the gun that goes from - 25 to + 750 F degrees (high enough to shoot exhaust tubes). It sells for about $180. "The higher the readings, the more money it costs," Rhoe says.
At one time, Intercomp was working on an on-board IR unit that would shoot tire temperatures while the car was on the track. "It was pretty neat technology, but so expensive that not many teams could afford to buy it," Rhoe says. The expense didn't stop Winston Cup teams from developing their own on-car, in-house IR tire temp systems. Robert Yates Racing was doing so in the mid-'90s. "There are some sophisticated devices out there, but most racers are Saturday-night guys and they have to live within a budget. We have to remember that when we look at developing products."
Rhoe says his personal IR unit is 10 years old. "If you take care of it-don't drop it on the ground or just toss it in a toolbox-it will last a very long time," he says. "That's what makes it a good investment."
Check It Out
Got a probe pyrometer you sometimes think isn't very accurate? Here's an easy way to check. Bring a pan of water to boiling and carefully insert the probe into the water. You may want to hang it from a piece of wire or use tongs; the steam will scald your hand. Depending upon how close you are to sea level, it should read within a degree or two of 212 F degrees.