Vital Signs Mercedes-Benz Engines Get a "Routine Checkup" With Every Pit Stop MONTVALE, N.J. (August 25, 1998) -- Whatâ€™s the first thing that happens every time you go to the doctor? Okay, after you fill out the forms. ...
Mercedes-Benz Engines Get a "Routine Checkup" With Every Pit Stop
MONTVALE, N.J. (August 25, 1998) -- What’s the first thing that happens every time you go to the doctor?
Okay, after you fill out the forms.
You sample the medicinal flavor of a thermometer, you hear the Velcro rip of a blood pressure cuff, and you feel the jolting cold of the stethoscope on your skin -- the doctor or nurse is checking your vital signs: temperature, blood pressure and heart rate.
Telemetry allows the Mercedes-Benz Trackside Support Engineers to perform the automotive equivalent of this routine checkup any time they want, particularly when one of the eight Mercedes-powered Champ Cars visits pit lane during the course of the Molson Indy Vancouver CART FedEx Championship Series race Sept. 6.
"Whenever the car comes into the pits -- unless there is some obvious issue that we need to address right away -- our first job is to assess the general health of the engine, and we usually don’t have much time," said Charlie Harris, one of two Mercedes-Benz Trackside Engineers supporting the PacWest Racing Teams. "The Magneti Marelli engine management software lets us configure the display pretty much any way we want to. I’ve set up a screen I call ‘Vitals’ which lets me check on the most basic and important engine function information right away."
"Squeaks and Leaks Check"
The attached graph is the "Vitals" screen Harris uses to monitor the vital signs of the Mercedes-Benz IC108E engine in Mark Blundell’s Motorola Reynard/Mercedes Champ Car. Although the numbers have been removed and the lines altered slightly to protect proprietary information, it depicts one of the most crucial engine checkups: the first lap out of the pits with a newly installed engine, affectionately known as a "Squeaks and Leaks Check."
"The ‘Vitals’ graph is set up to display color-coded readouts of water and oil temperature in degrees Celsius, oil and fuel pressure in pounds per square inch, alternator current in amps, and rpm -- all measured over time," explained Harris. "Everything keys off of the brown line on the bottom, because the other parameters fluctuate with engine speed."
The rpm line serves as a record of the activity for the lap. The timer starts (0.0 seconds along the X-axis) at engine startup. The fluctuations until about eight seconds (halfway through the first 16-second interval) indicate Blundell sitting on pit lane revving the engine. He’s waved out at 10 seconds, leaves pit lane at 62 seconds, accelerating and shifting from first to second gear when the line peaks at 66 seconds. At about 81 seconds, he shifts to third. From there on, it is a cautious, slow lap as Blundell and the team check out the new engine installation.
Reading the Signs
While Blundell is doing the driving, Harris continues to monitor the Mercedes engine’s vital signs. Here’s what he’s looking for:
Water Temperature: (Blue) A general assessment of the cooling system. Fluctuation can mean a loss of fluid, and a sudden increase usually means a blockage of sidepod-mounted radiators or a breach of the system.
Oil Temperature: (Green) Same as Water Temperature. Oil cooler located in left sidepod only.
Oil Pressure: (Orange) Fluctuates in proportion to engine speed. A large drop in pressure can signify oil pump failure, a faulty bearing or an oil leak.
Fuel Pressure: (Red) Remains basically constant. Drops to one-quarter standard when fuel runs out. Other fluctuations can indicate fuel pump trouble.
Alternator Current: (Black) A measure of the rate at which the battery is being charged. Fluctuates in proportion to engine speed. A decrease below normal limits means a problem with the charging system. An increase beyond normal limits implies a short or other electrical fault draining off current.
Revolutions Per Minute: (Brown) A measure of engine speed. Fluctuates with throttle position and gear selection. Key reference for all other parameters. The Mercedes-Benz Trackside Support Engineers will be practicing their own brand of preventative medicine at Concord Pacific Place in Vancouver, British Columbia, Canada, Sept. 4-6. The Molson Indy Vancouver race will be televised on ESPN starting at 5 p.m. EDT.
The doctor is in.