Fuel Economy Wins Races

JUST RELEASED! — The Official Directory for CART Racing
Fuel Economy Wins Races
©1997 SpeedCenter Internet Publishing, Inc.
Turning to position two means finishing number one
"Turn the fuel to position two, positiontwo..." comes the call on the radio from the team manager. "Position two,10-4..." is the response from the driver.
On race telecasts or scanners, PPG CART fans hear those commands — orvery similar messages — from the two-way radio communication between driversand their crew on pit lane.
But what does it mean, and what IS position two? Position two is merely one of eight stops of the fuel trim switch.Located on the dash of the seven Mercedes-powered CART Indy cars, the fuel trimswitch allows the team and driver to select the proper compromise between powerand fuel economy, through adjustment of the engine's air/fuel ratio and othervariables. Each of the seven Mercedes-Benz drivers will rely on the switch tomanage the correct amount of fuel burned at the ITT Automotive Detroit GrandPrix at the Raceway on Belle Isle in Detroit, Sunday, June 8.
"In PPG Cup racing, because of the minimum fuel-efficiency standardmandated by CART, we always have to be thinking about conserving fuel," saidMark McArdle, a senior trackside support engineer for Ilmor Engineering, therace engine-building arm of Mercedes. "The fuel trim switch gives us onesetting for maximum power — at which we make about 1.7 miles-per-gallon — andanother seven settings that afford different levels of compromise between powerproduction and fuel conservation, to make up the difference to CART's 1.85-mpgrequirement."
The Labels:
Each of the eight labels surrounding the fuel trim switch (also known asthe calibration pointer) are applied by the driver to ensure ease of readingwith the quickest of glances while driving at more than 200 mph. Each pointerposition indicates a different engine calibration. The calibrationelectronically determines the air/fuel ratio, spark timing and a myriad of otherengine control variables. These calibrations can change dramatically from onerace to the next and from one pointer position to the next, and are programmedby the Ilmor engineers.
"Because placement of the labels is so important, we don't want to have to movethem from week to week, so we make them generic — A through G or one througheight," said McArdle. "That also helps because we need to be able to refer tothe different positions simply and quickly when we're instructing the driverover the radio which calibration to select. What those stickers represent, onthe other hand, is anything but generic. The calibrations are customized foreach circuit and each driver every week."
The distinct fuel calibration settings are critical, and can mean thedifference between winning and losing.
The Switch and a Race Victory:
The fuel trim switch can play a decisive role in a winning race strategy,as it did for Paul Tracy and Marlboro Team Penske in Rio de Janeiro, Brazil,when race leader Bobby Rahal's Ford engine ran out of fuel with two laps left torun. How do the teams decide what settings to use during the race? Here is onescenario.
Because there is not enough fuel to run at full power for an entire race,a Mercedes team will likely start the race with a calibration in which power isslightly compromised for fuel economy, with an air/fuel ratio of approximately96 percent of optimum. Calculations indicate three pit stops will be necessaryduring the event, but several incidents occur in the early stages. Each time thecaution flag comes out, the driver is instructed to switch to the "yellow flag"calibration setting (usually about 88 percent of the optimum setting) whichoffers the least power and conserves the most fuel.
If enough laps are run under the caution flag and a lot of fuel is savedearly in the race (as at Brazil), the Mercedes engineer's calculations mayindicate that the team can make the finish with only two pits stops, but fuelconservation must start immediately. The driver is instructed to switch to avery fuel-efficient setting, perhaps 90 percent of optimum. This means slightlyslower top speed on the race circuit, but significant time saved by making oneless pit stop.
As the race continues, more incidents occur. The driver spends more timeat the yellow flag setting, and the need for fuel conservation decreases. He isinstructed to switch to one of the higher power settings, selecting the mostpowerful calibration available without running out of fuel.
Finally, when calculations determine that the driver has enough fuel togo to the end of the race, he switches to the best power setting, and uses 100percent of the power of the Mercedes IC108D engine to streak to victory.
Afterburner:
Generally, the driver is either using full power or conserving fuel, butthere is one exception. One setting is designed to make the engine burn evenmore fuel than it would at full power. It's called "Afterburner."
"Afterburner is designed to burn up excess fuel," explained McArdle. "Ifwe're getting towards the end of a race, and there has been a lot of time undercaution, we may have excess fuel in the car. That means excess weight. (Themethanol fuel used by Indy cars weighs six pounds per gallon.) In that case, wetell the driver to select afterburner. The mixture is set above the optimumair/fuel ratio, and, although we lose a tiny fraction of power, the loss is morethan offset by the advantages of lowering the weight of the fuel load."
Like Mercedes-Benz production engines, the Mercedes IC108D is bothpowerful and fuel efficient. The diverse new lineup of Mercedes-Benz passengercars includes the new SLK, selected the 1997 North American Car of the Year atthe North American Auto Show in Detroit. The product line-up will also sooninclude the American-built M-Class sport-utility vehicle.
Source: Mercedes-Benz USA


		JUST RELEASED! — The Official Directory for CART Racing

		Fuel Economy Wins Races ©1997 SpeedCenter Internet Publishing, Inc. Turning to position two means finishing number one "Turn the fuel to position two, positiontwo..." comes the call on the radio from the team manager. "Position two,10-4..." is the response from the driver. On race telecasts or scanners, PPG CART fans hear those commands — orvery similar messages — from the two-way radio communication between driversand their crew on pit lane. But what does it mean, and what IS position two? Position two is merely one of eight stops of the fuel trim switch.Located on the dash of the seven Mercedes-powered CART Indy cars, the fuel trimswitch allows the team and driver to select the proper compromise between powerand fuel economy, through adjustment of the engine's air/fuel ratio and othervariables. Each of the seven Mercedes-Benz drivers will rely on the switch tomanage the correct amount of fuel burned at the ITT Automotive Detroit GrandPrix at the Raceway on Belle Isle in Detroit, Sunday, June 8. "In PPG Cup racing, because of the minimum fuel-efficiency standardmandated by CART, we always have to be thinking about conserving fuel," saidMark McArdle, a senior trackside support engineer for Ilmor Engineering, therace engine-building arm of Mercedes. "The fuel trim switch gives us onesetting for maximum power — at which we make about 1.7 miles-per-gallon — andanother seven settings that afford different levels of compromise between powerproduction and fuel conservation, to make up the difference to CART's 1.85-mpgrequirement." The Labels: Each of the eight labels surrounding the fuel trim switch (also known asthe calibration pointer) are applied by the driver to ensure ease of readingwith the quickest of glances while driving at more than 200 mph. Each pointerposition indicates a different engine calibration. The calibrationelectronically determines the air/fuel ratio, spark timing and a myriad of otherengine control variables. These calibrations can change dramatically from onerace to the next and from one pointer position to the next, and are programmedby the Ilmor engineers. "Because placement of the labels is so important, we don't want to have to movethem from week to week, so we make them generic — A through G or one througheight," said McArdle. "That also helps because we need to be able to refer tothe different positions simply and quickly when we're instructing the driverover the radio which calibration to select. What those stickers represent, onthe other hand, is anything but generic. The calibrations are customized foreach circuit and each driver every week." The distinct fuel calibration settings are critical, and can mean thedifference between winning and losing. The Switch and a Race Victory: The fuel trim switch can play a decisive role in a winning race strategy,as it did for Paul Tracy and Marlboro Team Penske in Rio de Janeiro, Brazil,when race leader Bobby Rahal's Ford engine ran out of fuel with two laps left torun. How do the teams decide what settings to use during the race? Here is onescenario. Because there is not enough fuel to run at full power for an entire race,a Mercedes team will likely start the race with a calibration in which power isslightly compromised for fuel economy, with an air/fuel ratio of approximately96 percent of optimum. Calculations indicate three pit stops will be necessaryduring the event, but several incidents occur in the early stages. Each time thecaution flag comes out, the driver is instructed to switch to the "yellow flag"calibration setting (usually about 88 percent of the optimum setting) whichoffers the least power and conserves the most fuel. If enough laps are run under the caution flag and a lot of fuel is savedearly in the race (as at Brazil), the Mercedes engineer's calculations mayindicate that the team can make the finish with only two pits stops, but fuelconservation must start immediately. The driver is instructed to switch to avery fuel-efficient setting, perhaps 90 percent of optimum. This means slightlyslower top speed on the race circuit, but significant time saved by making oneless pit stop. As the race continues, more incidents occur. The driver spends more timeat the yellow flag setting, and the need for fuel conservation decreases. He isinstructed to switch to one of the higher power settings, selecting the mostpowerful calibration available without running out of fuel. Finally, when calculations determine that the driver has enough fuel togo to the end of the race, he switches to the best power setting, and uses 100percent of the power of the Mercedes IC108D engine to streak to victory. Afterburner: Generally, the driver is either using full power or conserving fuel, butthere is one exception. One setting is designed to make the engine burn evenmore fuel than it would at full power. It's called "Afterburner." "Afterburner is designed to burn up excess fuel," explained McArdle. "Ifwe're getting towards the end of a race, and there has been a lot of time undercaution, we may have excess fuel in the car. That means excess weight. (Themethanol fuel used by Indy cars weighs six pounds per gallon.) In that case, wetell the driver to select afterburner. The mixture is set above the optimumair/fuel ratio, and, although we lose a tiny fraction of power, the loss is morethan offset by the advantages of lowering the weight of the fuel load." Like Mercedes-Benz production engines, the Mercedes IC108D is bothpowerful and fuel efficient. The diverse new lineup of Mercedes-Benz passengercars includes the new SLK, selected the 1997 North American Car of the Year atthe North American Auto Show in Detroit. The product line-up will also sooninclude the American-built M-Class sport-utility vehicle. Source: Mercedes-Benz USA