Mercedes-Benz Champ Car Engines Breathe Deep for Power MONTVALE, N.J. (June 12, 1998) -- At the Budweiser/G.I. Joe's 200 CART event at Portland (Ore.) International Raceway June 19-21, Mercedes-Benz racing engines will power eight Champ Cars,...
Mercedes-Benz Champ Car Engines Breathe Deep for Power
MONTVALE, N.J. (June 12, 1998) -- At the Budweiser/G.I. Joe's 200 CART event at Portland (Ore.) International Raceway June 19-21, Mercedes-Benz racing engines will power eight Champ Cars, including defending race champion Mark Blundell's Motorola/Reynard/Mercedes.
To help Blundell and the other seven Mercedes-powered entries beat the competition, Ilmor Engineering, the racing engine design and manufacturing arm of Mercedes-Benz, took a clean-sheet-of-paper approach and developed an all-new, radically compact and light V8 engine.
While a smaller, lighter package like the Mercedes IC108E engine allows chassis designers to improve key areas like handling and aerodynamics, drivers always want more horsepower. Most people think that more horsepower comes from feeding more fuel to an engine but it's really air or engine breathing -- deep, fast and hyper-efficient breathing -- that holds the key to more power.
If breathing and respiration are necessary to sustain a human being, respiration is also critical for a racing engine to produce winning power. "There's a common misconception -- probably based on years of pushing the gas pedal when you want your passenger car to go faster -- that fuel is what makes the difference as far as an engine generating power," said Paul Ray, vice president, Ilmor Engineering. "The truth is that air is the most important element. That's why we spend so much time trying to make the Mercedes engines breathe better; that's the secret to making more power."
Champ Car engine designers develop their creations to maximize the amount of air forced into each cylinder during the brief time period that the intake valve is open. That can be as short as five milliseconds (.005 seconds -- talk about hyperventilation!). The more "fully packed" the cylinder is with air -- and the tiny droplets of fuel that are mixed with it -- the more powerful the engine.
"All modern race engines achieve a volumetric efficiency far greater than 100 percent," says Dr. Hans Alten, Ilmor's expert in thermodynamics and fluid dynamics. "The shape and length of the inlet tract, from the top all the way down to the inlet valve; the shape of the cams, which affect the frequency and duration of valve openings; the shape of the valves themselves -- all of it must be tuned to optimize volumetric efficiency."
Waiting To Exhale
The second part of the respiration function, exhaling exhaust, is just as important as the first. In fact, inhaling and exhaling are two halves of a single process, with the intake system affecting the exhaust system and vice versa.
"We are most interested in the overlap, the period of time when both the inlet and exhaust valves are open," explained Alten. "That is when the two halves of the system interact most directly and when the real gains in volumetric efficiency can be made. Using computer modeling of the flow patterns and pressure waves in the system, we remove the exhaust gases as quickly as possible, creating a depression (an area of low pressure) in the cylinder at just the right time to draw in the new charge when the intake valve opens. This constant process of charging and exhausting simulates breathing."