Concern over EFi at Bristol
The tight confines of the first short track of the Sprint Cup season could cause plenty of concern in Sunday's Food City 500. With each fender banged and each lap turned on the bone-chattering concrete, the impacts and vibrations could take their toll on the new electronic fuel-injection (EFI) system.
"We're worried about the life of the sensors," said Doug Yates, co-owner of Roush Yates Engines, which builds the Ford powerplants for Roush Fenway Racing and Richard Petty Motorsports. "We know how bumpy and demanding that place is. We feel like we're as prepared as we can, and it's another track we haven't been to with EFI. It'll be another box to check."
The system, which made its debut in NASCAR's top series this season after decades of using carburetors, has received mostly high marks through the season's first three races. There have been a few blips, though.
A minor change to the mounting relay box was made after several drivers experienced circuit-breaker overloading at Daytona International Speedway. A circuit-breaker malfunction at Phoenix International Raceway briefly rendered Tony Stewart's ignition useless. Last week at Las Vegas Motor Speedway, Penske Racing drivers A.J. Allmendinger and Brad Keselowski finished outside the top 30 because of fuel-delivery problems.
Toyota Racing Development President Lee White, whose company builds engines for Joe Gibbs Racing and Michael Waltrip Racing, said the debut of EFI still "has gone as well as anyone could have expected," but the inability to test high-stress race conditions makes it impossible to anticipate all the potential problems with a more complex assembly of parts.
"NASCAR has done their homework, and done a phenomenal job of sitting with people from the industry with fuel-injection experience to help create the rulebook," said White, who has EFI experience from sports cars. "But there's so many components to make the system work, no one can judge how each crew chief manages his car. No matter what you dictate, there's still a learning curve."
With the carburetor, a cable-driven fuel pump was used to deliver fuel at nine pounds of pressure. In EFI, there are lift pumps and a main pump used to deliver fuel at 70 pounds per square inch. Many teams such as Penske have used electrical pumps because they provide instant fuel pressure. Yates said Ford stuck with a mechanical pump because of its reliability.
"You always try to anticipate what could go wrong and put failsafes in place," Yates said. "Everybody has a different system, and NASCAR has given us a lot of freedom in configurations. It's a big change, and it's hard to simulate when the engine runs low on fuel and gets hotter. People will figure it out, it's just so different." USA Today