2007 Cosworth CART engine

The venerable Cosworth XFE turbo V-8 that will power each and every Champ Car in the 2007 season, sounds even better this year.

Refinements to the engine's electronics and a new exhaust system and wastegates to suit the new Panoz DP01 have resulted in a slightly smoother, sharper sound. The latest version of the XFE also runs without a pop-off valve thanks to a new electronic boost control and the duty cycle on each engine has been increased from 1,200 to 1,400 miles. Another change for this year is that Cosworth has ceded all the engine-related electronics to Pi Research

Ken Deagle is Cosworth's Champ Car track support manager working with his team of engineers and engine builders out of Cosworth's US headquarters in Torrance, California. Deagle has been with Cosworth for fifteen years and has worked on the XFE engine program since its introduction as the XF in 1999.

"The plan for '07 was to take advantage of every element of the new Panoz race car from all the suppliers that were involved," Deagle explained about the approach to this year's Panoz DP01. "Until this year we always did our own electronics, using various components from throughout the industry to make our own bits. We made our own ECUs, our own wiring harnesses, everything. But this year, Pi is doing that because that's what they do best. Pi is supplying all the electronics, from ECUs, to wiring harnesses, data logging, sensors and gearbox control units."

Cosworth has made more space available in the ECU by reverting from an electronic to a mechanical ninth butterfly in the XFE's turbo system.

"We've gone back to a mechanical ninth butterfly," Deagle commented. "For the last ten years we've used an electronic system to fine-tune the boost curve. But we've learned so much in the last several years that we've put the burden of finite boost control back onto the wastegates and made the ninth butterfly mechanical. That in turn has freed-up some of the processor space in the ECU.

"The SQ6M ECU provided by Pi is the latest generation of electronics available. I would say the ECUs we had developed were a bit dated and we pretty much had them running at full capacity to do everything we wanted. It handled the boost control and shifting so there was an engine control and a gearbox control. But the processors were maxed-out. They were at their capacity."

With no competition from a rival engine manufacturer, Cosworth has been able to eliminate the top-heavy pop-off valve, a thirty-plus year-old dinosaur of Champ Car racing.

"We no longer need to have a pop-off valve," Deagle remarked. "The pop-off valve was there to insure parity across the grid when there were multiple manufacturers competing in the series. For the last three years, we've frozen the boost adjustment to the teams. They couldn't adjust it. They could go down in boost if there was a problem, but they couldn't raise it, and with the advent of power-to-pass we more or less narrowed the range they could even adjust it down.

"Without the pop-off valve, the system controls to a set point which is 41.5 inches in normal conditions," Deagle continued. "We used to cycle through wastegates and keep pushing the set point until it about dumped the valve and back it off a tenth from there. The teams can do whatever they want with the wastegates and our control system will recognize it and compensate. In the worst-case scenario where a team gets really creative, the system will recognize that and shut the engine off. It'll start misfiring and the driver will come in with an alarm reading 'overboost conditions'.

"By removing the valve we've also eliminated the potential for a race-ending failure if a pop-off valve would break, and we've made a little weight-saving off the top of the engine as well. So by and large the system is more simplified and has been put back into the Cosworth engineers hands in regards to adjusting and optimizing."

Deagle also explained the reasons why the latest version of the XFE sounds sweeter and sharper.

"I think the different exhaust note that you notice is from the wastegates and a slightly different tailpipe arrangement compared to the Lola's system which was a bit longer and a bit more directional. The new exhaust is shorter and dumps straight out. We've also tuned-up some of the fuel-mapping in the new ECU and because we have a split system where the gear control unit is a separate ECU altogether. And that probably has some effect on the sound as well. The end result is that the engine is a little bit more powerful with a bit more smooth of a power curve.

"A lot of people over the years mistake rev-limiter for valve popping," Deagle added. "But the valve has never been audible in any capacity except for perhaps on a very high-speed oval where if the engine speed was below the maximum rev limit and the valve dumps, you probably would hear that. But on any circuit that Champ Cars typically have run on for the last three or four years, you would never hear that."

Improved pistons and oil control system have enabled Cosworth to add 200 miles to the duty cycle of each engine.

"The engines now will run to 1,400 miles," Deagle said. "The limiting factor on running more than 1,200 miles was the piston. After 1,200 miles they were pretty much used up. The duty cycle just beat them up and certainly, if a driver was a little overzealous on downshifting, that was a negative as well. What we learned in the last two years and last year in particular with piston development with our CA Formula One engine were some slightly different approaches for piston design in materials and manufacturing that carried over to this new program. We've also improved the oil control a little. So while the horsepower output is the same, the internal components have been improved to get an extra 200 miles between rebuilds."

Cosworth's engineers reckon the DP01's pneumatic paddle gear shifting system will have zero net effect on the life and performance of the latest XFE V-8.

"It shouldn't have any effect on the engine as long as any team doesn't get their calibrations wrong and finds out a way to over-rev it," Deagle observed. "It shouldn't have any effect for or against engine reliability."

Cosworth's rebuild agreement with the teams will start the new season from a clean sheet of paper.

"We have to same pool of just about one hundred engines," Deagle reported. "When we first started this single manufacturer engine program we offered the teams thirteen, 1,200-mile engine lives for a year, and that was entirely too many engine lives. A lot of teams had four or five lives left over so we started having carry-overs to the next year and going into the fourth year it all started to get a bit muddy.

"So as of January of this year there's a clean slate. Everybody starts with zero and they get six engine lives for the season. So the teams will have their usual three engines per entry with them at any given time. They rotate through those until one of them reaches its minimum mileage figure and we'll give them a fresh engine. With the addition of the two European races we may have to add another engine life for each team. Hopefully, each entrant will utilize all six or seven engine lives all the way through the last race of the year."

As in recent years, Deagle is one of twelve Cosworth engineers who work with Champ Car's teams at each race.

"We offer one engineer per team for a typical two-car team," Deagle said. "If it's a one-car or three-car team we'll close the gap up with dual support. At the moment we're at twelve people per event. We had three or four additional engineers from the UK at the Sebring test to help with software development and any bugs but the main maintenance staff you see at any event comprises twelve of us."

In a racing world dominated increasingly by normally-aspirated engines, Cosworth's 2.65-liter XFE V-8 stands out as one of the sport's few remaining turbocharged powerplants. Long may it continue to wail.

 

i didn't know all the cars in the champ used the same engines?
hopefully i'm not the only one who didn't know lol

 

they turned to spec engines a few years ago.

and now spec chassis as well....

 

sweet....though hearing them/feeling them go is the best part.