Inside an emissions lab, the precipice of 100 mpg
Pages of notes about Federal Test Procedure 75 are spread before me along with a graph about tailpipe emissions. Oxides of nitrogen, anyone?
The Edison2 Very Light Car has been in the lab throughout May and June. After the Shakedown stage of the Progressive Insurance Automotive X Prize, one of the four Very Light Cars was taken to Roush Enterprises in Livonia. It’s being tested to measure fuel economy and to ensure it will meet the Tier 2, Bin 10 limit required in the Knockout rounds. For the Finals in July, the standard is tightened to Bin 8, making the 10-rating seem like Bin Lotta.
My host during the visit was development engineer Burke Davis, who said Bin 8 compares to a new pickup’s output.
Davis led a tour and explained the general principles. The building with the test cell probably dates to the 1950s, like Livonia itself, and was rather dim and dingy. But Davis and the rest of the staff were enthusiastic about their work. After finishing engineering degrees at Youngstown State, he applied for his dream job at Roush and got it. This lab is the place for manufacturers to have one-off evaluations done on prototypes. When Edison2 leader Oliver Kuttner insists that the company has large capabilities, this is what he’s talking
Davis explains how the FTP 75 works.
“Basically, you put the car on the rolls and you drive a trace,” he said.
When I first saw the Very Light Car, it was in a room outside the test cell, and a big fan was pointed at the car’s back end. Davis said he’d started the engine earlier and wanted it cooled to ambient temperature before initiating the test with the all-important gathering of cold-start emissions. About three hours were needed to achieve the cooling.
The thermo-coupled exhaust system looked like a seriously ill patient, with probes and bypasses going every which way; the only thing missing was prayerful loved ones at the bedside. Among the most critically important data in the test would be the exhaust gas temperature before and after the catalytic converter. This is what the sensors measured.
Davis took me into the test cell. It can be chilled to 0 degrees Fahrenheit or heated to 120 degrees. The FTP 75 protocol calls for a temperature between 68 and 86 degrees; relative humidity was set at 50 percent. The cost for such a test is $1500, and $200 for modal analysis.
A major manufacturer’s preproduction prototype was driven out and parked. There wasn’t much to see: the dynamometer’s gleaming rollers obtrude slightly from the flat floor. Measuring the resistance against them determines the powertrain’s dynamics and enables the computation of fuel economy.
A homely computer monitor sits atop a stand that’s angled toward driver of the test vehicle.
The Very Light Car was pushed into the cell, rear drive wheels positioned over the rollers. The front of the car was strapped down.
Davis said that once the engine was started I would have seen just about everything there was to see. The cold-start portion of the test is most critical: the majority of engine emissions occur in the first 90 seconds or so before the catalyst “lights off,” achieving peak operating temperature. (Various catalysts are being used during testing, along with different maps for ignition. Exhaust-gas recirculation levels also vary until the most efficient combination of all factors can be achieved.)
Test engineer Patrick Filangi got in behind the wheel and put on ear protectors. He started the little engine and shoved the transmission into gear. (He had trouble getting first.) The rear drive wheels turned against the rollers as Filangi, working the gas pedal, tried to keep the target on the monitor between a pair of lines that bent and wiggled like a highway that leaps from one atlas page to the next.
After shooting a couple of pictures, I left the din of the cell and joined Davis and others in the control room. One screen showed live data about the exhaust gas constituents and the fuel economy. Another showed the target and the trace, which I presumed Filangi was seeing, too.
“Watch out for that hill!” Davis said under his breath.
The modes include not only simulated city and highway driving but also a hilly section that demands some aggressive use of the throttle. The exhaust gas sampling is captured in a large clear bag that hangs from a Horiba CVS-7200S console. (CVS stands for “constant volume sampler.”) The contents are analyzed using flame ionization, which couldn’t be anything you’d ever want for a pet or small child.
I stayed for about 90 minutes before bidding my hosts good-bye. Inside the building was the 100-mpg horizon.
The Edison2 team finds the Very Light Car ever so close.