With more 4x4 and all-wheel-drive vehicles in its product portfolio than at any other time, Fiat Chrysler Automobiles has invested $2.5 million to upgrade a climatic test cell with a 4x4 dynamometer.
It is the first FCA test chamber in the U.S. with snow-making capability and a 4x4/AWD dyno.
“This is must-have for testing purposes, especially with a large percentage of our Jeeps being 4WD and our large cars having an all-wheel-drive option,” said Pete Jonko, Drive Cell Operations Engineer responsible for FCA North America’s thermal drive cells.
Capability to power all four wheels is available in more than half of FCA's U.S. product lineup, including the 2015 Renegade, Jeep’s first compact SUV, and the 500X, Fiat’s first AWD vehicle since the brand’s U.S. relaunch in MY2012.
Jonko and other technical specialists spoke with Automotive Engineering at the recent opening of the new facility, part of FCA's 5.4 million ft2 Auburn Hills, MI, Chrysler Technology Center (CTC).
Kumar Srinivasan, Manager of the CTC’s Computational Fluid Dynamics Group, likes the convenience of a three-minute walk from the CFD group’s work area to the new 4x4 dynamometer cold test cell.
“The close proximity of this drive cell helps us to understand very quickly how a vehicle is performing under blizzard-like conditions," he said. "We can then go back and fine-tune or update our simulation models to more closely match what’s actually going on with the air intake system and other vehicle sub-systems.”
The climatic drive cell’s front dynamometer can handle loads of up to 350 hp (261 kW) while the rear dyno can operate up to 650 hp (485 kW)—a significant upgrade versus the test cell’s previous 200 hp (149 kW) and 2WD capability. Substantial ductwork revisions and exhaust alterations enable the new dyno to accommodate high input torque levels from vehicles such as the 2016 Ram 2500 and its 6.7-L Cummins turbodiesel.
ICE-powered vehicles as well as hybrid-electric and all-electric vehicles have already endured the cell's frosty climes, which range down to -40° F (-40° C). Wind speeds up to 100 mph (62 kph) are also available, according to Jonko.
“This is the tech center’s most capable dyno in terms of horsepower and vehicle exhaust management," he noted, adding that FCA's Chelsea (MI) Proving Grounds has the same dyno set-up but it's limited to hot testing. The newly renovated CTC cell can be heated to 125° F (51.5° C).
Testing 4x4 vehicles on a purpose-designed dyno also eliminates preparation slowdowns, because every 4x4 vehicle previously slated for the climatic chamber had to be reconfigured as a 2WD variant.
“With an old style 4x4 you could pull the front propshaft from the differential and essentially run in a 2WD/rear-wheel drive mode," Jonko explained. "But with AWD cars that’s not always possible." He said sometimes an AWD conversion meant unplugging wheel sensors and front or rear power transfer units. As driveline technology progressed, the FCA testers found it increasingly difficult and time-consuming to run their AWD vehicles on the 2WD dyno.
In addition to the upgraded drive cell, CTC has two other thermal drivability cells, three static hot/cold cells, and four conditioning/soak cells on its environmental test chamber roster.Continue reading »