Automakers do insane amounts of testing to make sure your vehicle can handle whatever you throw at it, even in freezing, snowy, slushy and icy conditions. Here are just a few of the many, many components and systems automakers have to put through the wringer to deal with winter.
When I was an engineer at Fiat Chrysler, I worked in a group called Aero-Thermal. We did lots of up-front design and analysis on engine cooling systems and aerodynamics. But when we wanted a break from our books, we did vehicle testing. That’s where the real fun was.
I remember melting in 120 degree heat at Chrysler’s Arizona proving grounds, wondering how many rust-free XJs there were in the vicinity. When I wasn’t daydreaming, though, I was out testing the new Jeep Cherokee KL, putting it through its paces, running through our standard test procedures, and trying my darndest to overheat and/or break the damn thing.
That’s what test engineers do: they try to wreck stuff so you, the beloved customers, don’t end up breaking them yourselves, and hating them after getting stranded in the middle of the Mojave or on the shoulder of Davis Dam.
Hot testing is fun, but seeing as how the East Coast just got buried under a thick layer of crystallized water, cold testing is a bit more relevant right now.
Cold testing—which automakers do in cold drive cells, climatic chambers and in places unfit for human life like Houghton, Michigan or Prudhoe Bay, Alaska—involves doing things like driving cars through slush pits, coating the underside in slushy water, and then freezing the cars solid.
It’s not for the faint of heart.
Types Of Cold Weather Tests
There’s a variety of things a manufacturer might want to test in cold conditions, and I’ll only be able to scratch the surface here. But here’s what I can think of from the top of my head, broken into three sections: warmup, dynamics and engine performance, and durability.
Warmup
It’s 7 a.m. and you click your remote start button on your key fob. The car fires up, sets your seat warmers and cranks up the heater. You eat cereal, brush your teeth, and walk outside to your car. You get in and your HVAC blower is shooting ice-cold air in your face.
That’s not good, and it’s something that automakers make sure doesn’t happen. Cabin warmup time is a function of many things including engine heat rejection to coolant, coolant flow to the heater core, heater core performance and blower airflow. And while heater warmup can be simulated, engineers always want to test to validate their sims.
I once had to spend six hours doing heater warmup testing in temperatures near 20 below. For safety reasons, we had to use the buddy system when going into cold climatic chambers, which are basically just heavily refrigerated rooms with thick, vault-like doors. My coworker and I threw on special thick jackets, sat in a Jeep, fired up the engine and waited.
We monitored coolant flow, coolant temperature, air duct temperature and a lot more. We wanted to make sure that the most recent engine calibration would indeed lead to cabin warmup times that met our goals.
But what I was really monitoring was my butt. How long was it going to take for the damn heated seat to unfreeze the block of ice that used to be my rear end?
Image: NHTSA
But heater warmup testing isn’t done just so customers can be comfortable during their morning commutes. Heater warmup performance is regulated by our friend Uncle Sam. The U.S. Government’s Federal Motor Vehicle Safety Standard 103 mandates that certain sections of a car’s windshield must be cleared of ice and fog within a certain amount of time to ensure safe driver visibility.
But there’s lots of other warmup testing besides cabin warmup and windshield de-icing, especially when you consider 20F conditions. That’s the temperature at which the EPA begins its fuel economy testing (the Cold CO test, in particular).
Under those EPA test conditions, automakers want to monitor transmission and engine oil temperatures to make sure their engine and trans get hot fast enough to minimize churning and pumping losses and maximize fuel economy. They might also want to verify that their engine and transmission calibration strategies are working properly in cold temps and that the catalytic converter warms up quickly to keep emissions down.
And if the car is a hybrid, engineers would monitor battery warmup times to make sure the cells’ charging and discharging capabilities rise quickly enough to maximize electric drive time for a better fuel economy rating.
From fluids to batteries to catalysts, there are so many things that need to be warmed up to achieve maximum performance, and engineers need to conduct cold testing to monitor them all.
Dynamics and Engine Performance
I never worked in vehicle dynamics, so I can’t really delve too deep into what sort of handling tests automakers do in ice and snow, but they do test their tires, ABS, Traction Control and Stability Control Systems in snowy and icy conditions.
Granted, many automakers don’t design their own ABS-based safety systems, those tend to come from suppliers like Bosch, so suppliers do a lot of testing themselves.
Still, once the ABS components and associated programming has been integrated into a vehicle, automakers have to do testing of their own to make sure it all works together with the rest of the car as a system.
But engineers also need to make sure their engine’s performance isn’t thwarted by harsh climates. Cars with active grille shutters need to be tested to make sure the shutters don’t freeze, because if they do, the radiator might not receive enough airflow and the car could overheat even in sub-zero temperatures.
The engine’s air intake also needs to be designed in such a way that it doesn’t clog up with snow. The top video shows an engineer talking about a Ram Active Air, basically a system that can draw air from multiple inlets. This means it can draw ice cold air from the grille when it needs maximum performance, but it can also draw air from another location less likely to suck in tons of snow. To test the intakes, engineers can use a dyno cell (like the one above) to blow snow at a high velocity into a vehicle’s fascia, or they can drive behind a lead vehicle kicking up snow with chains.
In addition to making sure the engine stays cool and that it can intake air, engineers have to test to make sure water can be extracted from oil. Positive crankcase ventilation systems are designed to do just that. Condensation tends to build up in the crankcase in cold winter driving (particularly when cars are only driven for short trots, and engine oil temperatures remain low), and it’s the PCV’s job to get that condensation out. Making sure the PCV works in the cold could mean a lot for engine longevity.
There are so many failure modes that get introduced by cold temperatures, and much of it isn’t intuitive. Intercoolers and emissions control systems, for example, can be brought to their knees by frozen condensation buildup. There are just so many new vulnerabilities in the cold season, and knowing what to test takes many years of experience.
Durability, Corrosion and Other Cold Testing
That machine you see in the video above is a shaker rig, which is often used for suspension testing. When it’s cold, rubber bushings and shock absorbers can behave differently and can become susceptible to failure, hence why automakers test suspension in a range of operating temperatures.
But perhaps one of the biggest ways cold temperatures can affect a car’s durability is through the change in viscosity of the vehicle’s fluids. We know intuitively that cold fluids are generally “thicker” than warm ones. This means it’s harder to pump those fluids where they need to be to keep components lubricated and cooled.
Perhaps less intuitively, it also means high pressures in things like transmission, coolant and power steering lines. Cold testing ensures that these lines don’t burst under those high pressures.
But the testing that I find most interesting, perhaps because it relates to me, is corrosion testing. The way Fiat Chrysler does it, according to Chrysler Test Services’ page, involves driving a car through a slush bath, then heat it up in a very high temperature, high humidity environment to accelerate rusting.
Fiat Chrysler tries to replicate U.S. salt belt conditions, as well as conditions in Eastern Canada. Chrysler Test Services says: “In 24 weeks, the test chambers simulate 10 years of real-world driving exposure to the type of severe weather conditions that aggravate corrosion.”
They can do rust testing on individual parts or on whole vehicles, and they follow the test plan described by the Society of Automotive Engineers’s SAE J2334 “Cosmetic Corrosion Lab Test.” The cyclic corrosion test repeatedly applies a salt solution (0.5 percent NaCL, 0.1 percent CACl2, 0.075 percent NaHCO3) to a part at 25C for 15 minutes, dries that part for 17 hours and 45 minutes at 60C and 50 percent humidity, and then exposes the part to 100% humidity at 50C for six hours.
It’s a grueling test that will make every weakness in a pinch seam rot into a giant, cancerous hole.
Between testing fluid warmup, component durability, corrosion, engine performance and vehicle dynamics, cold weather testing is rigorous not only on the cars, but also on the engineers who have to sit in them in the frigid conditions.
And I only touched on a small fraction of the cold testing that goes on in the auto industry. There are still things like high altitude cold-start testing, fuel property analysis, battery performance, material durability testing (plastics in particular), and much, much more. But In the end, you wind up with cars that start every time, keep you warm, drive seamlessly, get decent gas mileage, and last more than one or two winters. That can’t be said about cars from even a couple decades ago.
Topshot Credit: Ford