So @RacinBob 's https://opposite-lock.com/topic/63882/cold-start-stories/23 post about cold start stories got me thinking about my old job at GM where my job was to calibrate the Duramax (and a couple of others) to start at cold temps. Here are some of the stories.
First I worked on the 4.5L V8 LMK that was supposed to go into the GMT900 1500 trucks. It never made it...
After one start in Denver at about -5F I did a driveaway to make sure the engine would work well beyond just idling. Well, about 1 minute into the drive we heard a loud bang and the engine died. I pulled over and tried to start it again and it just cranked really fast showing there was no compression. We never found out exactly what happened to that engine because it was right before the canceled the program, but we assume the timing chain jumped and bent all the valves.
After the cancellation of the LMK I started to work on the LGH and LML - the 6.6L Duramax. We had cold cells at the proving ground that we would stick the truck in cool it down to whatever set point. Usually the starts were uneventful, but the driveaways is where the fun stuff happened.
At -21F we had to start the truck and slam it in gear and do WOT driveaways as fast as possible. One of my jobs was to protect the turbo during these events. Well, it didn't always go as planned. We tried to limit turbo speed to about 100k RPM while cold, and we did this mainly through torque limiting and some engine speed limits. While dialing that in I hit about 110k RPM and spun the bearing and it made a nasty noise. But after that it seemed to run fine, so I kept testing and driving for several days after that. What I didn't realize was the turbo was now leaking oil into the engine and it finally got to a point that I was blow tons of smoke out the back, and eventually the engine ran away to over 4000RPM (red line while fueling is about 3300RPM. I jumped out of the truck, popped the hood and tried to rip off the intake and stuff my shirt in, but luckily it burned itself out before I could do that. All said and done there was only 1.5 qts of oil left.
When driveaways go as planned, it's almost comical how slow these trucks are. Starting at -21F and doing a WOT driveaway the 0-60 is about 20 seconds. That comes from the torque limits (normally about 765ft-lbs) we would limit to ~300-350. Plus, the engine friction was incredibly high, and the Allison transmission would start in 2nd gear when that cold. One day my buddy who worked on the diesel vans which were normally severely derated to like 260hp and 520tq raced me while we both did -20F driveaways. He won.
Up at high altitude (about 9000ft in this case) we also did WOT driveaways. The coldest we could start up there was about -10F. We just couldn't get it going lower than that. But the funny part was due to the high friction in the turbo bearing due to cold oil, and the low density air, doing a WOT driveaway you could literally walk next to the truck for about 10 seconds before it would finally build boost and take off. I know this because I would do it with my colleagues. We'd talk while one was driving away and the other walking next to the drivers window.
One day I was doing testing in Denver, doing WOT driveways again. There were some service people there working on the building who witnessed our testing. One guy stopped me on the way back and in said "you guys drive those trucks like you hate them. I have a 6.0L [ford powerstroke] and I know I'd blow that shit up if I did that". Lol.
Our requirements were to start at -20F at sea level and at Denver. Once I had most of my cal done, I tried to see how low I could go. My record at sea level was -32F. It was a bit ugly, but it ran. I tried a -40F start but even with fully charged batteries it wouldn't even crank - it just clicked. Even at the -20F standard we'd only crank about 50-60RPM (the requirement was always 80RPM, but we never met it). The lights in the dash would go dim during every compression event and the system voltage would drop into the 5V range. If it dropped below about 4.8V then it would drop out and we'd just click.
Last story for now. This one is a bit embarrassing. After doing a cold idle inside the cold box I left the truck running while I looked at some data and closed up the box to prepare for the next test on Monday. Well, after doing all that I forgot to shut off the truck. Like, for the weekend. So I come in on Monday go in the box, the truck's not running and think to myself "this smells kinda bad, but whatever". I hook up the computer and go to start the truck and notice the key is in the run position. Weird. I turn it off and back on and the truck is completely dead. Then it dawns on me that I had left the truck running all weekend. I open the doors to start airing it out and warming the truck up. By this time my eyes are burning due to all the hydrocarbon in the air. After about an hour of charging the battery and warming up the truck I finally get it started. I drive around the track and because of all the unburned fuel in the exhaust I start POURING white smoke out the back. I mean, the most smoke you've ever seen. I don't think there was an insect left alive within a half mile of that track. Well, after the smoke slows down the DPF gets hot enough that it lights off and it start getting extrememly hot. It pegged all my sensors at 1000C. I was half expecting pieces of the exhaust to start falling off the truck. While all of this is going on, I have the windows down, but the fuel in just saturating in everything to the point I can't even keep my eyes open, so I finally just lean out the window Ace Ventura style to try to get fresh air.
I finally take the truck back up to my building (and get a car wash on the way to try to reduce the smell. At this point I borderline sick from the fuel permeating everything. I walk in the building and as I'm walking people at their desks starting asking "what is that smell? Is someone idling right next to the building". It was me. Everything on me smelled like diesel. I ended up going home at about noon (it took me 4 hours to get the truck started, cleaned up and get everything taken care of). I went home threw all my clothes (including my shoes) straight into the washer and I took a shower.
The next day I had to clean up the cold box because it smelled terrible too and my friend and I took a truck with a water tank down there and washed the walls and floor and everything the best we could, but it you could still notice the faint smell for several months after that.
Then to top it all off, I no longer used that truck, but a few months later a colleague did, came back in and said "there is something wrong with that truck, it's leaking gas or something". He didn't know that was the one that bathed in it's own exhaust for a weekend.
I estimated the truck burned about a 1/2 tank (~18 gallons) while idling and it finally died about Sunday morning probably due to lack of oxygen.
Oh, one last little bit of information.
The LML's (and others) had intake air heater (also called grid heaters) to warm up the incoming air while the engine is cold. These things took an immense amount of power. After starting really cold you'll still be discharging the batteries for up to 5 minutes because it's drawing about 100A and at idle the alternator can't keep up. We actually did a test where we kept it on extra long just to see what would happen and we actually got a dash warning to "service charging system" after the running system voltage dropped to about 10.5V.
I have so much more information about this stuff, but I think this post is already long enough.