2 weeks of research has taught me some things I didn't know before.
I have a 1985-1993 Delco glow plug controller on the truck. This is the one that is gray in color, has 4 leads and doesn't go into the cooling system. GM went to the black 3 pin controller when they went to the computer controlled DS4 IP around 1994. I have seen black and gray controllers and never thought about them being different. Now I know. Use the gray one for non computer trucks.
I have the self limiting 60G glow plugs in the engine. Actually, I have them in all of my diesel engines. I like the security blanket of non swelling or exploding glow plugs. However, the gray 4 pin controller wasn't designed for them. It was designed for the 9G, 11G and 13G glow plugs. They are not self limiting and hit their 1400° temperature almost immediately. The 60G plugs take a few seconds to hit that temperature.
So, the normal 4 pin gray controller glow time of 8-10 seconds just isn't enough time to get full use of the 60G glow plugs. I have the same controller on my M715. I have always turned it on, let it glow, turn the system off and then back on real quick for fast starts. It just works better every time. However, the used 4 pin gray controller on the Cowdog wouldn't let me do that. It would do a glow cycle and if I turned off the ignition. It wouldn't come back on again. It was defective. I swapped in a new one last week. Double cycle down to 29° and the truck starts within a second of trying every time. That problem was identified, diagnosed and kind of solved.
I could make it work I felt at altitude again. But, what if I forgot or someone else was needed to drive? I need to make it idiot proof. An internet search for 6.2 and 6.5 glow plug cycle time too short brought all kinds of hits. I had never searched for that before. It seems a 5 Ohm 2 Watt resistor in the wire for terminal C will make every glow period 12-16 seconds and nothing else is needed. I hope to do that in the next week or so when I have time and will report what I find.
Starting is solved. EGT issues were also researched. Lowering the temperature of the air going into the engine will improve combustion efficiency and reduce exhaust gas temperatures. It can be looked at two ways. More power made with less fuel means less throttle to do the same thing as before and therefore, less heat. Or, the same amount of heat at the exhaust means the engine is putting out more power and speed is therefore increased. Neither comparison can be graphed on a straight line. I am just giving some basic generalizations.
Stuffing more air into an engine makes the engine more efficient. A gear or belt driven pump is called a super charger and an exhaust driven pump is called a turbo charger today. Both have been around for more than 100 years. The road up Pikes Peak was used to perfect them actually. Here is a great story about charge air induction:
https://www.airspacemag.com/history-of-flight/hill-climb-2023375/
Many WWII planes had both super chargers and turbo superchargers. Like any air compressor, which is basically all they are, they heat the air. Hot air takes up more space inside an engine and is less efficient than cool air. So, air plane designers put an air to air cooler between the super chargers and turbo chargers. They called it an intercooler because it was between the two charging devices. Some even had an air to air cooler after the last compressor called an after cooler. After the war many of these planes could be bought for less than the value of the fuel inside their tanks. Many and in some cases. All of some models were bought and cut up for scrap. Racers soon learned that the somewhat small intercoolers could be made to fit their dry lake speed run cars. They used them as after coolers but since they technically were surplus intercoolers. They were called intercoolers. So today when you hear intercooler. People almost always mean aftercooler but like Coke for soda and Kleenex for tissue. The unknowing repeat wrong information enough that people think it is fact.
Raise the hood on any production diesel truck newer than 2000 and you will see a huge head light to head light aluminum radiator looking thing right behind the grill. That is the air to air charge air cooling device commonly known as an intercooler. They need to be huge because they are inefficient. Water to air cooling is actually more efficient. Either way, air or water cooled. Getting the intake air down to 200° is considered good. They also take up a lot of space and are expensive.
If 200° was the goal. I wasn't going to spend thousands and get rid of my A/C to put one on the Cowdog. There are several coolant cooled air charge coolers out there in the $500-$1000 range. But again, if 200° is the best they can do. Why add complexity to the air intake path and more leak opportunities?
Mainly because once installed. Any fixed air charge cooler is "on" all the time and working. It will always make the inlet air cooler than if it wasn't installed. It might not be much, but it will be better than nothing.
There are also consumable methods to cool the air going into the engine. Injecting small amounts of straight water mist into the intake path after the charger can result in around a 10% power increase or similar exhaust gas temperature decrease. Add a 50% methanol/water mix to the air and up to 30% power increases are possible or up to 300° drop in EGT. Again, aviation used this very successfully. Some WWII planes on all sides of the war had such systems installed. Mostly for help during overloaded take offs. Once in the air and the water/meth was consumed. There was no weight penalty for having they system.
Diesel engines seem to really love methanol/water. So do the tuner car guys. There are several companies making kits for diesel trucks and turbo cars. Sifting through all the WRX videos to find truck information is entertaining, but tiresome. I am still researching. But, I think this might be what works for me best. I did make it 1215 miles out of 1225 miles with no issues of wanting more power, speed or less heat in the exhaust. It was only above 3 psi of boost and with an extreme grade that I was having to slow down or even think about it. To me, that is not worth the huge expense/time/effort of fitting a grill mounted air to air or engine bay mounted water to air cooler.
People have cobbled together home made systems for less than $100 and just put tap water in and have it work great. The blue -20° washer fluid is next with a substantial gain in performance without much cost increase. 50/50 methanol/water mixtures are around $10 a gallon and another big step up from the washer fluid performance. Still researching.
Sorry for the extended history lesson. I wanted to make sure an apple was an apple and an orange an orange when someone read what I wrote.