I've had a turbo on my 3L powered LN106 since around 2010, truck had 174000km when I did the original Ct20 setup using stock bits from a surf. It has evolved several times since then, latest version uses a turbo common on many subaru applications with a top mount intercooler fed by three fans through a hood scoop. Truck now has 379000km on the ticker, finally time for a rebuild this year but thats another story. Engine never did give up, but was definitely tired. Adventures include lots and lots of wheeling, driving it from coast to coast here in Canada, countless multi day treks, trips to California, Utah, and plenty of other states, as well as daily driver duty for a couple years. This thing has been around.
A pre turbo egt probe is very important on these engines in my opinion. Without one you may have some very scary temps going on. I have run 11 psi for many years without issues. Any time I had coolant temp issues, it was always like clockwork after sustained egt redlining, which for me is 1200F pre turbo. I don't know how this fits with the consensus but its worked for me. Yes I feel it is asking alot, I also pay alot of attention to egts at shutdown.
Truck has 4.88 gears, plenty of armor, two winches, two fuel tanks, tools from hell blah blah. Fairly heavy for a mini truck platform. I've run a variety of 35's by different manufacturers, the heaviest being the 13.5 wide Toyo Mts.
Only time I had cooling issues was with the rad half full of mud, or during sustained maximum load operation such as climbing various mountain passes.
An OEM brass and copper Toyota rad is probably the highest quality unit you will find, particularly if you have it professionally recored to bring it back to original performance or in some instances even better. There are several (maybe many?) different types of core options, for example a two row with larger tubes (providing a greater volume of coolant flow) vs. a three row with smaller tubes that end up the same thickness front to back. The rad shop I used years ago assured me the type of two row mentioned here would provide superior overall performance. Many years down the road, based on my experiences I believe it. There are plenty of smarter people than me on here who may know better but I believe copper also has a greater ability to transfer heat than aluminum. Most aftermarket aluminum rads I've seen were just cheap bling junk. Not to say good ones don't exist, but I am saying your OEM rad operating at or tweaked beyond its original parameters may be capable of doing a better job. I also pull my rad and wash it once a year. Again, there are more knowledgeable people than me here, these are my experiences.
I also feel a mechanical fan is the way to go, provided it is operating as it should. Various reasons.
Another consideration, the engine compartments on these trucks are stuffed pretty full. I did install some hood louvers. All the hot air coming through your rad needs a place to go. I did the louvers at the same time as some other tweaks, but I can verify a whole wack of hot air does come flying out.
I saw a 100f egt decrease under all conditions by building a full 3'' diameter downpipe right from the turbo vs. the stock ct20 dump pipe into 3" out the back. Get that heat out. I agree with exhaust wrap and turbo blanket as well. I suspect the root cause will turn out to be more about Egts.
With my current setup with recored rad, original probably bagged clutch fan, original shroud, and top mount intercooler with hood louvers I haven't been able to produce cooling issues. Egts are holding me back on the big hills at this point, water to air setup could be in the works for the future.
Hopefully something of use in this big ol rant.
