"There is no excuse for a naturally aspirated diesel."
170 hp flywheel to 255 hp flywheel. 315 lbs-ft torque to 550 lbs-ft (6.9L stock specs shown, 7.3 a little higher). What's not to like? In my case, I saw an immediate 1-2 mpg increase, more when towing or hauling (stock mpg towing vs with the turbo).
If you used moderate fuel settings, yes, it could run cooler. I didn't do this on my 6.9 but I gradually built up a GM 6.2 for a story. I started with the usual exhaust and intake mods without a turbo but started with an EGT gauge. I was gobsmacked at how high the EGT a stock engine could get climbing a mountain pass. With a free flow exhaust and intake mods, it went down considerably and power went up a bit. After installing the turbo, with the pump set at the economy or "emissions" setting, EGT dropped a LOT. When I turned the pump up to the power setting, EGT came up but only when I was really wailing on it did it ever go as high as the stock engine did when being wailed on. Power output was about doubled. My 6.2 Blazer made about 94 hp at the rear wheels the way I got it, NA stock with 100K miles, 105 after a new pump & injectors, 134 with the exhaust and intake mods (a Banks Stinger kit) and 175 with a turbo. All these numbers were taken at a dyno facility at Denver, which is 5200 feet. Sea level numbers are a little higher in all cases. (you can still see this buildup from the '90s on the Four Wheel Magazine site: <www.fourwheeler.com/projectbuild/chevrolet_blazer_diesel_banks_sidewinder_turbo_kit/index.html>
Still, it 's a big chunk of change to add a turbo. It only pays if you need it. A lightly used truck at sea level has less need than a high altitude truck or one that works hard. If you were going to die in this truck (from old age, I mean ( : < ), then you could justify the cost but if this old IDI is just a step on the pickup ladder for you, then don't bother. Make sure your pump and injectors are 100 percent. Maybe some exhaust mods, a free flow, cool air intake and run her.
"Want" is a different issue. I don't think anyone wouldn't want a turbocharged 6.9 or 7.3.
Seriously though, if your going any faster than 15 mph, you will appreciate a turbo. A turbo can actually help to lower your egt's also if you tow, haul or drive in mountainous areas. Na engines get hot real fast when you turn up the fuel.
