Noticed the earlier replies came from folks driving Dodges... and I'm not totally convinced this site is free of trolls... so I will give you the perspective of a fellow who owns and runs a '91 Ford diesel and has upped its power by adding a turbo, new injectors, and injector pump refurb.
My standard load is a 10,000 pound horse trailer, right up against what Ford rated my truck's GCWR at back in '91. Before moving to California for graduate school, I pulled from Macon to past Tampa and back at 75-80 on all but the longer/steeper hills. Lots of runs between GA-FL to horse races with no trouble or lack of power. Acceleration is adequate with the turbo... good enough to merge safely and much better than before the turbo went on.
Before deciding to add the turbo, I priced a Cummins swap for my truck at $12,000 after I made the required air conditioning changeover and other changes that were needed for the trans to mate with the Cummins engine. I decided it just isn't worth the sawing and other mods you'd have to do, and the price was outrageous. If I really wanted a Cummins, which I don't, I could have bought the whole truck, used, for not much more than $12,000.
The 7.3 is a good engine and you can turbo, exhaust, and add a transmission performance module for $3000 if you do the work yourself.
Check out
www.ford-cummins.com for swap details... pricey and not necessarily better than a turbo'd 7.3 with appropriate supporting mods in my experience.
A couple of us are working on 400+hp, 850+ torque 7.3L IDI rebuilds for our trucks... we'll sort out the difficulties sooner or later and hopefully that'll provide a good path for others wishing to get performance out of their trucks. Those numbers are downrated from what is possible... need the engine to last.
There are folks with considerable knowledge on BOMBING the IDI engines. Ken at Diesel Performance Specialists and a couple of us on thedieselstop.com.
Elsewhere in this thread I read someone's post about EGTs being high with turbos on a 7.3 I have run my EGTs to about 1200 on longer hills before backing out of the truck to keep things cool while pulling my horses, 10,000+ pounds. BUT EGTs running hot have HARDLY been a troublesome issue. Slowing down 2-5 mph up that hill never has failed to cool things off... and I won't hit 1200 on any but the longer hills.
Performancewise, I pulled 6500 pounds of car, trailer, and gear from Macon, GA to Monterey, CA in the heat of last SUMMER and didn't have any EGT problems... but did have to slow down to keep the truck cool near Flagstaff, AZ and in some of the CA mountains. Not for lack of power, but for cooling.
No big deal. Semis have to slow down to keep temps cool, too. I was running with the semis through NM/AZ at 85-95mph, no sweat. Caught unloaded 4-bangers up long hills in CA. Had the attention of one semi driver who was wondering aloud how an IDI just passed him on the CB.
Bottom line... I'd suggest your friend consider putting a Banks, ATS, or Hypermax turbo on his truck. He should do a compression check on the engine first, then a Blackstone oil analysis, before spending the money on the turbo.
I turbo'd with 190,000 miles and have never looked back. Latest Blackstone engine oil analysis came up clean despite more than 4,000 towing miles and 5 months on the oil I sent for the sample.
Not trying to be offensive, but from the replies I saw here it looks like a couple fellows who replied may not have experience working with hopped up IDIs. Just trying to give you some knowledge based on my own experience with my truck since adding the turbo and other mods.
If I were you I'd go to thedieselstop.com and check the IDI forums out there. LOTS of honest information there that this site just doesn't have yet because it is brand new and may not have the experienced heads tuned in yet. Posts date back several years... so you can get lots of good, honest information based on folks' experience--not their suppositions/assumptions.
Mike