I just bought a 91 f250 7.3 with a 4" exhaust (not dual). It doesnt go fast with a load on... But it loves to pull. I bought this because i was in a pinch and couldnt afford a 1st gen Cummins (that ran). However, i am really happy with the 7.3 IDI.

 

My buddy has one of the IDIs with 520,000 miles. He's never done anything to it except replace one plug about a month ago. I drive an 87 IDI at work, it's in a Canadian F250 and runs like a top after 150,000 miles burning unprocessed fryer grease.

I have to be honest though, after reading about this motor I'd rather keep my gasser than get it. On the early NA ones, stock HP/torque is not impressive compared to a gas engine of equivalent displacement or even some smaller ones. The only thing I like about it is that it's an oilburner. I'd rather have a 390 gas or PSD. Better yet, 2011 6.0

 

I bought a 94 brand new and still have it, cant say enough good about it. May not be the most powerfull, but excellent combination for reliability. Look at the picture in my gallery of it towing a military 6x6. ( I wanted to add the pic to this post, but couldnt figure out how to do it,,, or the cheap membership wont allow it)

 

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No offense but you got your numbers confused:

6.9 late: 170HP 338TQ
7.3 early: 180HP ?
7.3 late: 185HP 360TQ
7.3 turbo: 190HP 388TQ

The number for the early 7.3 was from a valve cover sticker, I don't have any of the manufactures BS on that one.
I do not remember the early (low compression) 6.9 specs, nor do I have the pamphlets on it.
The "turbo" number listed here is for Fords factory turbo with the smashed downpipe.

One other issue is the differences in pump calibration, the 6.9 varied from 155-175

 

here is something that never comes into consideration: Elevation. I have seen those non turbo diesels run like a scalded dog in the flat lands and have power enough to set you back in the seat until you get up to about 5000 ft above sea level. Then their true colors come to life. If you are in the flat lands and no mountains give it a shot, if you are up in the mountains don't bother. We pulled a big boat from seattle, Wa with a 1988 7.3 idi and it did fine till you got up to the top half of the passes and they just run out of air, you catch second gear and hope for the best, but you pull the hills at 15 mph. We hauled a backhoe a lot of miles with that truck in our CO mountains, and weather the trailer was empty or had a backhoe on it, we went 15 mph up the hills.

Remember some of these hils were 12,000 ft mountain passes at the summit, and those trucks can't get enough air to make power, they make black smoke instead. It will do what you want, just remember that how long it takes you is the main factor. You might have to leave real early in the morning. In the flat lands those do wonderful, in the mountains they are pathetic, compared to a 460 or a 454 or even a strong 400 or 351. The main factor is air, that is what the turbo adds and that is what those NA diesels lack.

How stout? Plenty stout just remember that the less air, the slower you go. We are at 6000' and even here in the valley those NA diesels are nearly helpless. Take them to OK or KS or CA or MO and they are almost impressive. The problem is air, not power. The old non-turbo farm equipment is nearly the same it can't get out of its own way on a hot day. Be reasonable with expectations and you will be happy. Like f250 said, if you keep it rapped high, it helps, but 45 up the passes is all you can do around here with a souped up PSD or cummins. Good luck.

 

He is correct. The turbo turns into a necessity in the mountains.

 

Boy ain't that the truth! I've been all over the country in my N/A 6.9 Motorhome, it's fine in the flat lands, but once you hit the higher up elevations, she looses all power, and just smokes thick dark black smoke (lack of air, to much fuel, stock setting on the pump).

I have to keep it around half throttle - to 3/4 just to keep it from smoking to control my EGT's. I keep it right at the point where I see a very light little haze of clear black smoke, that tells me it's making full power without wasting fuel (black smoke).


In 2010, on my biggest trip ever, 11,000k miles done in 8 weeks, we went through the Montana Rockies..... climbing hills in 1st gear, doing 25mph, engine ridding the governor, and a LONG line of cars behind me (no passing lane)


Never quit, never complained, never gave it a break, real temp gauge never went over 210* and she was sounding awesome

 

I had a 1985 F250 4x4 supercab longbed with the 6.9/C6. It was far from a powerhouse but I liked it. Although, I seemed to have one of the "weak" ones. Case in point:

I went to a 4x4 play day my 4wd club was sponsoring. Towards the end of the day a buddy and me (with some coaxing from surrounding people) decided to play tug o' war. He had the "same" truck, just 10 years newer...'95 F250 4x4 supercab longbed, 7.3 PSD, E4OD...even the same basic colors...blue/white. I had better tires, he had more power. So we hooked up...first time...nobody moved.

Then somebody realized there was a slight grade on the ground we were pulling on (I was on the high side). We flipped them around and I pulled him. Then we flipped them around again and I started wrong so he pulled me. We did this about 4 times...but that's not what I'm getting at here...

On the last pull, somebody started waving their arms and freaking out trying to stop us...his transmission was puking fluid...bad. I looked at it (being a mechanic) and determined the front pump seal had blown. It pumped fluid out as fast as you poured it in. So we got a trailer and I proceeded to tow him home (normally a 4 hour trip). My truck overheated over any mild pass...dropped to 15-20 MPH over any kinda real grade (through Oregon). She did get us there though...in about 12 hours.

I honestly think something was wrong with that truck though...oh, and if anyone was wondering...3.54 gears...yea, it needed more gearing...but all-in-all, the 6.9/7.3 are good, stout engines...

 

The old 7.3s are very stout. Out here in MO they are all over the place, and hard to find for sale. I managed to pick one up last year hidden at a car lot in the back, and use it for work (I do industrial metal fabrication with a lot of traveling) and there isn't a load I can't haul at 70mph on the highway. Of course a lot of my work is here in the midwest, the most I may bog down to is 65mph in the Ozarks.