So my brother is wanting to change up his recreational tow vehicle. He tows about a 5000 pound travel trailer and usually has the pick-up, a 4 door 1977 F-350 loaded heavy with dirt bikes, fire wood, bbq, gas etc. The 460 gasser in the pickup is real healthy and he is used going up any hill as fast as he wants. But he is getting tired of the loud truck, the high rpm's and 5 mpg. So he is thinking of going the IDI route with a turbo and some kind of performance build. Question is: Just how much good clean power can you get from an IDI. And when I say good clean power, I mean minimal turbo lag, average IDI smoke and something like 280-300 HP at the rear wheels? Is this possible? We can pick up a 4 door 7.3 4x4 for about $600.00 for a starting point. He is thinking of putting $10-15k into the build. I'm just not sure that an IDI is the right choice for this application. Ideas?

Thanks,

 

For towing, can't go wrong. You're only towing 5k and getting under 10mpg. The problem seems that he likes going fast. 6.9idi gets about 205hp and 325 torque with turbo.

I personally don't mind going 40-55mph while towing. It's just the right/smart thing to do. Seen a few videos on YouTube of guys going too fast. Tire pops. Rv goes over. High winds, rv goes over etc.. I'll have family back there. No way would I go over 50/55

You should be able to easily get 225hp, 340 torque with a 7.3 turbo.

I'm on the same boat as your friend when it comes to spending whatever (over time). If this is the case, go with the idi. 10-15k will get you far.

Tell your friend to put a gear splitter. Not really necessary for 5k lbs, but his budget says why not. I used to own one on a 6.9. Fun times.

 

i say yes .. the idi will meet your needs ..

with a manual 4 speed i get / 15 city / 25 country / 20 highway / mpg

hauling ? yep it'll pull my boat like it's not even back there ..

loaded with wet coal ~ 6k lbs? the steering is squat but it's fast as ever ~ 70 - 75 and hauls it with ease ..

i don't know much about turbos .. but there are many available for whatever you need to do .. depending on what your driving preference / needs require ..

normally 200 hp is standard with these motors .. near 300 is possible .. certainly .. but not unless you're willing to spend some $$ in parts to get there ..

you can probably build a boss truck for half your budget .. if you do the build yourself .. and spend the other 7k on monster truck tires !!

get a manual transmission if possible .. and yes with this budget get a brownie under/over

 

My build might not be the fastest, so far being in the 227-250 wheel HP range, but I've towed quite a bit with it. Last known load was about 5K of trailer, and I had no real issue keeping at 75 on the flats and smallish hills... in double-overdrive(GVOD + ZF-5) Hit a couple of steeper ones and had to drop down to 65 and 5th gear, but that's all.

I've hauled 18K before(6 tons of hay + 4K of trailer), and that was heavy. I wasn't going to be going 75 with that; I managed 55 most of the way, but that was less about power and more about load stability going around curves. I think I still averaged like 8-10 MPG with that load.

 

I pull my 15k 5th wheel just fine. It's little slower but does good. Last time towing 100 bales of hay to CA i averaged 14 mpg

 

This gives me a good idea of what to expect out of my truck. Maybe not as good since I have a 6.9. But 55 mom is the most i would go anyway. You have the set up that I'm aiming for. GVOD is that gear splitter right?

 

Well can tell you, my brother is not interested in cresting large hills at 55 mph. He prefers something like 65 mph minimum.

 

Yup; for me, with a zf-5, 4.10 gearing and stock tires(31.7"), in top gear I'm running 1600 RPM @ 60 mph, = 2K RPM @ 75.
The GVOD will give me a 2nd-over(though the stock computer will lock it out until like 25 MPH), 3rd over which is slightly lower than 4th, and 5th over. 4th over is exactly the same as 5th.
It's a fairly stout unit and works nicely as long as you know it's limitations:
1. Change it's oil every 30k.
2. It will not do overdrive in reverse. You will get grinding noises if you do so*
3. Never engage it in 4x4... If it can engage, front and rear gearing will be at different ratios. *
3. It's rated for a good amount of torque, but with the gear multiplication effect, using it in too low a gear can damage the conical clutch inside. *
4. It is hydraulically actuated internally(using an external solenoid), and needs to build up pressure before engaging(i.e. going a few MPH)*

All the *'s above are moot in a normal GVOD installation - there is a computer box which prevents you from doing any of those. Of course, I did something wrong a few years back, shorted it, and bypassed the whole thing with a switch.


Well, he either needs to spend a lot of money on a newer truck(which may or may not do this), or put some decent money into an IDI. The one thing I would be concerned about with someone like that is that while you can make an engine have plenty of power, you have to be careful with it or you might overheat it.
I always drive(loaded) with my eye on EGTs, and water temps. Pulling some long(multi-mile), hot grades I've actually had to back off because my water temps were going over 220F, my safety range.
And, well, I'm not sure a new truck would do too much better -- radiator size is radiator size -- though they might well have an auto-fueling-limiter in there when it hits a certain temp.

Smaller hills I've never had any trouble with. It's things like I-90 from Seattle to Snoqualmie(Climbing like 2500 ft in 19 miles) with a heavy trailer. That can get interesting.

 

That's kind of whats going on here...........a fact finding mission. He likes the idea of an IDI because they are very simple, essentially a tractor engine as far as complexity goes. He's not real impressed with powerstrokes and what ever this rig turns out to be, it will be a Ford. Reason it has to be a Ford is he wants to take his beautifully restored 1976 4 door body and bed and install it on the running gear he selects. This definitely has to be a well thought out plan before embarking on this project. He is very used to having lots of pedal left as he goes up hills with his 460 gasser. I have a '93 IDI with a Banks and I think he wants a little more than that. I was actually thinking I would hook up my rig with a similar load and go climb a big hill near by and see what it does. I don't use my IDI for towing my trailer, usually it's a dump run truck and firewood hauling. I use a 2013 Duramax for hauling my trailer and it will go up any hill, any outside temp with any load at 70 mph or more if I want and the temp never moves from 210 degrees. I think that's what he is looking for in an IDI. Not sure it's possible. I am thinking if an IDI is selected, that a cam and intercooler of some kind will be necessary. Turbo will be a challenge as he hates turbo lag and my understanding is when you add a cam and intercooler you will need to go to a larger turbo to get he full effect of them and going to a larger turbo increase lag................Oh the joys!

 

Next year. Gear vendors! I think the part people don't seem to keep in mind is that these things are easy to fix. ****, I'm gonna by a tool box and put a bunch of belts, extra battery, 5gallons of diesel, back up fuel lines. All cheap stuff when compared to newer trucks. I can charge these things on the read if needed. I wouldnt be able to fix a newer truck, let alone have the $ out of nowhere. Belts, $1.75 at rockauto

I've said it before and I'll say it again, while towing, don't go past 55. Go to YouTube and see for yourself what can happen. Especially with family in the trailer. No way.