My next F700?

[teletech]

I dropped a heavy short box on the back of a 6.6L New-Holland F700 and at about 14,000Lbs it couldn't get out of it's own way. The AT Allison hurt me of course. Moving the fuel plate and turning up the star wheel meant I wasn't the absolutely-slowest rig on the road but still close. 6-7MPG. I then bought an F800 with a 7.8 MH and MT Allison, 18,000 lbs and it got the same mileage as the 700 and would out-climb it any day, still a pig though. more like 7-8MPG. So, I'm looking to re-mount the box from the 700 on something more useful. A couple cheap and local choices are:
1993 F700 with the 5.9. A bit more power stock than the 6.6 and lighter truck but with a fair bit of room to grow in terms of power. Should gross about 14K when I'm done. I'm thinking this might be the best MPG option for a truck about this size.
MPG?
1988 F700 with the CAT 3208. Not a sports car but enough power to move some stuff. Most of the time it would gross about 15K (same box, heavier motor) but I'd hope it would have the power to tow another 20K once in a while. Too much to hope for? What sort of mileage should I expect when I'm just running around at 15K?

Or, I could hold out for a 24V 5.9. Might not do the towing but lots more power that the 12v motor and hopefully better fuel economy.
Thoughts?

 

[79jasper]

It's a truck, mileage isn't really a factor. Lol
Skip the 5.9. Get a larger Detroit or a 8.3 cummins.

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[teletech]

It's a factor if you want to actually drive them.
The Detroit has a somewhat iffy reputation and is *really* long in the tooth at this point. I'd LOVE an 8.3 but that's a very rare fitment for the F6-800 trucks, at least it's rare for the prices I'm looking at.

It's a truck, mileage isn't really a factor. Lol
Skip the 5.9. Get a larger Detroit or a 8.3 cummins.

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[lotzagoodstuff]

Your going to have to spin that 5.9 to more RPMs to get the power out of it that you need, and at that point I think your fuel mileage will suffer. I have heard pretty good results from the motor home crowd on 5.9s with a Banks kit in terms of power and mileage on some of the 32-36 foot motorhomes.

I'm not sure what you think "bad mileage" is at 14K, but keep in mind that even a 6000-7000 F350 PSD with 4.10s isn't going to see much more than 14-16 MPG, and you are talking about something that's literally twice the weight. Heavy loads/towing and mileage do not go together. I have to agree with Jasper on this: displacement is probably the best solution for the weights you are talking.

Good luck

 

[79jasper]

It's a factor if you want to actually drive them.
The Detroit has a somewhat iffy reputation and is *really* long in the tooth at this point. I'd LOVE an 8.3 but that's a very rare fitment for the F6-800 trucks, at least it's rare for the prices I'm looking at.

You realize Detroit's are still being made? I'm not talking about one from the 60's.
What year range are you looking at? That'll help us give you more specific recommendations.
The cat c7 isn't bad, can be tuned for more power.
Trans is going to play a role as well. You want a allison or a manual?

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[Booyah45828]

The 6.6 and 7.8 are respectable engines. The reason the 6.6 was a **** was because of the AT allison. The torque converters are so loose in them that they're nearly out of the power band by the time it comes close to a 1:1 ratio.

Tuning the pump and modern turbos can really help the old ford-brazilian engines out. But those engines are pretty old by now and parts are getting rarer.

I'd go with the 93 w/ 6bt over the 88 w/ 3208. That's if the 6bt is backed by an mt allison or a manual, otherwise it won't be any better then the 6.6 you're replacing.

I'm not a fan of the cat 3208. Yes they did the job but they weren't the most reliable and there are better options available.

As far as mpg's go, 7-10 is about all you're going to get imo being that big and heavy. Those MD trucks have a lot more frontal area then a pickup, so any comparisons between the two is almost apples to oranges.

 

[u2slow]

93 or 94 is the last year of the 'Brazillian' engines and Cummins was the most common substitute where a mechanical inline 6 was spec'ed. The challenge is to find one with 6 or more speeds.

I don't like the Caterpillar offerings unless they're bigger 6's. (3306, 3406, etc)

 

[teletech]

Good feedback, thanks.
Sounds like not a ton of love for the CAT motor and the 5.9 might be marginal, so if I can't find an 8.3 Cummins then I'll hold out for a 24V 5.9 or keep with the 7.8 Ford/NH. I'll not be buying anything with an AT-series, I'm totally open to any other transmission and if I trip over a 10-speed Eaton so much the better.

Yes, they still make Detroits but since the trucks in question are from the mid 80s to early 90sI think that constrains the Detroit in question to the old 8.4.
Obviously I know I'm not going to get good mileage by pickup truck standards but the difference between getting 6MPG and even 8MPG is pretty vast when you start putting on some miles, I'd be thrilled to see double-digits even on the good days.

The 6.6 Brazilian I have has a P-Pump that is just too small to deliver enough fuel to really do the job. The 7.8 is enough motor.
They are getting long in the tooth it's true, but they are super cheap. For under a grand I can buy a complete motor with under 100K and set it on the shelf for spares.

Truck age: I like looks of the 6-th gen trucks, but would consider a seventh-gen and do a nose swap if I just can't take the looks.
So I think about 1984-2000 but really more like 1988-1994

Cheap. Did I mention cheap? Locally I can get a running-driving MDT F-series for $1500 if I don't care about the specs. A really well cared for/low mileage 5.9 or 7.8 with some interesting features might be more like $5K. The best price I've seen on an 8.3 truck is $12K. It's a really sweet truck but for something I don't use all that often that $7K buys a lot of diesel. If I knew the 8.3 would be much better suited to the work at-hand and would get the same or better mileage than a 7.8 truck (assuming both from 1993 or so) I'd consider it.

I terms of a better turbo for the 7.8, is there a recommended swap or do I need to reinvent the wheel?

Question about the CAT motor. I looked it up and saw 210HP as the base for a non-turbo motor but I just saw a motor sitting an a pallet yesterday with the small back-mount turbo that was plated as 210 HP. What would I expect to see out of an 3208 from 1988 either stock or light mods? It's massively heavy for 210 HP, but if it would make 300+HP with just a little tinkering it still might be worth considering at the price.

 

[lotzagoodstuff]

I'm no expert, but I was a little surprised to see the 3208 cat not get more favorable feedback. I have seen many rated at 375 HP in old motor homes, and I think Cat made a pile of these engines, so there's got to be a pile of them out there. I remember somebody who worked at the engine plant told me that at their peak they built 800-900 3208s per day. It's a wet sleeve design, so you can even rebuild one in frame, which might be some value to you as well.

A while back, it was quite common to see 3208 Cat engines in motorhomes, and now that those motorhomes are getting scrapped, I bet there's some nice pieces out there for very reasonable money.

Again, good luck to you. Sounds like a fun search/build/project.

 

[79jasper]

What I'm finding is the 3208 isn't great in a truck setting. They like to eat bearings when ran at higher rpms.
You can hop up a 5.9, but it's still small for the application, imo. We have a 98 F800 setup as a grabber truck. It has a 5.9 12v and allison. Empty isn't too bad, but any kind of load at all and it is lacking up hills.
If they would let me, I would swap in a 8.3 cummins. Or even a DT530.

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[teletech]

dup message, browser error and I don't know how to delete it.

 

[teletech]

I'm no expert, but I was a little surprised to see the 3208 cat not get more favorable feedback. I have seen many rated at 375 HP in old motor homes, and I think Cat made a pile of these engines, so there's got to be a pile of them out there. I remember somebody who worked at the engine plant told me that at their peak they built 800-900 3208s per day. It's a wet sleeve design, so you can even rebuild one in frame, which might be some value to you as well.

A while back, it was quite common to see 3208 Cat engines in motorhomes, and now that those motorhomes are getting scrapped, I bet there's some nice pieces out there for very reasonable money.

Again, good luck to you. Sounds like a fun search/build/project.

Thanks. 375HP would be pretty sweet.
I'm pretty sure the 3208 is sleeveless.

 

[teletech]

dup mssg

 

[Thewespaul]

I'm no expert, but I was a little surprised to see the 3208 cat not get more favorable feedback. I have seen many rated at 375 HP in old motor homes, and I think Cat made a pile of these engines, so there's got to be a pile of them out there. I remember somebody who worked at the engine plant told me that at their peak they built 800-900 3208s per day. It's a wet sleeve design, so you can even rebuild one in frame, which might be some value to you as well.

A while back, it was quite common to see 3208 Cat engines in motorhomes, and now that those motorhomes are getting scrapped, I bet there's some nice pieces out there for very reasonable money.

Again, good luck to you. Sounds like a fun search/build/project.

I don’t believe 3208s were wet sleeved but I may be wrong. Good engines still.

 

[teletech]

What I'm finding is the 3208 isn't great in a truck setting. They like to eat bearings when ran at higher rpms.
You can hop up a 5.9, but it's still small for the application, imo. We have a 98 F800 setup as a grabber truck. It has a 5.9 12v and allison. Empty isn't too bad, but any kind of load at all and it is lacking up hills.
If they would let me, I would swap in a 8.3 cummins. Or even a DT530.

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I did notice the bearings in the 3208 are tiny compared to modern motors.
I think I'll pass on the 5.9 12V and hold out for a 24V if I go the 5.9 route, it's not vastly more money.
If I were going to do a repower swap, I'd be shopping for a DT466 (of course).

 

[79jasper]

I wouldn't jump on a 24v over a 12v just because. They aren't making that much more power. Also, I believe the 24v will have the ve pump instead of the p-pump.(aka being electrical instead of mechanical)
It looks like 92+ is when the 5.9 and 8.3 became options.
Also, any reason you are only looking at the ford lineup?

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