1984 International Air Force Bus

[Famousinternetjesus]

The MEAN MUCCHINE

I purchased a sweet old 6.9l diesel, international airforce bus. Let me say that this thing is sweet. having replaced its cooked alternator i drove it 450 right off the bat over some pretty serious mountain passes coming up from sanfrancisco into oregon. it didnt go fast but it didnt want to stop either haha. ive begun my conversion process, seats out, floor in bed built and everything else is sort of built just enough to use. Im already living in it and loving it. the next step for me is to turbo charge this thing. If anyone has any input or experience with adding a turbo charger setup to one of these pre powerstroke idi diesels I would appreciate all the help i can get.

[ii_amnt]

Check out Oilburners.net. There is a lot of good info on there about the Ford IDI diesels. Do enough reading on there and you may decide not to go with a turbo.

Any plans on tearing into the bus? Pictures are always great, too.

[Famousinternetjesus]

really, hmm. all my research suggests ill gain about 70-80hp and a 20-30% gain in fuel economy on flat ground with the banks sidewinder setup tuned right at relatively low psi. Ill upload pictures tomorrow when i get a chance to put them on my computer. The guy i bought the bus from had pulled the seats out already and glued a hardwood floor down. I would have liked to put insulation in for warmth and noise purposes, but he sort of installed the floor in a way that is not easy to undo without totally emptying the bus.

[crazycal]

All my research shows you'll be replacing head gaskets if you don't use head studs. I doubt the 80hp number.

[Famousinternetjesus]

Everything I've read has been talking about adding the turbo these engines in a f250, or f350. But I can't seem to find any information from anyone that has actually done it much less on a bus, which is very frustrating. I can comfortably cruise the bus at 60-65 as it is, but when I hit a hill of any length or grade I have to downshift to 3rd to maintain 45 which is not super cool on the interstate. In the end id like to get a faster ratio differential and a turbo to provide the needed extra little push, plus the engine just feels like it's not working as hard as it wants to. I bought this for cross country travel/ full time living.

[Famousinternetjesus]

I'm hoping to find someone else that has this era of s1700 Air Force bus that has specific knowledge or at least someone that has has this engine and has made adjustments to get more power/fuel economy out her

[Famousinternetjesus]

So I either have an allison 545 or 643???? is there any good replacement for these, or if not, is there an overdrived unit? gear vendor? auxilary trans? is the solution a two speed rear end? id like to be able to cruise at 75 even 80 on flat desert roads like the 140 or I80 in the nebraska flats etc. and right now it seems like 70 is my top speed. any help would be appreciated, i cant seem to figure out how to add pictures here i dont have any online and the only option seems to be adding links...

[EastCoastCB]

Seriously... 70 isn't fast enough?
I'm lucky to get 65 downhill.

[opus]

You mean 80 as in 77, 78, 79, 80?? You've got the wrong bus for that no matter what you do to it.

My bus probably would do 80 but thats way too fast for something that weight and not built to go fast. Just my opinion though....

You'll have a 545.

[M1031A1]

Originally Posted by Famousinternetjesus

right now it seems like 70 is my top speed.

Feel blessed 70 is your top speed. Mine is 50! I'm going to change the gears, but I know I'll lose torque going up hill. I'm aiming for 64/65 mph @ 2300 rpm in my bus and NOT overextending the bus's braking abilities. ANYONE can go fast, but stopping is MORE important!!!!!

[nat_ster]

Every time I read "Gear Vendors" I just shake my head.

That stuff was never made big enough for a bus, and was a joke to begin with.
Nothing more than a band aid on a problem for a massive cost.

Hell them boxes cost more than most of us paid for our buses.

Bottom line, you need big engine, MD3060 trans, and 4:10 or higher gearing to make big speed.

Best advice, stay off the interstates with a vehicle that was never made to travel on them. Take the side highways, that's the kind of roads school buses where made to drive on.

Nat

[Scooternj]

Originally Posted by nat_ster

Best advice, stay off the interstates with a vehicle that was never made to travel on them. Take the side highways, that's the kind of roads school buses where made to drive on.

Plus that's where the most interesting rides are anyway. A friend of mine and her spouse drove from SoCal to Chicago on Old Rt 66 in a convertible Corvette, and they had a blast. Whenever I have to go down to Wilmington VAMC or into the Baltimore area, I take US40 for a good portion of the ride.

[Tango]

I prefer the "blue highways" and county roads for interest, but sometimes you gotta' get on the Interstates even if just to get to the next "back road". If you can make 60-65 you should be OK on most roads including Interstates as long as you stay to the right. Less than that is a problem, but just about any bus can make those numbers if geared and powered properly. That is one (more) reason why doing your homework before buying is so critical. One bus might make 70 all day long while the unit sitting next to it can't top 50. The power & gear packages can vary greatly and they will also greatly impact the build cost if you ever plan on actually driving it anywhere.

[Booyah45828]

I have the same bus you have.

70 is the top speed, turbo or not. You want faster? I'd recommend against it. I looked at an OD trans strictly to drop cruise rpm but I guess you could use it to go faster.

Someone mentioned brakes, Great Point! The brakes on mine(I'm sure yours are the same/similar) are half the size of those on a modern bus. They're adequate for it, but could easily turn hazardous if something happened. So don't hot rod at all, and leave plenty of space.

I've looked at turbo kits. They all look nice until the 2000+ price tag. Then you have to add the necessary hardware(head studs, Oil temp/trans temp/egt gauges). For that additional cost, you could have bought a 20 year newer bus and have the turbo/intercooler/additional power installed by the factory.

I did turn the fuel up on mine, and played around with the timing. I'd suggest reading all you can on the oilburners site. Mine is turned up 1 flat from stock with the timing advanced 2 degrees and that's where I'm happiest with it. You can see a slight amount of smoke come from the pipe but it's nothing significant. It's an improvement over stock but it didn't turn my bus into a Ferrari by any means.

Any other questions, just ask.

[crazycal]

Originally Posted by Famousinternetjesus

Everything I've read has been talking about adding the turbo these engines in a f250, or f350. But I can't seem to find any information from anyone that has actually done it much less on a bus, which is very frustrating. I can comfortably cruise the bus at 60-65 as it is, but when I hit a hill of any length or grade I have to downshift to 3rd to maintain 45 which is not super cool on the interstate. In the end id like to get a faster ratio differential and a turbo to provide the needed extra little push, plus the engine just feels like it's not working as hard as it wants to. I bought this for cross country travel/ full time living.

This is better than some.

Originally Posted by Famousinternetjesus

I'm hoping to find someone else that has this era of s1700 Air Force bus that has specific knowledge or at least someone that has has this engine and has made adjustments to get more power/fuel economy out her

Might as well end your search now.

Originally Posted by Famousinternetjesus

So I either have an allison 545 or 643???? is there any good replacement for these, or if not, is there an overdrived unit? gear vendor? auxilary trans? is the solution a two speed rear end? id like to be able to cruise at 75 even 80 on flat desert roads like the 140 or I80 in the nebraska flats etc. and right now it seems like 70 is my top speed. any help would be appreciated, i cant seem to figure out how to add pictures here i dont have any online and the only option seems to be adding links...

Here we go again. In case you hadn't noticed, you bought a school bus, not a dragster.

[Famousinternetjesus]

I appreciate the answer booyah, that's my main interest for the majority of the time I'll be driving (lower rpms). But that would also mean tht when I'm alone on a desert road I can push t a little faster. Crazy cal, I'm nt trying to race it, i ap

[Famousinternetjesus]

I appreciate your concern for safety etc, however, I have no reason to believe that with proper gearing I couldnt cruise at 80. I've got six new tires, The engine runs like a top and my alignment/steering are impeccable. If I could drop my rpms by 500 or so maybe a little more I could hit 75-80. I looking f

[Famousinternetjesus]

For mechanical advice on this however not people telling me to take back roads

[Famousinternetjesus]

I thought I'd mention it's not a full length, it's an eight window. Slightly longer than a short bus. In case people thought this 6.9 was on a full 40 footer. I know that my desires are unusual, but if I can do it it will be the coolest bus ever

[Famousinternetjesus]

Will the MD3060 mate up with the 6.9