Hey all, long time Diesel lover, newbie to maybe owning one. I have a 79 F-250 I wanna drop a diesel into. I have a line on a 99 powerstroke 7.3, but I stumbled upon an 85 6.9 IDI (?) that for some reason I can't get off my mind. I have never heard of a 6.9, and have no clue what the IDI stands for. Would this be an ok engine to transplant into my 79? Could I turbo it? Should I run far and fast?

 

Hi, personally I would get an IDI over any other engine, pretty much.. If your swapping in anything that you want.

It's an International Harvester, Indirect Injection engine, very strong motor. Durable, dependable, inexpensive to repair (comparatively). No computer, no emissions, no BS.

Not as much HP stock as others, though very usable. Fun to drive engine with great sound even with no turbo.

Yes with head studs can make as much power as a Powerstroke, and more if you like to build it. But 200 dollar studs will take a mild turbo.

Also early models 6.9 likely have 4sp transmission, so probably want a OD transmission or OD unit and this is an expense unless you have something.

I like the IDI, with T19 4sp and big tires, good all around up to 75 mph - unfortunately many people do 90 on the highway and my truck just ain't no 100 mile per hour Nascar. But the rear view mirror tilts and they can f off.

Great engine, I would get it, look for a ZF5 trans and big tires.

 

By posting in this forum, everyone is pretty biased for the IDI. It stands for Indirect Injection, and there is more about that here: https://en.wikipedia.org/wiki/Indirect_injection

The PSD will give you more power, but it'll cost more to maintain. The IDI is a helluva lot easier and cheaper to work on, but it will have less power until you put a turbo on it. The IDI's are really reliable too.

As for installing it an older Ford pickup, anything is possible. Maybe some of the truck guys can post a link to someone doing a transplant. (side note, does your donor '85 6.9 IDI come with the IP? also, do you know which tranny it had?)

 

i have both. i like the power of the powerstroke, and the simplicity of the IDI.
all you need to make that 6.9 run is a small 12 volt battery hooked to the fuel shut off switch in the injector pump. can't say that about the powerstroke. you need pretty much all new electrical system and computer installed in the old truck to make it run.
with a turbo to boost power a bit and an overdrive trans installed in the 79, you will have a truck that will run forever and also do damn near anything you want.

 

Be aware that the 6.9l/7.3l IDIs require a special tool to set Injection Pump timing. If you plan to use the 6.9l as a transplant you can easily set static IP timing by lining-up the timing marks, but to "dial-it-in" you need a tool covered in this thread:

https://www.ford-trucks.com/forums/1...-now-what.html

 

I think this timing meter also works for our IDI`s, and is brand new.

https://www.ebay.com/itm/DTI-Tech-Ti...EAAOSwal5YE5ww

Not a bad price as these thing go.


Charlie

 

6.9L installed 1983/87, replaced by the 7.3L in 1988.

 

By 85 the 6.9l IDIs were already in the 2nd casting, weren't they? I remember reading something about 6.9l blocks cracking around the block warmer but that was supposedly only in earlier years.

 

The power potential between a 6.9 and a PS can't be compared. With a few thousand dollars a 6.9 can be modded to stock PS power, and for just a few bucks the PS can be cranked up to power levels that will take serious mods on a 6.9. With a few thousand dollars the PS will make streetable power that is probably unattainable from a 6.9 even with a bottomless wallet.

A modded 6.9 has cool factor. The 6.9 is a little easier to swap in since there's less electrical to do.

 

While there is a grain of truth, very much of it is exaggerated.

I have a 7.3 in my 79 F350, fantastic swap. going from a "rv" cammed 400 with edelbrock performer intake and carb and headers, the 7.3 NA towed better and literally got double the mileage. That said, i also put a ZF5 in with the diesel. In a race empty, the 400 wouldve won, but towing it is literally no comparison.

Where the IDI gets its reputation for needing "thousands of bottomless wallets" to make power is they are normally aspirated from the factory. To get any real gains you need a turbo kit. They can be had used for 600-800 dollars usually, or new ones can be 2-3k. From there, its a simple matter of turning up the pump, and making basic air flow mods that you would to anything else. This will get you ~220whp, IE, the same power to the wheels, that a stock powerstroke makes at the crank. Comparable to a chipped 7.3 or stock 6.0. Yours being a 6.9 however, youre also going to want headstuds to push it. The studs are pretty affordable for the 6.9 as theyre only 7/16". Pretty easy to do, especially with the engine out. Dont have to remove injectors or anything like you would on a powerstroke. If you want more power than that, there are bigger pumps on the aftermarket, as well as retrofit turbos. I have an R&D110cc pump (wouldve went bigger, but finding a clutch that will hold it and tow...)and sxe 364 on my 7.3, i have plans to get it dyno'd this summer, but enough of them have been dyno'd to know it will be right around 300whp 650wtq, or roughly 400hp /850tq at the flywheel, right on par with a 6.7. Not exactly what i call several thousands, but its not a small investment. Pretty comprable to a set of injectors, new hpop, chip and turbo for a 7.3 psd to make the same power, and at that level, you "should" stud the psd as well. There are even bigger pumps, but with a 6.9 you would be getting into grey area of reliability with NA rods and the 7/16" headstuds if you go past 400whp.

 

Stock late model 7.3 Powerstrokes average a little over 200hp to the ground. Air filter, exhaust, and tune they average over 300. Early ones are weaker so they are much closer to an IDI with a turbo and mild tweaks.

A PS with nothing but a tune will drive similar to a big block gasser when empty, and much better when loaded heavy. My 7.3 Excursion with nothing but a tuner will outrun the gas version. Without a tune it won't win a drag race against the gasser, but will still out-tow it.