Which One Would You Pick for a Gasser Swap; 6.9, 7.3, or 7.3 PS?

[VandalS]

I’m running the numbers on different options for a diesel swap to replace the old 460 in my OBS. I’ve got sources for all three. The IDI engines do not have a turbo, but are only about 120-150k miles on them. The 7.3PS has 400k on it. Price wise they are all close.

I see the IDI as cheaper to own initially and easier to swap in. I see the PSD as the best option for big power, with a rebuild. PSD will take a little more to make it work in the OBS.

I’m not planning to tow much. Just want a diesel again. I’ll probably turbo the IDI if I get them, for the fuel economy. [emoji6]

 

[riphip]

7.3 IDI & stud it, port the water jackets in the block & heads to fit the 6.9 gaskets, use 6.9 Felpro gaskets, while the heads are off//port them and upgrade the valves and springs, find a set of turbo valve covers.
For the fuel economy.

 

[VandalS]

7.3 IDI & stud it, port the water jackets in the block & heads to fit the 6.9 gaskets, use 6.9 Felpro gaskets, while the heads are off//port them and upgrade the valves and springs, find a set of turbo valve covers.
For the fuel economy.

What do the 6.9 gaskets do to help?

 

[IDIoit]

idi or DT360

 

[Philip1]

What do the 6.9 gaskets do to help?

The 6.9 head gaskets have extra coolant passages that allows better cooling of the engine (so long as you also knock out the corresponding plugs in the block and heads) this helps with the overheating problems some people get with the 7.3 idi.

 

[no mufflers]

CuMmInS SwApIt BrO. lol

all jokes aside, id say it depends in how much power you want and what you tow, if much. the PSD can get expensive but has potential for much more power.

 

[VandalS]

Which one gives better mileage for power?

Price wise the PSD maybe cheaper for me because all I have to do is rent a trailer to haul it home. But long term the PSD will need a rebuild and the IDI are probably good for several years.

 

[79jasper]

the IDI are probably good for several years.

Ever heard of cavitation?

Sent from my SM-G988U using Tapatalk

 

[u2slow]

Inline mechanical turbodiesel.

Both DT360 or 6BT fit the bill of reasonable size... but the Cummins is easier.

 

[lotzagoodstuff]

Swapping a PSD is a lot more work due to the electronics. After you spend the extra effort to get it into your OBS, PSDs can definitely make a more power but they also cost a lot more to make that power. Go price a set of upgrades PSD injectors and you’ll start to understand. Nearly everything PSD vs IDI costs more.

Just my .02. Good luck whichever way you choose.

 

[VandalS]

Ever heard of cavitation?

Yeah, that's the risk with any IDI donor. The folks selling the 7.3 claim that they managed the coolant levels to prevent cavitation. No proof to show that they really did so...

Inline mechanical turbodiesel. Both DT360 or 6BT fit the bill of reasonable size... but the Cummins is easier.

I've been reading up on the DT360. Sounds like a great swap, but out of scope for what I'm doing. However, if there were a reasonably priced donor in the area I'd consider it. But so far I'm seeing too much money being asked for them.

Swapping a PSD is a lot more work due to the electronics. After you spend the extra effort to get it into your OBS, PSDs can definitely make a more power but they also cost a lot more to make that power. Go price a set of upgrades PSD injectors and you’ll start to understand. Nearly everything PSD vs IDI costs more.

Just my .02. Good luck whichever way you choose.

I appreciate the input. Either one is a risk. I'm looking for things to consider and weigh.

Based on stock numbers with Ford diesels and gassers anything is an improvement over the 460 for mileage, but maybe not for power.

Engine HP Tq
86 6.9 170 318 (10-20 mpg)
91 7.3 185 338 (10-20 mpg)
91 7.3 T 190 388 (10-20 mpg)
99 7.3 235 500 (11-15 mpg)

96 460 245 400 (9 mpg)
07 5.4 310 365 (14-18 mpg)
10 5.0 395 400 (unknown)

 

[VandalS]

Based on power, economy, and a full donor truck popping up for 1k, I went with the OBS PowerStroke. It was too good to pass up considering folks in my region were asking more than that for a long block IDI. Now to strip it down to what I need.