I think someone in the know of these engines here on OB's should sit down and write a nice read on why these engines, even @ 420 & 444 CI repectively, are not capable of huge amounts of power. By huge I'm talkin' 450+ hp, and 700+ torque. These are great reliable engines, and will go as many miles as any Diesel engine ever marketed in a pickup truck. They're just not huge power generators. This is primarily due to the indirect-injection concept that these engines were engineered with, and a host of other details that have been layed out time and time again here. There's a limit on how high one can go with them. Definitely not ever gonna scare or discourage anyone from their interest in one of these trucks, just trying to be up front about it. We could always use a fresh mind, energy, and bank account to stir the perverbial pot every now and then and try some new ideas. Ultimately most of us would love to be proven WRONG on our statements (where else can you find that on a forum).
I'm tired at the moment, but here's some common issues that limit the safe power limit:
6.9L - 420 CI:
-7/16" head bolts, easily stretched with anything over say 12 psi of boost. Result is a blown head gasket. Surf craigslist and tell me how many 6.9l trucks that you find with a blown head gasket, at times it's a fairly substantial number. Head studs cures that sufficiently.
-Early 6.9l blocks were known to crack the block near the block heater (not really power related, but still)
7.3L - 444.6 CI
-Thin cylinder walls. Read up on cavitation, this can be a problem, especially on a rebuilt motor where the cylinders were bored over stock. One nice thing about a 6.9l is that the cylinder walls are ~ 1/4" thick.
-7.3L's do have 1/2" head bolts, which are a great improvement, but also means that 6.9l heads won't interchange.
There's more, but I'm tired at the moment.
In the name of efficiency, a blower on a 4-stroke diesel won't cut it. But in the name of cool, definitely. A lot of folks I meet out there hear the word blower and automatically think it's cool. And sometimes that's all a person wants is for their stuff to generate conversation. There's nothing wrong with that at all, it's really about how it's presented. I sense this Detroit blower is more cool than efficient, and there's nothing wrong with that, not one bit. You only live once, why not do something no one else has done, Right? Im the same way about some things.
We're always interested in people willing to sink a bit of money into these engines, and try new ideas. Most of the fore-seen criticism is actually people, out of the goodness of their heart, trying to help steer you in the right/most desirable direction, so that your hard-earned coin turns into money well spent. 13,000+ posts on FTE tells me your serious about what you do. As of late here, there's been a number of new folks show up with a 'them vs the world' attitude trying to tell us we're a bunch of square-headed, set in our way folks that don't know as much as we think we do. So if some established folks come off a bit edgy in the beginning, definitely cut 'em some slack, cause it's been getting pretty deep at times here of late. There's a world of information waiting at your finger tips if you get to know the search function, and all it's quirks. Most of the time when I've got a problem, an hour searching this site will answer my question. Just takes some figuring out how to work the search.
Anyway, welcome to the forum. May your stay be long and productive!
and i do plan on doin a lot of portin and polishin on the heads. are 7.3 turbo heads pretty much identical to the 6.9 heads? my mind is to just pop a set off a 7.3, tune em up, and just swap the heads on the reassembly. thoughts?
