While some of the Powerstroke engines
like the 6.0 liter and 6.4 liter have earned a reputation for being pretty
horrible, the earlier 7.3 liter Powerstroke has earned reputation as being
one of the most reliable diesel engines ever. It might be an underpowered
dinosaur by today's standards but the 7.3 is still a pretty interesting engine
so let's dive in and discuss everything you need to know about the 7.3 liter
Powerstroke. to stay ahead of GM and gain some ground on Dodge, Ford released the Powerstroke in 1994. While it wasn't anything incredibly special at the time
it was far better than anything GM had to offer and it was pretty comparable to
the 5.9 Cummins. Starting out with the basics it's a 7.3 liter or 444 cubic
inch v8 with direct injection, a beefy cast-iron block, cast-iron heads, an
overhead two valve per cylinder design, and it. featured a fixed geometry
turbocharger which we'll talk a little bit more in-depth about later in the
video. Internally, the 7.3 is incredibly simple
and it really doesn't feature anything special or unique. Bore measures at 4.11
inches with a stroke at 4.18 inches and depending on the year
either had a Garrett TP38 fixed geometry turbocharger or a Garrett GTP38. Power ranges anywhere from 210 horsepower up to 275 horsepower and 425. pound-feet up to 525 pound-feet. What's particularly interesting about the 7.3
Powerstroke is that it didn't really have any emission systems other than a
catalytic converter and as you might already know modern diesels are really
choked down with emission systems and they really really restrict them so the
fact that it didn't have any emission systems is a really big plus. Despite the
lack of emission systems other than a catalytic converter the 7.3 was somehow
more emissions friendly than Dodge's 5.9 Cummins at the time while also producing more horsepower and more torque upon initial release. With parts like forged
connecting rods and six bolts per head cylinder it was pretty obvious at the
7.3 was a really stout engine when Ford initially released it. The only thing
which was a concern when it first came out was the new HEUI system but that
since proved itself to be pretty reliable. Compared to diesel's of today
210 horsepower and 425 pound-feet is comically weak there's really no getting
around it. But at the time that it came out it was a solid number and it was
actually more power than anything GM or Dodge offered when
the 7.3 was initially released. One of the most important design features that
made the 7.3 as strong as it is are the six 12mm head bolts. Now
for reference you can look at the older 7.3 IDI engines which only had five head
bolts per cylinder or even worse so you can go forwards and look at the 6.0 liter Powerstroke which only had four head bolts per cylinder. As you can
probably imagine six head bolts per cylinder gives us 7.3 a lot of clamping
force and it's able to withstand a lot of boost pressure upwards of 40 psi
before the stock head gaskets become an issue. Now having six bolts per head
cylinder also means that you have even more clamping force when you go to
either aftermarket head bolts or aftermarket head studs. Speaking of
things which make the 7.3 pretty reliable we have to talk about the
connecting rods. For the most part the 1994.5 - 2000 models have forged connecting rods and the 2001 to 2003 are a mix between
powdered metal and forged connecting rods. Either way you go, both connecting
rods are pretty strong with the forged connecting rods holding up to around six
hundred wheel horsepower and the powdered metal connecting rods holding
up to around five hundred wheel horsepower. All the advancements on the
7.3 engine the direct injection system is arguably the most important.
The HEUI injectors came from caterpillar who leased the technology to Navistar to
use for the 7.3 Powerstroke as well as some other Navistar engines. The
hydraulically actuated electronically controlled unit injector also known as HEUI is a system which revolves around a high pressure oil pump sending
oil volume through oil rails integrated into the engines cylinder heads. This
allows oil to feed the top side of each injector the high-pressure oil pump is
designed to get oil into the rails within the heads once oil exits the high
pressure oil pump the injector pressure regulator pressurizes it as high as
3,000 psi. From there the pressurized oil acts on an intensifier piston
compressing the fuel below it and resulting in injecting pressure as high
as 21,000 psi inside the cylinder. Moving on to the turbochargers
we have three different turbochargers featured throughout the 7.3 Powerstrokes lifespan. First up is the non waste gated TP38 with a 1.15 AR
housing which was used on the earlier nom intercooled models. In 1999 an
air-to-air intercooler was added and it still used the TP38 turbocharger but it
came with a tighter 0.84 AR housing and a wastegate. After that, the GTP38 was used, whch had a larger exhaust housing and a much larger wastegate. Although each version
this turbocharger is slightly better they all used a 60 millimeter inducer
and a 70 millimeter exducer. although these simple fixed geometry
turbochargers can't really make as much low power and high end power as
something like a variable geometry turbocharger found on modern diesels, the fixed geometry design is super reliable and there's very few things that can
actually go wrong with a fixed geometry turbocharger, especially compared to a
variable geometry turbocharger which can have all sorts of issues in the long run.
Now of course compared to modern turbochargers the TP38 and GTP38 are
pretty inefficient and they really don't have all that much power potential but
if you just want something super reliable they're a pretty decent
turbocharger. Now speaking of things that make the 7.3 Powerstroke as reliable as
it is, we have to talk about the fact that it's underpowered. Let's be real,
it's kind of hard to break anything when you're making 210 horsepower out of a
7.3 liter engine. Now realistically torque is what breaks things and not
horsepower, but the point still stands the 7.3 Powerstroke is pretty
underpowered for such a large diesel engine. Now while that might make the
Ford trucks that it powers incredibly slow or not able to tow all that much it
makes them really really reliable in the long run. Now that being said the 7.3 is
still really reliable once you turn the power up either by adding more boost or
sticking on a different turbocharger or just cranking up the fuel or whatever
you're doing, the 7.3 is still going to be pretty reliable even when it's making
double the factory power output. Other things like the 6 head bolts per
cylinders, long lasting the injectors, super simple internal design, strong
bottom end components, and fixed geometry turbocharger just really make the 7.3
Powerstroke it is simplest and arguably the most reliable Powerstroke ever
built. Now it's also important to note that 7.3 Powerstroke was around at a
time when manual transmissions in diesel trucks were actually fairly common and
that's just another thing that made these Ford trucks so reliable, Automatic
transmissions might be nice and convenient but realistically they're not
going to be as reliable as a manual transmission, although pretty much all
modern Diesel's have moved to automatic transmissions just for ease of use. Now
after years with the 7.3 Powerstroke being super reliable and really great
for Ford eventually it wasn't really able to keep up with emissions standards
because it wasn't designed for emission systems in the first place. So Ford and Navistar eventually moved to the 6.0 liter Powerstroke which was a pretty
problematic engine, which we've covered in our 6.0 liter versus 7.3 liter Powerstroke video which I highly recommend you watch. So that's pretty much all I
have for you guys today. The 7.3 Powerstroke is a really basic and
really simple engine but it's ultimately really reliable and it has a really big
cult following. If there's anything I missed or anything you want to add be
sure to drop a comment down below and let me know while you're down there hit
the thumbs up button and be sure to subscribe so you don't miss out on
future videos this is Bryce with Dust Runners Automotive Journal, signing off.
