Unfortunately, both of these engines are plagued with various issues, and there are more problems than what we’ve discussed in this video. The important thing to remember here is that both engines have a decent amount of potential once the most common issues are fixed with aftermarket parts. At the end of the day, both of these engines were so unreliable and bad that Ford ended up developing the 6.7L without Navistar.
after we made our 6.0 vs 7.3l powerstroke video it became very apparent that there are a lot of people who wanted to see a similar video comparing the 6.0 liter and the 6.4-liter power strokes.
both the 6.0 liter and the 6.4 are some of the most problematic diesel engines which have ever been used in the automotive market but with the right modifications , they can actually be pretty decent so let’s dive in and find out which one is better.
It would probably be an understatement to say that the 6.0 liter was one of the most hated diesel engines of all time. It was riddled with problems when compared to the 7.3 liters and eventually, Ford just ended up not using it because it couldn’t no longer meet power standards or emission standards, on top of being incredibly unreliable.
Although Ford and Navistar’s relationship really started to break down after the 6.0 liter and all the problems that occurred, they still worked together to build the 6.4 liter. The 6.4 liter’s architect is actually quite similar to the 6.0 liter’s architect and they do share a lot of similarities but there are a lot of major differences, most of which have to do with emissions, which gets stricter every single year.
Eventually, the design flaws and endless problems with the 6.0 liter and 6.4 powerstroke forced Ford to abandon Navistar and develop their own 6.7-liter engine, but that’s a discussion for an entirely different time. Both engines use a 4.13 inch stroke, however, the 6.4 liter uses a larger 3.87 inch bore which is what allows for that extra 400cc of displacement. Of course the larger bore requires a completely different piston which is one of the weak points of the6.4 liter but we’ll get into that a little bit later. Both engines use a castiron block with cast iron heads, a single cam in the block, and four valves per cylinder.
I’ll put some basic information on the screen here for you to read that way I don’t have to go through it all and waste your time. One of the biggest and most notable differences between these two engines is the injection system. The 6.0 liter uses a revised version of an HEUI injector, similar to that of the 7.3 liters, but unlike the 7.3 the system used on the 6.0 liter is full of all sorts of issues. The 6.4 liter, on the other hand, uses a common rail injection system with advanced piezoelectric injectors and a high volume K16 VDO injection pump.
Unfortunately, the 6.4’s injection system is also full of major problems and can lead to a number of catastrophic engine failures throughout the engine’s lifetime. As we’ve discussed in previous videos, the 6.0 was the first power stroke to receive a variable-geometry turbocharger. A variable turbo gave the 6.0 liter really good throttle response and a lot of low-end power as well as a lot of top-end power, but it did come at the cost of a slight reliability decrease when compared to a standard fixed geometry turbocharger of the time.
The variable turbo system works by using electronically controlled vanes inside the exhaust housing which allowed the effective internal size of the exhaust housing to be changed which ultimately changed exhaust gas velocity. It’s a great system, but it isn’t perfect and it does have some issues which we’ll talk about a little bit later.
When Ford and Navistar moved to the 6.4 liters they introduced an all-new compound turbocharger setup. This setup combined two turbos in series and it was manufactured by BorgWarner, combining a 65mm fixed geometry turbo and a52mm variable geometry turbo. When combined these turbos output over40 psi of boost in total stock form which is pretty impressive for a diesel-engine of the time.
One of the really nice features of this compound turbocharger system is that it has the ability to flow a huge amount of air when turned up and the ability to support upwards of 600 wheel horsepower without modifying the turbochargers at all. Part of the reason that Ford killed off the old 7.3 liters is that it no longer met emission standards of the time which means the new six-liter was the first Powerstroke engine to receive an exhaust gas recirculation system.
Now the EGR system does do a good job at reducing emissions output, however, it’s definitely not the most reliable system in the world. Moving to the 6.4 liters, emission standards were getting stricter so to meet these emission standards Navistarsimply stuck on another exhaust gas recirculation system as well as better EGR coolers. approximately 25% of the air that the 6.4 liter breathes in is recirculated from the exhaust system and although Ford and Navistar worked really hard to solve the EGR issues that plagued the 6.0 liter, they still had issues with the EGR system on the 6.4 liters.
To put it simply, both of these engines have EGR issues, however, they’re not absolutely detrimental, they are just really obnoxious problems. As you might already know, on the 6.0 liter the top end is where most of the problems occur. The 6.0 liter uses four torque to yield head bolts per cylinder and the head bolts are only14 millimeters in diameter which ultimately allows the head bolts to stretch under high pressure and lead to blown head gaskets.
This is especially problematic if you turn up the boost. In total stock form you’re not likely to run into this issue, but as soon as you turn up the power the excessive cylinder pressures are going to stretch those head bolts and you’re gonna end up with blown head gaskets. On top of that, once you pull the heads to install new gaskets it’s common to find cracks in the heads. By the time the 6.4 later rolled around Ford and Navistar had already figured out the 6.0 liter’s head gasket problem and worked around it with the 6.4L, so it’s not an issue that plagues the6.4 at all.
That being said, the 6.4L still suffers from cracked heads. The major weak point of the 6.4 liter is the valvetrain, where the rocker arms can suffer from excessive heat and wear due to lack of oil supply. The bottom end is one of the areas that the 6.0L is actually known for being a pretty decent engine.
The pistons and rods are well known for holding up to extreme mileage and are capable of holding upwards of eight hundred wheel horsepower or so. The crankshaft is secured with a bedplate which makes the bottom end extremely strong. To put it simply, at the bottom end of the 6.0-liter isdefinitely one of its better features.
This is completely different compared to tothe 6.4, where the bottom end is actually one of the weak points. To be fair, the connecting rods on the 6.4 liters are incredibly strong and are well known for holding up to massive amounts of power, but the pistons are a completely different story. Due to excessive cylinder pressure, age, abuse, and a design that retain heat, the pistons are prone to cracking in both stock and modified applications. As you can imagine, a cracked piston is not an easy repair and basically requires fully disassembling the engine, which is incredibly expensive.
Unfortunately, both of these engines are plagued with a bunch of issues and there are a lot more problems than what we talked about in this video. The important thing to remember here is that both of these engines have a massive amount of potential when you fix these issues that plagued them. At the end of the day, both of these engines were so unreliable that Ford ended up ditching Navistar when they created the 6.7 liter.
That being said, the question still remains, which one of these engines is actually better? I think which one is better actually kind of depends on what you’re willing to do to fix an engine and make it super reliable. The 6.0 liter is gonna need a bulletproof kit, where the 6.4L is probably going to need new pistons as well as a few other things. Both engines are going to need work to be made reliable, so it’s kind of just a toss-up as far as which one is better because it’s really up to you to decide how much work do you want to do to make that engine better.
Both engines are pretty stout once those issues are fixed, but the 6.4 liter’s compound turbocharger system actually has way more potential than the 6.0L’variable geometry turbocharger. So if you just want to go for big power on the stock turbos, 6.4 is definitely the way to go. I think I’m gonna let you guys decide which one is better in this case. Both engines have a lot of pros and a lot of cons and I personally can’t really pick one to be a better engine. Be sure to drop a comment down below tell me which one you think is the better engine and why. Before you drop down there be sure to hit the thumbs up
