The automotive world is filled with good engines and bad engines, but some of them are so reliable and indestructible that they’ve reached legendary status.
So, today we’re going to look at some of the most indestructible engines of all time. Some of these are from GM, Jeep, Honda, Toyota, and more.
Alright, before we get into this I want to mention that the list isn’t in any particular order and there are plenty of other indestructible engines out there, so if I didn’t mention your pick, drop it down in the comments below.
That being said, no engine is truly indestructible, as all engines are mechanical and all mechanical things can fail in one way or another.
#1 Toyota 22R/22RE
Okay getting straight into this, what better place to start than with one of the most legendary borderline bomb-proof engines of all time, the Toyota 22R and 22RE?
This little 4-cylinder engine powered various Toyota models from the late 1970s through the 1990s and gained quite a reputation for being nearly bulletproof.
One of the most important features that gives the 22R its longevity is its lack of features. It’s a very uncomplicated design and straight to the point.
Overseas you could find this engine most famously in the Toyota Hilux, which was sold here in the US as the Toyota Pickup.
You can also find this 2.4-liter motor in the 4Runner, Celica, and Cressida. It doesn’t make a whole lot of power, but it also doesn’t die, practically ever.
The only thing you have to do to keep one of these in commission nearly indefinitely is change the timing chain every 100,000 miles or so.
In typical fashion, Toyota overbuilt both the 22R and 22RE, as they simply wanted to offer the most reliable vehicles on the market, even if it cost them some profits in the end.
Part of the 22R’s ridiculous reliability is the fact that it doesn’t make a whole lot of power and the rev limit is pretty low for a modern four-cylinder engine.
It might make vehicles like the 4Runner absolutely gutless, but it also means they’re extremely hard to kill. The 22RE would eventually be retired in 1995, which ended its nearly 15-year production run.
To this day, it’s one of the toughest engines we’ve ever seen on the road.
#2 Cummins 6BT
Moving from one small truck engine to a much larger truck engine, let’s look at the Cummins 6BT.
And before you get your panties in a bunch, yes the 6BT Cummins was used in a wide array of different applications.
It’s a lot more than just a truck engine, which is partially what makes it so bulletproof.
Before going further on the 6BT, it’s worth mentioning its one major flaw, which is the Killer Dowel Pin, also known as KDP.
As a quick explanation, KDP is simply a timing cover alignment dowel pin on the front of the engine.
After many many hours of engine run time, vibration and heat allow the pin to wiggle loose and then fall into the timing gear assembly, which can either result in the pin falling all the way to the oil pan safely, or the pin getting lodged in the gears and blowing your entire timing system.
Luckily, it’s a well-documented problem with very well-engineered solutions, so with that problem out of the way, this is one of the most indestructible engines ever.
Part of that is the injection system, which on the 12-valve Cummins, is fully mechanical. There are zero electronics involved with controlling and running the engine. That means no stupid sensors causing problems, ever. It just runs.
Granted, there are still things like an electronic starter, but you get the point I’m trying to make here. The later 24-valve Cummins isn’t blessed with a fully mechanical injection system, but it’s still a very strong and reliable engine.
It’s not uncommon to see these things well over 300k miles without any major problems or rebuilds. I’ve seen quite a few of them cross over one million miles.
It is flat out, one of the most dependable engines of all time, and I know diesel bros like to argue about what company offers the best engines, but it’s hard to deny the dependability of the 6BT Cummins, period.
#3 Honda D-Series
Now I think it’s pretty obvious that any list talking about indestructible engines has to mention something from Honda.
But, for this particular video, we’re going with the D-Series, arguably the least loved Honda engine out there. Why you might ask?
Well, the B-Series, H-Series, F-Series, and K-Series are also incredibly reliable and robust engines, but there is something that separates the D-Series from the rest, and that’s the fact that it wasn’t designed with performance in mind.
The lower power output and more civilian nature of the D-series give it much greater longevity, by a lot.
The D-series was designed as an ultra-reliable little commuter engine. All the other engine series I just mentioned a moment ago had a much larger focus on power and performance, which ultimately does sacrifice the engine’s “indestructibility” if you will.
And for those who don’t know the D-series is Honda’s most basic engine that you’ll find in things like EF, EG, and EK Civics.
The majority of these little engines are single overhead cam, but Honda did make a few variants with dual overhead cams and more focus on performance.
Now these little turds were available for quite some time and displacement ranges from 1.2L all the way up to 1.7L, but you’ll generally find these as 1.5L or 1.6L engines, as those are incredibly popular here in the US.
In terms of features, there is genuinely nothing special about the D-series, which again, adds to its reliability.
It’s just a basic bare-bones four-cylinder engine from Honda. It doesn’t have any real flaws other than being bad at making power.
It’s simple, and simple means indestructible. I can’t tell you how many stories I’ve heard of people boosting these little engines and quite literally trying to blow up the engine and it just wouldn’t fail.
#4 GM 3800 V6
Now I know the GM guys are waiting to see something in this video that makes them proud to own a GM vehicle. But, to your disappointment, I’m not going to list a small block from any generation.
I hate that I’m about to say that these engines are reliable because they sound like absolute turds, but there is no denying the truth: GM’s toughest engine ever is the 3800 V6.
The 3800 was officially born in 1988 when GM’s old six-cylinder got a major redesign, but right off the rip, the 3800 was nothing special to write home about.
It was a little 160hp, naturally-aspirated turd, but it had a handful of changes and innovations that made it better than GM’s previous V6 engines.
It got a few small upgrades in the early 1990s that bumped power all the way up to 205hp thanks to the addition of forced induction through a supercharger.
Arguably the best version of the 3800 came around in 1995 and it was known as the 3800 Series II, which had a ton of new changes that made it smoother, lighter, and produce quite a bit more power, with the naturally aspirated version coming in at 205hp, the exact same amount as the previous supercharged models. And then the new supercharged models output a much healthier 240hp.
I know on paper that 240hp from supercharged 3.8L V6 sounds pretty bad, and well, because it kind of is pretty bad.
But, GM left tons of super reliable power on the table that can be easily extracted with a smaller supercharger pulley and some tuning.
Even if the performance figures weren’t particularly great, it doesn’t matter in this context, because it was super tough.
I can’t tell you how many of these little engines I’ve seen chugging along well after they should’ve been dead, which is even funnier in something like a Buick Regal which can be turned into the ultimate super sleeper grandpa sedan.
If you want a sleeper that’s stupid tough and will put up with your terrible tuning skills as you learn HP tuners after putting on a smaller pulley and wanting to run ethanol, this is the perfect engine for the job at hand.
#5 Ford Inline Six 300
Unfortunately, when Ford went to an overhead cam design for their V8 engines in the 1990s, they ended up sacrificing on reliability.
But, long before they made that move, Ford offered one of the most bulletproof engines in history, with the Ford Inline-Six.
And no, not the Barra inline-six, but the real Ford inline-six. Now this came in a few different forms throughout the decades, including four different generations with a total of 11 different displacements spread throughout those various generations.
To give you an idea of how old these things are, the very first 226ci was introduced all the way in 1941 and used a flathead design, which put simply, means the mean is just a flat piece of iron, and the valves reside in the block upside down from their typical orientation.
The two versions of this engine you are most likely to see are the 240ci and 300ci engines, both of which are part of the fourth-generation family.
And these weren’t designed for big performance like Ford’s famous V8 engines were, but rather for the masses.
From the beginning, it was meant to be a simple do-it-all engine for the common man.
An interesting feature that you’ll see on one other engine on this list is the cylinder head, which forces both the intake and exhaust ports to the same side of the head. This isn’t great for performance since the intake ports end up receiving extra heat, but it’s very simple.
Eventually, the 240ci version was phased out because of its poor performance relative to the 300ci version, which stayed around for even longer.
The larger 300ci engine’s block was quite a bit beefier than the smaller engine, with seven main bearings down low, and up top included an improved cylinder chamber design helping out with performance.
And frankly, part of the reason that this engine is so tough and reliable is the fact that it’s not a powerhouse.
This big ole 4.9L engine only managed to squeeze out anywhere from 100 to 150hp depending on the model, but on the bright side, it was much more torquey and the torque practically arrived right off of idle.
As a good example of how tough this engine truly is, we can look at Scott Donohue’s rally truck that used a Ford 300 and raced in the Baja 1000 multiple times, winning three total times.
That’s arguably the toughest race in the world for both the driver and the machine, and the Ford 300 managed to hold up to it quite a few times and even win.
On top of that, this engine also ended up in loads of non-automotive-style applications, such as tractors, ski lifts, generators, wood chippers, and so much more.
This engine was and is truly as tough as they come.
#6 Chevy Iron Duke
Now this next engine we have covered as one of the weakest engines of all time in a previous video, but strictly for the fact that it barely makes any power despite having 2.5L of displacement, and that’s the Chevy Iron Duke.
This is yet another engine that partially gets its absurd reliability from the fact that it doesn’t make much power. The less power you make per liter of displacement and per cylinder, the less stress the engine deals with it, at least in theory.
Now this is a little 2.5L four-cylinder GM offered as a fuel-efficient alternative to their larger V8 engines, but the power is comically crappy just 85hp.
That’s just 34hp per liter.
For context, this would put a 5.0L engine at just 170hp. It’s impressively bad, to say the least.
But, on the bright side, this was a very burly engine with an all cast iron construction and a complete disregard for weight in the entire design.
That, combined with the ultra-low power output combines for an engine that never experiences any major stress and ultimately never really breaks.
In terms of design, it’s a very simple inline-four engine with a 4-inch bore and 3-inch stroke. The block and head are cast iron and the compression ratio was kept pretty low at 8.25:1, with a max RPM of just 5,000.
It doesn’t even feature overhead cams, instead using a more traditional overhead valve design, relying on pushrods to connect the valve train together.
While it might go down as one of the worst engines ever in terms of performance, it’s a special engine in terms of being indestructible.
#7 Jeep 4.0L
Now I saved this engine for last, because it’s my personal favorite on this list, as I’ve had tons of hands-on experience working on these things, and let me tell you, it’s really hard to kill one of these, and that’s the Jeep 4.0L.
Now don’t get it wrong, although this is known as a Jeep engine, at its core it’s an AMC engine, and not just any AMC engine, but an engine that can trace its roots all the way back to 1964, with the AMC Rambler American.
This was a small compact car that was available with a few different engines, including a 232ci Typhoon Six, and while Jeep 4.0L doesn’t share a massive amount with those older AMC engines, they laid the groundwork that the 4.0L was built on.
During the development period of the 4.0L, AMC wasn’t exactly thriving incredibly well, so to save on development costs, the 4.0L used many of the same parts and dimensions as the other inline-sixes in the 232/258 family.
This is evident by the fact that the cylinder head can be bolted to the earlier 232 and 258 blocks with some minor modifications. And because of the fact that the Jeep 4.0L has some pretty old roots, it has some odd design features you might not expect for an inline-six engine.
For one, the cylinder head only has one side. On just about every other modern automotive engine, the intake ports and the exhaust ports are on opposite sides of the head for a variety of reasons, but the ole Jeep 4.0L has all the ports on just the driver’s side of the head.
Unlike the large majority of modern inline-six gas engines, the Jeep 4.0L doesn’t feature overhead cams, instead using an overhead valve design, with one camshaft residing in the block with pushrods to activate the rockers.
Through and through, this engine is much like a tractor engine and they’re surprisingly hard to kill.
I’ve personally seen these engines run on 5 cylinders for thousands of miles, run while overheating, run too cold from lack of thermostat, run for hours on near zero oil pressure, and a lot more.
It’s flat-out known for its durability and simplicity, and this engine has often been cited as one of the most durable engines ever made. It’s not impossible to kill one, but it’s definitely hard.
What Makes an Engine Indestructible?
It should be noted that the longevity of an engine doesn’t just depend on its design, but also on factors such as maintenance, driving conditions, and even a bit of luck. Even the most robust engines can suffer from neglect or poor maintenance.
What exactly separates an “indestructible” from a normal engine is a variety of things. Unfortunately, making an engine extremely reliable and tough isn’t exactly easy and in the long run, it often costs the manufacturer more, since vehicle repairs are a massive part of the dealership business model.
There are very few automotive manufacturers who work towards building ultra-reliable engines, which I would really only qualify to be Honda and Toyota.
While you can’t definitely claim one particular design feature makes an engine indestructible, there are a few things that can help you get in that direction.
- A full cast iron construction: Now this is far from necessary, but it goes without saying, that iron is much stronger than aluminum. You’d be hard-pressed to find a cast aluminum block with similar strength as a similarly designed cast iron block.
On top of that, by using a fully cast iron engine, you eliminate the difference in thermal expansion and contraction from the head and the block using different materials. Now this is very rarely ever a problem, but for something like the Vega 2.5L that uses an aluminum block with an iron head, that is a massive problem.
- Relatively loose tolerances: I say the word relative because I’m more or less referring to simply not using excessively tight-bearing tolerances. A good example of this is the BMW S65, which has very tight tolerances that ultimately cause premature engine failure. Tolerances too loose are bad and tolerances too tight are bad.
There is a sweet spot that most manufacturers have found for the best longevity. More lubrication will always result in a longer-lasting bearing and a longer-lasting engine.
- Third, using a simple and reliable timing chain system without the use of plastic chain guides. This is partially the reason why I would never add something like a Ford 4.6L to this list.
- And finally, simplicity. At the end of the day, the simpler any mechanical thing is, the more indestructible it is. If there are fewer moving parts, then there are fewer failing points. Simpler engines aren’t always more reliable, but it’s pretty damn close.