The Best Naturally-Aspirated Engines, Ranked Based On Size and Reliability

Reliability has always been tricky to quantify. Finding a source that gives a reliability score is downright challenging and with good reason. With good engines, there will always be those who share their bad experiences, and with bad engines, there will always be those who don’t experience the expected problems. Car enthusiasts will argue for days on end about which engines will last the longest, and we won’t always agree. Heck, mechanics won’t always agree when it comes to reliability because it ultimately depends on what they see in their shop.

Despite the impossibility of precisely pinning down what is the most reliable, there is some consensus on which engines ought to be the most reliable and cost the least in repairs. The engines on this list have great reputations for reliability and should be a good bet if you’re ever looking for a car with an engine you can count on. These engines are also all naturally aspirated. This means no forced induction, so no dulled exhaust sounds due to turbocharging, and less complexity.

It’s true; turbocharging does not necessarily mean an engine will be less reliable. That said, with even naturally aspirated four-cylinder engines becoming less and less common, we thought we’d celebrate some of the most reliable naturally aspirated engines of the modern era, ranked by size.

To give you the most up-to-date and accurate information possible, the data used to compile this article was sourced from various manufacturer websites and other authoritative sources, including MotorReviewer.com, CarComplaints.com, and Tuningpro.co. Engines are ranked by displacement, but each engine is included due to its reliable reputation, lack of known issues, and the presence of high-mileage examples on the used market.

10 Honda K24 Inline-4

Engine Displacement: 2.4-Liters

When four-cylinder swaps are concerned, the K24 is the king. K24s get swapped into Miatas, RX-7s, RX-8s, and custom car builder/YouTuber Emelia Harford even swapped one into a Toyota Prius. When the car community frequently uses an engine as a swap candidate, that is usually a sign of a strong engine. The K24 is highly ‘modable’ and can easily make 300-400 horsepower on stock internals without blowing up. That said, modding may not be everyone’s bag, and that’s okay because, in stock form, the K24 is likely at its most reliable.

Performance Specifications

(Data was collected from Honda, and Motorreviewer.com)

There are many versions of the K24, but two of the most reliable in stock form are the K24A4, and K24A8. The A4 found its way into the 2003-2006 Honda Element and the 2003-2005 Honda Accord and produced 160 horsepower at 5,500 RPM and 161 lb-ft of torque at 4,500 RPM.

The A8 was an updated version that included improvements to the intake and exhaust systems and a new drive-by-wire system to replace the cable-actuated throttle. The A8 can be found in the 2007-2011 Honda Element and the 2006-2007 Honda Accord and produces 166 horsepower at 5,800 RPM and 160 lb-ft of torque at 4,000 RPM.

There is an overabundance of examples of Accords and Elements equipped with this engine that have over 200,000 miles, and a significant number listed for sale with over 300,000 miles. These engines can take a bit of abuse, but treat them well, keep the oil fresh, and 250,000 miles will be a safe bet.

Pros

• Simple design
• Easy to work on
• 300k or more common

Cons

• Exhaust cams can wear prematurely
• Camshaft seal leaks

9 Toyota/Lexus 2GR-FE/FKS V-6

Engine Displacement: 3.5-Liters

Traditional wisdom tells us the simpler an engine, the longer it should last. Four-cylinder engines are typically the least complex of the bunch, or at least they can be when they aren’t powering an AMG that deserves a V-8. Thankfully, for those of us who find four-cylinder engines lack charisma, there are plenty of V-6 options that suit our reliability needs.

The 2GR has been around since its introduction in the Toyota RAV4 and Toyota Avalon in 2005. Since its first appearance, it has undergone some changes, but the best and most common versions are the 2GR-FE and 2GR-FKS. The 2GR-FE can be found in just about any non-hybrid V-6-equipped Toyota between 2005 and 2016, except the Camry and Avalon, which offered this powertrain until 2017 and 2018, respectively.

The 2GR-FKS is an update to the 2GR-FE and can be found in many of the same vehicles and other Toyota products that are still in production. The major change was the move to direct injection. However, because Toyota also opted to use port injection, the 2GR-FKS doesn’t suffer any issues resulting from carbon buildup like most GDI engines.

Performance Specifications

(Data was collected from Toyota, and Motorreviewer.com)

The 2GR did have some issues early on with oil leaks, the major one being a rubber oil line for the VVT-i system. A few years into production, this was replaced with a metal oil line, so 2010 and later models should not suffer from the same issue. Premature failure of ignition coils has been reported, but given the accessibility of the engine bay, coil and spark plug replacement should be a breeze. Thankfully, either way, these are not costly repairs.

Like with the K24, there are gobs of cars with these engines for sale with over 250,000 miles and still going strong. They aren’t exactly going to blow your doors off with performance, but they should be a safe bet if you want a car that’ll last you 15 years and do minimal damage to your savings.

Pros

• Durable timing chain
• Smooth power delivery
• Room for repair in the engine bay

Cons

• Premature ignition coil failures reported
• Pre-2010 cars have rubber VVT-i oil line that can fail
• Not as powerful as modern turbocharged engines

8 Honda/Acura J35 V-6

Engine Displacement: 3.5-Liters

Toyota is the top dog in terms of reliability, especially overall as a brand. That said, Honda doesn’t fall far behind and may even eclipse Toyota when it comes to engines. Now, we know Honda has a few black spots on its resume for some poorly built automatic transmissions. In fact, some of the cars on this list come with these awful transmissions and should be avoided despite being powered by the excellent J35 V-6.

If you want to avoid these transmissions, find a 6-speed manual Accord and enjoy the wonder of a SOHC VTEC V-6 paired with one of the best manuals south of six figures. Despite the transmissions, the J35 is one of the most reliable engines on the market today.

Performance Specifications

(Data was collected from Honda, and Motorreviewer.com)

The J35 has gone through many iterations, from the J35A series in the seventh-generation Accord to the more modern “Earth Dreams” J35Y series, which can be found in late-model Hondas. It’s one of the most durable V-6 engines ever. More modern J35 engines (except the J35Y2 in the 2013-2017 6MT Accord Coupe) are equipped with what Honda calls VCM or Variable Cylinder Management.

These VCM units often experience premature gasket failure and can leak on the alternator, causing potential electrical issues. Thankfully, the gasket replacement is cheap, but some also say VCM takes its toll on the overall longevity of the engines.

The J35 is a mostly trouble-free engine. Some of the inclusions on this list have a few caveats, but the J35 really doesn’t. Sure, the exhaust cams tend to wear prematurely, but if you adjust your valve clearances every 30,000-40,000 miles, this shouldn’t be an issue. These engines consistently hit 200,000 miles with just basic maintenance, and you can find a number of examples for sale that are close to 400,000 miles.

Pros

• 200,000 miles is just breaking it in
• Very few major issues
• Good power and VTEC noises

Cons

• Timing belt needs replacing every 80,000-100,000 miles
• VCM-equipped models suffer from oil leaks
• Often paired with unreliable transmissions

7 Nissan/Infiniti VQ37VHR V-6

Engine Displacement: 3.7-Liters

No conversation of modern naturally aspirated engines would be complete without a Nissan VQ V-6. The infamous trombone-like exhaust timbre and a slammed G35 Coupe with a slew of ghastly modifications might be the first thing you think when considering a VQ V-6, but let’s not forget how good these engines are, irrespective of their place in car culture.

They make impressive power, with the VQ37VHR in the Infiniti G37 making 328 horsepower and as much as 350 horsepower in the Nissan 370Z. The 37VHR is a DOHC engine and is able to rev quickly, which is a natural pairing with the optional 6-speed manual transmission. They also just happen to be pretty darn reliable.

Performance Specifications

(Data was collected from Nissan, and Motorreviewer.com)

VQ engines are generally considered to be very reliable. This author owned a 200,000-mile 1998 Infiniti I30 with a VQ30DE under the hood and never had any major issues. The 37VHR is possibly the most reliable and is undoubtedly the best blend of durability and performance. There are a few issues, the only major concern being the oil gallery gasket.

These gaskets were made out of paper and were prone to leaking. If the gaskets fail, you can lose oil pressure, which can cause severe engine damage. There is a metal replacement gasket that can be part of preventative maintenance, and all 2013 and newer model years should include the updated gasket.

Though not quite as bulletproof as some of the other engines on this list, the VQ37VHR is interesting, reliable (apart from the oil gallery gasket), and is the heart of some of the most memorable modern Nissan/Infiniti products.

Pros

• Unique exhaust and induction noises
• Significant power out of the box with a good aftermarket
• Incredibly durable

Cons

• Oil gallery gasket failure repair can be expensive
• Higher mileage examples tend to consume oil
• Catalytic converters are sensitive to low-quality fuel

6 Buick 3800 Series V-6

Engine Displacement: 3.8-Liters

The Buick 3800 V-6 is a legend, and one of the greatest American V-6 Engines ever made. It’s not known for sounding particularly good or being the most impressive performer, especially in the naturally aspirated form. What it is known for, is being absolutely bulletproof. Some mechanics have even said it’s one of the best engines ever made, and it was featured on the Ward’s 10 Best Engines of the 21st Century list.

In naturally aspirated Series II and Series III forms, the 3800 makes over 200 horsepower and 225 lb-ft of torque. That doesn’t make the cars it powers particularly quick, but it’s enough to feel modern and make merging a breeze.

Performance Specifications

(Data was collected from General Motors, and gmtuners.com)

The 3800, as with any engine, is not without its issues despite its unkillable status. The Series II had an issue with coolant bypass elbows that could crack, so making sure those have been replaced with updated parts is a must. The Series II originally had a poorly designed intake manifold gasket that could cause engine damage.

There was an updated manifold gasket, so later model years and any vehicle with the updated part should be safe from this issue. It’s also worth noting that a recall was made about fires caused by oil dripping on the exhaust manifold. These are avoidable issues, but if you want to play it safe, the Series III is exempt from these problems.

Ultimately, any used Chevrolet, Pontiac, Oldsmobile, or Buick equipped with a 3800 is a great value, given how inexpensive they are to repair, as well as their legendary durability.

Pros

• Made to be worked on
• Very fuel efficient
• Parts are cheap and plentiful

Cons

• Not a big performer
• Intake gasket failure can cause hydro lock (Series II)
• Coolant bypass elbow failures (Series II)

5 Porsche M1A/9A1 Boxer-6

Engine Displacement: 3.8-Liters

A Porsche is a safe bet if you’re in the mood for the track. Yes, the M96 and M97 engines are widely known for the infamous IMS-bearing issues. Though the IMS bearing problem only affected around 6-8% of vehicles, it convinced most people to avoid 986 Boxsters, 996 and 997.1 911s, and 987.1 Boxsters and Caymans.

The MA1/9A1 engines were introduced for the 997.2 and 987.2, and are mercifully devoid of an intermediate shaft. This means the timing chain is now driven from the front of the crankshaft rather than the intermediate shaft. This requires the timing chains to be of higher quality because, without an intermediate shaft, they are driven at the same speed as the crankshaft. Thankfully, this hasn’t yet resulted in premature wear on the timing components compared to the old M96/97.

Performance Specifications

(Data was collected from Porsche, Stuttcars.com, and Excellence-Mag.com)

Though the MA1 engine comes in different displacements and should all be quite reliable, the one we have chosen to focus on is the 3.8-liter variant found in the Porsche 911 S and the Cayman GT4. This engine produces as much as 395 horsepower and 325 lb-ft of torque. With every family car having 500 horsepower these days, you may not recognize 400 horsepower as impressive, but from a naturally aspirated H-6, it is massive power.

If you own a 911 or Cayman with an MA1/9A1, you’ll need to make sure you give the engine plenty of warm-up time before carving up a backroad, or you could cause bore scoring. The 9A1/MA1 is, at the moment, one of the least troublesome Porsche engines, so if you require the howl of a Boxer six-cylinder, this is a good place to start. It won’t be inexpensive to run, but it has proven to be very reliable, even on a track.

Pros

• No IMS bearing to worry about
• Closed deck and cast “Alusil”
• Durable even on track

Cons

• Engine damage can occur without proper warm-up time
• High-quality oil and more frequent oil changes are required

4 Ford 2V Modular V-8

Engine Displacement: 4.6-Liters

Have you ever been in a Crown Victoria taxi? How about a Lincoln Town Car livery vehicle? Hopefully, you haven’t been in the back of a P71 Interceptor… Still, if you’ve had exposure to any of these vehicles, you’ve encountered one of the most notoriously long-lasting engines of the modern era.

The 4.6-liter 2V Modular V-8 is an engine known to last upwards of 500,000 miles with limited repairs required. It’s certainly not without some imperfections as the early plastic intake manifolds are known to crack prematurely and can cause a coolant temperature sensor to come loose, meaning you’ll risk overheating. In 2001, this part was revised with a new aluminum manifold that solved this issue.

Performance Specifications

(Data was collected from Ford, and Motorreviewer.com)

The spark plug threads lack depth and are liable to strip, so be gentle when installing new plugs in your 4.6 modular. It’s also admittedly not a big power motor, but in the 1999-2004 Mustang GT, they pumped out a pretty reasonable 260 horsepower. The Panther body cars barely cracked 235 horsepower even by the end of their run in 2011, but the engine’s lack of stress is a significant contributor to its longevity.

They aren’t working very hard, which is why they are so well known for being borderline unkillable. If you need a sub $7,500 car that can handle tons of miles without major issues, find yourself a 2003-2001 Ford Crown Victoria, Mercury Grand Marquis, or Lincoln Town Car. You won’t regret it.

Pros

• Can last 500,000 miles
• Cheap parts and cheap to repair

Cons

• Not nearly as powerful as the “Coyote”
• Plastic intake manifold is prone to cracking
• Easy to strip spark plug socket threads

3 Lexus 2UR-GSE V-8

Engine Displacement: 5.0-Liters

The 2UR-GSE is the most modern engine on the list but is not exactly new. It first appeared in the Lexus IS F in 2007. After the IS F’s discontinuation in 2014, the 2UR-GSE was reintroduced with a higher compression ratio in the 2015 RC F and GS F. Perhaps the most well-known vehicle that the 5.0-liter V-8 calls home is the Lexus LC 500, one of the most beautiful and distinct grand tourers on the market today. In the old IS F, the 2UR only made 416 horsepower, but power has been increased to 475 horsepower in more modern cars like the LC. With a 7,200 RPM redline, dual overhead cams, and no forced induction, the 2UR-GSE is incredibly charismatic and exciting.

Performance Specifications

(Data was collected from Lexus)

Granted, a Toyota/Lexus engine being reliable is about as unsurprising as gambling in professional sports, but the Lexus 5.0-liter V-8 has next to zero known issues. There is a potential leak from the valley plate gasket, which is located at the top of the engine. Coolant can pool in that area, leading to complications, but at the very least, some major cleanup.

This issue has only popped up on the older IS F, but even if Lexus fixed the problem for the newer iterations, it’s worth keeping an eye out for coolant. Otherwise, the 2UR-GSE has port and direct injection, sounds incredible, and should have no problem hitting 200,000 miles. If only it weren’t so expensive to get a hold of one.

Pros

• Limited known issues
• Beautiful soundtrack
• Port and direct injection

Cons

• Coolant leaks from valley plate
• Mediocre fuel economy

2 Mercedes M113 V-8

Engine Displacement: 5.4-Liters

The M113 is considered one of the last “money no object” Mercedes engines. The M113 was first introduced in the 1997 W210 E 55 AMG. The more beloved M113 is the M113K, which is the supercharged (Kompressor) version of the naturally aspirated 5.4-liter V-8 included on this list. Despite the lack of a supercharger whine, the free-breathing M113 is still a performer.

With as much as 362 horsepower and 391 lb-ft of torque, any 55 AMG equipped with this engine should be a blast when the pedal hits the floor. Unlike some more modern Mercedes engines, planting your foot in the M113 won’t immediately result in tears and overdraft fees.

Performance Specifications

(Data was collected from Mercedes, and sportlichleicht.com)

Okay, it’s still not cheap to fix when it does break, but these V-8s break ever so rarely. However, there are a few things to look out for. The rear main seal is known to leak, and given the advanced age of most M113-equipped Mercedes, the chance of leaking gaskets is increased. Specifically, look out for oil pan gasket leaks because the repair requires the subframe to be dropped, which can get pricey.

The M113 also has two spark plugs per cylinder, so many owners understandably procrastinate replacement. Most important for the longevity of your M113 is to install an aftermarket oil pressure sender. Inexplicably, this hardware is not included. It is surprising, given what happens to an engine if it loses oil pressure.

That said, the M113 is pretty rock solid. If you’re going to buy an older AMG, one fitted with a naturally aspirated 5.4-liter is one of the best ones to get.

Pros

• Exceptional build quality/engineering
• Impressive power
• No major known problems

Cons

• Expensive when it does break
• 16 spark plugs to replace
• No oil pressure sender

1 General Motors LS1 V-8

Engine Displacement: 5.7-Liters

The K24 may be a common swap candidate, but no engine has been swapped more than the LS. The LS is the GOD of swaps. It was first introduced in 1997 for the C5 Corvette where it made 345 horsepower and pumped out 350 lb-ft of torque. The LS is one of the most legendary naturally aspirated engines of the modern era, and it all started with the LS1.

Tuner guys don’t always sing the LS1’s praises, as they require more expensive modifications to handle more power reliably. Despite that, in stock form, they can easily hit 200,000 miles. In fact, most of the common problems are caused by modifying the engine.

Performance Specifications

(Data was collected from General Motors, and summitracing.com)

The most severe issues are piston slap and piston ring failure. Simply keeping the engine stock can decrease the likelihood of either issue, but it’s worth getting a leakdown test done to check the viability of the piston rings. The LS1 is also known to suffer from oil pump cavitation and bent pushrods if over-revved.

Basically, keep it stock, keep it under 6,000 RPM, and it should treat you well. It may not be the most trouble-free engine on the list, but it has got to be the cheapest way to get exceptional naturally aspirated performance in a versatile and reliable package.

Pros

• Endlessly ‘modable’
• Tremendous power and decent fuel economy
• Extremely durable, especially in stock form

Cons

• Reliability is compromised when modified
• Oil pump can fail if engine is over-revved
• Potential for piston ring failure