Are Naturally Aspirated Cars More Reliable than Turbo'ed Cars?

"Long Live the Longdoor" (victoryred08)
09/06/2013 at 13:42 • Filed to: Oppo Questions

Goodday Oppo! I have a question that I've been mulling over for a while now: Are naturally aspirated cars more reliable than turbocharger (or supercharged) cars? I am referring to cars from the factory (not aftermarket forced induction setups).

Now, I realize this is a fairly general question and not all cars from all manufacturers are the same, but the more research I do and the more I learn about cars seems to point to the fact that turbo'ed cars have more longterm reliability issues. Perhaps thats because they have more parts working together (more to break), perhaps it's because many turbo'ed cars can be tuned to offer an abundance of power with a simple tune, perhaps I'm looking into things too much?

What say you oppo? When you're looking for long term reliability, do turbos scare you?

DISCUSSION (39)

Victorious Secret > Long Live the Longdoor
09/06/2013 at 13:45

Yes.

Simply because there is less to go wrong on a NA car.

WhiskeyGolf > Long Live the Longdoor
09/06/2013 at 13:46

I wouldn't say scare me, but the added complexity of the exhaust, intake and intercooler circuits does add to the "things that can go wrong" factor. I'd be curious if there are actual studies for this, because not many standard production cars come both NA and boosted (Diesel is invalid because it has different design requirements).

dieselwagon > Long Live the Longdoor
09/06/2013 at 13:47

More mechanical components = more potential for mechanical problems.

Doesn't scare, just something to be aware of.

Sparf > Long Live the Longdoor
09/06/2013 at 13:47

I drive a turbo car ('88 Celica GT-Four/All-Trac) with more than 100,000 miles on the odo and no documented engine rebuilds. I'm thinking of overhauling the engine next year, but it runs so damn well at the moment that I'm not concerned about it at all.

I have heard that N/A rotaries have quite a bit more longevity than turbo'd ones though (which is very apparent if you compare an N/A to a tuned turbo). I'm thinking of getting an '85 FB RX-7 GSL-SE as my second car, and I plan on keeping it N/A (which is mainly due to Swedish regulations and because I think high-revving N/A engines are badass, but still).

DasWauto > Victorious Secret
09/06/2013 at 13:48

There is less to go wrong but that is not a universal qualifier for reliability. There are still N/A engines that will last half as long as some turbo engines.

Arch Duke Maxyenko, Shit Talk Extraordinaire > Long Live the Longdoor
09/06/2013 at 13:49

Kinja'd!!!

Well there's your problem. Racist turbocharger.

hangus77 > Long Live the Longdoor
09/06/2013 at 13:50

I would say that NA is absolutely more reliable because of this:

You NEVER hear of a "million mile TURBO Porsche 911". Remember that Toyota truck with one million also? I believe that was a 2.4L NA 4? Basically, there are general significantly less amounts of heat and other stressors on an NA engine than a forced induction engine.

HammerheadFistpunch > Long Live the Longdoor
09/06/2013 at 13:50

the simple answer is, probably. Its all about absolute manifold pressures, duty cycles and heat managment

1. the higher the manifold pressure the more stressed the engine is, everywhere, if the components are up to the task its not so bad, but you will still burn through seals and blow by rings more quickly given the materials we have can only do so much.

2. duty cycles. While its true that turbo engines can turn slower engines speeds saving you from having to rev the nuts off it to make power thus burning through your seals, bearings more quickly, the turbo components themselves have CRAZY duty cycles. i.e. 100,000 plus rpm turbines.

3. heat management - while its more thermally efficient to capture and reuse exhaust heat energy, it also means that more heat energy stays in the system and that means you have to abbate it with more components (more to break as Victorious Secret mentioned) or deal with it in the metallurgy and that means either higher costs, less durability or both.

On the flipside, high performance NA means high piston speeds, high rotational speeds, and lightweight components so there is a fragility there as well...but it all depends on how you design it.

The case study here would be the toyota 1fz-fe engine, a low stress, low speed, high strength NA engine that is designed to just keep going and going and going without rebuild. but at the same, the gm 6.5L turbo in the hummer is equally designed for long service life...so which is more durable? neither since they were built around long service life. but...all things considered...yes turbo engines are typically less reliable in the long term.

IDROVEAPICKUPTRUCK > Long Live the Longdoor
09/06/2013 at 13:51

You need to me much more careful about your maintenance and your maintenance will probably cost more. As people have said, more things to break, more things to maintain, more moving parts.

That being said assuming it's a fairly conservative setup (think economy car with a turbo not a GT-R) I doubt it would be much less reliable or complex than a DOHC VVT engine.

But in general, yeah NA is more reliable than Turbo.

doodon2whls > Long Live the Longdoor
09/06/2013 at 13:52

In the days of mechanical boost control and cabled throttles, one might be successful at arguing the reliability of turbocharged cars was less than naturally aspirated cars.

With modern day state-of-the-art sensors, servo controlled surge valves & waste gates, and electronic throttles, the engine calibration engineers have many means by which to protect the engine from hurting itself. Besides the added complexity (and therefore minimally reduced reliability) of plumbing and turbomachinery, I don't think there is a significant difference in reliability.

I recently passed 110,000 miles on my 2.4L Turbocharged, A/A Intercooled car and it hasn't missed a beat. It has three electromechanical vacuum solenoids to control the turbomachinery and the car has a cables throttle. I plan on driving it until the body falls apart (which is a long way off). There are many examples of higher mileage modern turbo cars that are still pulling strong.

Audio Tachometer > Long Live the Longdoor
09/06/2013 at 13:52

Let me begin by saying that I am not an engineer. But I would say that generally, (very generally) NA cars would last longer. That doesn't necessarily mean more reliable. The whole schtick is pressure on the rotating assembly. Forced induction engines feed more air in, increasing pressure. More pressure means more wear. Now, a Hemi with a 12.5:1 compression ratio will probably not last as long as a 1.6 turbo from a Cruze, and that is because of pressures on the pistons, rods, and mains. Also turbos have a big turbine that spins at a ridiculous speed. That needs a lot of precision to not spin itself apart, and logically would not last as long as something that spins at a max speed of 6000 RPM (NA engine). Just my observation and keep in mind this is pretty generalized.

ZeroOrDie - Powered By MZR > Long Live the Longdoor
09/06/2013 at 13:53

Less heat. Heat kills parts no matter what they are. Unless there is a way to disperse the heat or use it somehow.

I would say this is a general rule kind of thing not something set in stone.

Casper > Long Live the Longdoor
09/06/2013 at 13:59

The real answer is that it has nothing to do with intake mechanisms. It's all about the engine, design, and tune. A turbo does not actually add additional stress to components other than gaskets/seals unless you are running extremely high boost or are out of tune. An optimally tuned, properly sized turbo, engine will last just as long as the same engine without a turbo. If a turbo failed in OEM configuration, it either wasn't given what it needed by the engine or had a design defect from the factory.

The reason people think turbos are less reliable is because of the incredibly high levels of stupid in the world. Back when turbos were new to production cars, manufacturers tried to cut corners and made generally shit cars which gave the turbo a bad rap. Then you have the people who take a perfectly tuned car and start "improving" by increasing boost, fuel, etc. The car was tuned to be stoichiometrically optimal and safe... you are now unbalancing it to try to get more power. This is why the turbo or engine fails, not simply because it was turbo charged originally.

MontegoMan562 is a Capri RS Owner > Long Live the Longdoor
09/06/2013 at 14:13

My bet is yes.

They are also easier to work on in the driveway, less complicated.

There's no definitive yes or no to this question though. I just think simpler is more reliable.

Joe_Limon > DasWauto
09/06/2013 at 14:29

True, but put a turbo on said engine that lasts half as long, and it will then last a quarter as long.

DasWauto > Joe_Limon
09/06/2013 at 14:36

Also true. I'm just trying to prevent unfair generalizations.

Joe_Limon > DasWauto
09/06/2013 at 14:42

So, rather then saying "forced induction vehicles suck for long term reliability"

We should be saying "forced induction does not help a vehicles long term reliability"

DasWauto > Joe_Limon
09/06/2013 at 14:47

I'd rather not say that either. Yes forced induction is tougher on a vehicle's components but if those components are designed to cope with that, then it may well last longer than a naturally aspirated engine. There are so many other factors in reliability that it is not fair to generalize based only on whether the engine it naturally aspirated or not. It is best to look at it on a model by model, engine by engine history basis and compare from there.

Joe_Limon > DasWauto
09/06/2013 at 14:53

But if the components are built tougher to withstand forced induction, is that really, the forced induction that is causing the increased reliability? Or is that merely the effects of producing stronger/more reliable components?

killerkoolaid37 > Long Live the Longdoor
09/06/2013 at 16:39

Given two identical engines other than one having forced induction (Turbo- and/or Super-Charger) and the other not having it, the one without will last longer under similar driving conditions. There are multiple reasons behind this, but the two main reasons are:

1) More parts = more things that can fail causing the engine to fail.

2) Forced induction adds more stress to the entirety of the drivetrain.

Long Live the Longdoor > Arch Duke Maxyenko, Shit Talk Extraordinaire
09/06/2013 at 17:32

Lmao, I didn't even see that.

Note to self, when car buying, make sure my turbo does not make racial slurs instead of whooshing noises.

Long Live the Longdoor > HammerheadFistpunch
09/06/2013 at 17:44

Thanks for the explanation. I feel edumacated.

I think what we can take away from this is that if you're buying a car that you want/need to keep for a long time, it really pays to do your research on the car/engine setup, as generalizing towards the reliability of car based on its aspiration isn't wise (especially if it's a car you want).

HammerheadFistpunch > Long Live the Longdoor
09/06/2013 at 17:46

what are you looking at per-chance?

Long Live the Longdoor > Audio Tachometer
09/06/2013 at 17:47

Interesting, I like generalizations!

Long Live the Longdoor > hangus77
09/06/2013 at 17:50

Makes sense. Speaking of cars that last forever, I find it interesting how two of the most reliable brands in Northern America (Honda & Toyota) don't currently have any turbo cars in their lineups. Coincidence? Perhaps...

Long Live the Longdoor > WhiskeyGolf
09/06/2013 at 17:52

I'd like to see some science on this too. Time to phone Motortrend or Car & Driver.

Long Live the Longdoor > HammerheadFistpunch
09/06/2013 at 18:02

What aren't I looking at? I own a 1.4T Chevy Cruze right now but I seem to have made a perennial habit of looking at cars and seeing how they fit into my life. I was thinking for a while that my next car would be NA instead of FI as the power deliver on my car drives me nuts and it has been less than reliable (I'm not excited to see how it holds up). But the more I read about power delivery on different turbo cars (and from what I've seen here about their reliability in the comments here), I think I need to take a comprehensive test drive to see if a car meets my tastes.

HammerheadFistpunch > Long Live the Longdoor
09/06/2013 at 18:05

my last car was a 2005 forester xt 5 speed and the turbo was sure a blast, but laggy below 2500 rpm, the new stuff is pretty pokey, but im wiling to bet anything will be better than the 1.4t, i've heard its not a great engine.

we also have a tsi sportwagen that I quite like, but again, laggy. Part of it is that I live at 5000 feet so the turbo has a little work to do before real boost builds.

DasWauto > Joe_Limon
09/06/2013 at 19:40

No, it's not the forced induction making it more reliable and that is exactly my point. Forced induction shouldn't be a qualifier for deciding whether you think a vehicle is reliable or not. If properly designed, it doesn't matter.

highpsi > Long Live the Longdoor
09/07/2013 at 15:07

If you take care of your cars well, there is no difference in reliability. I would recommend that the average appliance purchaser not get a turbo car.

A better argument may be if NA cars are cheaper in the long run, and that would be a resounding YES.

Manuél Ferrari > Joe_Limon
10/24/2013 at 23:21

Was wondering the same thing...

Kinja'd!!!

bob and john > Long Live the Longdoor
02/11/2014 at 05:34

it really depends on the company.
and as always, you have to maintain it. turbos are a little more expensive to maintain (think always using synthetic) and what not.

also, turbos themselves have a lifespan as well, but i place that under maintenance stuff.

as far as long term reliability goes, the only thing that scares me is how did the PR treat the car?

Nedzad Mehic > hangus77
02/22/2014 at 13:09

Never??How about this: http://www.saabnet.com/tsn/press/0612… ?? I myself drive a 2006 9-3 2.0T,currently at 104K,that has yet to see a mechanic for anything but maintenance that i can`t do myself..If you change your fluids regularly,and use only the highest quality synthetic stuff,don`t boost all the time,let it cool of for 30 seconds after driving,keep on top of all your maintenance and never,ever,push it hard before it`s warmed up,they will last just as long as N/A engines..P.S. I also never let it warm up just sitting there idling,but slowly drive away after a minute or so,but never floor it or rev past 2500RPM until it warms up..

steve____ > Long Live the Longdoor
09/12/2015 at 04:55

I bought an imported a factory twin-turbo ‘94 Toyota Soarer with the 1JZ-GTE.

A lot of people have horror stories about turbo failure on these cars, but mine have 150,000+km on the and are going strong. It has been nothing but reliable since I’ve owned it. I wouldn’t hesitate to purchase another turbo car in the future.

Equana > Long Live the Longdoor
10/06/2015 at 06:10

So compare a 230 hp turbo 4 to an NA V6 of the same hp. At least you are comparing comparable products. There are more moving parts on the turbo even with 2 fewer cylinders so reliability takes a hit right there.

The turbo requires better components (rings, bearings) to reach the same drive mileage as the 6 before wear out because peak pressures are higher and has less bearing area per hp created. But that is durability, not reliability. Don’t confuse the two.

So, yes, turbos are less reliable.

Equana > DasWauto
10/06/2015 at 06:11

Lasting half as long....

That is durability, not reliability.

Behzad > Victorious Secret
11/12/2015 at 13:13

there is lesser pressure on the engine , there’s lesser load , there’s lesser wear , and yes there’s less complexity

Behzad > Long Live the Longdoor
11/12/2015 at 13:20

Turbochargers are Overcompensation for the lack of true power in the face of well engineered N/A Engines

an ancient cheap piece of junk + Turbocharer = a happy fool thinking he’s driving a Ferrari ....

Matthew > Long Live the Longdoor
11/08/2017 at 18:59

To make the answer simple, yes. More moving parts, gaskets, etc. means more potential for failure. Now having said that, I believe the auto manufactures have done a great job at mitigated much of the risk associated with the added potential for failure. Manufactures have continued to improve the manufacturing processes and technology associated with complex turbo cars. In addition oil technology has improved as well as metallurgy at an incredible rate in recent years. I am in no way an expert in these matters but In my humble opinion these technologies have improved so greatly in the last ten years that I believe that the latest turbo engines are going to prove to be more reliable and durable than most naturally aspirated engines developed just ten years ago. That of course is provided that the maintenance schedules are done at the scheduled intervals under the same operating conditions.