Turbo vs Naturally Aspirated Engine

[NICAT]

Hi Friends.
Google search already provides too many results about the comparison.
But i have more specific questions.
1. Given the both engines has same HP, which engine feels quicker ? For example , Hyundai has 2.0 L turbocharged engines with 275hp, and 3.5L Naturally aspirated engines with 290HP. While It may change from engine to engine, but is it likely that NA engine would feel quicker ? No Turbo lag, instant throttle response, more low RPM Torque ?
2. Which engine would be more reliable ? Are Turbo engines are less reliable than NA engines ? Because they are utilizing more advanced technology and have more parts and running hotter than NA engines?

PS: I know that every engines (both Turbo and NA) are different in design and made by different manufacturers. So we cant generalize that any NA engine is more reliable or feels quicker than its Turbo counterpart (Even if they actually are generally)

 

[Quattro Pete]

1. Would need to see the hp/torque curve for each engine to determine. In many cases a turbo engine will have more low RPM torque than a larger NA engine, so it may feel faster despite some lag.

2. Looks like you answered this one yourself in the PS comment, but generally yes - turbo is just another part/system that can potentially fail.

 

[BMWTurboDzl]

Today's technology.

Turbo's typically develop more torque and do so at a lower RPM. They all maintain that torque through a wider part of the rev band. The majority of consumers drive torque. It's torque which makes a turbo car feel like it's quicker.

Turbos themselves make the engine less reliable. They can develop their own oil/coolant leaks, wastegates, diverter valves and charge pipes can fail.

NA engines make more power at highest RPM but their torque curve isn't as flat. NA engines are more sensitive to altitude.

 

[WylieCoyote]

I own a turbo 4 and a N/A V6 Mustang, and the turbo feels, and is, quicker, even though only 5-10 horsepower separates them. Torque numbers are further apart, however, as with most turbos vs. N/A.

The turbo is going to feel quicker because boost comes on almost immediately with these smaller turbos. With your foot to the floor from a standstill, the engine is up to full steam by the time it hits 2,500 rpms, whereas the V6 won't get into its powerband until later. I really have to work the 3.7 to (attempt to) keep up with the Ecoboost. I can say that they would be more closely matched if the V6 also had the 10-speed transmission.

I think reliability will depend on your maintenance habits. If you like stretching out your oil changes, a turbo may give you trouble before the N/A will, but they're building them out of better materials now, and tuning the engines better than they did when turbos started to become common.

Its no longer safe to say that the turbo engine is going to fail before the N/A will, because that depends on a few factors that you can only see in a crystal ball.

The Ecoboost is a hoot, but I prefer the V6 mainly due to sound, and its relaxed nature on the highway.

 

[Tjbouwhu]

Much will depend on the transmission…specifically how well it matches up with the torque curve of the particular engine.

 

[MrHorspwer]

I'll give my own experience with my wife's Chevrolet Blazer we picked up earlier this year, which is available with a 2.0L turbo or a 3.6L naturally aspirated V6.

2.0L makes 228 HP and the 3.6L makes 308 HP. 2.0L makes 258 lb ft and the 3.6L make 270 lb ft. Thing is, the 2.0L makes that 258 number from 1,500-4,000 RPM, where the 3.6L makes peak torque at 5,000 RPM.

The 2.0L drives better in 90% of situations. That lump of torque, even though less than the peak torque of the V6, is right in the area where you spend most of your driving and the 9-speed transmission makes the most of it. It is a great powertrain package for the vehicle. Go deep into the throttle and the 3.6L is unquestionably quicker. No doubt about that.

We ended up with the 3.6L not by choice but because that's what was available when our previous lease was up. We were lucky enough to even get hands on a Blazer, let alone one with the engine I preferred. That's life, I guess. The vehicle is also a lease, so we'll have the V6 for two years.

 

[Dave9]

It's safe to say that the turbo engine will fail sooner with "all else equal", though it's never ALL else equal, but not too far off if a manufacturer takes an existing design and only mods it enough to add the turbo.

That busy feeling turbo engine is encountering more stress. However there is also something to be said for decreasing the complexity of the non-turbo, will be more reliable using same materials tech if not variable valve DOHC, V-engine, etc. Up to you how much fuel economy to eat in exchange for that, but it also makes rebuilding easier and cheaper, and a used engine a more viable candidate for reuse, with the age of vehicles on the road expected to continue to rise as new become more and more expensive.

I don't drive near the avg US driver mileage per year, tend to hold onto vehicles for a long time, and never find myself bothered by lack of torque, so have little incentive to pick a turbo engine, but again this is if "all else equal". Same goes for hybrids, more to fail, more expensive to repair, and requires more technical skill to DIY which can effectively make repairs a lot more expensive for the average shade tree mechanic, paying for more shop labor to supplement what they can DIY.

 

[Kurtatron]

Volvo 700/900 series are 80s tech turbocharged that are renowned for reliability. Turbocharged engines can be reliable if they are built right.

 

[edyvw]

My wife is a driver that takes local roads bcs. hwy is fast, and absolute horrid scenario for her: merging on busy hwy. Never drove turbo until she tried my VW CC when we were dating. She was so happy bcs. merging was a breeze especially with the fact that this one had dual clutch gearbox.
That seals her choice when we were moving to CO and she wanted AWD, turbo or nothing.
She was thinking it is hp, but it is torque. Most drivers think more hp is better when actually they need torque.

 

[Passport1]

Volvo 700/900 series are 80s tech turbocharged that are renowned for reliability. Turbocharged engines can be reliable if they are built right.

Absolutely true. Volvo has engineered their engines to be turbo charged. They are generally strong and reliable. Mine has >300K w/o any problems. They are modest in their HP ratings compared to most turbo engines today which seem to last as long as a Roman candle.

 

[Pelican]

It used to be that the turbo gave more power at higher RPMs so a bigger engine gave more torque at low RPMs, but that has obviously changed judging by the comments, unless you have a Volvo with a supercharger (low RPM torque) & a turbocharger (high RPMs power) I always though that Turbos had a shorter lifespan, but apparently that's no longer so due to improvements to the lubrication. Gee I'm too old and I ought to get out more!

 

[CharlesInCharge]

I'd say that it just depends. Some turbos are done very well and are quite useful and reliable. Some heavy duty trucks are using these, which apparently shine at high altitude where air is thinner. But yes, they are pushing a smaller engine to do more work than a NA counterpart and they do offer another (expensive) point of failure.

I don't know if one can make a blanket across the spectrum statement on "better" or "worse" than NA. Some are great, and some not so much.

 

[IndyIan]

I think in general if you multiply the turbo engines displacement by 2.5 or 3 you can make an NA engine with the same torque curve and it would be quite under stressed, but it wouldn't be nearly as fuel efficient. In Fuelly.com, if you compare a the new 2.0L turbo Camaro motor to the early 90's small block Camaro, the torque numbers and hp match up but the 2.0 is getting around 25mpg and the 5.7 is getting 17-18mpg.
I don't think anyone would be betting on the 2.0 turbo to outlast a 1992 5.7 under any driving conditions, regular driving or racing?

 

[Rand]

It used to be that the turbo gave more power at higher RPMs so a bigger engine gave more torque at low RPMs, but that has obviously changed judging by the comments, unless you have a Volvo with a supercharger (low RPM torque) & a turbocharger (high RPMs power) I always though that Turbos had a shorter lifespan, but apparently that's no longer so due to improvements to the lubrication. Gee I'm too old and I ought to get out more!

Thats true my 2.0L t-gdi jeep is more like my 1994 v8 tbird as far as redline and torque.

by comparison the 3.2L jeep acts more like a 4cyl civic.

 

[Passport1]

In some applications forced induction is an absolute necessity over naturally aspirated;

 

[Trav]

Volvo 700/900 series are 80s tech turbocharged that are renowned for reliability. Turbocharged engines can be reliable if they are built right.

That is a fact! I have owned Saab and VW gas and MB, Peugeot (and a few others) turbo diesels over the years and every one of them has been as reliable as a pet rock. Subaru turbo are on the other end of that spectrum but that is not the fault of the turbo but a totally crap engine (open deck models) to begin with, the turbo only exacerbates the issues.

 

[mightymousetech]

With a good, modern turbo like a BMW twin scroll, you can be at max boost, and max torque below 2000 RPM. Torque is what accelerates you from the line. By the time that NA starts winding up to make power, they will be looking at the taillights of the turbo car.

 

[930.engineering]

.
Personally I have much more faith in my two turbo'ed vehicles than I have in my NA Mini Cooper PSA engine.
.

 

[antonmnster]

only under the right circumstances can I hear mine, but it interesting to hear the little one spool up, then the big one. It’s fairly seamless, and makes the car great to drive despite a throttle that feels ropey. I’d be surprised if mine weren’t replaced early as the watergate don’t make much noise, but even if they were they’re doing just fine at 235000.

 

[MRC01]

Question 1: What feels fast is subjective. A car with lots of low end torque but no top end feels faster to some people because it gets off the line quick and has that part-throttle squirt. But it can feel slow and boring to people who expect and enjoy the feel of an engine that pulls harder as you rev higher. Horses for courses.

Question 2: all else equal, turbos are less reliable with shorter longevity; they are more complex with more moving parts and run hotter. But all else is not equal. A well engineered turbo can be more reliable than a NA car, especially if the NA car is tuned to the edge to squeeze out more performance.

Power is what moves the vehicle, but it's actual power developed through the RPM range, not just peak numbers. An engine with more peak power may develop less power in the low and midrange and actually have less total area under the power vs RPM curve.