[ajayc123]

When in the market for a car, one encounters engine options with 3 and 4 cylinders. Sometimes, the same model offers both 3 cylinder and 4 cylinder variants, and that becomes confusing. Add turbo to the mix, it becomes even more confusing.

Each of the options have their use cases & value proposition with some of the variables including: refinement, NHV, cost, fuel efficiency, power spread.

While theoretical comparisons are available, and even engineering solutions to overcome some of the weaknesses of each type have been devised, but the available information is often laced with the hype and the marketing.

Real user feedback is the ultimate armoury to improve the understanding (proverbially: separate the wheat from the chaff), and help reach an informed decision on the choice of a suitable engine for a specific use case.

I am requesting the team-bhp members for their poll on their preference for 3 cylinder vs 4 cylinder. Also requesting for their commentary on their experiences about these and use cases where one option should be preferred over the other.

Also, if its a turbo engine, how different would be the experience between a 3 cylinder vs a 4 cylinder when compared to an NA engine?

What are good and bad use cases for?
3 cylinder NA
3 cylinder turbo
4 cylinder NA
4 cylinder turbo

PS. I have intentionally left out 6 cylinders or more so that we can stay focussed on the two options, but any commentary that helps the discussion is welcome.

Hopefully, this discussion will be helpful in choosing the right engine for the our needs and make us happy.

Thanks !

[GTO]

Thread moved from the Assembly Line to Tech Stuff. Thanks for sharing!

Going to our homepage today .

We have an older thread on Triple vs 4-cylinders, but the game has much moved on since, so we can certainly have a fresh discussion on this topic.

All things being the same, I would obviously pick 4-cylinders over 3 (and 6-cylinders over 4, 8 over 6 but NOT 12 over 8 due to complexity ). But in the real world, all things aren't the same. As an example, Skoda-VW's 1.0L turbo-petrol is a maniac to drive - too much fun. I would buy that over some competitor 4-cylinders. Among NA motors, Ford's 1.5L 3-cylinder Dragon was a jewel of a motor and I'd pick that over Maruti's 1.5L 4-cylinder NA & Hyundai's 1.5L / 1.6L NAs. Although there are many tamer ones too (Maruti's 1.0L Boosterjet) and ones that suck (Ford's 1.0L EcoBoost with horrible lag, questionable FE & suspect reliability).

Hence, voted for "depends on the car / brand".

[Jeroen]

I voted depends on the car too. I have driven cars where I did not even know it was a three cylinder until somebody told me.

In general I like the more cylinders the better. Not necessarily a very rational choice I admit. Just a gut feeling and I am an engineer at heart. More bits to fiddle with!

Jeroen

[ajayc123]

For those folks voting, please supplement with real world contemporary examples to enrich the discussion, especially the ones choosing the universal answer 'it depends'.

[Gypsian]

I voted for depends on the car. For instance the Mahindra XUV 300, VW 1.0 TSI 3 cylinder petrol engines are preferred over Suzuki K12 engines in refinement and performance. However if technology is at par in both the engines, I would prefer one with more cylinders.
Basically these cylinder configurations are much more significant in motorcycles as they define the very characteristic of that respective motorcycle. In cars though technically it makes a difference, it is not as evident as in motorcycles.

[tharian]

Voted for 'depends on the car'.

Although I prefer 4 over 3 cylinders, a recent purchase of a 3 cylinder engined WagonR made sense over the 1.2 litre 4 cyl engine.

The car was for my father who would be driving it only in the city. I thought of going for the 1.2 engine while booking and that was only for me to enjoy the car whenever I use it and at times take it for a short burst on the highway. I didn't think about the 3cyl thrum or vibrations and the fact that the 1.2 is much smoother and priced only slightly more. The 3 cylinder is not bad either when it comes to vibrations.

It's been 6 months with the WagonR and I realized I made the right decision by not going for the 1.2 engine. The car is just too light and only a commuter car basically, for the more powerful engine. Even with the 1 litre engine, it picks up speed quickly and is perfect for city use.

The tall boy design and the light weight of the car makes it a risky proposition with the 1.2, at least for me.

[ajayc123]

Originally Posted by Jeroen

I voted depends on the car too. I have driven cars where I did not even know it was a three cilinder until somebody told me.

Jeroen

Originally Posted by GTO

All things being the same, I would obviously pick 4-cylinders over 3 (and 6-cylinders over 4, 8 over 6 but NOT 12 over 8 due to complexity ). But in the real world, all things aren't the same. As an example, Skoda-VW's 1.0L turbo-petrol is a maniac to drive - too much fun.

I would buy that over some competitor 4-cylinders.
Hence, voted for "depends on the car / brand".

Wow this is turning out to be very exciting and a bit unexpected.

So far, I have had a firm thinking that the 3 cylinders are noisy, power distribution is not as good, blah blah. Now, I am reminded of my Internal Combustion Engine course during my college days. Theory is one thing, real world is another. One belief debunked.

Is that all marketing jargon, to push folks to more expensive 4 cylinder engines, if 3 cylinders can do so well ?

Or is it too early to jump to conclusions?

[GForceEnjoyer]

Voted depends. 4-cylinders are naturally more refined and have better low end torque too, but it depends on more than just that. I've experienced both the Hyundai Venue 1.2 liter petrol and the 1.0 tGDI motor, and I'd pick the 1.0 liter 3 cylinder any day because it drives so much better. However with the cade of the Ford EcoSport, I'd choose the fantastic 1.5 liter three cylinder dragon engine over the previous 1.5 liter 4-cylinder sigma engine, because the former was a beautifully tuned engine used in the appropriate car.

[ajayc123]

I have also been reading up the famous Skoda Kushaq review thread, and have noted that a few people have raised concern about the 3 cylinder turbo tsi 1.0 being a noisy one (and the engine noise creeping into the cabin), even though it's fun to drive.

Is the 3 cylinder one is much more noisier than the 4 cylinder tsi 1.5 on Kushaq ?

Is the 3 cylinder concept playing it's role or is it due to some other factors?

Do we have some reliable tools / apps to measure the noise levels?

[attinder]

4 pot NA for me. 3 cylinder engines have more moving parts (turbo) and bit more sensitive to bad quality fuel.
And no real benefit over 4/NA in day to day driving.

Didn't Honda image got a hit globally when they switched to turbo engines ?

[Gautham_v6]

Well, though I have no option to vote , if there were a fourth option and have to vote for it it has to be obviously " Engine's performance/reliability worth the amount you pay" (pardon me for the convoluted coinage ).

I beleive the majority of people buying a car first time or experienced alike, cost to package factor varies. And the usability is another factor that plays another huge aspect.

[ajayc123]

Originally Posted by GForceEnjoyer

Voted depends. 4-cylinders are naturally more refined and have better low end torque too, but it depends on more than just that.

Do you imply that the 4 cylinder engine would have better low end torque because typically the 4 cylinder engines are usually higher cc that their 3 cylinder counterparts ? Or is due to the different mechanical characteristics of the two engines?

Originally Posted by attinder

4 pot NA for me. 3 cylinder engines have more moving parts (turbo) and bit more sensitive to bad quality fuel.
And no real benefit over 4/NA in day to day driving.

My current drive a 1.2 NA 4 cylinder engine (Baleno) mostly in Delhi, and I have noticed that I hardly get a chance to even cross 1500 rpm in the city due to the traffic. As per my understanding this rpm is insufficient to derive tangible benefit from turbo. So it appears, I would be better off using a larger NA rather than a turbo for such use case.

I conducted a small test using the Sound Meter app inside a stationary car, by starting the car and gradually increasing the rpm. While the app is not calibrated, but the data seems to be close to real life situations in relative terms.

Initially the car is stopped, with all doors/windows closed, which shows a reading below 30 dB.

Engine is started at around 4 seconds. A spike is observed due to start, but the reading settles around 40 dB while idling at 600 rpm.

Gradually, the rpm is increased to 4000 rpm, which takes the reading to around 70 dB.

It would be interesting to try this out in a car which is identical in all respects (like Kushaq) but has 3/4 cylinder options to note the difference in the noise and establish if the 3 cylinder is indeed noisier.

[prajwalmr62]

Originally Posted by ajayc123

My current drive a 1.2 NA 4 cylinder engine (Baleno) mostly in Delhi, and I have noticed that I hardly get a chance to even cross 1500 rpm in the city due to the traffic.

Turbo starts spooling at 1400-1500 rpm, so you need to be in that range if you want peak torque. But for bumper-to-bumper traffic, you don't need peak torque and even NA engine isn't generating its peak torque. On the other hand, you will get peak torque in turbo at 1500 itself instead of revving it at some 3000rpm, enabling you to cruise easily even in lower gears on the highways.

Originally Posted by ajayc123

It would be interesting to try this out in a car which is identical in all respects (like Kushaq) but has 3/4 cylinder options to note the difference in the noise and establish if the 3 cylinder is indeed noisier.

What you are testing is noise, which can be more or less same in 3 or 4 cyl with or without turbo (it can be less in 3-cyl also, because you burn less fuel on idle hence less energy generated), it is dependent on exhaust system. You won't find any difference there. What you will have to check is for vibrations.

The reason is, 3-cyl vibrate more at start because the engine is inherently imbalanced. But after engine starts, you cannot feel much of a difference. And even this can be well masked by clever engineering.

Because most people cannot find differences in NVH levels of turbo vs NA, we are seeing many turbo cars today.

---

I found a nice article on TopGear which might be of interest - https://www.topgear.com/car-news/nat...rced-induction

[ajayc123]

Originally Posted by prajwalmr62

Turbo starts spooling at 1400-1500 rpm, so you need to be in that range if you want peak torque. But for bumper-to-bumper traffic, you don't need peak torque and even NA engine isn't generating its peak torque. On the other hand, you will get peak torque in turbo at 1500 itself instead of revving it at some 3000rpm, enabling you to cruise easily even in lower gears on the highways.

Thanks for that input. If I look at it, actually, I end up being more around 1000 rpm more than 90% of the time. You really don't get any space to drive freely even on the ring road in the Delhi, what to say of bylanes. And you are blessed by the sightings of the nicely dressed traffic cops every now and then. Does turbo have a use case for such a scenario?

What you are testing is noise, which can be more or less same in 3 or 4 cyl with or without turbo (it can be less in 3-cyl also, because you burn less fuel on idle hence less energy generated), it is dependent on exhaust system. You won't find any difference there. What you will have to check is for vibrations.

The reason is, 3-cyl vibrate more at start because the engine is inherently imbalanced. But after engine starts, you cannot feel much of a difference. And even this can be well masked by clever engineering.

Because most people cannot find differences in NVH levels of turbo vs NA, we are seeing many turbo cars today.

Yes, I was testing noise, because that also becomes irritating at times. Especially, because I have heard that the 3 cylinder TSI 1.0 from VW/Skoda can get noisy. I am researching on TSI 1.0/ TSI1.5 as potential options for my next vehicle.

You have a solid point on vibrations in 3 cylinder engine, which is also a consideration for my research. I am curious to know if we have some measurements on these in public domain or some easy hack to objectively measure these.

I am reminded of my 2001 days, when I was on an assignment in the UK, when I had got a Merc A class for rental for a few months. After I returned to India and rode my 4 cylinder Zen again after that, and I was shocked at the level of NHV of the Zen when compared to the former.

In this example, even though both were 4 cylinder, the NHV difference was huge. So much for the real world difference due to implementation. It can't get any better in a 3 cylinder.

I found a nice article on TopGear which might be of interest - https://www.topgear.com/car-news/nat...rced-induction

Even though this is a 10 year old article, but it is indeed very comprehensive and relevant even in todays time. I found it pretty useful.

[itsmeparvathy9]

I have always felt 4-cylinder engines to have lesser vibrations at idle than 3-cylinders, so I went with 4-cylinders. The small displacement 3-cylinder turbos aren't exactly my thing, there are very sensitive to throttle input and mileage takes a toll when you accelerate hard.

I know it doesn't make sense comparing a petrol to a diesel but a major reason why I prefer the 1.5L 4-cylinder Diesel AT over the 1.0L 3-cylinder Petrol DCT in my KIA Sonet is because of the larger displacement and 4 cylinders.