[VWAllstar]

Originally Posted by Guru_GPS

The Rapid 1.6 MPI can also be given a thought, which I also own. Though it is very different to the Fiesta, its NA engine is adequate for me, a first time car buyer. Have felt its handling and steering response also confidence-inspiring.

The chassis and suspensions are good of the Rapid but the 1.6 MPI is very coarse. It sometimes feels like a diesel engine. Nowhere near to the benchmark set by ivtec. I too own a Vento 1.6 MPI, though I have had fond memories in it still I would prefer the TSI over it.

For a naturally aspirated engine there is no better than ivtec and for a turbo charged petrol engine there is no better than the TSI (considering the fact that the engines aren't being sold anymore)

[Guru_GPS]

Originally Posted by VWAllstar

The chassis and suspensions are good of the Rapid but the 1.6 MPI is very coarse. It sometimes feels like a diesel engine. Nowhere near to the benchmark set by ivtec. I too own a Vento 1.6 MPI, though I have had fond memories in it still I would prefer the TSI over it.

For a naturally aspirated engine there is no better than ivtec and for a turbo charged petrol engine there is no better than the TSI (considering the fact that they engines aren't been sold anymore)

Yes Sir, I agree on the refinement part here. But I feel the coarseness only during idle, and for a few moments, probably only till it gets warm. I am ok with the 'slight kick' on up-shifting to second gear even in moderate RPMs also, but yes, somehow I feel that, for the price paid, had it been a 1.6 TSI, it would have been more lively.

[arjab]

Naturally aspirated. Specifically:
1. The 1st generation Honda City V-TEC variant.
2. Suzuki K12 series
3. Mitsubishi Lancer Cedia petrol
4. E39 BMW 5 Series 525i with its naturally-aspirated straight 6 engine
5. First generation Honda NSX's C30A V6

[marutifan]

Originally Posted by sammy_automoto

Hi,
Could you also give a reasoning?

Thanks

GDI engines lack the inherent self cleaning properties of the engine intake ports that PFI engines have. For me reliability is an important aspect when choosing a car. So buying a car which is designed to be less reliable doesn't make sense when better alternatives are available.

[nsbhagwat]

I voted for turbo petrol, primarily based on my driving experience of the bento and polo tsi.

Large petrols specially the overbore engine found in Innova petrol provide good power but lower mileage.
Small cars unfortunately do not have a overbore engine in the 1.3 litre space. I may be wrong here.

[shankar.balan]

Driving my Gypsy today with its humble 82 bhp naturally aspirated engine, feels lovely and almost like that wind in the hair feeling.

K&N Performance intake installed and a slightly modified end can exhaust, makes it growl a bit.

And on a highway when driving anywhere between 80-110kmph in top (5th) gear, the vehicle feels perfect.

Most enjoyable.

Of course it does not and never will have that turbo kick and so on, but despite being a jeep type thing, it has an unique rally vehicle feel to it.

I still voted Turbo because of the sheer pushed back in the seat feeling one gets in a Turbo Petrol especially one of those higher powered ones, like my Cooper S.

[sammy_automoto]

Yep, fair enough.
Spoken like a true Maruti fan!

[King_pin09]

I would prefer an NA engine with higher displacement over a Turbocharged engine.

While the pushed into the seat experience may be addictive to some, I would respect equally the comfort requirements of my co-passengers esp family members some of which might get sick due to sudden thrusts combined with indian traffic conditions.

[shankha007]

Before going into the debate, i would like to share some of the technicalities involved. Most of you must be knowing, but repeating for the sake of others who might not be aware. The post can get a little long.

Turbocharging helps in increasing the volumetric efficiency of an engine. Imagine i have a lung capacity of 50 cc, but by breathing, i can only fill up to 80% of its capacity. This inefficiency happens primarily due to the hindrance to the path of the airflow, like the shape of our nostrils, the cavity inside, etc. Similarly, in a naturally aspirated engine, the amount of air-fuel mixture (port injection) / air (direct injection) that it is designed to take inside the cylinder, is less than what actually goes inside it, and it is usually in the range of 80% and above. Increasing the volumetric efficiency would result in better output, just like a healthy lung enables us to perform better. Smart design and engineering, like manipulating with the shape, length and placement of the air intake circuit, air filter design, shortening the overall distance for the air to travel, manifold and valve designs, tinkering with the valve timing and lift, etc, can improve the volumetric efficiency quite a bit.

Now if we add a turbocharger to an NA engine, additional air would be forced into the cylinder, which increases the volumetric efficiency way beyond what any of the methods mentioned above would have been able to, often around 130%. So cramming in more air increases the levels of oxygen, and more fuel is injected to burn the same, and increased output can be achieved compared to its NA counterpart.

Now the fun part begins. This forced air induction leads to higher cylinder pressure, and in turn, higher temperature. Now we all know what high cylinder temperature can lead to: pre-ignition and/or knocking, and higher NOx generation. Do we want that? No. How do we resolve? Decrease the compression ratio a little and make the air-fuel mixture rich. The efficiency of an engine is directly proportional to the compression ratio of the engine. So a lesser CR, means lesser fuel efficiency. Injecting more fuel in the cylinder has a cooling effect, and hence a rich air-fuel mixture is used to keep the temperatures under control, but affects the fuel efficiency.

Let's come back to the present situation, where downsized engines, often missing a cylinder, are being turbocharged. Before the boost kicks in, these engines drive like any other small engine and as is the case with all small engines, it is possible to achieve good fuel economy. Smart gear ratios help. But the moment we try to push it a little, the fuel economy goes for a toss due to the reasons mentioned above. All the ARAI tests are done at low RPMs, where turbo boost does not play a big role, and respectable efficiency figures are achieved.

In an NA engine, the average pressure in the cylinders is a lot less, and it can run leaner. Also, a non-turbo direct injection engine, or a stratified engine can achieve similar power figures, while burning a lot less fuel, when compared to a regular NA engine. But as soon as a turbocharger is added, things get less efficient, and hence, engines are downsized. However, removing a cylinder means, we are dealing with less moving parts, and hence, less frictional losses.

Also, a turbocharger helping in reducing emissions depends on the RPM and is very debatable. A lot of complexity goes into the aftertreatment system and ECU mapping.

So the thing in favour of turbocharged engines, however, is the high power and torque figures from a small engine, which an NA engine of the same size cannot even dream of. Then again, you have to downsize it in order to show it to the world that it is more efficient. Also, some really enjoy the sudden boost.

But the higher complexity and costs involved kill it. Turbochargers are expensive. The high pressure injectors these systems require are expensive. The engine components need to be made stronger in order to withstand the higher pressure and temperature. Efforts towards saving the turbo on our daily use adds up to the complexity.

I feel, petrol turbocharged engines lie somewhere in between NA petrol and turbo diesel engines in terms of performance and complexity.

Where will i put my money, depends on how appealing the entire package is turning out to be, which includes build quality, reliabilty, ride and handling, maintenance, features, etc.

Regards!

[evil_grin]

It depends a lot on the engine itself and the rest of the car.

But if you do want to compare than you need to keep something the same.

If you keep the size the same then a turbo charged engine will be more fun to drive. E.g. the 1.2 TSI on the Polo vs the 1.2 iVtec on the Jazz. Or the 1.8 TSI on the Octavia vs 1.8 iVtec on the Civic.

If you keep the price of the car the same then it depends on whether the engine size is large enough for the car. E.g among B2 hatchbacks the Polo TSI is more fun than the Jazz. But among C2 sedans the City 1.5 iVtech is more fun than the Vento 1.2 TSI

If you keep the power the same then the larger NA will be more fun because of more low end power. E.g. the 1.8 iVtech 140bhp Civic vs the 1.4 TSI
138 bhp Octavia.

[John316_WRC]

Voted for the NA petrol engine. I feel anyone who has driven the Honda 1.5 iVTEC for 100 Kms and above would also do the same. Notable mention to the K series 1.2 unit as well.

[BLUEK12]

Voted for the NA family. The clean, screaming note of a NA engine climbing through the RPM range cannot be matched by a turbo. Also NA engines of the mass market including the 1.5 iVtec & 1.2L K12 has always proved to have enough low end grunt for pottering around in the city as well as rev all the way to the redline Effortlessly in the highway and all of these is delivered along with repeatable FE figures. They're also much much simple, reliable and thus gives peace of mind after many years of ownership.

For sure the likes of 1.8 TSI and all are faster than their NA counterparts. But it feels much more connected in the NA than the turbo equipped ones. Which is the main reason why a type 2 city will always be more fun to rev all the way than the TSIs.

[Night Raven]

Voted for others because the choice depends on other factors as well. If the size of the engine and the number of cylinders are same, I would choose a turbo petrol over a NA petrol. For instance, between a 4 cylinder 1.4 L turbo petrol and a 4 cylinder 1.4 L NA petrol my obvious choice will be the turbo one. But when u chop off one cylinder or compare between two different engine sizes, then the choice depends on a multitude of factors and a simple answer is difficult.

[arindambasu13]

Originally Posted by BLUEK12

Voted for the NA family. The clean, screaming note of a NA engine climbing through the RPM range cannot be matched by a turbo.

Couldn't agree more. I have been fortunate to have driven three of the best NA petrol engines available in India during the last 8 odd years - the K12 on Swift, the 1.5 iVTEC on the current gen City and the 1.2 iVTEC on the Brio. Each of then have showcased the best of naturally aspirated qualities, and especially the 1.5 iVTEC has absolutely lovely low and mid range grunt for both the city and highway use.

TC engines have their set of virtues for sure, and I will probably need to graduate to them when the time comes to upgrade a few years later, given the way the market is heading - but till then, I will continue to enjoy and relish the clean upward sweep of the tacho needle and the lovely throaty growl of the 1.5 iVTEC as much as I can.

[Repsol]

Voted for NA engine. Simply because I am kind of fed up taking care of turbo by following this 60 seconds idling. At times it becomes really irritating, for e.g., when I have to do a quick trip to the grocery store and back.