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Old 8th May 2013, 18:17   #1
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Default Small displacement, turbo engines

Hey guys

I was having a discussion in Kizashi discounts thread which led me to think that there is no thread in team bhp discussing naturally aspirated vs turbo engines. Mods please merge this topic if it already exists.

I feel the manufacturers should stop increasing the size of the engines making them less efficient and more polluting. Instead they should start strapping on turbos to smaller engines making them more effecient, less polluting more powerful and cheaper.

For example: If we take the 1.2 L k series engine of maruti suzuki and strap on a turbo to it the engine which is initially developing 87 BHP can develop upto 130 BHP which is more than enough to power a car as big as SX4 or Ertiga. The cost might be equivalent to the 1.6 in the sx4 and the 1.4 in the ertiga but this would increase efficiency and you would get more for what you pay. It will help maruti reduce costs by just having a common engine for the whole lineup rather than having 3 different engines for three different cars.



If Ford can do it so can other manufacturers. Ford ecosport has a small 1L 3 cylinder engine but developes as much power as a civic and at the same time is fuel efficient.
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Old 8th May 2013, 21:35   #2
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Default re: Small displacement, turbo engines

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Originally Posted by rockporiom View Post

If Ford can do it so can other manufacturers. Ford ecosport has a small 1L 3 cylinder engine but developes as much power as a civic and at the same time is fuel efficient.
While the power figures are real, I think the FE numbers - I will take them with a pinch of Salt.

Of all the small turbos that are out there, I think in normal use on the VW/Audi and the BMW turbos deliver anywhere near their rated fuel efficiencies. So as they say, your mileage may vary. You really have to baby your car to get the rated FE's - by that I mean stay out of the boost zone. Once you are in the turbo boosted area of revs, you are pushing in more fuel to burn right? If you check fuelly.com etc., most of the Ford Ecoboost engines just don't deliver anywhere near as close to their rated numbers. The same is true for Sonata Turbo also. BMW 2.0 turbo and Audi/VW 2.0 turbo are however more closer to their ratings in real world conditions. I will wait till real world numbers start to show on the Ecosport 1.0l turbo.

I'm gonna put my head on the line and say that it would be no better than the NA 1.5 l petrol Ford has on the car. Indian driving conditions will mean you keep stopping and going, and going into boost range often - burning as much fuel as a larger engine would do.

The other thing that would be holding back most manufacturers is fuel quality and operating conditions. Most of the euro turbo petrols require high grade high quality fuel to perform as rated. These cars will work with lower quality fuel, but the engine will adjust its parameters to accommodate for the lower octane number. If you are ready to fill premium fuel, that would definitely mean a lot more money to be spent. Operating conditions in India are also not as great as the western world - water logging, dust etc. are not the best of conditions to operate a boosted engine under.

I would also think that maintenance and care for a turbo engine is maybe a little more than a normally aspirated engine - with more moving parts and higher operating temperatures. So on the one hand, you may (or may not) benefit through the increased fuel efficiency, you are very very likely to spend more on maintenance.

Lastly, one thing that surely goes out of the window - refinement and engine note. Drive a turbo and a NA motor back to back - tell me what feels better. The ecoboost almost sounded like a diesel to me in Ford Escape. Also, on hard acceleration, the exhaust note is just not good at all. Also if not managed well, the sudden turbo boost is a handful in our traffic conditions to manage.

So while it may just sound very attractive to go turbo/direct injection etc. in terms of real world fuel efficiency, long term reliability, drive-ability, refinement and safety etc. a lot needs to be ironed out before manufacturers produce cars with these high tech engines.
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Old 8th May 2013, 22:36   #3
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Default re: Small displacement, turbo engines

Below are are my view points. Brick & bats all welcome.

Lets me start by saying gone are the days of the thought "No replacement for displacement". Its a goner. Why? please read below.

1. Turbo charged engines produce more power & torque figures in comparison to a NA engine.
2. Full torque is available at a very low rpm. Eg. VW 1.6 TDi 250 nm torque at 1500 rpm.
3. Better fuel economy compared to NA engines. My Vento delivers close to 18 Kmpl under pedal to the metal mode on expressways. Could easily extract 20+ Kmpl if I drive at 65 Kmph. I don't plan it anytime.
4. Better combustion of fuel and lower NOX. May be wrong, I say so, since VW 1.6 TDi employs EGR for the purpose.


Biggest question everyone has, turbo more maintenance. A big NO. Why?
Ans. Idle the car for 1 min before starting off and turning off the engine. You could listen to good music for that 1 min and talk to your car. Yeah do talk to my car.

Another bigger misconception, being in turbo boost zone delivers lower fuel economy. Again wrong, why?
Ans. When you drive in the turbo zone the engine gets the maximum air for combustion resulting in better fuel economy & power.

E.g. In my Vento turbo zone for 250 nm torque is between 1500-2500 rpm. If I lug the car below 1500 rpm I get lesser fuel economy compared to driving at 2000 rpm.

Thumb rule drive in turbo zone and don't drive in higher rpm which would certainly result in lower fuel economy. Say if I drive my Vento at 3500 rpm I did get lower fuel economy compared to driving at 2000 rpm.

A hope manufacturers start strapping turbo that too VGT not a FGT to get that true power figures out of the engine.

The best engine out there certainly for a petrolhead is BMW 328i Power: 242bhp at 5000-6500rpm; Torque: 350 nm at 1250-4800rpm from a mere 2 liter engine.

For dieselheads, VW 1.6 TDi remains the best with a remap thrown in at 128 bhp and 320 nm torque which gives even D+ segment cars sleepless nights coupled a very good efficiency.

Just my 2p.
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Old 8th May 2013, 23:20   #4
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Default re: Small displacement, turbo engines

For companies like Maruti, Honda etc which are still naive to manufacturing diesels, this might be the future. Now that diesel prices are slowly going up, investing too much in Diesel Engine R&D will not help either. Hence, they might learn from the likes of Ford, etc and develop smaller engines with greater output. That does seem like a sensible option, as this is easier compared to developing a diesel engine from scratch.

Coming to fuel efficiency, I feel that diesel engines are not that sensitive to driving style compared to petrols. I dont say this with technical data, but we see that reported mileage for diesel cars is far more consistent compared to petrol cars. You need to really feather a petrol car in order to extract the best FE. Given a turbocharged petrol, I dont think FE as well as power can be extracted simultaneously but only one at a time. For a big car with a small engine, say for example a D segment sedan with a TC'ed petrol engine or a C segment sedan, like the Honda city with a 1.2l TC'ed i-VTEC or an SX4 with a 1.2l TC'ed K series engine, I dont think driving lightly will help move the bigger mass of the car.

If turbo lag is present, it will become annoying and also it will demand harder driving to keep the car in momentum. In the end, the car will end up giving the same FE compared to having a bigger engine. The only advantages I can think of having a small sized turbocharged engine is 1. Better efficiency if driven sedately, 2. Lesser emissions(as per previous post) and 3. Lesser duty for manufacturers(exise etc)
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Old 8th May 2013, 23:50   #5
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Default re: Small displacement, turbo engines

Quote:
Originally Posted by vineethvazhayil View Post

Lastly, one thing that surely goes out of the window - refinement and engine note. Drive a turbo and a NA motor back to back - tell me what feels better. The ecoboost almost sounded like a diesel to me in Ford Escape. Also, on hard acceleration, the exhaust note is just not good at all. Also if not managed well, the sudden turbo boost is a handful in our traffic conditions to manage.

I think this will clear most of the doubts regarding the engine note

and this should clear doubts about performance

this should clear doubts about mileage


I can agree to the point"no replacement for displacement" only if I am explained is to why the worlds fastest car uses 4 turbos with a 8L V16.
Veyron could never have been the fastest car without the turbos which contradicts the point of displacement.

Last edited by rockporiom : 9th May 2013 at 00:17.
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Old 9th May 2013, 00:34   #6
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Default re: Small displacement, turbo engines

Quote:
Originally Posted by rockporiom View Post

I can agree to the point"no replacement for displacement" only if I am explained is to why the worlds fastest car uses 4 turbos with a 8L V16.
Veyron could never have been the fastest car without the turbos which contradicts the point of displacement.
I agree to disagree.

None of the current cars available to the public tick all the boxes like you say it does. The turbo's sound like tin cans or diesel engines. How can you compare it to a glorious NA V8 engine ever? Listen to a Lexus LFA or an Audi RS5 exhaust note. Apart from the BMW turbo 4/6 and Audi turbo 4/6 - I don't think any other manufacturer is there yet in terms of the pinnacle. They all have one or two loose ends. I want an engine with all three things u quoted in one - if not, I would gladly take my V6/V8.
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Old 9th May 2013, 00:44   #7
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Angry re: Small displacement, turbo engines

Quote:
Originally Posted by rockporiom View Post
Ford ecosport has a small 1L 3 cylinder engine but developes as much power as a civic and at the same time is fuel efficient.
The news about ford ecosport is clear that there are 1L ecoboost engine and the 1.5L n/a petrol engine. Now, if ecoboost engine is better by means of power, fuel economy and cost, why should ford provide 1.5L engine? Very well it could have stopped with ecoboost and diesel engine without the n/a engine.
So the choice of choosing turbo and n/a engines lies in the likes of the consumer just like the diesel- smooth drive, lag, engine sound, maintenance cost, isn't it? I would be happy if someone would correct me if am wrong and explain me if have a poor concept.
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Old 9th May 2013, 01:06   #8
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Default re: Small displacement, turbo engines

Quote:
Originally Posted by vineethvazhayil View Post
I agree to disagree.

None of the current cars available to the public tick all the boxes like you say it does. The turbo's sound like tin cans or diesel engines. How can you compare it to a glorious NA V8 engine ever? Listen to a Lexus LFA or an Audi RS5 exhaust note. Apart from the BMW turbo 4/6 and Audi turbo 4/6 - I don't think any other manufacturer is there yet in terms of the pinnacle. They all have one or two loose ends. I want an engine with all three things u quoted in one - if not, I would gladly take my V6/V8.
I can understand your point as I myself own a a car that has a big naturally aspirated engine and agree that the engine sound and exhaust note is music to my ears. But the downside of that is that the engine is a guzzler and leaves more Co2/km.

Manufacturers are also turning their heads to turbos. The new M5 has a 4.4L twin turbo V8 instead of a Naturally aspirated V10. Can you explain to me as to why have they not stuck to a NA V10 if turbos are so bad as you mention them. Even the SLS AMG and the C63 AMG are going to downsize from the massive NA 6.2L V8 to a smaller twin turbocharged 5.5L V8 and 4.0L V8 respectively. Even the next M3 and the Cadillac CTS V will have a smaller twin turbo charged V6 instead of a Naturally aspirated V8. It is simply impossible to keep on increasing displacement to churn out more power from the engines nor is it possible to keep on increasing the number of cylinders.

Almost all the diesel cars here are turbocharged units and even petrol cars are slowly headed in that direction(polo GT TSI 1.2L turbo instead of 1.6L NA). It is much more economic for the companies and since more air is forced in, combustion is cleaner and hence less emissions, more FE and power.

There is a question on reliability of the turbos now but the advancement in technology and R&D can help in fixing most of the concerns.


Quote:
Originally Posted by vineethvazhayil View Post
You said it yourself. All I'm saying is till the technology is tuned to the best possible levels, I would prefer my NA engines. The day comes when turbo technology is not just good on paper, I would gladly accept it.

Btw, NA engines are getting more powerful with direct injection and lighter moving parts and other technologies. Read up Honda and Mazda engine tech through their SkyActiv and Earth Dreams programs.
Another manufacturer moving away from naturally aspirated engines. Please read this link

Last edited by rockporiom : 9th May 2013 at 01:16.
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Old 9th May 2013, 01:10   #9
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Default re: Small displacement, turbo engines

Quote:
Originally Posted by rockporiom View Post

Manufacturers are also turning their heads to turbos. The new M5 has a 4.4L twin turbo V8 instead of a Naturally aspirated V10. Can you explain to me as to why have they not stuck to a NA V10 if turbos are so bad as you mention them. It is simply impossible to keep on increasing displacement to churn out more power from the engines nor is it possible to keep on increasing the number of cylinders.


There is a question on reliability of the turbos now but the advancement in technology and R&D can help in fixing most of the concerns.
You said it yourself. All I'm saying is till the technology is tuned to the best possible levels, I would prefer my NA engines. The day comes when turbo technology is not just good on paper, I would gladly accept it.

Btw, NA engines are getting more powerful with direct injection and lighter moving parts and other technologies. Read up Honda and Mazda engine tech through their SkyActiv and Earth Dreams programs.

Mind you, some of my observations are coming from personally driving some of these new cars. I end up driving a different rental car every week. I have driven a Ford Fusion Ecoboost 1.6 and a Nissan Altima 2.5 on rental. The Altima gives way better fuel economy at both city and highway speeds with the CVT. It is whisper quiet and the NVH levels are much better.
Similarly I had a Ford Escape Ecoboost 1.6 on rental - same problem. My own forester 2.5 from the previous generation delivers better NVH, fuel efficiency and comfort with its antiquated 4 speed transmission on the same route, same speed, same traffic patterns. So my feeling is, while on paper, it is all rosy, the same has not translated to real world conditions. I know however that the BMW/Audi turbo 4's are doing much better. To get those cars, you have to pay a price. Till the technology comes to the lower segment cars, the current turbo engines just don't cut it for me.

Last edited by vineethvazhayil : 9th May 2013 at 01:16.
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Old 9th May 2013, 01:31   #10
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Default re: Small displacement, turbo engines

Quote:
Originally Posted by vineethvazhayil View Post
You said it yourself. All I'm saying is till the technology is tuned to the best possible levels, I would prefer my NA engines. The day comes when turbo technology is not just good on paper, I would gladly accept it.

Btw, NA engines are getting more powerful with direct injection and lighter moving parts and other technologies. Read up Honda and Mazda engine tech through their SkyActiv and Earth Dreams programs.

Mind you, some of my observations are coming from personally driving some of these new cars. I end up driving a different rental car every week. I have driven a Ford Fusion Ecoboost 1.6 and a Nissan Altima 2.5 on rental. The Altima gives way better fuel economy at both city and highway speeds with the CVT. It is whisper quiet and the NVH levels are much better.
Similarly I had a Ford Escape Ecoboost 1.6 on rental - same problem. My own forester 2.5 from the previous generation delivers better NVH, fuel efficiency and comfort with its antiquated 4 speed transmission on the same route, same speed, same traffic patterns. So my feeling is, while on paper, it is all rosy, the same has not translated to real world conditions. I know however that the BMW/Audi turbo 4's are doing much better. To get those cars, you have to pay a price. Till the technology comes to the lower segment cars, the current turbo engines just don't cut it for me.
One thing is for sure the future of automotive engineering is not big naturally aspirated engines but smaller turbocharged engines in order to support sustainable development.
It is expected that in the next 10 years 70% of the cars will be turbocharged.
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Old 9th May 2013, 09:17   #11
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Default re: Small displacement, turbo engines

Folks, when on the topic of turbo charges Petrol vs Diesel and small displacement vs large displacement arguments also need to kept in mind. The implementations vary significantly based on the displacement/fuel.
Coming specifically to the small turbo petrol engine and thus Ecosportís 1.0L Ecoboost engine, this is I think it will be less than adequate. The engine is too small. The engine without the boost should be producing enough power to meet 80-90% operating needs of a user and the boost should help satisfy adrenaline rushes or overtaking needs when additional power is needed. This will let one get the fuel efficiency of a small engine and response of a big engine. But Ecosportís 1.0L engine is too small to meet those 80-90% operating needs, which means the turbo will always need to spool in and provide boost, more so in our country. Now while in theory turbo is expected to utilize energy getting wasted with exhaust gases, in practice it is not so. To provide immediate response from the turbo, more fuel is injected so that higher energy levels exist in the exhaust which in turn makes more boost. So when the turbo is called in for duty, the engine actually consumes more fuel. This is true for most petrol turbo engines. So as vineethvazhayil mentioned one needs to babysit the engine to get those juicy looking FE numbers. Now if it was 2.0L turbo engine it would have been a slightly different story. The base engine without turbo would be enough to meet a userís needs most of the time with the turbo coming in to satisfy any adrenaline rushes.
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Old 9th May 2013, 11:54   #12
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Default re: Small displacement, turbo engines

Quote:
Originally Posted by el lobo 6061 View Post
Another bigger misconception, being in turbo boost zone delivers lower fuel economy. Again wrong, why?
Ans. When you drive in the turbo zone the engine gets the maximum air for combustion resulting in better fuel economy & power.

E.g. In my Vento turbo zone for 250 nm torque is between 1500-2500 rpm. If I lug the car below 1500 rpm I get lesser fuel economy compared to driving at 2000 rpm.

Thumb rule drive in turbo zone and don't drive in higher rpm which would certainly result in lower fuel economy. Say if I drive my Vento at 3500 rpm I did get lower fuel economy compared to driving at 2000 rpm.
I actually have tried both. i.e. driving in the turbo zone and out of it. And my experience has been quite different.

I has been the case with the Safari TCIC, the Laura 1.9 PD and the Aria 2.2

In all cases I do better kmpl if I drive at speeds of about 60 kmph.

In the Laura AT it automatically shifts upto 6th gear by 60 kmph and it does keep the vehicle out of the turbo zone. Driving in Turbo zone would require me to either drive much faster or in S mode and in both cases the FE is atleast 20-30% lesser.

In the Safari TCIC being in the Turbo zone most of the time got me a FE of 8-9kmpl over 175,000 kms. Due to the 90 bhp on offer it did need to be driven that way for one to feel alive. The same engine on the Sumo got people in the transport business 14 kmpl in a Non Turbo Lower BHP form - it was a 25% lighter vehicle though.

In the Aria there is a green band shown on the speedo (the boost rpms) I used to drive mostly in this band (shifting up accordingly) but this lead to me getting an average of 9.5 kmpl, recently (last 6000 kms) I changed my driving style and now I tend to shift up earlier (much before the green zone) and drive at more conservative speeds (it is not possible to drive slow and be in the green zone without being in a lower gear) Now the FE is an average of about 11.6 kmpl over the last 6000 odd kms A jump of 20%.
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Old 9th May 2013, 12:21   #13
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Default re: Small displacement, turbo engines

Quote:
Originally Posted by rockporiom View Post

For example: If we take the 1.2 L k series engine of maruti suzuki and strap on a turbo to it the engine which is initially developing 87 BHP can develop upto 130 BHP which is more than enough to power a car as big as SX4 or Ertiga. The cost might be equivalent to the 1.6 in the sx4 and the 1.4 in the ertiga but this would increase efficiency and you would get more for what you pay. It will help maruti reduce costs by just having a common engine for the whole lineup rather than having 3 different engines for three different cars.
Let us for a moment forget about big engines/supercars for the moment and markets outside India.
From what I understand rockporiom's original post is about popular mass market cars. There is a reason why turbochanged petrols are not common in these cars. The fact is these technologies cost money. Initial investments in production facilities if any + more components in the car will push the prices for the petrol models and bring it closer to their diesel models. There was a time when (atleast in bangalore) the petrol-diesel price difference was 25 rupees. In such a case who would opt for petrol. The companies were already having a tough time clearing petrol stocks which were almost 1 lakh cheaper than diesel. Moreover even with turbocharging most petrols do not offer as much FE as diesel.
Now with the fuel price gap reducing, ecoboost, tsi, tjets might have a future.
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Old 9th May 2013, 12:42   #14
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Default re: Small displacement, turbo engines

Sadly NA engines are a dying breed, having used several turbo charged engines I can say that NA engines have a raw power feel that is hard to match by turbo charged engines.
This was the prime reason why I picked the Audi RS5 as in the future it would get hard to find a NA V8 engines. The linear power delivery and engine sound are both superior in a NA engines compared to a turbo charged one. A price example of this is the F10 M5, inspite of being a v8, BMW has opted to use synthetic sound playing through the audio speaker for the car to give a strong v8 rumble that a NA V8 gives. Moreover the car wheel spins till third gear due to the torque surges the turbos bring (the absence of AWD is also a major contributing factor to this) !
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Old 9th May 2013, 19:51   #15
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Default Re: Small displacement, turbo engines

I always wanted to ask this question to experts here, didn't find the right thread. Can the same turbo setup in diesel car be used in a petrol one? If no, what are the differences? Also need to understand why petrol turbo cars are expensive than diesel turbos, shouldn't it be less? Eg. Polo and Linea.
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