[Neil.Bhujbal]

Turbocharged Stratified Injection (TSI) In Skoda
Turbo Fuel Stratified Injection (TFSI) In Audi
Fuel Stratified Injection (FSI) In Volkswagen
Stratified Charged Gasoline Injection (CGI) In Mercedes

Q.Now what is this stratified fuel injection?

A.It is a one of the mode in which these engines run.
Fuel is injected directly into the cylinder.
The other mode is homogeneous mode.(On which our normal cars run )

Q.What’s so special about this mode?

A. 1) The engine runs on leaner AFR’s (upto Lambda 3.0).
Lambda 1.0 = 14.7 : 1 i.e stoichiometric air fuel ratio
2) The fuel is injected at the end of compression stroke (like common
rail diesels)
3) The butterfly/throttle valve is kept full open & injection of fuel is
controlled via accelerator pedal (like common raid diesels)

Q.Draw backs of lean air fuel ratios?

1) Combustion of lean AFR’s is doubtful

• To overcome this drawback they have made the Air Fuel Mixture inhomogeneous.

• The air fuel mixture near spark plug is rich (Resulting is guaranteed combustion)

• The air fuel mixture away from spark plug is lean (resulting in complete burning of fuel

• The air fuel mixture near cylinder walls is leanest (resulting in a thermal insulation to the cylinder liners)

2) High Heat produced results in high engine temps & makes the inert gases react

• To overcome this drawback the EGR has been reworked. Air Intake Charge consists of 30% exhaust gas which helps in lowering the combustion temps & keeping the inert gases intact.

3) Higher emission of harmful gases especially Nitrogen oxide

• New exhaust system has been designed with a additional Nitrogen Oxide Storage Catalytic Converter behind the normal catalytic converter which comes on conventional cars.

• This new catcon stores the nitrogen oxide & nullifies it slowly. When it exceeds the capacity of holding more nitrogen oxide it tells the ECU & the cars running mode is shifted from stratified to homogeneous. The exhaust gases coming from the engine during homogeneous mode react with this stored nitrogen oxide & go out into air as nontoxic gases. This way the catcon is flushed out & the car can go back to stratified charge mode if required.

• This catcon works in high & narrow temperature band. So to reach the desired temperature quickly & maintain it in the narrow band working temps various sensors & pipes are a part of this exhaust system.

Q.What is Homogeneous mode?



A.This is the normal mode in which air & fuel is sucked in together during suction stroke then compressed & ignited.
The air fuel mixture in this mode is homogeneous like on our normal cars.
The air fuel mixture is kept rich since engine is switched to this mode on sudden throttle & high power delivery modes only.


Q.Selection of modes based on what?

A.Selection between Stratified Mode (Economy mode) & Homogeneous

Mode (power mode) is dependent on the engine load & throttle position.

• Low speed, low loads – stratified mode.
• Medium speed, low load – stratified mode.
• High speed, high load – Homogeneous mode.

Q.Why are these stratified engines useless in India ?


A.They need min 95 Ron fuel. Anything less then that has high sulphur
content which damages the new nitrogen oxide storage catcon. The
result is high nitrogen oxide going into atmosphere which the sensor
senses & tells the car to run on homogeneous mode thinking the catcon
is full and needs to be flushed.

So in short the car never runs on stratified charge mode & you don’t get the fuel economy you should be getting.
All you get is just a little more power compared to normal fuel injected petrol engines.

This is just a small part of my college presentation copy pasted.There are many other changes such as head design (swirl ports,charge ports),fuel system,etc in startified charged engines.
If any specific question let me know will try my best to answer.

[shekhar_gogoi]

Post deleted by the Team-BHP Support : Please do NOT post one-liners that add little or no informational value to the thread. We need your co-operation to maintain the overall quality of this forum.

Please read our rules before proceeding any further.

[adisag]

Originally Posted by Neil.Bhujbal

A. 1) The engine runs on leaner AFR’s (upto Lambda 3.0).
Lambda 1.0 = 14.7 : 1 i.e stoichiometric air fuel ratio

Wow! very nicely explained - excellent post

Does the leaner mix actually translate directly to better FE - or are there some other variables - a FE of 3x as much as normal (when running @ Lambda 3.0) seems unreal

[pranavt]

Direct injection is the future. Whether it is relevant to India or not is the wrong question to ask. We should be happy that we are getting some nice tech in the cars compared to some other manufacturers who will keep reusing the same engines for 2-3 generations of their vehicles.

Stratified mode will allow you to run at insanely lean AFRs only as long as you are pussyfooting around. Give it a bit of throttle and it will have to richen the fuelling or the heat would kill the motor. The joke is that most of our driving consists of stopping and starting, which consumes a heck of a lot of fuel more than just cruising. You are not losing anything by not being able to run it leaner on Indian roads.

[Neil.Bhujbal]

Sorry i have no idea about it. Earlier skodas were TPI & then came TSI.
You can check it by looking under the hood. See if the fuel injectors are fixed in intake tract of inlet manifold or directly into the block through head.

Originally Posted by adisag

Wow! very nicely explained - excellent post

Does the leaner mix actually translate directly to better FE - or are there some other variables - a FE of 3x as much as normal (when running @ Lambda 3.0) seems unreal

thank you. Leaner air fuel ratios translate directly to high mileage & little more power in stratified mode.

The main reason for invention of this technology was to reduce petroleum consumption in automobiles because even the non toxic gases from exhaust such as carbon dioxide are also causing problems like global warming.

[Shivank]

Neil, as you have mentioned in your posts. There are three different modes in which the motor runs. Out of three, two modes are stratified. And only one is homogeneous.

Only two questions from my side:

- Lets suppose I am cruising at 120kph on highway, what mode I am in? Stratified or Homogeneous?

- Is it the sulphur content that makes the stratified motor useless or fuel characteristics?

[Neil.Bhujbal]

Originally Posted by pranavt

Direct injection is the future. Whether it is relevant to India or not is the wrong question to ask. We should be happy that we are getting some nice tech in the cars compared to some other manufacturers who will keep reusing the same engines for 2-3 generations of their vehicles.

Stratified mode will allow you to run at insanely lean AFRs only as long as you are pussyfooting around. Give it a bit of throttle and it will have to richen the fuelling or the heat would kill the motor. The joke is that most of our driving consists of stopping and starting, which consumes a heck of a lot of fuel more than just cruising. You are not losing anything by not being able to run it leaner on Indian roads.

Agreed. But you are having some high tech which is eventually not being used because of the low octane fuel.
The excesses air in the cylinder itself acts as a heat insulating materiel.

Originally Posted by Shivank

Neil, as you have mentioned in your posts. There are three different modes in which the motor runs. Out of three, two modes are stratified. And only one is homogeneous.

Only two questions from my side:

- Lets suppose I am cruising at 120kph on highway, what mode I am in? Stratified or Homogeneous?

- Is it the sulphur content that makes the stratified motor useless or fuel characteristics?

There are only two modes in which the cars run.
The 3 things i told were just the conditions depending on which one of the two modes are selected.

1)In low loads & speed of 120kmph the car can run on stratified mode

2)Its the sulphur content which reacts with 'nitrogen oxide storage catcon',destroying it & resulting in nitrogen oxide going into atmosphere.The sensor in the exhaust end reads it & thinks the catcon is full to its capacity & needs to be flushed.For this it tells the ECU to run the car on Homogeneous mode (power mode) so that the cat con can be flushed out.This way the car never actually runs in stratified mode.

[pranavt]

You are not paying anything extra for the new technology.

In return, you are getting something that is leaps ahead of most of the trash that is released here with nothing more than a new name or a fancy bumper redesign, take the case of the Honda Civic.

By your own logic, we shouldn't get cars which are very powerful because we do not have the roads or racetracks to exploit the power. I hope you're getting what I'm trying to say.

Whether the technology is beneficial to us or not is a moot point. It is a proven method of fuel injection, one that is much more efficient than what's currently available. The fuel quality will catch up, atleast in Metro cities sooner or later. Some of you may be surprised even by the quality of regular fuel that's currently available. Most of the armchair experts commenting on the "horrible" quality of fuel have probably not got a gas chromatograph report of pump fuel in their hand which they are referring to when the spread their "facts." Or they've handed over their engines to fools who are too stupid to understand what can be done even on pump fuel.

The last statement isn't relevant to most of the public here or most road cars sold today. But I still stand by my belief that any new technology introduced here should be welcomed. Let the Government and fuel companies catch up.

[Vik0728]

Amazing info Neil.Bhujbal and what a time to post this vital data.

So Neil, correct me if I'm wrong -
# Basically you are pointing out at the fact that though Skodas, Audis, VW's might come up with Supercharged/turbocharged Petrol engines, their full potential will never be achieved ?
# Is there any proof or data that says these Auto giants are not tuning/building these powertrains according to Indian fuel but are basically global designs ?
# Other than the obvious fuel, do you think there might be another way of ensuring that these engines deliver the optimum results ?

All the best with your project dude and hope I did not sound too investigative, just curious !!

[Ford5]

When Bajaj was doing their DTS-i & DTS-Fi PR activity in the years from 2006-2008 everyone amongst the junta buyers, automotive press, were in awe that a local manufacturer could get 2 Spark plugs inside the combustion chamber and make it work which even technologically ahead competitiors like HMSI and Yamaha did not do. What happened finally?

It was revealed by a Bajaj technical head himself that Twinspark technology is not at "work" always in the Combustion chamber. Instead the second spark only comes into play when the combustion cycle needs extra go, and this go would be provided by the second plug as determined by the onboard ignition map. Then the junta was like ohhh . But have the Dtsi engines proven themselves against their single spark competitors? Yes and no. Yes because during high rpms the second plug did work and no because it never needed to function otherwise.

But homogenous or stratified in case of Tsi engines it is definitely a success regardless of us enthusiasts finding out that full potential of these engines is never achieved in pursuit of fuel efficiency.

[anandpadhye]

Neil,

Good thread.

But,
Do you want to say that stratified injection actually never comes into play in India at all???
Do you think my Laura TSi will give me incredibly higher FE if I use Speed 97?

[prakash_ajp]

Originally Posted by pranavt

You are not paying anything extra for the new technology.
....
By your own logic, we shouldn't get cars which are very powerful because we do not have the roads or racetracks to exploit the power. I hope you're getting what I'm trying to say.

Whether the technology is beneficial to us or not is a moot point.

How can you be so sure that we are not paying anything extra? There are still many people, for whom, the purpose rather than owning a marvelous piece of technology is more important.

May be the quality of the fuel will improve. But will I bet on that and invest in the technology, which costs me and I don't need or use? No!

[mempheS.D]

Originally Posted by pranavt

You are not paying anything extra for the new technology.

In return, you are getting something that is leaps ahead of most of the trash that is released here with nothing more than a new name or a fancy bumper redesign, take the case of the Honda Civic.

By your own logic, we shouldn't get cars which are very powerful because we do not have the roads or racetracks to exploit the power. I hope you're getting what I'm trying to say.

Whether the technology is beneficial to us or not is a moot point. It is a proven method of fuel injection, one that is much more efficient than what's currently available. The fuel quality will catch up, atleast in Metro cities sooner or later. Some of you may be surprised even by the quality of regular fuel that's currently available. Most of the armchair experts commenting on the "horrible" quality of fuel have probably not got a gas chromatograph report of pump fuel in their hand which they are referring to when the spread their "facts." Or they've handed over their engines to fools who are too stupid to understand what can be done even on pump fuel.

The last statement isn't relevant to most of the public here or most road cars sold today. But I still stand by my belief that any new technology introduced here should be welcomed. Let the Government and fuel companies catch up.

Dear pranavt,

the explanation here is neatly done and definitely needs to be understood before one takes the plunge to pay the extra few shillings just because the engine spec is "in". I agree with you that these new-gen engine technologies at par with the current age. But, what's the point if we really cannot use it to meet the intent? (It's like how the whole of India was crazy about multimedia phones in the early 2000s, but the network providers still didn't have the infrastructure to utilize thees phones to the limit!)

[v.anand]

I agree with pranav here. The technology in Skodas and VWs are not charged at any premium over the competitors. In fact Laura sells at a price less than Civic and Altis with cutting edge technology under its hood. If it has any adverse effects, then I am concerned.

A very nicely presented and comprehensive report by Niel, never understood the differences earlier. I also am interested in knowing whether TSI performs much better with speed 97 available here.

[Tats07]

Originally Posted by Neil.Bhujbal

Q.Why are these stratified engines useless in India ?


A.They need min 95 Ron fuel. Anything less then that has high sulphur
content which damages the new nitrogen oxide storage catcon. The
result is high nitrogen oxide going into atmosphere which the sensor
senses & tells the car to run on homogeneous mode thinking the catcon
is full and needs to be flushed.

So in short the car never runs on stratified charge mode & you don’t get the fuel economy you should be getting.
All you get is just a little more power compared to normal fuel

Laura 1.8 TSI doesn't need 95 RON fuel. It is also known to be pretty fuel efficient and very powerful. What could be the possible changes introduced by Skoda?