[anupmathur]

Originally Posted by longford

Yeah.. the rolling is quite silent too as compared to the fuel combustion based rolling..

Longford, the point is that when you shift to neutral the engine goes to idle rpm and keeps firing. Fuel is being consumed.
In most MPFI cars, if you do the downhill in gear under engine braking, say 4th or 5th gear, the ECU will cut off fuel to the injectors.

[quote=anupmathur;1207359]For understanding how and why the fuel-cut is used, please read: Stealth 316 - 3S Fuel Injection Control and Fuel Cut

Gr8 article on fuel cut-off technicalities.

[travelwriter]

There is always a reference to engine RPM in any post related to FE, maintenance or anything related to owning a car. I have an Alto and it does not have any needle to show the RPM. In such a case, how do I know if my car is in the optimum RPM band?

Is engine lugging of sound a good enough indicator? And in absence of an indicator, how do I manage to prolong engine life?

[blacmagic]

Originally Posted by travelwriter

There is always a reference to engine RPM in any post related to FE, maintenance or anything related to owning a car. I have an Alto and it does not have any needle to show the RPM. In such a case, how do I know if my car is in the optimum RPM band?

Is engine lugging of sound a good enough indicator? And in absence of an indicator, how do I manage to prolong engine life?

you could try fixing an aftermarket rev meter.

[reveal_da_zeal]

Originally Posted by anupmathur

For understanding how and why the fuel-cut is used, please read: Stealth 316 - 3S Fuel Injection Control and Fuel Cut

See the section on fuel-cut towards the end.

While this explanation is for two specific cars, it describes all the functions quite clearly.
All FI cars work in much the same way.

Love the F1 hehe, But dear the thingy of No Fuel burned is too amazing. To keep an engine running you need fuel, don't you? Isn't it something like The fuel burned downhill is less as compared to when goin uphill which is obvious.
I have regular trips to Manali and back and trust me its not safe to leave car to neutral and let it reach speed of 60 downhill. Rest is yes its a practice to let car go downhill freely most of times but at low speeds and its fun as far as you are in gear and car in control.
Beleive me saving Fuel is not so important as to be safe by keeping control over your vehicle.

[supremeBaleno]

Originally Posted by travelwriter

Is engine lugging of sound a good enough indicator?

Yes. The engine provides enough feedback to user that should help him drive at optimal speed/rpm for that gear. And even for those cars that have tachometers, most people don't shift the gear each-and-every-time by looking at the rpm meter - you go by feel/instinct.

EDIT : I was reading an article about the new V6 3.5litre Accord in some newspaper yesterday. It mentioned how this car could be used both in economy and power mode. When in power mode, all 6 cyclinders are firing away to glory and work to deliver all the promised horses. But when in economy mode, this car can switch off 4 of the 6 cylinders and run on only 2 cylinders. Result being lesser fuel consumed. Does sound cool and logical.

This is different from the other theory as per which the cars we use today can run for hours (in engine-braking conditions) on ZERO fuel.

[loving_alaap]

Originally Posted by supremeBaleno

EDIT : I was reading an article about the new V6 3.5litre Accord in some newspaper yesterday. It mentioned how this car could be used both in economy and power mode. When in power mode, all 6 cyclinders are firing away to glory and work to deliver all the promised horses. But when in economy mode, this car can switch off 4 of the 6 cylinders and run on only 2 cylinders. Result being lesser fuel consumed. Does sound cool and logical. .

Sounds great.

Honda is really doing a revolution in the engine technology.

This will be of immense use for enthusiastics.

So it can be a good economical luxury car in city driving, & still one can have fun with the devil V6 on expressways.

3 Cheers to Honda.

[anupmathur]

Originally Posted by loving_alaap

Honda is really doing a revolution in the engine technology.

General Motors was the first to modify existing, production engines to enable cylinder deactivation, with the introduction of the Cadillac L62 "V8-6-4" in 1981.

Read about it here: Active Fuel Management - Wikipedia, the free encyclopedia

[anupmathur]

Originally Posted by reveal_da_zeal

Love the F1 hehe, But dear the thingy of No Fuel burned is too amazing. To keep an engine running you need fuel, don't you?

LOL, reveal_da_zeal, you do need to learn quite a bit more about modern cars!
Does that posted article mean nothing to you? Maybe you should do more Googling.

Of course to keep an engine running, as in firing, you need fuel.
But what if the engine is being used as a compressor?! No firing, no fuel!

[supremeBaleno]

I know that this is going to open a can of worms and bring things back to square one.
But still hey, we are here for discussing and learning, right ? So why not ? Expect people to take this as a genuine doubt and nothing personal. I have no issues with being proven wrong.

When the engine is being used as a compressor and there is "No firing, No fuel", would it not be logical to expect the car to have "No sound" also ?
As in the absence of the 'normal engine sound' which results from the combustion cycle ? Eg. when we push start a car, till the moment the engine fires, the engine is being used like a compressor and there is no sound. So, by that logic, if there is 'no firing and no fuel' during engine braking, I would expect no sound also, which is not the case.

[anupmathur]

Originally Posted by supremeBaleno

the engine is being used like a compressor and there is no sound. So, by that logic, if there is 'no firing and no fuel' during engine braking, I would expect no sound also, which is not the case.

Please go and stand next to a working compressor.
Tell me if you heard only the sound of silence.

Further, please note that the sounds you hear in your car are usually not so much the engine as the transmission and drive-train sounds.

Ever rolled down a hill with the engine cut off and in gear? Please be careful if you plan to try it!

And please, leave me alone. I'm not interested in educating you. Sorry if that sounds harsh, but you've been trying to bait for quite a while! Am I wrong about this? Sorry again!

[Guna]

Originally Posted by supremeBaleno

EDIT : I was reading an article about the new V6 3.5litre Accord in some newspaper yesterday. It mentioned how this car could be used both in economy and power mode. When in power mode, all 6 cyclinders are firing away to glory and work to deliver all the promised horses. But when in economy mode, this car can switch off 4 of the 6 cylinders and run on only 2 cylinders. Result being lesser fuel consumed. Does sound cool and logical.

This is different from the other theory as per which the cars we use today can run for hours (in engine-braking conditions) on ZERO fuel.

There is a test drive report thread of new accord V6 which also has a pictorial description of this technology. How they can have a balanced rotation with just two cylinders firing is amazing.

[supremeBaleno]

If you thought I was trying to bait you (which I don't see any need for), you need not have answered my query. I knew you would assume things, which was why I added 3 lines of preface, for God's sake. Anyway, whether you want to reply or not is your prerogative.

And this is not about educating anyone. This is a public forum and if we post anything here, there are bound to be someone or the other asking doubts or even questioning our theory. If we feel too touchy-touchy, maybe we should restrict ourselves to a blog with comments disabled and feel all smug.

[anupmathur]

Originally Posted by supremeBaleno

If you thought I was trying to bait you (which I don't see any need for),

Originally Posted by supremeBaleno

- dont want this thread to end up on the lines of the alternator vs battery thread. Just saying that if solid proof is available, I will embrace the theory.

Come come now, what do you suppose this very special line meant?!

There are people that don't want to learn. Nothing strange about that - the world has many such.

[supremeBaleno]

Originally Posted by anupmathur

Come come now, what do you suppose this very special line meant?!

It means that I did not want this thread to go the way that thread went, where you and some others were going personal instead of sharing knowledge/ideas/beliefs. Which resulted in guys like me (and others) for whom those concepts were new, were feeling frustrated by the mudslinging and personal snide remarks flying around. I even went to the extent of trying out some of the stuff mentioned there on my car, but backed off because I no longer could make out whether the people who I thought were knowledgeable about the subject were serious or joking. Having knowledge is a good thing, but feeling proud about it or looking down upon others is not.

Originally Posted by anupmathur

There are people that don't want to learn. Nothing strange about that - the world has many such.

Quite a strong statement. And quite personal too. Anyway, I'll let it pass because I don't see any good in stooping low just to score a point. Good night.