fastGkid

wow i hate 5-->4. i hate it!

roast

iTrader: (2)

Kolia... my hero.... to the rescue!!!

Agree 100%

Agree 100%.

Agree 100%. 6-3-1, is also the way I usually do it when daily driving.

Agree 100%. Coasting in neutral is a waste of gas, eh?

When are you going to say something I can disagree with.

tattoo60012

Quick question Roast:

When you are coasting in neutral and your engine idling with no load on it, using the least amount of fuel possible, how is that a waste of gas? There is no point in time when your engine consumes less fuel than at idle which is the status of the engine in neutral, unless you are a complete moron that likes to rev the engine while in neutral, but for the time being let's assume that you aren't trying to show off.

I do agree that the worst thing to do to your car during normal daily driving is to ride the clutch, other than that there is very little you can passively do to "hurt" your engine or transmission.

You are completely wrong about one thing Roast and Kolia, downshifting has a great deal to do with slowing the car down, and using the brakes is not always the correct answer. I'm assuming that both of you young gentlemen live in a relatively flat area of the country, probably the Midwest, and as such have little to no experience driving in the mountains. If you were ever to find yourself in a hilly or mountainous area of our fair land you would soon learn that riding the brakes while going downhill is not an acceptable method of slowing your car down unless you intend to come to a full and complete stop. When descending grade gravity has the effect of pulling your car forward, causing you to go faster. If you were to use the brakes to counteract this effect and maintain your velocity, your brakes would heat up rapidly and never have the chance to cool down. The excessive heat will eventually cause your brake fluid to boil and be rendered partially gaseous, neutralizing the pressure transmitting properties of your brake fluid, thereby causing a general failure of your brake system. If you have studied hydraulics at all you would know the negative effects of a gas in a hydraulic system. This is the same reason you bleed the air from your brake system. You combat this situation by selecting a gear in which the combination inverse load of the engine and transmission will slow the vehicle down to the appropriate speed without using the brakes.

I just wish everyone would remember there is no black and white in the world, just infinite shades of Grey. Often there is more than one correct answer to a question. Every correct answer is also subject to definition by a number of other variables often not given when the question is asked.

roast

iTrader: (2)

I'm sure you're aware that an idling engine requires fuel to remain at idle, or else the engine would stop running. However, when you engine brake(aka compression brake), the cars momentum keeps the engine turning thus no fuel is required/used.

100% incorrect. Read above.





Exactly what are we wrong about? Brakes are for decelerating and stopping(who could have guessed). That's all they are designed to do. Yes engine braking can also contribute to deceleration, but stopping is not why you engine brake.

Have you ever driven coast to coast? Are you an avid snowboarder? (thus requiring obvious trips to mountains) Do you drive for a living? Please don't inform me of what I do and don't have experience with. You'll just end up burning yourself (like you did at the beginning of your post).

I live in the midwest, good guess. Kolia lives in canada. Either way, I'm pretty positive we both are well aware of how to descend a mountain without cooking the brakes. Again, engine braking down a mountain has nothing to do with stopping. It has to do with keeping your speed down without having to ride the brakes.

I'm impressed, but you appear to be arguing with yourself, since neither of us said anything to the contrary. Considering most people don't descend appreciable mountains in their daily driving routines, it is trivial at best.

What is 2 + 2?

Kolia

iTrader: (2)

Quote War !!!! Lol

Actually I live in the Midwest too Roast. I miss Europe a lot when it comes to fun roads! I’m sure we’ll find things to disagree about. Like what beer goes best with fries… ;-)

As for our newbie friend, please drop the “American-looking-for-a-missing-disclaimer-lawsuit” act and use your brains a bit. Then we won’t need to list each and every possible situation that can be encountered out there…

And feel free to check our profiles so you know how you’re talking to.

lilquazyvietboi

no kolia.. u live in the mid-east....

coming from cincinnati ^^
steve

Kolia

iTrader: (2)

Please don't say that in front of the Border Patrol ! lol

lilquazyvietboi

the nati aint that bad ^^

tattoo60012

Gentlemen,

Apparently a well worded narrative describing the fundamental flaws in some of the answers given in this thread is not appreciated. I have no care for writing the ultimate disclaimer, I have no care for impressing anyone, and I have no care for what most people think. The only reason I have made comment at all in this thread is to correct the gross misrepresentation of opinion as fact. Some people however seem to be taking the clarification as a personal offense against their character, this was never the intent. If someone were to read this thread who actually needed it because they were not previously experienced in the world of driving a manual transmission they would not have the ability to sort out fact from fallacy making this thread useless at best. The goal is to educate, and in order to do so one must first understand the subject matter at hand.

Case in Point:
Wrong: the fuel to your engine is partially controlled by a sensor sometimes called the Mass airflow sensor, sometimes a manifold air pressure sensor. Each intake stroke of your engine produces vacuum that must be filled with the proper air fuel mixture in order to keep your engine running. More revolutions means more intake stroke, more intake strokes means more air, more air means more fuel to maintain the air fuel mixture. If you have too much air and not enough fuel (running lean) your engine will not run. If you have too much fuel and not enough air (running rich) you engine will not run. It makes no difference what you want to believe, but that sound coming from the exhaust of your car should be a good indicator that fuel is being consumed.


Stopping is one thing, the comment I was answering was:
Had you said downshifting had nothing to do with stopping the car I would not have made the comment, however in your rebuttal you yourself stated that there is a difference between slowing down and stopping and one does not necessarily have anything to do with the other. As I stated above this isn't intended to teach someone who already knows how to drive a manual transmission, this is to teach someone who does not know how to drive a manual transmission.


Thank you for making this comment. Yes, I have driven coast to coast in a round about way. Six years ago, I took a month and drove from my home in Chicago through Canada, down the Eastern seaboard, to Miami, back through Tennessee, down to Houston, and back home. The following year I took 6 weeks, and drove from Chicago to Washington state, down through Oregon, to San Diego California, finally heading back home Via Phoenix Arizona, Denver Colorado, and Iowa City Iowa. I guessed you two were from the midwest, because I also am from the midwest, I however have the added experience of living in Colorado, and Northern California where I was an avid Skier, causing me to spend extensive periods of time in the mountains.

I'm happy you are impressed, though that was not my intention. I never suggested that anybody had contradicted my statement, I was simply clarifying an overzealous black and white answer. I will grant you that you probably don't know anyone who descends any appreciable hills or mountains in their daily commute, however if you would like to keep this streak going, I would suggest not making friends with anyone from New Hampshire, Vermont, Colorado, Utah, Wyoming, Oregon, Washington, Northern California...... you get the idea. There are plenty of people who descend good size grades every day, just because you don't know them, doesn't mean they don't exist.

2 male cats + 2 female cats = a whole mess of kittens
2 bowls of oatmeal + 2 pop tarts = a super filling breakfast
2 men + 2 women = a killer party especially if you can find rum

Ok, now I'm just being ridiculous, but then again aren't we all.

Kolia

iTrader: (2)

Wow. I'm so impressed !

Should I write an essay in my native French now? Or maybe Italian? I know perty word too you know !

Now, if we're goign to talk about cars, let's do so. I'll talk "Dumb", but at least I'll have the correct information...

Idling burns fuel Tattoo. And a fairly large quantity as the ECU will run the engine rich to help with the cooling of an immobile car.

Engine braking on the other hand burns... zero fuel. The injectors will be kept closed as long as the engine's rpm are above ~1,000rpm and the thottle is closed. At or near 1,000rpm it will switch to its idle mapping and reopen the injectors to prevent the engine from stalling.

Back to engine braking. If you take some time to browse the forum, you will find some people have interresting ideas when it comes to driving a car. One that surfaces often is the concept of adding engine braking to the action of depressing the brake pedal to "slow down more". It is misconceptions like those Roast and I try to reason people out of (How's my synthax by the way? Should I swap language now? No? English still? Okay).

So, if you want to have your share of the limelight, okay. You get the "Engine braking is good to control your speed down a hill" award. I would assume pretty much everybody should be aware of that from when they first got their driver's licence. It's also explained in the owner's manual...

In pretty much any other decelleration situation, it's not playing an important role. Engine braking alone will generate ~0.1g of decelleration when the brakes can do in excess of 1g. Plus, you can't add these two factors either. I trust you know why?

tattoo60012

Kolia,

Check your sources again on the zero fuel burn using the engine for deceleration, I assure you the information you have is incorrect. If you want proof, go out find a hill, and engine brake down the incline, that sound you hear coming from the exhaust is combustion taking place in your engine. If you don't want to believe me then believe your ears. That's also why there are signs posted in urban areas restricting engine braking. I will grant you that you are not dumping as much fuel as if you were to match rev for rev using the accelerator, however it is more than at idle. The notion that your engine can continue to operate without the addition of fuel is illogical at best, naive at worst. I understand the momentum of the car feeding back through the engine is assisting in the increased rpm, however you seem like the kind of guy who wants proof. Here you go, after you take your roll down the hill and hear the sound of fuel being burned, take another trip up the hill only this time part of the way down, rotate the key back until the engine cuts out, but not so far as you lock the steering column, and notice the increased deceleration caused by the lack of combustion and notice how the sound changes when your injectors truly are shut off as you suggest they are.

If you are truly certain of your claim, and you have experience in this area, I suggest you take a moment to pony up the proof. I can back up everything I say with simple tests that most anyone can do, so they may also verify the validity of my statements. I'm not asking anyone to take me at my word, or worse yet to blindly believe everything they read on the Internet. I've come across more wrong information than right information while browsing various Internet sites, so I would caution everyone to take the things you read with a grain of salt. Don't be afraid to check multiple sources, but ultimately use your best judgement. Remember; at one point in time everyone was convinced the world was flat and the earth was the center of the universe. Popular opinion is just that, popular and opinion, neither of which make the idea more or less correct.


I would like to add however that in spite of the disagreement regarding some of the information in your post, I found your writing to be clear concise and relatively easy to read. I wish everyone would write as well as you do. I had no idea that English was not your first language and you should be proud to have the ability to read and write in multiple languages. I personally only speak English and extremely broken Spanish, and I have the utmost respect for anyone who is fluent in more than one language. I do however find it interesting when people become offended after reading "big words". In no way am I trying to insult anyone, nor am I attempting to appear superior in any way. I am simply conveying an idea, and in doing so have chosen the words that I feel are best at completing that task.

This is a great point, and I thank you for bringing it up. I won't comment on the g numbers you have quoted, as I have no evidence to support or dispute your claim. I'm not sure if you want me to answer the last sentence or if it was entirely rhetorical, but I always try to err on the side of caution. If you didn't want the question answered please stop reading now. The answer of course is quite simple, no matter what method you use to slow your car down, the one thing they both have in common is they reduce the speed of the wheels causing an increase in friction between the tires and the road. Your brakes are designed to have the capability to completely stop the revolution of your wheels at most any speed. Since you can't reduce the speed of your wheels beyond zero your limiting factor in the stopping ability of your car is the friction between your tires and the road.

Kolia

iTrader: (2)

We can do tons of tests if you want.

Personally I like the one where you cruise at 15mph in first gear and let go off the gas. The car slows down until rpm gets really low and then it magically keeps on going at a crawl. I very much doubt it is now consuming less fuel than while it was decelerating.

Seriously, what I hear going down hill on engine braking is air being pumped in and out of an engine. You are right in saying that some fuel is still injected on engine braking. But only for a short period of time, after which all fuel supply shuts off to every cylinder. You can feel that as a second moment of deceleration.

Cutting the ignition might also change how much braking torque the stalled engine generate. Who really know what happens to the throttle of a drive by wire car? It probably closes 100%. But I’m not sure. It sure didn’t make any difference in my 2002 Impreza (cable throttle).

I fully agree with you on the “Do your research” part. For the record, in this particular case, I take my info from the Nissan technical manual for the 350Z. I will gladly make the engine control chapter available for you if you want. It’s very interesting to read. And zero fuel after a time of engine braking. I won’t copy and paste passages of it, I’d rather point you to the passages in the manual.

It’s note a none sense to have an engine run with no fuel. When you think about it, what’s the difference to the accessories if the crank shaft is powered by the cylinders firing or the wheels spinning driveline? None.

The “No Engine brake” sign is not for cars. It’s for the Jacob brake equipped truck. A different beast altogether that plays with the intake/exhaust valve actuation mechanism. And much noisier as you’ve certainly noticed.

Very good answer to my last comment The figures for the decelerations are from my own data acquisition. I can make that available too, with the analysis software. I have a Race technologies DL1 GPS/Accelerometer logger I use on track days.

Finally, about your excellent English, I have the feeling it conveys the idea that the author is adding all the flourish to camouflage a lack of hard knowledge. It also sounds like the author prefers to hear himself talk about cars than the subject itself. I’m not saying it’s your case. But that’s to be expected when you use a type of “slang” not typically used by your audience. That’s just life in our society. Funny, I had a similar discussion with an other member of this forum, for opposite reason. Overly technical (yet rigorously correct) vocabulary that was lost to almost everybody. Lol

the7ferret

Keep it in gear untill you know you are about to stop. Saved my butt once from getting t-boned by a dumbass comming out of a gas station...

roast

iTrader: (2)

Quote war III

I think most of the flaws were made apparent before you ever decided to open your mouth. Everything since has been a bunch of nonsense that no newbie in his right mind would ever read. Congratulations. What is not appreciated is when some forum newbie (you) decides not only to fabricate an argument just for the sake of arguing, but also go to the trouble of oh-so-eloquently telling someone they are full of **** when in fact they are not. You have dug yourself a nice hole, and I think you know what happens next.

Maybe that was never your intent, but you should not attempt to insinuate that I don't know what I'm talking about, or that you have any business trying to correct me. I reserve that right for people like kolia who know what they're talking about. You should also be a little more careful with your future usage of the word moron.

In that case, I suggest you shut your piehole already, crack open a book and start studying.

There you go again with your silly assumptions. You do not know me, what I have experience with, or who I know. You also misconstrued my response which I will not bother getting into. There are bigger fish to fry here.

How about you just stop making assumptions? Where the hell are your sources anyway? I'm very curious where you get your information.

You cannot be serious? You do realize there are a million other things in this world that make sound other than combustion? You proved absolutely NOTHING. You stated something which is incorrect(again). In the case of the Z, the noise you hear is NOT combustion. I say this as a fact and it's not up for debate AFAIC. If you want to argue, go find a tree or a brick wall.

This was the best response yet. It's funny and ironic that you referred to signs that ban engine braking, yet you obviously aren't aware that those signs are in reference to jake brakes, because if you were aware of that you would understand why it goes completely against your failed argument. Jake brakes rely on COMPRESSION (not combustion) to aid in slowing a truck.. the best part is... if you've ever heard a jake brake you would know they are loud as hell (hence the reason they are banned in certain places)... and it's all due to compression. Kind of shoots your previous theory to pieces, huh?

What does that make you?

Is it dark up there? You know, where the sun doesn't shine? Let me ask you a question. Do you even own a Z? If the answer is yes, have you ever even bothered to follow your own scenario? It's glaringly obvious to me that you haven't, because if you had, you would already know that there is no perceivable difference in sound whatsoever. I encourage anyone in doubt to engine brake and try it. Then just for good measure, with the key still off, try to accelerate and see what happens.

If that alone is not enough to convince you(which ironically was your own idea), I have another scenario for you. As you begin to coast down a long hill, reset your MPG gauge and coast in neutral until you get a reading. Do the exact same thing again, except engine brake, reset the gauge, and engine brake until you get a reading. Compare the OBVIOUS differences in what the computer reports and get back with me. Surely the cars very own computer is proof enough that you're a friggin' genius. And I thought only chuck norris could divide by zero.

Guess I was wrong after all....

Kolia

iTrader: (2)

I just got up this morning. And it's already a good day !

Merry Christmass to all!

luty77

I finished all of my popcorns.
Is the show still on?

97supratt

iTrader: (61)

+1

lilquazyvietboi

mmm, im a slow reader... and i read everything... -_-

does it really matter which way u slow down and how much fuel u are consuming?

i use the e-brake to stop... both of ur ways suck... e-brake owns u both. now stfu

Miko

iTrader: (2)

Just curious, if one is in gear and off the gas and turns off the engine, what happens? Does it continue to roll till low rpms and stall?

horse110

iTrader: (3)

^ u can park on a hill with engine off, put in 1st, release any brakes and the car will stop on the gear, that's why we park in gear.