I've driven a Volvo around a town with only minimal brake usage, namely when the exhaust brake stopped working in really low speeds. Does that make me a complete retard?
Poll : Which method is more efficent.
A few more revs with a bit less throttle
61
A few less revs with a bit more throttle.
39
I've driven a Volvo around a town with only minimal brake usage, namely when the exhaust brake stopped working in really low speeds. Does that make me a complete retard?
Rubbish. Utterly rubbish.
10 seconds to drop 10km/h???? Something is wrong with your car!! Unless, of course, you left it in top gear and just lifted. That's not what you do on a downhill stretch of road. You use a lower gear and higher revs. Not redline revs, but around the peak torque rpm. I can assure you that it will reduce brake temperatures by around 50% on the way down a mountain.
Perhaps the naysayers have never driven down a mountain in a car with weak brakes, and had to rely on engine braking?
Perhaps the naysayers have never driven down a mountain in a car with weak brakes, and had to rely on engine braking?
Rubbish? No. I posted a factual statement (I can get video evidence later to show this IS what happens), that simply proves that engine braking is not all it's cracked up to be. And that is in 5th gear, hitting about 5000 revs at 160km/h, with obviously at least 160km/h worth of wind against me, and no other cars around causing disturbances.
I couldn't care less about what your car does in the situation, I'm telling you this is what happens in my car, and that is why engine braking is pointless in my car. I don't remember saying "Engine braking is shit and anyone who does it is a complete tool"? Unless you happen to own a 1st gen 1.0l Yaris VVT-i and can prove this isn't what happens, don't claim it to be rubbish
Yes it does. Your brake lights are there for a reason. Stopping in town with minimal brake usage is what causes crashes, when the driver behind you can't anticipate you stopping.
Tristan, that's what happens in my car, in the situation earlier in this post. I couldn't have selected a lower gear without pushing the redline, which I have no intentions of doing (although it does sound amazing in this car, it goes all the way to 7k :schwitz
, and as you say is not what you would be doing going downhill. There's nothing wrong with it that I know of, it has the exact same performance as every other Yaris. Granted, the engine power isn't exactly astounding, and I wouldn't expect it to have amazing engine braking as a result (I'd imagine bigger engines would have more of a vacuum effect? Not sure on this though...).Also, I have a Mini. Don't talk to me about dodgy brakes
Look, if a a ****ing 26 ton lorry can do it, so can your petty yaris. Plus, if you crash into the back of one of those... without spotting it moving slowly (as they normally do), I wouldn't blame the truckdriver first.
Et cetera ad nauseam.
Yes, because a 26 ton diesel lorry (presumably it's the FM series if it's around 26 ton, so it's at least 9l displacement and turbo'd) follows the exact same physics as a 900 kg petrol 1l car :rolleyes:
Actually, it's far more likely to happen in a truck. The driver behind can't see what's in front of you, and doesn't know if you're slowing down or stopping. At least in a car he could see the traffic in front and anticipate your braking.
Actually, it's far more likely to happen in a truck. The driver behind can't see what's in front of you, and doesn't know if you're slowing down or stopping. At least in a car he could see the traffic in front and anticipate your braking.
so when your engine is idling, it is using the 'idling cam'.
so it is using less fuel than when using the other cams...
... which is still more than when coasting downhill, in gear (0).
but the saving is even better?
lolwut?
I meant the engine wear saving. Sorry, but I'd rather spend an extra 0.004 MPG at most (my MPG indicator only has 2 decimal places, so it's probably less...) to save 4 times the work on the engine, plus as you say, it's even more of a saving when the idle cam position is open. The car gets enough of a thrashing at times, so I try to save every little bit where I can I agree that the reduced engine wear won't be visible during my time with the car (only another 8 weeks), but sitting at 600 RPM for a few hundred yards is better than sitting at 3000 RPM.
And in the Mini, it doesn't use "0" fuel when coasting. As it runs on a carb, the throttle is always slightly open to allow enough fuel through to keep the engine ticking over at idle. Without an ECU, this is always open, even when coasting. I presume that doesn't apply to injected engines though, as the ECU should close the throttle when coasting?
I agree that the reduced engine wear won't be visible during my time with the car (only another 8 weeks), but sitting at 600 RPM for a few hundred yards is better than sitting at 3000 RPM.And in the Mini, it doesn't use "0" fuel when coasting. As it runs on a carb, the throttle is always slightly open to allow enough fuel through to keep the engine ticking over at idle. Without an ECU, this is always open, even when coasting. I presume that doesn't apply to injected engines though, as the ECU should close the throttle when coasting?
Dude, you're not paying attention. It's obvious I meant that you use the engine to maintain a normal speed. If you're not in gear you'd have to be on the brake all the time not to speed up. Of course you'd use the brake if you needed to stop or slow down a lot.
Basically you're saying I left out "only" or "a lot" from my sentence (which any normal person would've figured out I meant anyway) and you get on such a tantrum over one word?
just because one is a small number, doesn't mean that the content can't change completely just from one word.
and if a normal person can figure out what you wanted to say, without you actually saying it, why would i want to listen to you, then?... and why would you want to do the effort?
and if a normal person can figure out what you wanted to say, without you actually saying it, why would i want to listen to you, then?... and why would you want to do the effort?
Actually state side (at least in mine) putting it in neutral is illegal.
You mean there are different laws of physics for trucks and cars?
So that explains why I sometimes get pimply 17 year old kids in their Mum's Yaris thinking they know best about what constitutes safe driving.
That's ad hominem, therefore your argument is invalid.
Most engines brake a lot by themselves at high rpms. In fact, if you'd go down a steep hill, putting your car in first gear would keep it at a steady 20km/h, without needing to touch your brake pedal. Ofcourse it won't come to a complete stop without using your brakes, but it's enough for keeping your speed low.
On-topic: I'm not sure which one's the most economical, but I do know that using a lower gear will stress the engine less. Just like going up a hill on your bicycle, in a high gear, will stress your joints more than using a lower gear.
Sarcasm detector broken, or just plain trolling
When did I say it was safer to do anything? I said what I do when I'm driving, as I believe it to be the most beneficial for the car. I don't think taking the car out of gear is going to make me spin off the road and barrel roll into the nearest field, thank you very much. I don't know why you're having a spa attack over it anyway, I don't even live in your country, so when I cause an over 7000 car pileup because I popped into neutral going down a slight hill, you're not going to be involved.
And I do know better than quite a few people on the roads, I passed my test first time after 2 lessons, I've been driving almost a year on the road, and 3 or 4 off the road, with not even a scratch on anything I've driven. I've a fully clean license, not even been cautioned before. And guess what, I've been coasting downhill in neutral for the past year, and I haven't even had a car implode as a result
Sorry, did I touch a nerve?
I never take my car out of gear when moving, with the exception of going <10mph on the approach to red traffic lights when I pop it into neutral and coast the last metres for a gentle stop (and even if it was in gear, I'd have the clutch pedal depressed anyway rather than force it into first gear whilst moving).
Having the car out of gear robs you of control, and in the UK I believe you'd fail your driving test for coasting. An automatic transmission isn't a valid comparison as power is applied again as soon as you open the throttle, unlike being in neutral in a manual.
I'm not really concerned how long you've been driving (although if we're comparing e-penii, I've been driving 12 more years than you, never needed a formal driving instructor, and, touch wood, have never so much as had a scrape. W00t, go me.), it's the fact that you obviously don't understand the physics and reasons behind why you shouldn't coast. It's inherently linked to safety and your ability to control the car in the event of an emergency or unforeseen situation, and if you think there's no way you're going to have any unforeseen situation when coasting down a slight incline, then you're only proving that you've only been driving on the road for less than a year, and if I may say so, don't know shit.
No not really. Just, as Erik said, your post loses any points it may have had (which it didn't) after you attacked the poster. If you're stooping to that level, you can't have much of an argument to fall back on
Good for you. I never said this is wrong or dangerous, even though you would equally fail a driving test for this.
What is this control everyone is talking about? I'm no less in control when I'm out of gear, as long as I have a hand on the wheel. Sure, I can't sharply accelerate instantly, but when do you ever need to do this? I'm still only a couple of seconds from re-engaging a gear if I need to speed up, what situation could this possibly spell disaster for? You would fail a test for this, yes, but 90% of drivers on the roads do things that they would be failed for anyway (like you coasting up to the lights, you hypocrite
)I'm not comparing anything, I'm just pointing out that statistically I'm as safe a driver as you, so your argument of the massive dangers associated with coasting is quite null. I do understand the physics of coasting, you're relying on gravity to keep you going, it's not that hard. I never said there's no such thing as an unforeseen situation, please stop putting words into my mouth
I clearly do "know shit", as I passed a driving test. Therefore I have a certificate showing that I do indeed "know shit" I bet you can't corner as well in neutral as you can in gear (with the clutch engaged of course). Therefore you have less control. Plus you render an active safety system - accelerating out of the way of the juggernaut with no brakes for example - useless.
You can deny it all you like, but being in neutral gives you less control over your vehicle. If you can't see that then I feel sorry for your passengers, who deserve more respect (probably; unless they're chavs of course!!
)
You can deny it all you like, but being in neutral gives you less control over your vehicle. If you can't see that then I feel sorry for your passengers, who deserve more respect (probably; unless they're chavs of course!!
)As I said before, I never mentioned cornering out of gear, if there's a significant corner in the road it's more than likely too steep to coast down anyway. Even still, if it was downhill, you could corner just as well, unless you were trying to keep to rally speeds
In all fairness, it's not hard to see a truck coming towards you at speed in your rear-view mirror. Taking an extra couple of seconds to engage a gear won't make the slightest bit of difference there, as you'd have seen him coming a mile back.
I've yet to find a hazard on the road that requires sharp acceleration (other than having to reach a gap in the ditch when a boy racer comes against you at night on a back road with no intentions of stopping, fairly common on our 1.5 car width roads 
), rather than sharp braking...I'm not trying to justify my driving techniques to anyone, I don't need to, especially over an internet forum. It's what I do, and it seems to work fine, haven't heard any complaints from the back yet
And they're not all chavish, but coming from Stab City what would you expect?? While everyone is trying to have a go at my driving, you should also know that I drive with one hand on the wheel (on a related note however, I am not a chav, so my seat is not reclined at 45°...), I regularly text whilst driving on the motorway and I usually don't stop at the lights if I see them turn amber. Oh, and I have a habit of tailgating anybody going at or below the speed limits. Fire away
Economical driving depends on what part of the actual driving do you mean.
You accelerate with full throttle using gears so you stay around the peak torque revs -> least amount of fuel mass / kWh -> the best efficiency.
Maintaining constant speed should be done in the highest possible gear that the engine is comfortable running in, this usually means 1000 - 2000 rpm below the torque peak.
With a "modern" engine, decelerating should be done by coasting in highest possible gear that keeps you above the rpm range that enables fuel injection again (usually 1500 rpm). While coasting, the lower the revs, the longer you get zero fuel consumption. With a carbureted engine I guess it's irrelevant (or less significant) whether you coast or change to neutral.
Using the brakes wastes the kinetic energy of a car, energy that has been produced by burning fuel. Surviving on the road without using your brakes all the time means you have to learn how to keep a safe distance to the car in front, and continuously observing what happens around you so you can be prepared to lift off and slow down by coasting instead of wasting the energy by heating your brakes.
Of course there are situations where you actually need to brake, and brakes in general need to be used for them to stay in good condition..
Other notes: a car that weighs around 1000kg and takes 10 seconds to decelerate from 160km/h to 150km/h has a Cd*A of around 0,25. Even less if you use engine braking to slow the car down. By comparison, a Mitsubishi Eclipse from late 90's has Cd*A of 0,515.
Toyota VVT-i doesn't have different cams, it just has an adjustable intake cam pulley.
:twocents:
You accelerate with full throttle using gears so you stay around the peak torque revs -> least amount of fuel mass / kWh -> the best efficiency.
Maintaining constant speed should be done in the highest possible gear that the engine is comfortable running in, this usually means 1000 - 2000 rpm below the torque peak.
With a "modern" engine, decelerating should be done by coasting in highest possible gear that keeps you above the rpm range that enables fuel injection again (usually 1500 rpm). While coasting, the lower the revs, the longer you get zero fuel consumption. With a carbureted engine I guess it's irrelevant (or less significant) whether you coast or change to neutral.
Using the brakes wastes the kinetic energy of a car, energy that has been produced by burning fuel. Surviving on the road without using your brakes all the time means you have to learn how to keep a safe distance to the car in front, and continuously observing what happens around you so you can be prepared to lift off and slow down by coasting instead of wasting the energy by heating your brakes.
Of course there are situations where you actually need to brake, and brakes in general need to be used for them to stay in good condition..
Other notes: a car that weighs around 1000kg and takes 10 seconds to decelerate from 160km/h to 150km/h has a Cd*A of around 0,25. Even less if you use engine braking to slow the car down. By comparison, a Mitsubishi Eclipse from late 90's has Cd*A of 0,515.
Toyota VVT-i doesn't have different cams, it just has an adjustable intake cam pulley.
:twocents:
...A few more rev's and little more throttle, time = money.
when its about uphill its better to shift down.
Of course it doesn't have 4 different cams, it does have 3 different intake cam positions, like I said
I guess my car is fairly aerodynamic then?
Maybe it does have something wrong with it, I don't know. It does have a good bit of engine braking when driving in traffic at low speeds though. I can usually drive in traffic just using the gears, without having to touch the brakes, by using engine braking in 1st. I'd still need to use the handbrake just to stop it rolling at <2km/h though. But that's highly dangerous driving, so I don't do it He was pointing out that even with aerodynamic drag alone, your car will slow down faster than you claim, as your car doesn't have a Cd of 0.25.
I'm sorry, I misunderstood your line thinking that what you meant was a 3D cam profile like in Ferraris
Well, a Toyota Prius has a Cd of 0.25, and some cars like Opel Vectra has 0.3.. So he might be ABOUT right.
Economical driving
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