Engine Braking in Emergency Situations

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HighlyEvolved
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Engine Braking in Emergency Situations

Post by HighlyEvolved »

So the other day I was driving at around 50mph on a somewhat rainy pavement, I had to brake just a bit hard and the car slipped a good 10 feet. with my foot fully stepped on the brakes, the damn car still slid along the street like a cube of ice. Thank god there were no cars nearby, so after this scary experience I realized that I forgot how to engine break lol :P
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Post by FaKk2 »

Downshift with no rev match. Although be careful and do not block your leading wheels.
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Post by jomotopia »

you shouldn't use active engine braking to slow down in an emergency, especially in slippery conditions. engine for go, brakes for slow. it sounds like you don't have ABS so when your wheels lock up you should release and reapply the brakes.
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Post by FaKk2 »

jomotopia wrote:you shouldn't use active engine braking to slow down in an emergency, especially in slippery conditions. engine for go, brakes for slow. it sounds like you don't have ABS so when your wheels lock up you should release and reapply the brakes.
Why you shouldn't use engine braking in emergency?
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Post by jomotopia »

b/c it's more stuff to do and more stuff to screw up. and especially when it's slippery it will upset the balance of the car and the tire's traction. in an emergency braking situation, just brake. you have much more control of slowing the car with the brakes than with the clutch and that is what the brakes are designed to do. it is not what the clutch and engine are designed to do.

actually i'm not a proponent of active engine braking at all but some people will disagree.
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Post by FaKk2 »

jomotopia wrote:b/c it's more stuff to do and more stuff to screw up. and especially when it's slippery it will upset the balance of the car and the tire's traction. in an emergency braking situation, just brake. you have much more control of slowing the car with the brakes than with the clutch and that is what the brakes are designed to do. it is not what the clutch and engine are designed to do.

actually i'm not a proponent of active engine braking at all but some people will disagree.
I am sorry, but you are missing an important point. Let's emagine a situation, you are driving on a slippery road at 50 mph on 6th gear doing 2500 rpm. Suddenly you see a person jumping on the road just in front of you. You hit the brakes and the clutch. Even tho you have ABS, you are just moving too fast, in s split of a second you realize that and try to dodge, spinning your steering wheel to the left. But sorry... there is nothing to pull you to the left, b/c your wheels are on their own.
Now imagine another situation: You hit the brakes and downshift into third, your RPM jumps to 5000, you feel the sudden car brake lug. Same thing, you realize that you are moving too fast and you try to dodge left. You let go the brakes, floor the gas, and b/c at 5000 RPM your engine has most of it's power it easily pulls you to the left, and you successfully pass the idiot.
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Post by jomotopia »

^^ as long as your wheels are rolling, you can still steer. but that is also why you should brake in gear and not slam the clutch until the last possible second to keep from stalling.

if i needed to speed up to avoid them i would downshift when i realized it and i could have it in gear in the time it takes me to get from the brakes to the gas. but the situation where you will need to brake hard first and then turn and speed up is probably not nearly as likely as one where you will just need to brake and/or steer. and most of the times i can recall that i needed to speed up i needed to do so right away, not brake hard first.
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Post by PureLife »

You shouldn't (and I guarantee you never will) engine brake in an emergency ... sure, it might work in certain situation, but an emergency is ... well quite urgent and I can almost guarantee you wont remember to shift ... instinct takes over when things get hairy.

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Post by FaKk2 »

jomotopia wrote:^^ as long as your wheels are rolling, you can still steer.
You can steer, but there is no power for you. You don't need to just steer, you need to manoeuvre and avoid, which cannot be done effectively without engine at its power peak.
jomotopia wrote:if i needed to speed up to avoid them i would downshift when i realized it and i could have it in gear in the time it takes me to get from the brakes to the gas.
Don't forget that such situations develop very quickly, so your only chance is do preventive steps just in case you'll need it.
jomotopia wrote:but the situation where you will need to brake hard first and then turn and speed up is probably not nearly as likely as one where you will just need to brake and/or steer. .
Again, for a manoeuvre you need power and without having it available you might not be able to complete it.
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Post by Prodigal Son »

FaKk2 wrote:Downshift with no rev match. Although be careful and do not block your leading wheels.
If you downshift without rev matching, you get clutch braking as well as engine braking. Active engine braking can be achieved with a rev-matched downshift. As long as the wheels are driving the engine, you get engine braking. The faster the engine is being driven by the wheels, the more engine braking you get. If you must engine brake, rev match it and spare the clutch.
FaKk2 wrote:
jomotopia wrote: ^^ as long as your wheels are rolling, you can still steer.

You can steer, but there is no power for you. You don't need to just steer, you need to manoeuvre and avoid, which cannot be done effectively without engine at its power peak.
I don't know where people get this notion that power improves traction and steering. It is quite the opposite. Power is the enemy of traction. Power is the enemy of steering. Your car will grip the road better and steer better with no power applied. The only thing that stops or steers a car is the traction between the tires and the road, and power fights that traction. Write it in big letters and stick it on your dashboard: Power is the enemy of traction.

The only thing that engine power is good for is acceleration and the maintenance of speed. It is bad for everything else. Unless you need to accelerate to avoid an accident (like you have stupidly pulled out into traffic without a sufficient gap) then power is not your friend in an emergency.

In the case you posit, of trying to avoid a person in the road, you need to slow down as rapidly as possible and to steer as accurately as possible. Neither of these things is enhanced by power (other than the power that runs the power brakes, steering, and ABS). On the contrary, power gets in the way of both.

In a modern ABS car, it is brake and clutch to the floor and steer away from the obstacle. Remember, you will tend to steer towards what you are looking at, so look for the escape, not at the obstacle.
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Post by jomotopia »

FaKk2 wrote:
jomotopia wrote:^^ as long as your wheels are rolling, you can still steer.
You can steer, but there is no power for you. You don't need to just steer, you need to manoeuvre and avoid, which cannot be done effectively without engine at its power peak.
the last thing you want to do in an emergency, especially when it's slippery, is try to apply max power to the ground. esepcially if you have a powerful car. you can steer perfectly efectively with no power.
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Post by eaglecatcher »

Prodigal Son wrote:
I don't know where people get this notion that power improves traction and steering. It is quite the opposite. Power is the enemy of traction. Power is the enemy of steering. Your car will grip the road better and steer better with no power applied. The only thing that stops or steers a car is the traction between the tires and the road, and power fights that traction. Write it in big letters and stick it on your dashboard: Power is the enemy of traction.
I'm going to disagree. I know that when you come out of a corner, and you feel the car losing grip, adding some gas can pull you through and change the momentum from horizontal/sideways, to the direction you want to go, putting less sideways force on the car. Now, too much, and like you said, it is the enemy, it will spin you out even easier, but some power in a turn, can stabilize the weight. I have found that lane changes on the highway are also smoother if you give it some power, instead of just coasting over. I would assume because it helps the car over come the drag at such high speeds. In both cases, adding gas (power) can help shift the momentum from across the cars intended path, more towards the direction you want to go, which in turn makes it more secure. This is not talking about icy or wet or any other variable conditions, just your basic average day, dry, clean pavement, with good tires.

edit: I forgot to mention this, but I am in no way inferring applying max, or even a decent amount of power will help you, rather that a little bit of power, helps you stabilize, which is why you would want to stay in gear, and preferrably out of max power range, because you are not going for speed, you are going for control.
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Post by Prodigal Son »

eaglecatcher wrote:
Prodigal Son wrote:
Power is the enemy of traction.
I'm going to disagree. I know that when you come out of a corner, and you feel the car losing grip, adding some gas can pull you through and change the momentum from horizontal/sideways, to the direction you want to go, putting less sideways force on the car.
This is not really a contradiction. This involves applying power to wheels that have traction to correct wheels that are losing traction. Power is still the enemy of traction. I'll allow that there may be certain situations (outside the race track) where a driver with the appropriate skill, training, and experience, might be able to correct a certain kind of skid with a slight application of power. Most of us, however, would just make things worse by trying.

Though many of us are interested in racing, and in racing techniques, it is important to remember that racing and the street are two different worlds.

For example, when a racing driver skids, their aim is to continue with as little loss of time as possible. On the street, your aim should be to get stopped before you hit anything.

Another example: Threshold braking, if performed correctly, is reputed to give more control and shorter stopping distances than ABS. But threshold braking is a precise skill that takes constant practice to achieve and maintain. For the average driver, mashing the pedal and letting the ABS do its job is a much better option.

For a street driver, it is vital to drive within your skill level. And remember that you cannot learn advanced driving skills on an Internet forum. It requires professional instruction and supervised practice. I think it is really important not to recommend advanced driving techniques without making it abundantly clear that they are advanced techniques and not something people should just go out and try on the streets without instruction and supervision.

Racing driving is all about finding the edge. Responsible street driving is about staying far far away from the edge. (If you find yourself losing traction coming out of a turn on the street, you are driving too damn fast!) Racing driving is about skid control. Street driving is about skid avoidance. The street driver who tries to power their way out of an emergency situation is more likely than not to get themselves and others killed. For most of us, the best hope we have of a successful outcome is to get off the power and steer.
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Post by screenname »

paul34 wrote:If you don't have ABS, pump the brakes. Otherwise if you can, apply enough pressure to right before the brakes start to lock up.
That latter technique is called threshold braking. It isn't something you'll be able to do after a quick spin in the car - you have to know the exact amount of pressure to apply to get that much braking.
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Post by TomCivic »

If your not going highway speeds, would it be a good idea to just pop it in 2nd and break at the same time?
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