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      04-16-2012, 11:58 PM   #1
SD_F30
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Engine Braking

There are two 3 series in my garage. My wife's 2006 330i who used to be the darling of the home and now my F30 328i. Before the F30 I had an E46 325i. I love driving all three but I was really surprised by the lack of engine braking the new motor provides.

I've always been more apt to down shift and allow the motor to help me brake before entering a corner, or while I'm going down hill and don't want to over use the brakes. The 325i and the 330i have no issue with this at all. In fact both are quite good at it.

Downshifting the N20 feels like it has little effect on slowing the vehicle. I guess I need to adapt my driving style and use the brake pedal more. Is anyone else experiencing a similar adjustment? Is it frustrating? or just that... an adjustment...
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      04-17-2012, 12:23 AM   #2
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In the auto, the car is now 8 speeds so downshifting a gear will do less to slow down the car than it would in the older cars with less gears.

If we're speaking of manual transmissions, my best guess is that a 6-cylinder naturally aspirated car will have a lot more resistance to keeping revs up compared to a 4-cylinder turbo during engine braking. Also, lower horsepower cars do tend to lend better engine braking capabilities.

The car (F30 328i) has been an adjustment for me as well. It may be called a BMW 3-series but from someone who is very familiar with the previous generations... it is definitely a different car in terms of feel. Still a great car, but definitely different.
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      04-17-2012, 12:40 AM   #3
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I have been told that modern transmissions aren't designed for actively braking the vehicle, and by using your engine to slow you down you're likely to trash the gearbox.

The only time I engine brake is when I'm going down a steep hill and I want to keep the car from accelerating without overheating my brakes.
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      04-17-2012, 01:40 AM   #4
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I also owned a 04 325ci, 06 330i, and 09 328xi before. Tomorrow I will pickup my 12 328i Sport. For engine braking I did a lot on my 325ci and 330i but the 09 328i has so little effect in that. I will see how it feels once I have the new 328i. When I test drove the new car, one thing I notice immediately was that the car is so "artificial" and so much electronic involved in the driving experience.

For the pleasure of driving, I still like my 04 325ci and 06 330i.
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      04-17-2012, 01:42 AM   #5
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Engine breaking is no longer in favour in the modern age and driving instructors are placing less emphasis on it.

Simple reason: brake components are cheaper to replace than engine and transmission components so drivers are now encouraged to place the wear & tear on the brakes.

Whether or not you agree with this philosophy is another matter but it makes sense.
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      04-17-2012, 01:52 AM   #6
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Quote:
Originally Posted by PrinceBarin
Engine breaking is no longer in favour in the modern age and driving instructors are placing less emphasis on it.

Simple reason: brake components are cheaper to replace than engine and transmission components so drivers are now encouraged to place the wear & tear on the brakes.

Whether or not you agree with this philosophy is another matter but it makes sense.
+1 ^^

Although I downshift with my 330d (6MT) to utilise engine braking, it is usually in combination with light braking, unless going down a hill, in which case I solely rely on engine braking unless slowing to a stop.
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      04-17-2012, 04:05 AM   #7
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Engine braking is really a result of high pumping losses, and to a lesser extent, helped by friction.

Latest engine designs reduce both, the key area is the valvetronic function, reducing the vacuum and resulting pumping losses on the over-run. Hence why the older engines with throttle plates have better engine braking. Smaller valvetronic I4 turbo engines will reduce the losses even more, as will the effect of extra (and longer) gearing. To get engine braking we need to change down more gears and get the help of more friction, so we will be stressing the drivetrain parts more.

Diesel engine cars have always had less engine braking, principally due to having no throttle plate in the intake manifold.

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      04-17-2012, 08:27 AM   #8
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There is certainly a lot less engine braking in my new 335 versus my old 135. It's kind of annoying to accelerate downhill in sixth gear.
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      04-17-2012, 08:35 AM   #9
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I'm glad that this post came up. Like most of the people have mentioned, I think that we were all trained to use engine braking 1) as a good practice w/ manual transmissions and 2) as a great method to avoid overheating the brakes in downhill slope situations. I know that this practice saved me a lot of $$ in the 90's on brakes and rotors when I was driving steep inclines on a regular basis back and forth to university.

However, with my E92, I've found myself questioning the benefit of engine braking in the past couple of years. I live in Columbus, Ohio now (which is about as devoid of steep inclines as a corn field) and I've seen the negative effect that engine braking has on my average fuel economy. Still, by matter of training, I find that it's a hard habit to break, and it's like unlearning a good practice.

I definitely agree with the comment about the braking components being less expensive than the engine components, and for those of us that are in (or will be moving to) an automatic transmission with the F30, it really makes more sense to let the brakes handle the stopping component, from both a fuel economy perspective and also from the design of the transmission.

Am I right in this line of thinking?
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      04-17-2012, 10:03 AM   #10
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Kind of sucks with this engine breaking thing. During winter I use it very much in my manual vw 2007 golf/rabbit tdi. But in the Audi q5 7speed auto there is next to no engine breaking when I downshift. Almost got me in some trouble.
From where I am people put the emphasis on engine breaking during winter, so it disappoints me that manufacturers are stepping away form this practice.
Well, I guess you can't have them all when it comes to technological progress.
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      04-17-2012, 10:16 AM   #11
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Fuel Economy? I'm not sure there is a negative impact on fuel economy when your foot is off the gas and the engine is being used to slow the vehicle. If there is anything I have learned so far in life it's " I could definitely be wrong!". So let me know if I've got the wrong idea.

My sport line is equipped with the 8 speed transmission and it seems to be an ace at rev matching. Am I wrong in believing the rev match is a feature that decreases wear on the motor and transmission when down shifting?

I live on a huge hill and have to go up and down it all the time. Going up wreaks havoc on my gas mileage. But I'm hoping I can decrease the wear on my brakes by using 5th while going down the hill. If I just take my foot off the gas and let the car go down the hill with no brakes I'll end up doing 85mph near the bottom. So fun! But highly irresponsible...

As far as the twisty roads go, of course getting into the right gear quickly is the best way to take the corners but I'm finding the sport auto setting is pretty damn good at getting the right gear first. The paddles are getting neglected!

Thanks for all of your thoughts!
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      04-17-2012, 11:00 AM   #12
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Hi SD_F30, are you referring to engine braking only for manual transmission cars, or have your 325i and 330i been auto transmissions which you've been able to do a lot of engine braking on?
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      04-17-2012, 11:15 AM   #13
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Quote:
Originally Posted by tr0tt3r View Post
From where I am people put the emphasis on engine breaking during winter, so it disappoints me that manufacturers are stepping away form this practice.
Well, I guess you can't have them all when it comes to technological progress.
I'm not sure the manufacturers are stepping away from engine braking, as if being built in, the advances in design mean it just isn't there, as we know it.

Sure we can still engine brake, just means we need a lower gear and more revs, to retard the vehicle.

I've been driving diesels for years, so engine braking went 'soft' for me years back, but I still use it on the 330d auto when needed, particularly in the mountains and in winter driving.

The six speed auto will instigate engine braking on a descent, even in the diesel, (I'm sure the 8-speed will do so as well), just feels hard on the drivetrain as it ups the revs, by typically instigating a double down change.

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      04-17-2012, 03:02 PM   #14
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I just don't understand the point in engine braking.

People used it in the past because brakes just weren't effective enough, but why use it these days except for keeping your speed in check when going downhill?

If it's winter, put winter tyres on and if you're still sliding then brake earlier and more gently.
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      04-17-2012, 03:32 PM   #15
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Moreever, brake pads and rotors are much cheaper than driveline components.
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      04-17-2012, 03:58 PM   #16
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Quote:
Originally Posted by Feanor View Post
I just don't understand the point in engine braking.

People used it in the past because brakes just weren't effective enough, but why use it these days except for keeping your speed in check when going downhill?

If it's winter, put winter tyres on and if you're still sliding then brake earlier and more gently.
I know our brakes are so much better these days, but there is still a good feeling when pushing on, balancing a car on the throttle. That can only happen when you can load/unload the drivetrain.

Autos aren't really designed for that anyway, just the following, as applied to the 6-speed autoboxes.

Quote:
Driving downhill
If the EGS control unit detects downhill driving, it will automatically shift down a gear if the vehicle's speed picks up. This enhances the engine's braking effect. A downshift is only effected if the engine speed is below the maximum speed of the lower gear.
The EGS control unit detects downhill driving on the basis of signals from the throttle valve potentiometer (load), wheel speed sensor (road speed) and brake light switch (brake activation).
As to driving in snow, even on winter tyres (as I use), engine braking using the rear wheels, is the safest and more controlled way to deccelerate fast and straight, if conditions are bad.

Plus it means if the roads are empty (as they often are up here), you can press on a bit faster on snow, with the benefit of engine braking.

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      04-17-2012, 09:14 PM   #17
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SGSCUBA

All of my BMW's have been autos. Which is funny because I've always been a manual tranny snob. I wanted to buy the F30 in manual but then I drove the 8spd. That is an amazing transmission it literally transforms the car into a racing beast! Best $500 I've ever spent.

I am making adjustments to how I drive with the lack of substantial engine braking in the F30. I do think about how it effects, maybe wears, the drivetrain if over used, but I believe the vehicle is designed to handle it if used moderately.

Again that 8spd is AMAZING! I'm do in live with this car!
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      04-17-2012, 10:32 PM   #18
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Quote:
Originally Posted by SD_F30 View Post
I do think about how it effects, maybe wears, the drivetrain if over used, but I believe the vehicle is designed to handle it if used moderately.
I wouldn't be too concerned; there is little engine compression and the auto will not allow a downshift which over-revs. Competent brake modulation provides much greater control however.

Quote:
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. . . it literally transforms the car into a racing beast!
Uh, no. Not even close.

It's a nice transmission and a pleasant car, but not a sports car and nothing like a race car.
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      04-18-2012, 08:04 PM   #19
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Quote:
Originally Posted by SD_F30 View Post
There are two 3 series in my garage. My wife's 2006 330i who used to be the darling of the home and now my F30 328i. Before the F30 I had an E46 325i. I love driving all three but I was really surprised by the lack of engine braking the new motor provides.

I've always been more apt to down shift and allow the motor to help me brake before entering a corner, or while I'm going down hill and don't want to over use the brakes. The 325i and the 330i have no issue with this at all. In fact both are quite good at it.

Downshifting the N20 feels like it has little effect on slowing the vehicle. I guess I need to adapt my driving style and use the brake pedal more. Is anyone else experiencing a similar adjustment? Is it frustrating? or just that... an adjustment...
I found this problem also, but I found in Sport mode it holds a lower gear which provides fairly good engine braking downhill. (I have Auto)
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      05-03-2012, 09:33 AM   #20
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Engine braking is an essential part of brake force regeneration. While engine braking the crank pulley is revved up. Alternator & AC compressor are driven by the crank pulley and thus benifit from these extra revs. In the case of the F30, the alternator is engaged only during engine braking. BMW thus must have thus used valve idling. A technique used to eliminate engine resistance during engine braking and make available the entire returning force available at the crank pulley for the alternator to harvest. The alternator should be providing resistance now. But from what you guys say, obviously its not the same. :'(

Last edited by Ganeshbabu2008; 06-27-2012 at 08:04 PM.
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      05-03-2012, 10:44 PM   #21
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Quote:
Originally Posted by PrinceBarin View Post
Engine breaking is no longer in favour in the modern age and driving instructors are placing less emphasis on it.

Simple reason: brake components are cheaper to replace than engine and transmission components so drivers are now encouraged to place the wear & tear on the brakes.

Whether or not you agree with this philosophy is another matter but it makes sense.
I never bought that argument even when I heard oh so so many years ago. Most instructors and drivers use the engine not to save brakes, but to be in gear if needed.
There is no more strain on the engine helping slow the car than there is on the engine accelerating the car.
In decel the engine is simply helping slow the car, you still need your brakes to come to a stop. Using this method means you are in gear and have acceleration available if you need it.
Coasting should only be done under 20mph then braking to stop.

If the extra wear were true, then all automatics would be wearing their engines quicker as the trans is always engaged, unless you put it in neutral, and who does that in an auto.

It doesn't make sense and thus I don't agree with it.

To this issue of less compression braking, the N55 and N20 use valvetronic, which does not have a throttle plate.
So, there is likely less restriction, less vacuum by which to slow down as hard.
The benefit is less pumping loss as well, and better MPG overall.
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      05-03-2012, 11:02 PM   #22
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Quote:
Originally Posted by HighlandPete View Post
Engine braking is really a result of high pumping losses, and to a lesser extent, helped by friction.

Latest engine designs reduce both, the key area is the valvetronic function, reducing the vacuum and resulting pumping losses on the over-run. Hence why the older engines with throttle plates have better engine braking. Smaller valvetronic I4 turbo engines will reduce the losses even more, as will the effect of extra (and longer) gearing. To get engine braking we need to change down more gears and get the help of more friction, so we will be stressing the drivetrain parts more.

Diesel engine cars have always had less engine braking, principally due to having no throttle plate in the intake manifold.

HighlandPete
Yes. I posted before I read your post.

Back to the question of engine braking, in general, not directed at you;
I think some overstate this. It's not recommended to slow from 60mph by putting your trans in 2nd gear thus the engine will rev to near red line. Slowing using the proper technique means you are downshifting accordingly to vehicle speed. So if you are at 60mph in 6th, you let off the throttle and begin slowing down. As your vehicle speed reaches 40, for example, you downshift to say 3rd or 4th, or the gear that puts engine speed/rpm where it would allow you to accelerate if needed.
Of course all this time you are braking, and the brakes are still your main source of slowing down. Slowing on a hill is a different consideration.

I only downshift to about 3rd. Once I'm down to about 20mph I'm mostly coasting but using my brakes to come to a stop, but I'm in 2nd gear in case I need it. It's just that by that point there is no need to actually be in 2nd as you're about to stop. The gear is selected in case you need to accel for whatever emergency, like the car behind you is not slowing and you need to get out of the way.
Some people are over simplifying the use of engine braking as if it's an all or nothing condition.
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