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Old 06-22-2022, 02:47 PM   #15
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Never thought about this until Diesel hit $5+. Does the use of engine braking cause a significant change in MPG? I'd imagine it would not when trips are long and on the interstate. How about backroads and in town driving? Would the additional fuel burned ever equal a brake drum/pad replacement?

Of course not. If the brake is on and you depress the accelerator, it disengages. When you're using it to slow down your foot is not on the accelerator. If it was, it would disengage. Using it is no different from coasting. It doesn't matter what kind you have. It doesn't use any fuel to do what it does.
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Old 06-22-2022, 02:49 PM   #16
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I seldom leave my PacBrake on if not actually using it.

If it is on and I inadvertently take my foot of the accelerator the brake will activate and I put more pressure on the accelerator.

Agree with concept of coasting and squeezing a little better mpg out of the rig.



But if I'm going down any type of grade that requires the PacBrake I don't hesitate to use it. No doubt in my mind it reduces wear and tear on the brakes and the costs to repair/replace.
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Old 06-22-2022, 03:02 PM   #17
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Of course not. If the brake is on and you depress the accelerator, it disengages. When you're using it to slow down your foot is not on the accelerator. If it was, it would disengage. Using it is no different from coasting.

Disagree, in terms of MPG, coasting is very different than "brake on" (be it engine brake or service brake).
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Old 06-22-2022, 03:20 PM   #18
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As others have said, it depends on what unit you have and how you are using it.

My pick up has an exhaust brake and if I leave it on all the time I lose some of the coasting effect meaning I will use more fuel. How much, I do not know.

In my HDT, I have: Auto, 1/3, 2/3 and Full. I leave mine in auto driving down the road most of the time. It does not engage unless I hit the brakes enough to really start decreasing motion. A simple tap does not engage it. When I am driving in areas that I need a fair amount of braking, I will bounce between the 3 non-auto settings. I only use enough braking to accomplish my needs. Sometimes that is 1/3 and others it is Full plus service brakes.

I also have a "eco-roll" mode that kicks the transmission into neutral if powered acceleration or deceleration is not needed.
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Old 06-22-2022, 03:23 PM   #19
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The Colorado Department of Education requires all school buses used in the mountains must be equipped with retarders(usually electromagnetic on the driveshaft on FREDs) or keep all passengers out of the most forward curbside seat unless they have and use a seatbelt. The district chief mechanic told me they get at least 200,000 miles out of a set of foundation brake pads when the drivers use the retarders as designed and intended. I have used the Klam or Telma brand electric retarders for thousands of miles and am a big fan.
My coach has a Pacbrake brand of engine exhaust retarder. I have learned to operate it effectively over the years to get the best performance it can provide by modifying my driving techniques. I use it all the time by manually engaging and disengaging it with the OFF/ON switch on the leftside switch panel.
The key is keeping my eyes focused 15 seconds ahead of the coach when at all possible given the sight distance or following distance conditions. Very little escapes my notice. Slow movers, drivers with poor lane or speed discipline, stale or fresh red or green lights ahead, exit and entry ramps, side traffic which may run stop signs or run red lights to turn right without first stopping as the law requires, etc. When I change my focus point it quickly goes to the side mirrors before quickly returning to down range. Especially useful when some doofus enters a freeway well behind you and tries to get in front of you before he runs out of the acceleration lane.
I like to coast instead of wasting fuel or brake linings when I see the need to slow down because of existing or developing conditions I can see and anticipate. I play the Exhaust Brake switch like a single key piano when I feel the time is right or immediately when I feel the need to stop immediately.
The foot comes off the GO pedal first. The SLOW switch comes on next. The foot pushes on the STOP pedal last until stopped or slow enough to reverse the procedure and accelerate.
Result is the most mileage out of the fuel, most miles out of the brake linings and the least drama and stress during the drive.
...
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Old 06-22-2022, 03:27 PM   #20
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I think the key word is BRAKE. Anytime you convert motion into heat, you are not maximizing fuel mileage. Doesn’t matter which kind of brake it is.
So, stopping is a waste of fuel. Not sure how to avoid that.
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Old 06-22-2022, 03:33 PM   #21
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I have learned to operate it effectively over the years to get the best performance it can provide by modifying my driving techniques. I use it all the time by manually engaging and disengaging it with the OFF/ON switch on the leftside switch panel.


The key is keeping my eyes focused 15 seconds ahead of the coach when at all possible given the sight distance or following distance conditions. Very little escapes my notice. Slow movers, drivers with poor lane or speed discipline, stale or fresh red or green lights ahead, exit and entry ramps, side traffic which may run stop signs or run red lights to turn right without first stopping as the law requires, etc. When I change my focus point it quickly goes to the side mirrors before quickly returning to down range. Especially useful when some doofus enters a freeway well behind you and tries to get in front of you before he runs out of the acceleration lane.
I like to coast instead of wasting fuel or brake linings when I see the need to slow down because of existing or developing conditions I can see and anticipate. I play the Exhaust Brake switch like a single key piano when I feel the time is right or immediately when I feel the need to stop immediately.

Result is the most mileage out of the fuel, most miles out of the brake linings and the least drama and stress during the drive.
...

EXACTLY!


No different than in your gasoline car.



Some are on the throttle right up until they have to hit their brakes, others of us go from throttle to COAST to brakes. It is the looking ahead and anticipating that makes the difference. Sadly, today many drivers are so distracted that they don't even think about driving economically.



See the light turn red 3 blocks ahead? Choice-- take your foot off the throttle and coast or continue on the throttle right up until you need to brake. Same decisions in any type of vehicle.




Hopefully, they will continue to have the $$ to pay for their "less than economic" driving habits.
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Old 06-22-2022, 06:20 PM   #22
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I have my exhaust brake programed so the activation/deactivation is controlled by my foot.

The switch is always in the ON position (with the exception of inclement weather), but is not activated until I step on my service brake. It remains active until I tap on the throttle which deactivates it.

I live in the west and do a lot of mountain driving and this setup allows me to keep both hands on the wheel and still be able to activate and deactivate the exhaust brake as needed. For example if I'm in rolling hills I can step on the brake at the top of the descent to activate the brake, and then as I get close to the bottom I can tap the throttle to deactivate it and coast a bit prior to ascending the next climb.

A friend of mine has a coach with an engine brake and has his programed the same way. He leaves his switch in the LOW position and then has the option of selecting the HIGH position if required.
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Old 06-22-2022, 08:08 PM   #23
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The answer is IT DEPENDS.


On flat ground, not so much.


In rolling hills, quite a lot. Instead of coasting down the small downgrade and building a little speed, you apply the BRAKES (doesn't matter if service brakes, exhaust brake or engine compression brake). Then on the next uphill, instead of trading some of the extra speed for elevation, you very quickly go to WOT to climb the next hi.


And, if in power mode vs economy mode, you would probably quickly drop a gear so WOT at higher RPM.


I would never want to eliminate my favorite "gear"-- COASTING!



YOUR CHOICE.
YES, to all the above. I like your style.
I have some stories I could tell when I hauled our equipment to different job sites, that's Heavy Equipment folks.
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Old 06-22-2022, 08:19 PM   #24
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EXACTLY!


No different than in your gasoline car.



Some are on the throttle right up until they have to hit their brakes, others of us go from throttle to COAST to brakes. It is the looking ahead and anticipating that makes the difference. Sadly, today many drivers are so distracted that they don't even think about driving economically.



See the light turn red 3 blocks ahead? Choice-- take your foot off the throttle and coast or continue on the throttle right up until you need to brake. Same decisions in any type of vehicle.




Hopefully, they will continue to have the $$ to pay for their "less than economic" driving habits.
Yep. That's the way I do it. I just hate it when I am riding with someone who throttle up to the stop and then hit the brakes instead of just coasting. I mean it drives me crazy, lol. Guess who does that in my house. Hint: Their are only 2 people living here. You probably didn't need the hint.
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Old 06-22-2022, 09:20 PM   #25
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I think the OP was asking something different then some of the responses that were provided. I believe the OP was asking if more fuel was being used when the engine brake was on. The answer.....no fuel is being used when the engine brake is being applied, so no loss of mpg.

Now you could argue that some loss of mpg is happening because you're not coasting down a hill, but if you're using your engine brake/exhaust brake properly, it shouldn't affect the mpg at all. As soon as it's not needed, turn it off and coast or add throttle. You can't argue that you can coast or use engine brake at the same time. If you can coast safely, there is no need for engine braking. And....just the opposite, if engine braking is needed, you're certainly not going to be coasting.

Lastly, engine/exhaust braking shouldn't be used excessively during stop and go traffic, like in town, or slow traffic on the highway. It can cause foot brake glazing and later squealing.
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Old 06-22-2022, 09:25 PM   #26
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Yep. That's the way I do it. I just hate it when I am riding with someone who throttle up to the stop and then hit the brakes instead of just coasting. I mean it drives me crazy, lol. Guess who does that in my house. Hint: Their are only 2 people living here. You probably didn't need the hint.
I am in the same boat and it definitely does drive me crazy! I have about given up on the situation ever improving. We're both long out of warranty and still upside down.
...
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Old 06-23-2022, 05:52 AM   #27
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My engine brake is programmed the same as Bob said in #22. It's so easy to control the Jake with a tap on the brake to engage or a tap on the accelerator to disengage. I've descended a hill both ways. I highly doubt that over the course of a 500 mile day, the use of the Jake has any measurable impact on mpg. Certainly not enough for me to care one way or the other. Driving 3-4 mph slower will result in a greater savings.
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Old 06-23-2022, 06:11 AM   #28
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I don’t know what my mileage is without my engine brake.
It’s on 100% of the time.
Heading to Yellowstone now. I’m at 7.4 mpg for my first 1000 miles pulling my Jeep.
I did slow down to 62-64mph this yr. Last yr I was riding at 70mph.
Trying to save 1/2 a mile per gallon
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