Quick Q for those in the know… does using a retarder/exhaust/aux brake waste fuel?
I was always under the impression it doesn’t, but I’m now led to believe that certain types of exhaust brakes will still be using fuel (makes sense for compression brakes, I guess) and some places now actively discourage use of all/some aux brakes. If it depends on the type, which do/don’t ?
Anyone shed any light?
Also, was ‘told off’ for using exhaust brake when above the green band. Again, was always under the impression that it’s more effective at higher revs
I wouldn’t have thought they use more fuel. In fact they shouldn’t use any fuel as you are not using the accelerator when the exhaust brake is being used. Fleetboard eco support in my Actros encourages use of the exhaust brake as the way to get the best fuel economy from the truck.
damoq:
I wouldn’t have thought they use more fuel. In fact they shouldn’t use any fuel as you are not using the accelerator when the exhaust brake is being used Fleetboard eco support in my Actros encourages use of the exhaust brake as the way to get the best fuel economy from the truck.
On the Mercs unused fuel goes back into the tank so if you’ve used the continuous brake a lot the outside of the tank should feel warm with the fuel which was un spent and sent back to the tank.
Modern exhaust brakes are very fuel efficient. If your foot is off the throttle you aren’t using ANY fuel and the exhaust brake is simply using the compression of the engine and therefore no fuel.
They do need higher revs to be effective but because no fuel is entering the engine it doesn’t make any difference to fuel usage
Aye that was exactly what I thought, & said… on a steep downhill at ~45/50, bang on the exhauster 2 clicks and let the auto-box drop a gear, holds speed back fine without riding the brakes. Only to be told I was burning ■■■■ loads of fuel in doing so
damoq:
I wouldn’t have thought they use more fuel. In fact they shouldn’t use any fuel as you are not using the accelerator when the exhaust brake is being used Fleetboard eco support in my Actros encourages use of the exhaust brake as the way to get the best fuel economy from the truck.
On the Mercs unused fuel goes back into the tank so if you’ve used the continuous brake a lot the outside of the tank should feel warm with the fuel which was un spent and sent back to the tank.
Chris1207:
Aye that was exactly what I thought, & said… on a steep downhill at ~45/50, bang on the exhauster 2 clicks and let the auto-box drop a gear, holds speed back fine without riding the brakes. Only to be told I was burning [zb] loads of fuel in doing so
who ever told you that was talking rubbish and shouldn’t be trusted with a bag of sweeties .
Chris1207:
Quick Q for those in the know… does using a retarder/exhaust/aux brake waste fuel?
Also, was ‘told off’ for using exhaust brake when above the green band. Again, was always under the impression that it’s more effective at higher revs
Ta,
Chris.
As far as I’m concerned whoever has told you that obviously has no idea what they’re talking about.
According to these guys it doesn’t use extra fuel, Ok so it’s a promo video for a company that makes retarders and the primes is a bit unbelievable the script is corny and the acting wooden, but I reckon the message is accurate and nobody of any note has told me different.
What a load of b&&&&&&s ! Foot off throttle = fuel cut. Exhaust brake closes flap in exhaust and works better at higher revs. Engine / compression / jake brake retards by using compression on some cylinders while fuel is cut. But don’t worry, bking will be along to come up with another load of crap like the not forgotten thread about hub reduction or brake chambers, both of which he / she has gone quiet about.
Our company training manny must have been misinformed by Volvo, they told him that their Euro 6 engines should be driven with the engine brake set in auto because fuel consumption will be higher if it kicks in more often in manual
I do not know how true this is however I do know that in auto I had to use the brakes more often than I would normally so I knocked it back into manual to save my brakes.
LowRange:
Our company training manny must have been misinformed by Volvo, they told him that their Euro 6 engines should be driven with the engine brake set in auto because fuel consumption will be higher if it kicks in more often in manual
I do not know how true this is however I do know that in auto I had to use the brakes more often than I would normally so I knocked it back into manual to save my brakes.
If you talking about the VEB, similar to the older Volvo’s, if you have it in auto it will only kick in when you operate the service (foot) brake and you’ll also be in E+ mode, which means you’ll get the Iroll where the truck freewheels in neutral.
However if you leave it in position 1,2or 3, I think it will operate every time you take you foot off the accelerator, which will slow the truck down quicker, which means you won’t roll as far without power on, and therefore will need to be on the accelerator more and therefore use more fuel, you will also be in E mode and therefore won’t have Iroll.
However you can use setting 1,2,3 or B to give you extra braking into junctions and roundabouts or to hold it down hills, and then go back to Auto when you finish the manoeuvre and go back on cruise control.
Chris1207:
Quick Q for those in the know… does using a retarder/exhaust/aux brake waste fuel?
I was always under the impression it doesn’t, but I’m now led to believe that certain types of exhaust brakes will still be using fuel (makes sense for compression brakes, I guess) and some places now actively discourage use of all/some aux brakes. If it depends on the type, which do/don’t ?
Anyone shed any light?
Also, was ‘told off’ for using exhaust brake when above the green band. Again, was always under the impression that it’s more effective at higher revs
Ta,
Chris.
on the over-run or jake the older engines will sill be using about the same amount as when ticking over, but on modern commonrail / drive-by-wire type the fuel is cut to zero when above a certain rpm (1000 ?) and you should be well above that to get any value from the exhaust brake.
I wonder when we will see retarders being replaced with energy recovery systems ? huge amounts of energy is being wasted. I think there has been quite a lot of work has went into capturing the energy as electric, but I did read an interesting article for storing it as compressed air (8000psi or something wacky) this would then be used to supplement the engine up the next hill.
Yes, perfect sense Muckles. I maybe mistook the way the guy at my work mentioned that using the engine brake (VEB) manually would increase fuel usage and what he actually meant was how you described it. All he said was that Volvo recommend it stays in auto to save fuel so I figured it must be something to do with Euro 6. I was of the same opinion as the others on here and didn’t think it would use any fuel at all.
Chris1207:
Aye that was exactly what I thought, & said… on a steep downhill at ~45/50, bang on the exhauster 2 clicks and let the auto-box drop a gear, holds speed back fine without riding the brakes. Only to be told I was burning [zb] loads of fuel in doing so
Post a Photo of them.
If you use exhaust brake the Fuelpump goes to Zero. But,for safety,…if Reps go under special number exhaust Brake gets switched off to keep Power Steering alive.
On older Engine this didnt happen and you switched the Engine off with Exhaust Brake. (European Engines)
US Engines may differ.
If you would inject Fuel in a high repping Engine it just would blow the Head off.
Yes, perfect sense Muckles. I maybe mistook the way the guy at my work mentioned that using the engine brake (VEB) manually would increase fuel usage and what he actually meant was how you described it. All he said was that Volvo recommend it stays in auto to save fuel so I figured it must be something to do with Euro 6. I was of the same opinion as the others on here and didn’t think it would use any fuel at all.
That’s good, I hate trying to explain things in writing much easier to show somebody, and I can’t imagine it would be different for Euro 6.
Bluey Circles:
on the over-run or jake the older engines will sill be using about the same amount as when ticking over,
No they won’t. ALL DIESEL ENGINES cut off the fuel on overrun, all of them. The only vehicles that don’t are those with carburettors, i.e petrol engined vehicles pre-1992.
Bluey Circles:
on the over-run or jake the older engines will sill be using about the same amount as when ticking over,
No they won’t. ALL DIESEL ENGINES cut off the fuel on overrun, all of them. The only vehicles that don’t are those with carburettors, i.e petrol engined vehicles pre-1992.
Hmmm, you say that with some certainty in your voice, now I’m not so sure! I am going back to mechanically driven pumps, and have always understood they would continue to deliver the min amount on the overrun, the rational being the pump always needed to be lubed. ?
certainly commonrail cut off fuel above certain rpm when on the overrun.
Bluey Circles:
Hmmm, you say that with some certainty in your voice, now I’m not so sure! I am going back to mechanically driven pumps, and have always understood they would continue to deliver the min amount on the overrun, the rational being the pump always needed to be lubed. ?
Apprentice trained City and Guilds 381 qualified mechanic. Mechanical pumps cut off the fuel. Half of a pump is lubricated by engine oil - the camshaft etc, the plungers are by diesel. On overrun there is still diesel in the plunger but the metering in the pump keeps it below a pressure that the injector needs to open so you still get the lubrication from the fuel but you don’t get fuel being injected into the engine.
Conor:
Apprentice trained City and Guilds 381 qualified mechanic. Mechanical pumps cut off the fuel. Half of a pump is lubricated by engine oil - the camshaft etc, the plungers are by diesel. On overrun there is still diesel in the plunger but the metering in the pump keeps it below a pressure that the injector needs to open so you still get the lubrication from the fuel but you don’t get fuel being injected into the engine.
thankyou for that … how does the pump (traditional mechanical pump) know it is on the overrun ? manifold vacuum ?
I hate trying to explain things in writing much easier to show somebody, and I can’t imagine it would be different for Euro 6.