tdipoet
Top Post Dawg
i watched all of these videos while driving, and my mileage didn't go up at all.
Hypermiling videos to better fuel consumption
- Thread starter Vekke
- Start date
Vekke
Veteran Member
http://www.youtube.com/watch?v=qVEFsJH7ymU&feature=youtu.be
Long time since the last video. This video shows how stupid it is to drive with small safety gaps and waste fuel on the motorway. I try to post more videos in the next couple of weeks.
Long time since the last video. This video shows how stupid it is to drive with small safety gaps and waste fuel on the motorway. I try to post more videos in the next couple of weeks.
VeeDubTDI
Wanderluster, Traveler, TDIClub Enthusiast
Excellent! You and I have very similar driving styles. Thanks for sharing.
My MPG has gone up significantly since following your YouTube videos.
My MPG has gone up significantly since following your YouTube videos.
Someone on the first page stated that while under engine braking the injectors do not fire any fuel at all...as in zero fuel use. Is that really true? I would think with the compression on any diesel you would just grind to a halt if that was the case. I have seen Dodge Cummins trucks with the manual tranny try to "push start" a manual truck and the only result is that the truck skidded to a halt like you had mashed the brakes. I just wanted some clarification for those in the know. I know for a fact that the common rail cummins (cp3 injection pump), is still firing fuel when you are coasting in gear with zero throttle.
VeeDubTDI
Wanderluster, Traveler, TDIClub Enthusiast
You're absolutely right, except for one thing... inertia. Had you read the entire thread and watched the videos, you would have learned the following...
While in gear, the inertia of the moving vehicle keeps the engine rotating while no fuel is injected - engine braking. If you press the clutch, the injectors fire to maintain idle speed - no engine braking.
Engine braking and coasting are very useful tools for obtaining high MPG. Engine brake while coming to a stop rather than using your brakes. Coast in neutral down slight grades (highway, rolling hills, etc) rather than setting the cruise control or applying fuel to maintain speed... you'll be surprised by how far you can coast without having to use fuel (the difference is ~200 mpg vs ~80 mpg, coasting vs light load).
Remember that true hypermiling requires a lot of attention, planning and patience. It's a pretty fun game - see how high you can get the MFA or Scanguage to display.
Welcome to TDIClub! If you start using some of these techniques, let us know what your results are!
While in gear, the inertia of the moving vehicle keeps the engine rotating while no fuel is injected - engine braking. If you press the clutch, the injectors fire to maintain idle speed - no engine braking.
Engine braking and coasting are very useful tools for obtaining high MPG. Engine brake while coming to a stop rather than using your brakes. Coast in neutral down slight grades (highway, rolling hills, etc) rather than setting the cruise control or applying fuel to maintain speed... you'll be surprised by how far you can coast without having to use fuel (the difference is ~200 mpg vs ~80 mpg, coasting vs light load).
Remember that true hypermiling requires a lot of attention, planning and patience. It's a pretty fun game - see how high you can get the MFA or Scanguage to display.
Welcome to TDIClub! If you start using some of these techniques, let us know what your results are!
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Well a diesel engine doesnt actually "engine brake" as would a petrol engine. A petrol engine brakes itslef via restricting the air intake thus creating a vacuum on the intake stroke. Petrol engines are air throttle engines, air and fuel are always in the the same ratio. Though I imagine some of the newer DI petrol engines operate over a moderate range of air fuel ratios, nonetheless they are still air throttle engines.
Diesels are fuel throttle engines. They take a full gulp of air on every intake stroke, there is no butterfly valve to restrict air intake. Thus a diesel will run drastically different air fuel ratios at idle vs full throttle. And you get no intake stroke engine braking.
The only ways I kow of to "engine brake" a diesel are:
1. a "jake brake" which releases the pressure of the compression sroke so the cylinder has the drag of compressing air but not the power provided by the power stroke because the cylinder doesnt fire. This is the most effective form of "non friction" braking, but its loud and somewhat costly.
2. "Exhaust brake" basically a butterfly valve placed after the turbo, usually right after the turbo downpipe. This device simply creates a back pressure on the exhaust stroke, kind of analagous to the petrol engine creating a vacuum on the intake stroke via an air intake restriction.
3. Turbos, by nature are both gas pushers (they stuff air into cylinders) as well as gas restrictors (they inhibit exhaust gasses from escaping to the atmosphere.
And in my opinion this is what we are experiencing in our VW's...a nice little variable geometry turbo that creates an exhaust restriction when under light or no throttle, which creates a braking effect. I still find it hard to believe that there is NO fuel injection event at all during a "no throttle, still in gear" situation. My feeling is that there is about the same fuel injected as would be injected at idle. That why its more efficient to coast in neutral vs coasting down in gear, which has more frictional losses and that lil variable geo turbo in the way.
Diesels are fuel throttle engines. They take a full gulp of air on every intake stroke, there is no butterfly valve to restrict air intake. Thus a diesel will run drastically different air fuel ratios at idle vs full throttle. And you get no intake stroke engine braking.
The only ways I kow of to "engine brake" a diesel are:
1. a "jake brake" which releases the pressure of the compression sroke so the cylinder has the drag of compressing air but not the power provided by the power stroke because the cylinder doesnt fire. This is the most effective form of "non friction" braking, but its loud and somewhat costly.
2. "Exhaust brake" basically a butterfly valve placed after the turbo, usually right after the turbo downpipe. This device simply creates a back pressure on the exhaust stroke, kind of analagous to the petrol engine creating a vacuum on the intake stroke via an air intake restriction.
3. Turbos, by nature are both gas pushers (they stuff air into cylinders) as well as gas restrictors (they inhibit exhaust gasses from escaping to the atmosphere.
And in my opinion this is what we are experiencing in our VW's...a nice little variable geometry turbo that creates an exhaust restriction when under light or no throttle, which creates a braking effect. I still find it hard to believe that there is NO fuel injection event at all during a "no throttle, still in gear" situation. My feeling is that there is about the same fuel injected as would be injected at idle. That why its more efficient to coast in neutral vs coasting down in gear, which has more frictional losses and that lil variable geo turbo in the way.
davidm2232
Veteran Member
i have done this on an alh jetta with vag-com. when slowing down with the accelerator pedal at 0%, injected quantity is 0 mg/stroke and fuel usage is 0l/hr. It really does cut off all fuel, that is, until the revs drop to near idle.
rotarykid
Top Post Dawg
- Joined
- Apr 27, 2003
- TDI
- 1997 Passat TDI White,99.5 Blue Jetta TDI
This has been discussed over and over here, the debate of staying in gear in overrun or using nuetral for coasting. In my experience using N for coasting allows for more distance to be covered saving fuel than staying in gear in overrun unless you are going down a very steep grade.
The best way to use less fuel on city loops is by watching road conditions to try to avoid overacceleration which requires brake use which wastes fuel. Gravity can also be used to save fuel on city loops if you have rolling terrain. A pulse of energy from burned fuel to get moving then allow gravity to get you up to your desired speed. If you drive the same route over and over with a down grade you can judge just how much energy needs to be derived from the engine to allow available gravity on the grade to propel you up to your desired speed.
On the question of bus and truck speed limits, in the western US all traffic can legally and is allowed to go 65-70 mph on two lane rural highways and 75-85 mph on rural freeways. Everyone travels these speeds regardless of what we are in!!
In diesels and gassers with both automatics and manuals I have clocked as much as a 10 and more mpg difference when using N for coasting over just staying in gear when a grade is available. I have pushed my Passat TDI as high as the mid 60s mpgUS using these techniques. While if you just put the car in gear and spend as little time as possible out of gear coasting low to mid 40s are the best.
In my current 05 Accord just getting into gear and staying there around town high 10s to maybe 22 mpgUS at best. With as much N use as conditions allow over the same routes at the same speeds it 27+ to 34 mpgUS, the last tanks were 31.3 and 27.4 with ~30 % alcohol (splash bleeded to E-30). I have close to 3 years 40k miles of data on this now in this car.
The best way to use less fuel on city loops is by watching road conditions to try to avoid overacceleration which requires brake use which wastes fuel. Gravity can also be used to save fuel on city loops if you have rolling terrain. A pulse of energy from burned fuel to get moving then allow gravity to get you up to your desired speed. If you drive the same route over and over with a down grade you can judge just how much energy needs to be derived from the engine to allow available gravity on the grade to propel you up to your desired speed.
On the question of bus and truck speed limits, in the western US all traffic can legally and is allowed to go 65-70 mph on two lane rural highways and 75-85 mph on rural freeways. Everyone travels these speeds regardless of what we are in!!
In diesels and gassers with both automatics and manuals I have clocked as much as a 10 and more mpg difference when using N for coasting over just staying in gear when a grade is available. I have pushed my Passat TDI as high as the mid 60s mpgUS using these techniques. While if you just put the car in gear and spend as little time as possible out of gear coasting low to mid 40s are the best.
In my current 05 Accord just getting into gear and staying there around town high 10s to maybe 22 mpgUS at best. With as much N use as conditions allow over the same routes at the same speeds it 27+ to 34 mpgUS, the last tanks were 31.3 and 27.4 with ~30 % alcohol (splash bleeded to E-30). I have close to 3 years 40k miles of data on this now in this car.
MikeMars
Veteran Member
- Joined
- Mar 6, 2008
- Location
- UK
- TDI
- Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
It even says it in the car's owner manual - no fuel injected when in overrun. Take a look at the VW leaflet in my signature, page 12, which describes when each technique should be used.
(Note also that they mention engine braking... the engine braking effect is obvious if you flip between neutral & overrun). The reason that neutral is better than overrun, despite using fuel to spin the engine at 850rpm, is that in overrun the engine is having to overcome the resistance of spinning at 2200rpm or whatever, which takes a lot more energy than 850rpm. It is this frictional resistance which causes engine braking in diesels.
PS read the entire leaflet. There are a lot of good tips in there from VW.
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VeeDubTDI
Wanderluster, Traveler, TDIClub Enthusiast
You are completely forgetting (or ignoring) friction and pumping losses.
Try a little experiment. First, get up to 60 mph and take your foot off the accelerator. See how long it takes to drop to 50 mph. Then do it again in neutral.
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Fair enough, I stand corrected. I knew there were pumping losses, and obviously friction losses. I was just under the impression that the primary braking was provided by the vgt turbo. Well live and learn, thanks for the clarification guys.
On another note I have definately seen better milage by accelerating fast to speed, featering the throttle over hills and coasting in neutral down grades and while coming to a stop. Traffic often makes it impossible to drive that way but when possible I sure am on board with the principles espoused by this thread.
At 5k mi on my 2012 I am seeing about 42-44mpg, and we still have a bit of #1 diesel in our blend.
On another note I have definately seen better milage by accelerating fast to speed, featering the throttle over hills and coasting in neutral down grades and while coming to a stop. Traffic often makes it impossible to drive that way but when possible I sure am on board with the principles espoused by this thread.
At 5k mi on my 2012 I am seeing about 42-44mpg, and we still have a bit of #1 diesel in our blend.
VeeDubTDI
Wanderluster, Traveler, TDIClub Enthusiast
Not bad mileage for still being on winter fuel.
Vekke
Veteran Member
From this chart you can see your fuel consumption at idle and choose the point where its wiser to start engine braking. Its only wiser if you have to stop anyway or slow down faster...
https://www.facebook.com/photo.php?...10597758.84063.163711023642791&type=3&theater
MPH 12,4 9,3 6,2 3,1
MPG 94,1 70,6 47,0 23,5
https://www.facebook.com/photo.php?...10597758.84063.163711023642791&type=3&theater
MPH 12,4 9,3 6,2 3,1
MPG 94,1 70,6 47,0 23,5
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Vekke
Veteran Member
I cannot give you answer for that because I dont own such a car.
I have many hypermiling videos coming but my internet connection is very slow and it takes many attempts to finish long video...
Here is one new video which shows that my lupo was able to fo under two liters 117 MPG us+ on Juni 2012.
http://www.youtube.com/watch?v=rh4-MyGec-g&feature=youtu.be
I have many hypermiling videos coming but my internet connection is very slow and it takes many attempts to finish long video...
Here is one new video which shows that my lupo was able to fo under two liters 117 MPG us+ on Juni 2012.
http://www.youtube.com/watch?v=rh4-MyGec-g&feature=youtu.be
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IchbineinDiesel
Active member
Vekke!
As a newbie to the TDI world, I am really enjoying your posts and videos. Continue with the good work.
As a newbie to the TDI world, I am really enjoying your posts and videos. Continue with the good work.
Vekke
Veteran Member
http://www.youtube.com/watch?v=AChCK2egMPs&feature=youtu.be
Here is one long video. My pernal best on that route is at the moment 2.1 liters and I am very close to getting it to 2.0 liters.
Here is one long video. My pernal best on that route is at the moment 2.1 liters and I am very close to getting it to 2.0 liters.
usarmy132
Veteran Member
Read your manual, it is not recommend to coast in neutral with DSG.
berserkerx
Well-known member
What I actually picked up from the manual is to just put it back in gear and it will be fine. Just make sure that before you do put it back in gear you are back to engine idle speed. I put mine in N a lot and no wear 25k miles so far on the tranny. Now if I could convince my wife her foot is too damn heavy and she should calm down I would net much better economy.
VeeDubTDI
Wanderluster, Traveler, TDIClub Enthusiast
Good point! The commentary is excellent.
rotarykid
Top Post Dawg
- Joined
- Apr 27, 2003
- TDI
- 1997 Passat TDI White,99.5 Blue Jetta TDI
This is correct, in other parts of the world the DSG is programmed to automatically freewheel while in overrun.
So if you make sure you don't apply throttle until the trans is fully re-engauged there should be no more wear than is suffered during normal shifts.... And if you use N enough ( at idle & when coasting )and use it properly the trans will suffer less wear....
Jagerbecher
Well-known member
P&G with DSG
Can anyone give us a reliable information about what is the best way to P&G with DSG? And I mean reliable info from someone who really understands how the DSG works, no guessing or assumptions please. Driving P&G style means switching between N and D quite often. Isn't it too much stress and wear for the tranny/clutch that's not worth of fuel savings? I can imagine that changing from D to N at highway speed may not be a problem for tranny, but particulary switching back from N to D at for example 55mph seems like putting too much unnecessary strain for clutch (or some rpm synchronization mechanizm, if any) that it has not been designed for, because going from N to D at 55 or 60mph often just is't a normal driving. That's why I have always thought that stepping of the gas pedal and giving the engine the rpm about equal to the speed just before shifting from N to D is relieve for the tranny. For example, at 60mph the rpm is around 2k. So if while coasting in N I rev the engine to around 2k and then shift to D seems to me a lot smoother and better for tranny because of minimum rpm difference between engine and tranny, then just shifting to D while engine in idle speed. Another aspect is that If the engine is idling and you shift from N to D (at 60mph) the engine revs to 2k rpm not from it's own produced energy but the tranny transfers the momentum to the engine and only second or two later you would step on gas once you feel that the clutch is fully engaged.
So, that's why I feel it is better to raise the the engine rpm before shifting from N to D at hw speeds. Does anybody knows for sure that this is not a good practice? If yes, why? And again, expert views only, no guessing please.
Can anyone give us a reliable information about what is the best way to P&G with DSG? And I mean reliable info from someone who really understands how the DSG works, no guessing or assumptions please. Driving P&G style means switching between N and D quite often. Isn't it too much stress and wear for the tranny/clutch that's not worth of fuel savings? I can imagine that changing from D to N at highway speed may not be a problem for tranny, but particulary switching back from N to D at for example 55mph seems like putting too much unnecessary strain for clutch (or some rpm synchronization mechanizm, if any) that it has not been designed for, because going from N to D at 55 or 60mph often just is't a normal driving. That's why I have always thought that stepping of the gas pedal and giving the engine the rpm about equal to the speed just before shifting from N to D is relieve for the tranny. For example, at 60mph the rpm is around 2k. So if while coasting in N I rev the engine to around 2k and then shift to D seems to me a lot smoother and better for tranny because of minimum rpm difference between engine and tranny, then just shifting to D while engine in idle speed. Another aspect is that If the engine is idling and you shift from N to D (at 60mph) the engine revs to 2k rpm not from it's own produced energy but the tranny transfers the momentum to the engine and only second or two later you would step on gas once you feel that the clutch is fully engaged.
So, that's why I feel it is better to raise the the engine rpm before shifting from N to D at hw speeds. Does anybody knows for sure that this is not a good practice? If yes, why? And again, expert views only, no guessing please.
Tachypsychia
Active member
Just drove about 2000 miles attempting to improve my mileage where I could using these tips. Best I got was 51mpg, which was my record best, and lowest was 49mpg. Seems to work pretty well, although it does require you to constantly work to gain those extra miles out of the tank.
Bob Sacamano
Veteran Member
interesting
Vekke
Veteran Member
Here is one new video how to drive on groovy roads.
https://www.youtube.com/watch?v=lFX58axKpU4
Read the descriptions on the video for more instructions.
https://www.youtube.com/watch?v=lFX58axKpU4
Read the descriptions on the video for more instructions.
GreyTDIowner
Well-known member
Thanks for all the information, Vekke and others.
Is it better to coast in neutral or with the clutch depressed only? I ask because I did have a throwout bearing failure at 325k and I did practice hypermiling by coasting down many large hills with the clutch depressed. It may have been unrelated but I did want to check to be sure.
Is it better to coast in neutral or with the clutch depressed only? I ask because I did have a throwout bearing failure at 325k and I did practice hypermiling by coasting down many large hills with the clutch depressed. It may have been unrelated but I did want to check to be sure.