Archives

I'm thinking about going diesel on my next truck. If they ever get biodiesel around here I might even think about a sedan someday as well. What kind of mileage are the best diesel drivers getting? What kind of techniques do you use? Do you/can you FAS a diesel?

I'm thinking about going diesel on my next truck. If they ever get biodiesel around here I might even think about a sedan someday as well. What kind of mileage are the best diesel drivers getting? What kind of techniques do you use? Do you/can you FAS a diesel?

lakedude,

You do know that GM is having their 72 Hr. Sell on right now, Right?

72-Months No-Interest: :D

Everything but the Corvette is what I understand.

I'm not {Positive} but today (Tuesday) 4th of July may be the LAST DAY of the Sell:

HOPE YOU READ THIS POST IN TIME:

Good-Luck;

Terry

Hi Lakedude:

___I have done a bit of research into this area ;) FAS’ing can be performed in the TDI’s but with a turbo spool down at an initial 700 - 800 degree temps to 400 degree temps with a normal stop, idle for 30 - 45 seconds, and the shut down vs. a 700 - 800 degree temp to shut down via FAS, I am sure you can see my misgivings wrt a FAS and most turbo’s fluid bearing setup. A friend of mine actually installed pyrometers by drilling taps into the exhaust manifold just before the turbo in his 04 Jetta to get me this info just 3 weeks ago! Some of us just wanted to know :eek: The good thing however is that the TDI only burns .3 - .4 L/hour at idle with as high as a 64:1 A/F ratio so FAS’ing can save fuel but nothing like our hybrid’s and non-hybrids. Watching the TDI forums as listed on the front page, they have their own hypermilers but they do not appear to reach anywhere near the same levels that we all do. I do not know if its poor training or the TDI’s capabilities but they just do not approach the numbers we do is all? Some of the information posted in those threads is not only way out there, it is completely wrong knowing the how’s and why’s any number of us have achieved with std. SI-ICE’s plus knowing what the TDI’s should be capable of?

___As far as a truck diesel, make sure you read up on the IH in the Ford Powerstroke’s, Cummins in the Dodge, and Duramax in the GM’s before making a decision. They do not get the FE you would think when unloaded and there are Injector issues with the 6.0 Powerstrokes from 03/ through 04 that I know about first hand.

___Good Luck

___Wayne

The Dodge/Cummins is probably the most reliable and likely to be about the most fuel efficient. I know a guy with one of the earlier model extended cab, short bed, single axle Ram pickups who did a turbo upgrade and dyno'd at around 400 wheel horsepower and something like 750 or 800 ft-lbs of torque. With the 5-speed manual transmission he said he'd get high teens around town and around 25mpg on the highway. The newer, bigger/wider trucks might not be able to manage that due to the overall higher drag, but I know the Cummins 6-cyl was supposed to be one of the best. Agreed with Wayne about maybe avoiding the Powersmoke trucks.

I don't know about the trucks but here is June's mileage competition over at the TDI club.
Nothing earth shattering there, the #1 place is a bug which is extensively modified.
http://forums.tdiclub.com/showthread.php?t=140877

If Honda comes out with a clean diesel full size van it would be very tempting for our family as a replacement to the Grand Caravan.

There is a lot I don't know on this, but the diesel offering seem to be fewer than they were - and will be in a few years.

Even with clean American diesel this year, passenger diesels are being dropped because they don't satisfy the EPA. I hope Honda delivers on their clean diesel committment and VW can sell TDI diesels in the US again.

The TDI crowd still can't regen brake, so they probably lose
a lot right there. You'd probably have to ask about other
driving-style aspects and/or how they try to mitigate that..
.
_H*

The TDI crowd still can't regen brake, so they probably lose
a lot right there. You'd probably have to ask about other
driving-style aspects and/or how they try to mitigate that..
.
_H*
regen is useless if you coasted to the light with barely any speed left (aka less than 10 mph)

Diesel hypermiling is related more to engine/aerodynamic efficiency than driving habits. Sure, FAS'ing can net a bit better mileage, but given the higher compression ratios I don't think running a diesel engine through more starts than needed is especially wise since they don't suffer from pumping losses and use very little fuel at idle. The best thus far in diesel economy performance has been set by VW's 3L Lupo (http://www.volkswagen.co.uk/press/Lupo_3L_in_Guiness_World_Record). Getting over 100mpg while while averaging ~50mph is something most Insight/Prius drivers would be proud of. Something else to consider is the 3L Lupo has a Cx of .29 (compared to the insight's .24) but still gets ~ the same mileage, although I'm not sure about the FA, but one would think it's ~ the same.
Anyway, what's really crazy is that full sized diesel pickups can get ~25mpg highway, while a little 80's diesel vw with ~1/3-1/4 the FA and weight can only get ~50mpg at the same speed. Why the difference? From what I've gathered it comes down to T/DI versus T/IDI, direct injection (DI) is ~25% more efficient than indirect injection (IDI), and to further add to that, the leaner you run a diesel, the more *efficient it is, up to a point.
When compared to gas motors, they usualy are ~ as efficient. For example, sticking an old vw idi diesel in a honda insight will probably net ~ the same mileage figures, and a leaned out tdi with water injection will probably net a ~90mpg EPA rating. To reiterate, diesel hypermiling is harder since diesel owners see less variation in fuel efficiency with driving habits, and also have to deal (comparing cars) with higher Cx's (.3x) and greater frontal areas (~25-30 ft^2) than most hybrids. There's plenty of additional info, but this post is already going in twenty different directions, so just ask if you'd like more info on anything.

*This is how those diesel chip manufacturers can increase fuel economy and power. They lean out the mixture compared to stock at the majority of pedal positions (getting better mileage) and when you put the pedal to the medal, they richen the mixture compared to stock (more power). Now the factory can't/won't do this because leaner mixtures have higher NOx emissions so they have to comply with emissions standards from the factory (can't), and increasing fueling increases particulate emissions (can't) and cylinder temeprature, which may also lead to a reduction in engine life (won't). Cars must comply with more stringent emissions regulations, so they must run richer than large diesels (reduced efficiency), and equip the exhaust systems with particulate traps to deal with the increase in soot.

Hi Lyeinyoureye:

___Very interesting view into the TDI. Looking over Steve’s TDI link, there is some variances from top to bottom and I wonder how they are achieved? I would love to try out a TDI for a week and actually see if they can be pushed into much higher plateaus then what most TDI drivers have actually achieved for themselves. My Accord is sort of an Aero pig itself at 0.30 but nothing compared to the New Beetle at 0.38!

___About the Lupo … IIRC, it has 2 modes of operation and the high FE mode has an AS and acceleration performance of 15 -16 seconds to 60? Do you know of any Euro Lupo drivers with a FE history we can look at? I would really like to see how they are performing in the real world as well. Insight’ers for the most part are in the low 60’s range with the outliers and I bet the Lupo would be similar? I thought I remember reading that the Lupo would be rated at 84 mpg highway on the EPA’s HWFET although I highly doubt it was ever connected to a treadmill and ran through that specific test?

___Dan and I saw some Scan Gauge like equipment on a few of the Bio-Diesel run CI-ICE based automobiles at the Tour Del Sol but with the wildly varying A/F ratios, is there anything one can use to measure iFC without a proprietary CAN-View based scanner attached to a laptop? Ron at Scan Gauge says you can calibrate a SG to the TDI’s but that 64:1 idling A/F must raise havoc with the actual results for those of us that would spend almost as much time in a NICE-On as we would on the accelerator? Let me know of your thoughts on this when you find the time …

___Good Luck

___Wayne

Hey Xcel! :)
If you look at the top contender in the diesel FE list, you'll notice that the gap between it and the next best diesel is the greatest diesel gap on the entire list, probably becuse the beetle (http://www.greencarcongress.com/2004/12/on_the_wings_of.html) in question has had a couple of items to increase FE. I bet a plot of fuel efficiency versus number of drivers per fuel efficiency interval (like how many get 45-50mpg, etc..) would yield a nice bell'ish curve. Might even be within error given the small number of samples. ;)
I'm searching google.de right now, as so far the best automatic 3l lupo fuel efficiency I've seen has been 2.3l/100km via this (http://www.dooyoo.de/auto/vw-lupo-1-2-tdi-3-liter-auto/) and babelfish.
The most important first, consumption. In order to anticipate it, our personal record for a travel Eschweiler/Remscheid/Eschweiler 2.3 l/100km amount to! Similarly low consumption we reached several times also afterwards. Upward the scale goes with full power on the motorway to the 5-6 l/100km, whereby we already reached in addition, after Tacho 205 km/h. Our practice average with economical driving fashion in everyday traffic to the work amounts to between 2,9 and 3,3 l/100km. Can less be obtained only when expanded cross-country travels or driving on the motorway between 90 and 110 km/h.
However, I saw a few other drivers getting 3-4l/100km, so you're probably correct about 3l Lupo drivers mirroring the fuel efficiency pattern of Insight drivers (40-50mpg@~130mph is downright impressive). After I post this, I think I'll register here (http://www.motor-talk.de/f251/s/) and search for/ask 1.2l TDI owners what they're getting to verify this trend. Iirc, the Lupo's AS only kicks in when the brake pedal is depressed for more than four seconds at a stop, so it's not quite as rigorous as a gasoline hybrid in that respect. As for measuring iA/F ratios on mechanical diesels, I was thinking that an accurate way to measure fuel consumption wrt to speed and gearing would be to put in an extremely accurate digital tach (http://www.4crawler.com/Diesel/CheapTricks/Tachometer/index.shtml) and a couple of digital flow meters to the parallel port of an onboard computer (it's cheaper/cooler than putting in a new stereo system ;)), but i was told this would be a bad idea because digital flow meters are not very accurate. However, I read this (http://www.vwdiesel.net/phpBB/viewtopic.php?t=3983&postdays=0&postorder=asc&highlight=measuring+injector+opening&start=0), which implies that if I can set up a piezo to record when each injector opens and closes, after setting breaking pressure and measuring flow rate for each injector, I'll probably have a really accurate way of measuring fuel. On TDI's, I think the injectors are electric, so all you'd need is a jumper to measure when they open and close, and a flow test for each one. Air flow can probably be measured by a MAF-sensor from the junkyard, but you'd probably have to find out how much current is put out during different conditions. I think I have more in my bookmarks/google, but I should really clean the house, so I'll post that up later. :D


I also found this (http://66.102.7.104/search?q=cache:S2Wa0fB9u90J:www.folkecenter.dk/plant-oil/publications/PPO-emissions.htm+VW+Lupo+1.2+TDI+3+Liter+Auto&hl=en&gl=us&ct=clnk&cd=7&client=firefox-a), which seems pretty interesting. Any idea what the prius/insight NO ppm levels are?

I don't know how accurate it is but just today I installed a scanguage on my wifes 04 Golf TDI and it shows a fuel flow of .2 gph at idle and .3 gph at idle with the ac on....Louis

Hi Sno779:

___Getting back to the SG, IIRC, Ron told me that he is measuring fuel consumption via injector pulse width at a given pressure to the rails and the VSS so once the SG is calibrated to your specific TDI, it should give you an accurate representation of both i and aFC at any A/F ratio(s) …

___Lyeinyoureye, I really enjoy your CI-ICE related posts! Keep them coming as the diesel side of the house is where I am at an extreme disadvantage. I do enjoy reading about their FE capabilities no matter what they are currently being fueled with …

___Good Luck

___Wayne

Sorry for digging this up but it seemed a waste to start a new thread just for this.
My issue with hypermiling diesels is this: The exhaust clogs up with soot. Power goes down, never to recove until the exhaust is cleaned (replaced?) I say this because i have been hypermiling in my new diesel car. I pootle along at 80kph.
a: don't seem to get massive mpg numbers.
b: exhaust spews clouds of soot that was accumulating.

A mate of mine was recently almost converted to hypermiling. He drives a 1.9 tdi audi A4
and was getting 100 miles more from a tank when he slowed down. However, he too reported clouds of soot when throttling up. He also had a lot less power until the soot was gone.
Here's my hardware slant on this: I think the fitting of a smaller diameter exhaust would solve the soot issue but would remove the cars ability to accelerate like it used to.
It's probably not as simple as a smaller exhaust but i'm sure someone here with more knowlege on this subject would know what to do.

ollie

Hi Vtec-e:

___I/we placed only about 7,000 miles on the iCDTi with all of 18,000 miles on her and I know she was driven hard and put a way wet when it was not in our hands. When it was in our hands, gentle as a baby and she was never spewing any soot but we never really got on her either?

___FE? Tremendous!

___Good Luck

___Wayne

Hi wayne,
I must correct myself. The soot comes out when i get up to motorway speeds (120kph)
I'm thinking that if i hypermile it permanently, never to let the rpm's get high or put the foot to the floor, my exhaust will literally fill solid with soot. Of course, i'm not going to stop hypermiling because of this!
By the way, my FE in the kia was 3.3l/100k at an average of 60kph. It's still improving as there is only 6000km on it.

ollie

soot used to be common in my car until 10/2007 when the U.S. switched to 15ppm diesel down from 500ppm. I know in europe you have more sulphur in your diesel than the U.S. now. I can still produce soot if i kick down the accelerator over 3500rpms, but no where near the old diesel, where i could spew black clouds on any hard acceleration.

I find it hard to hypermile my tdi other than slowing down. Im not going to run it under 2000rpms and burn out my turbo. I think at 90km/h you would probably increase your fuel effeciency by 10% at least over 120km/h

Hi vtec-e, the soot issue is often in my mind when I'm trying to hypermile From reading on TDIclub, it seemed that Europeans never had the soot clogging problems that North Americans had, so that makes me think that your 15ppm ULSD may have something to do with it. Now that we have 15ppm ULSD, there may be less problems with intake / turbo clogging. I still try to blow any accumulations out once every day or two with a high rpm, high boost run. I know that really sucks down the fuel economy but I want to do whatever I can to keep my engine and turbo clear of accumulations.

toastblows, in the city the TDI can hypermile without much difficulty. Running under 2000rpm is fine as long as you're not on the boost. Constant 35mph in 5th gear needs very little boost. You are in the turbo surge zone though so if you do need quick acceleration, downshift a gear or two. And make sure to give your engine a high rpm high boost run once in a while. That helps clear the turbo and keep the VNT vanes moving properly. I've just started exploring what I can do with my car in the city and have had a number of runs in the high 50's or low 60's. The car is capable of more than that, I just need to learn how to do it or slow down.

You are right that hypermiling on the highway is tough. 90km/h vs 120 km/h makes a big difference. ~90 puts me somewhere in the mid 50's. I haven't spent much time at 120 recently ;) but I think it gives me numbers in the low 40's.

90km/h is 58 miles per hour. Thats pretty much the lowest you can go on the rpm scale before you start killing your turbo spin. If im in the city i use 4th gear, 5th is too much hassle to keep the engine going and having enough power for the 50 people that cut you off when you are all packed in 5 feet from each other. Im happy at 50mpg combined city/hwy...its a good engine.

Yes, 50mpg is nothing to complain about. As I understand, the problem with being under 2000 rpm is not lack of turbo spin. The VNT mechanism in the turbo helps it to spin up quickly in all conditions. The problem is that under those low rpm conditions, the turbo can actually spin up too quickly, creating boost spikes or conditions where the engine would be running at very high boost and low rpm's. Both are very hard on the turbo. A second problem with running under 2000 rpm constantly is that the VNT vanes don't get to cycle through their full range of movement. If the low rpm boost spikes can be avoided and the turbo sees exercise above 2000 rpm, the turbo should provide you with reliable performance.

Hi All:

___2,000 RPM? The iCDTi was traveling at 71 mph at those R’s? She usually camped in the 1,400 – 1,500 RPM slow speed highway cruise in 6th. TDI’s have to be geared nearly as tall even with a 5-speed, aren’t they?

___Good Luck

___Wayne

Hi All:

___2,000 RPM? The iCDTi was traveling at 71 mph at those R’s? She usually camped in the 1,400 – 1,500 RPM slow speed highway cruise in 6th. TDI’s have to be geared nearly as tall even with a 5-speed, aren’t they?

___Good Luck

___Wayne


03 tdi runs 2300-2400 at 65mph. 1900-2000 at 58mph...5 gears sucks. tdiclub people talk about the .681 and .658 5th gear modifications, but even then they report 52-53mpg average driving. Not worth my time. 6 gears rok.

They rock if the 6th gear is a proper high speed cruising gear! I've yet to have the pleasure of driving such a transmission, though. :(