fuel consumption

[4630]

I always cancel the automatic start/stop function on my diesel. I much prefer the reassuring rumble from the engine when stationary at traffic lights. Silence from an engine is just disconcerting unless it's parked, IMHO.

[Titan]

another thing to think on is the effect of stop start on bearings etc you come off a long high speed run on the motorway and into town and typicaly get into a gyrater traffic light sytem strait away so tthings like the turbo bearings which are nice and hot and will continue to spin after engine shut down are no longer recieving oil under pressure from the engine cant be good for the bearings 

 

Actually that's a good point, shutting down is particularly bad for turbo's as many use the oil to cool them. Suddenly stop the oil supply when the turbo is hot an the latent heat in the turbo can cause the bearing temperature to skyrocket cooking the oil, even after they have stopped spinning. The carbonised oil blocks the oilways and bearings and pretty soon its bye bye turbo!

[jjb1970]

I find that after the initial sense of strangeness that I now don't even notice the stop/start system. Whilst the concerns raised are all valid points it is also true that the system has been very widely used for a long time now, I had a BMW with their efficient dynamics package in 2007 with the 2.0Lt. turbo-diesel and to date engine reliability and longevity appears to be very good. Electric parking brakes work well in automatics but I'm not such a fan of the idea in manuals.

Emissions control is actually a mature branch of engineering and many of the things that are sometimes portrayed as new (such as SCR) have actually been around for decades. And used for decades, not just known about in theoretical text books. My own opinion is that there has been no valid excuse for dirty exhaust for quite a long time, it is poor maintenance and operators unwillingness to invest. My day job is marine engine emissions and every time the emissions regulations change the industry assures the world that the sky will fall in, civilisation will collapse and inflation will go into triple figures as a result of higher shipping costs and then when they're told to just do it they get on with the job and nobody even notices. Unfortunately despite media spin my opinion is that if you want industry to reduce emissions then they have to be ordered, relying on their goodwill is pointless. I'm old enough to remember the campaigns of the electricity industry to deny all responsibility for acid rain and claim that there was no point fitting flue gas desulphurisation despite the fact that FGD has been used in power stations since the 1930's.

[Sweeps]

Okay we've done diesel, what about electric locos, how far would one go on a unit of electricity?

[Titan]

Now that could get complex, especially if you take account of regenerative braking!

[ZiderHead]

It strikes me that flywheel KERS could be a fairly simple retrofit for diesel electric locos and could provide significant improvements in economy.

[ColinK]

In Germany DB have recently introduced some diesel locos which have four small diesel engines instead of one big one. If low power is needed, one engine is used, but as power needed increases, the other engines get started too. The theory is that it saves on fuel and exhaust emissions. It would be interesting to know how they really perform and how the maintainance costs work out?

[russ p]

In Germany DB have recently introduced some diesel locos which have four small diesel engines instead of one big one. If low power is needed, one engine is used, but as power needed increases, the other engines get started too. The theory is that it saves on fuel and exhaust emissions. It would be interesting to know how they really perform and how the maintainance costs work out?

We had one of these in 1950 designed by one Col Fell! And another in 63 DHP1

[Baby Deltic]

I believe the Fell had six engines in total. There where two under each bonnet to drive the thing, plus another two in the central transmission compartment to power all the auxiliaries. I think.....

 

Best not mention the Fell too much because Chard will get upset...... Fell.....ooops....

[Vin]

Hi all,

 

The small multiple Diesel engines isn't a new idea (a Deltic on one engine), but in does add to a dead weight being dragged about which in turn means a higher fuel consumption for the engine/ engines that are running. As usual it's an engineering compromise between efficiently and economics. Would you pay the bill for the extra loco if one could haul the load or would you buy a loco that could haul more with more engines?

As for stop/start technology, we discussed this in the early nineties when I was doing auto engineering. The general consensus was that the ECU maps needed to be closed loops for it to work properly and the driver has the power to over-ride it (BMW system powered by Motorola (remember their mobile phones!)).

Don't MTU power units on idle only fire on 4 cylinders on a V16 in order to save fuel?

 

Regards

Vin

[F-UnitMad]

In Germany DB have recently introduced some diesel locos which have four small diesel engines instead of one big one. If low power is needed, one engine is used, but as power needed increases, the other engines get started too. The theory is that it saves on fuel and exhaust emissions. It would be interesting to know how they really perform and how the maintainance costs work out?

They've had similar locos like that in the USA for some time now. They call them Gensets.

[keefer]

Is that the same as is being used on the 'new' 73s? I believe they have 2 engines etc, I'd heard genset used but didn't appreciate what that involved

[45125]

Hi all,

 

The small multiple Diesel engines isn't a new idea (a Deltic on one engine), but in does add to a dead weight being dragged about which in turn means a higher fuel consumption for the engine/ engines that are running. As usual it's an engineering compromise between efficiently and economics. Would you pay the bill for the extra loco if one could haul the load or would you buy a loco that could haul more with more engines?

As for stop/start technology, we discussed this in the early nineties when I was doing auto engineering. The general consensus was that the ECU maps needed to be closed loops for it to work properly and the driver has the power to over-ride it (BMW system powered by Motorola (remember their mobile phones!)).

Don't MTU power units on idle only fire on 4 cylinders on a V16 in order to save fuel?

 

Regards

Vin

The MTUs go in to half engine i.e. a V8 and change over every 5 mins or so.

[newbryford]

Is that the same as is being used on the 'new' 73s? I believe they have 2 engines etc, I'd heard genset used but didn't appreciate what that involved

 

Only the Network Rail 73/9's are fitted with two diesel powered "gensets". The GBRf 73/9's are still only single-engine.

 

Cheers,

Mick

[Pugsley]

Don't MTU power units on idle only fire on 4 cylinders on a V16 in order to save fuel?

Heading off topic to cars again, the latest Dodge Challengers have an Eco mode where they function as a 4 cylinder when only limited power is being demanded from the engine.

[jjb1970]

The VW 1.4 turbo (also used by Audi, Skoda etc) runs as a two cylinder much of the time, it switches between 2 and 4 cylinder mode seamlessly and works remarkably well.

[Vin]

Hi all,

 

I'm surprised that the MTU power units only shut down by 50% (V16 to a V8) there must be a way of keeping the engine rotation going using only 4 cylinders rather than eight?

 

Regards

Vin

[russ p]

All this technology, my maestro van does 50-60 mpg, no electronics whatsoever.

Mind it's red hot all year round in our village due to the greenhouse effect it has caused locally and all the trees are dead! Oh and most people have been deafend.

Russ

Royston Vasey

[Vin]

If your vehicle does 50-60 mpg that's good for a non electronic machine. When I started the average engine efficiency (in the 1990's) was only 32%. What I mean by that is the amount of energy put in and converted to useful work on the output side. In order to reduce nitrogen dioxide output the efficiency goes down which in turn raises the fuel consumption. So a HST will beat a Voyager on certain runs because the idle/cruising time will alter the results.

 

Regards

Vin

[russ p]

Does restrictive silencing also increase fuel consumption? The exhaust systems on 66s and 57s is very restrictive as both have servere elbow joints from the turbo to the silencer. The 68 looks a lot more efficient with a straight pipe into the silencer. The GM engined loco's are pretty thirsty but is the because they are two strokes?

[Vin]

The more you restrict the output gases your mpg will go down as the energy required to get rid of them is higher. When we did catalytic converter tests it was about 4% extra power usage. I've always wondered what the difference between the original silencers fitted on class 66 and the later modifications they had? Does anyone have a definitive answer?

 

Regards

Vin

[Vin]

Ps.

I've looked into the class 68 fuel consumption and it looks bad. Also there are no output gases values.

[newbryford]

The more you restrict the output gases your mpg will go down as the energy required to get rid of them is higher. When we did catalytic converter tests it was about 4% extra power usage. I've always wondered what the difference between the original silencers fitted on class 66 and the later modifications they had? Does anyone have a definitive answer?

 

Regards

Vin

 

The later 66's are classed as "low emission", so it pretty much means "higher fuel consumption".........

 

But against the lower emission/higher fuel consumption argument. I previously had a Ford Fiesta Zetec 1.4 diesel and it's CO²emissions are rated as 110g/km. My current car is another Fiesta Zetec, but has the newer/larger/a bit more power & torque 1.5 diesel with "only" 99g/km CO² but the fuel consumption is about 10% better for my work usage (lots of stop/start and not particularly high speed)

 

Cheers,

Mick

[royaloak]

If your vehicle does 50-60 mpg that's good for a non electronic machine. When I started the average engine efficiency (in the 1990's) was only 32%. What I mean by that is the amount of energy put in and converted to useful work on the output side. In order to reduce nitrogen dioxide output the efficiency goes down which in turn raises the fuel consumption. So a HST will beat a Voyager on certain runs because the idle/cruising time will alter the results.

 

Regards

Vin

My 21 year old Pug 106 1.4 diesel is currently returning a real world 58mpg (measured over 3500 miles of 47 mile commutes), it was 62mpg (measured over 8200 miles of 58 mile commutes) but my new commute has some hills and the car doesnt 'do' hills very well.

It is only used to go to work and back, we use her car for days out and town stuff.

[peanuts]

The VW 1.4 turbo (also used by Audi, Skoda etc) runs as a two cylinder much of the time, it switches between 2 and 4 cylinder mode seamlessly and works remarkably well.

apparently was originally designed by engineers at Rover to go into the mini and the replacement for the 45 . got shelved during final testing when rover group went bust tech sold on to VAG group the engine in the fiat 500 @ panda is very very similar