Fuel saving device ( home made), well could be!

[Yostumpy]

I hope that this isnt in the realms of oft banded SNAKE OIL, but a simple solution occured to me to-day. Now knowing everyone on here is well clever and well sceptical. here goes.

Suppose one was to to go to the breakers yard, and get hold of an old Mini floor starter button, (or some such other device) and attatch it to the floor of your truck, near the handbrake(90-110) by your heel, and this was wired somehow to your fuel shutoff valve, thus when coasting down long hills, one could depress the button with ones heel, thus killing the engine, using the engine as braking, whilst leaving the ignition on, and the truck in gear, and saving fuel, and whenst the gradient levels a tad one simply removes ones heel from said button a BINGO the ol' beast BURSTS back into life agian and off you jolly well !!!!! A bit like the decompressor on lorries, but if your running down a long gradient at say 60 with your foot off the gas and the engine is still doing say3000rpm, its still using deisel is it not. Kill the engine with your depressed heel and it usees nothing! OR am I missing something!

I'M NOT MAD!!!!!!!!!!!

[daveturnbull]

Or just dip the clutch when coasting down a long hill like everyone else does.... 800rpm on a tdi doesn't drink much.

[yellow]

thus killing the engine, using the engine as braking, whilst leaving the ignition on, and the truck in gear, and saving fuel, and whenst the gradient levels a tad one simply removes ones heel from said button a BINGO the ol' beast BURSTS back into life agian and off you jolly well !!!!!

I'M NOT MAD!!!!!!!!!!!

You are as mad as a mad hatter... Going downhill without the power steering or any other ancillary taking its guts off the normally running engine.

No thank you...

[landmannnn]

Even more user friendly would be a switch that cuts fuel off when you press the brake pedal a couple of mm, ie before the brakes actually start working.

Thinking harder it would need to turn the fuel back on again when pressed further so a full stop did not create a stall.

Not sure how much it would save..

[FridgeFreezer]

Or you could just use this:

[sotal]

In my newer car the computer thingy tells me I do better MPG when in gear and clutch out rather than clutch in/out of gear.

With it in gear it says 999mpg, if I coast out of gear it drops to about 100mpg

So it seems to be that your better in gear any way in newer motors. It might make a slight difference in an old series with a long enough hill

[landroversforever]

I would certainly not want to coast without the engine on !

[FridgeFreezer]

With it in gear it says 999mpg, if I coast out of gear it drops to about 100mpg

Probably doing the same thing as my post - cutting the injectors on overrun. As soon as it senses a load, it squirts fuel again and the engine picks up where it left off. If you clutch down, it has to inject some fuel to keep the engine ticking over, whereas with the clutch up you don't need combustion to happen at all.

[Landowner]

You could save more by changing up from first earlier and doing a couple of hundred revs less in all the other gears, anticipate the traffic as if you had very very poor brakes and save a lot more. Try this for a week and see how much you save

[110_USA]

I know this doesn't help and I'm sorry, but.

If you are concerned about fuel economy, wouldn't not driving a 4,500lb vehicle with the aerodynamics of a brick be the simplest way? I'm not saying that saving fuel is bad, I do simple stuff, like moderate my acceleration; but a big, heavy, boxy, all time 4x4, and fuel economy just don't go together, that's just the way it is. If you are resorting to extremes such as a fuel shutoff while you're still driving then you need to reconsider your vehicle of choice.

That's like driving a tank and complaining that it's heavy.

For the sake of tinkering and entertainment, certainly. For any sort of practical application, it's a little loony/dangerous/irresponsible.

[cipx2]

..... OR am I missing something! ...

There's no need for a device like that. The governor in the pump takes care to cut the fuel on engine overruns if the accelerator pedal is not pressed.

Try to find a manual/pdf/something about how a Bosch VE injection pump works.

[GBMUD]

a big, heavy, boxy, all time 4x4, and fuel economy just don't go together, that's just the way it is. If you are resorting to extremes such as a fuel shutoff while you're still driving then you need to reconsider your vehicle of choice.

Of course, one should not loose sight of the fact that a Discovery is more fuel economical than a Mini Cooper S.

Or at least, it was a few years ago.

Chris

[Retroanaconda]

I'm in fact quite suprised how efficient my Defender is, I get 30mpg pretty constantly at the moment....more than my landlord/landlady do in their brand new X3

That is a petrol though, so maybe it's more the diesel engine that's helping

[SteveG]

or take your roof rack off

[nicks90]

You are as mad as a mad hatter... Going downhill without the power steering or any other ancillary taking its guts off the normally running engine.

No thank you...

why wouldnt he have power sterring or anything else?

as he is still in gear and the engine is still turning over at however many revs - the power steering pump, water pump, vac pump etc will still be running as normal.

all he is suggesting doing is cutting the fuel supply off on over run. Therefore the wheels would drive the gearbox, which in turn would drive the engine. BUT the cylinders would be getting no fuel and would not have a compression/bang stroke - just a compression stroke. Engine braking would theoretically be improved as well. I believe TD5's already have this.

The only concern i would have is how important the diesel is for upper cylinder lubrication on his motor (is it a tdi?)

[Orgasmic Farmer]

On a similar subject of DIY improvements, I came up with this as a way to cut emissions.....

Do you think it will catch on? :lol: :ph34r:

[JST]

On a similar subject of DIY improvements, I came up with this as a way to cut emissions.....

Do you think it will catch on? :lol: :ph34r:

what getting a focus?

oh i see low rear tyre pressures - yep that should help.....

[TheRecklessEngineer]

On a TDi you will find the injection pump will not inject any fuel on overrun anyway, so adding an additional fuel cutoff will not improve fuel consumption.

On an EFI V8, the electrickery bit does the same.

You may get an improvement on a carb V8, however you would have to empty the float bowls before you would be running without any fuel getting into the engine. The float bowls on SU carbs will get you about 1/2 a mile if you are careful (Ask me how I know....)

[patch1]

Im pritty sure you could get some SUs with shutoff solenoid/valves in the side of them at one point that would be an idea on a carbed V8, no need to wait for the float chambers to empty.

[Top90]

I used a diesel Ford Galaxy from work (same weight as the 90) and got an average over three tanks of 54mpg.

That saved quite a bit over driving the defender.

I thought modern diesels did something to the injectors so you used next-to-no fuel when coasting anyway?

[FridgeFreezer]

I thought modern diesels did something to the injectors so you used next-to-no fuel when coasting anyway?

Almost all modern engines, petrol or diesel, shut off the injectors by one means or another when coasting.

The trouble with carbs is that even if you kill their fuel supply, they will use the fuel that's left in the carb itself unless you can find a way to totally close the thing down.

[OilIT]

Dont laugh......

I actually read something interesting in a well known LR magazine this week.....

ok now youve got yourself up from the floor and stopped your belly laugh ..........

They have been running a series of tests of various LR over a set course and speeds to determine real life mpg versus those published by the manufacturer - if you can skip thru all the c*** about how the disco is more limo like than a defender (oh really ???) their figures suggest that a P38 does more mpg than a tdv6 disco, and if my memory serves me right they are claiming the same P38 did more than their Frelandeer (alzeimers may be affecting my memory on the last point)

If this is true - its hardly a good advert for progress is it - if you include the cost of diesel versus petrol and the increased road tax liability - I am surprised P38s havent shot up in price

I had a couple of the P38 4.0 petrols when new and I managed to convince myself that it was cheaper to run than a new 300 tdi disco if you took into consideration fuel costs and servicing intervals and costs, but this article is quite enlightining - although its not clear if the P38 was the petrol or the diesel?

Anybody else seen this article - or am I the only subscriber courtesy of a xmas present from SWMBO (Im out of socks though !!)

[JimAttrill]

I always thought a Ford Galaxy was a thing built like an aircraft carrier with a 7 litre petrol V8. They used to race against Minis back in the old days even though the brakes and handling weren't up to much Fun to watch, though.

[missingsid]

Or just dip the clutch when coasting down a long hill like everyone else does.... 800rpm on a tdi doesn't drink much.

This is absolutely mad and coasting down hill is illegal for a very good reason, whereas cutting the fuel is not and all modernish cars do it.

[MissDriver]

Ok, so I'm probably going to be "that chick" who gets laughed off of this forum, but aren't Land Rover doing that now with their Freelander 2's. I was on their site the other day and was browsing around what they have been doing for the environment (I'm a bit of a tree hugger in my spare time) and under their innovation section they said something about a stop/start system. It was all very technical and very over my head but you should have slapped a patent on the idea while it was still fresh;)

I'm not sure I'm even on the right end of the stick here but check it out http://www.landrover.com/int/en/about-us/o.../our-planet.htm