Thread: What to do first when looking for better economy?

If your worried about its fuel consumption the best thing you can do is sell it now

The beast will not do better than 15mpg around town and 17mpg on country trip cruisng at steady 100

None of them ever have or ever will

My 1993 range rover 3.9 does 5 km per litre of fuel and ahs done so since l got in 2005.

Well what is your economy now?

I guess having owned my 92 for 10.5 years now, I have tried just about everything that I deem to be economically viable to improve economy with less than stellar results, although I think about 14.5 ( l per 100Km) towing a 600KG trailer at 100Kmh is pretty good.

What does NOT work
Hiclone- have tried one with NO change
Tin pellets -tested in my motorcycle with NO change
Low restriction exhaust. By 92 LR had large volume muffler sthat were OK for cruise back pressure. I have a Flowmaster which gives more power at high revs but very little if any economy change.
Streamlining- tried vortex inducers on the rear of the car. No noticeable difference.



What works-sorta
Unichip/Haltech etc piggyback - gives much more advance at cruise revs so adds power and economy, but at $1400 will never pay for itself in fuel savings.
Thor manifold- gives much better low down torque so lighter throttle at cruise, but will never etc etc .
New Bosch 4 hole injectors. Much better idle but no noticable economy difference.
O2 sensors- I think these have had an effect by staying in closed loop at lambda for most of the time, but drop a bit of power.

Modded heads- more power across the board so maybe some economy difference.
Reduce weight- took off rear step bumper and bullbar.

Things that are possible but not tried

Replace viscous with electric fans from Falcon. Seems like a good idea for highway work but in my case I distrust for remote work.

Replace auto with manual. All of my efficiency/power improvements now mean that my torque converter can slip up to 25% from 1800 RPM to 2200 RPM on load. Either a tighter converter, early lock up etc may improve . But not economic. Doesn't matter on cruise as locked upand pretty good on steep hills as gives extra gear between 3 and 4. LOL

Replace 14CUX with fully "on the fly" programmable ECU with timing control. Well maybe but a LOT of time will be needed with a laptop plotting advance curves . Will never pay for itself.

THE FIRST things to do IMHO is to revitalise your 14CUX by replacing the sensors, such as ECU temp, fuel temp, TPS . Ensure the MAF is working and set to 1.2 volts or so. Replace injectors with modern ones.

Check that the cam, compression etc are within spec as you can do nothing with a dying engine. maybe repalce the head gaskets and have head service done.

Have fun.
Regards Philip A

in aerodynamic and gross vehicle mass terms, it's a brick large and heavy. Once you get to 80 kmh the drag effects are considerable...I don't know what the drag coefficient (CD) is but I suspect it's 'way up there'.
Probably a complete 'aerobody' kit (whatever that is) and 500kg weight reduction are required before any real improvement is gained with existing engine/transmission.

Or a 3L commonrail diesel and 7 speed transmission...

I did 2 trips BNE/Canberra last year in my MY2000 P38...same route. ... almost idential driving time. On one trip the vehicle was packed solid (probably near maxweight) and the overall fuel consumption was a shade under 15l/100km. second trip.. just me/overnight bag and emergency tool kit (20kg)..13.9l/100km over 3,200km...

The easiest way to dramatically improve economy (in the true sense of the word) is to install lpg.

cheers, DL

The only thing to do for cheap is to advance the ignition timing from the recommended setting to 10 degrees BTDC static. You may possibly need premium fuel to cope but none of the dual fuel cars I work on seem to have any trouble on standard petrol at this advance setting. Check that your vac advance is working as well.
Other than that, put in a 300TDi from a disco. Relatively simple conversion providing you get a whole setup at a sensible price.

Originally Posted by cartm58

If your worried about its fuel consumption the best thing you can do is sell it now

The beast will not do better than 15mpg around town and 17mpg on country trip cruisng at steady 100

None of them ever have or ever will

My 1993 range rover 3.9 does 5 km per litre of fuel and ahs done so since l got in 2005.

Haha, I beg to differ. My 1993 Range Rover achieved amazing economy recently on a trip from Sydney to Brisbane. Used exactly 110 litres of fuel for the 950km. There was one section, where I achieved 550km and used 60L of fuel. Mine has the unichip in it so that helps a lot

Cheers

Interesting thread.

So far in my own personal testing I have found the only consistent way to gain fuel economy was to drop weight. I have removed the carpets and sound matting, the rear seats, the stereo and the hood lining is next
All up it's approx 250kgs lighter at present (currently weighs 2060kgs, wet with me inside)

It's drastic, and doesnt look pretty, but worked .

It also handles much better in the corners and under brakes.

Cant wait to remove the glass and maybe even the doors

Thanks for the banter!

My economy at present is hovering around 20l/100 and that included a drive from one end of Stockton beach to the other at the weekend.
My main concern was that I used to get the same economy in my carburettored 83 4door. I thought, perhaps a little naively, that the fuel injected 3.9 might be a bit better...

I might go through and check the compressions later in the week when I get some 'spare' time.

Thanks all.