Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
Quote:
How can I improve my Land Rover's performance?
Diesel engines run most efficiently between 1200 and 2000rpm. Petrol engines are best between 1500 and 2500 rpm. Changing gear earlier to stay within these engine speeds will help improve your fuel consumption, as will using the Dynamic function on your in-car navigation system to avoid stop-start conditions on congested roads.
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
...except most peoples experience indicates that running the TDV6 in 6th giving revs much lower than 2000 gives worse economy than 5th closer to 2000....which is what you were saying wasn't it??? 1200 to 2000 is a heck of a range...really its only saying <2000rpm>2000rpm
Thought my 1900rpm post was supporting your 2000rpm post, couldn't understand why you got hung up on the 100rpm difference in what was said....Cheers
Simon
29th Dec 2008 10:48 am
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
I wasn't hung up on your post Si...
Either way... stay around 2K revs for more efficient motoring.
29th Dec 2008 10:52 am
simonsi
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
OK, thought we were heading for a giant game of "simon says" from both directions Cheers
......max efficiency on any engine is at the max torque point, its where the output (torque) exceeds the friction and other losses in the engine.
......I disagree that max efficiency is at max torque point - max torque point is just what it says max engine torque - it doesn't consider fuel intake or road speed.
The torque figure that Land Rover quote is from an engine dynamometer test - which should compensate for variables & can simulate the changeables - it is just raw data - a number that says what one of the parameters the 2.7 D3 engine has.
The efficiency that Disco 3 drivers want to know & understand is the ratio of a road speed to engine revs to fuel consumption...basically a sweet spot that when achieved can give a "happy" balance in these fuel critical times.....if you look at the torque curve it is lower than the max point but the graph line slopes away gradually....ok there will fractionally less available torque at 2000 rev/min as compared to 1900 rev/min - but can this be related to a vehicle efficiency....not engine output.
There are that many other variables (which include - ambient temperature, atmospheric pressure, specification of fuel &c.) & changeables which ought to include (age /condition of vehicle, load in & on vehicle, tyre pressures &c.) + the other big variable - the driver ! it would be hard & not viable scientifically to make hard & fast comparisons. Also the comparison we are talking about is about theoretical constant road speed - on most of UK motorways its more viable (& safer) to "go with the flow" for that volume of traffic dependent on road conditions, time of day &c.
Another way of looking at this is to use the cruise control......it attempts to give a constant road speed once set not a variable road speed & constant engine revs/ output....on a motorway set cruise to say 75 mph in "D" watch how it holds speed & keep a good eye on consumption figure - on my D3 at least this value is all over the place......when all said & done the consumption meter is only an indication - its hardly a calibrated instrument + the complexities of the D3 engine / gearbox management processors will also factor in other variables.
Interesting thoughts.....at christmas time when trying to shut down & recharge batteriesBREXIT - done properly.
Right now ...We need Government - not Politics
Save the Dipstick Flagbearer-keep it simple, less likely to fail campaign-agenda items:Starting Handles, Acetylene Lamps.
Founder: Dipsticks-R-Us Inc
D3 HSE-perfectly formed, passenger friendly...has real DIPSTICK
Jag XK-but sadly no DIPSTICK...HUGE design fault
FL2 has DIPSTICK..."real comfort in rear seats"
VW Golf wondermobile (?)..has real DIPSTICK
Morris Minor..original DIPSTICK technology..and a real KEY.
29th Dec 2008 11:32 am
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
I've found that CC does not predict inclines or declines as efficiently as your brain and foot does... I believe that manual control of your go peddle is more efficient than letting the D3 do it. Especially on a manual D3.
CC will wait until road speed decreases before applying more power, you can pre-empt the drop in road speed and apply slight throttle immediately to compensate.
The best use of cruise control is for what its designed for... keeping a steady set speed not as a mechanism to drive efficiently.
Others mileage may vary (pun intended)
29th Dec 2008 11:39 am
simonsi
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
BLFarrar wrote:
simonsi wrote:
......max efficiency on any engine is at the max torque point, its where the output (torque) exceeds the friction and other losses in the engine.
......I disagree that max efficiency is at max torque point - max torque point is just what it says max engine torque - it doesn't consider fuel intake or road speed.
The max torque is for the engine and (I missed a bit out in my original post), it is the engine speed where maximum output torque is available, this must be where the internal losses of the engine are proportionally at their lowest (otherwise max torque would appear somewhere else in the rev range. If you are spending proportionally least fuel on losses then that is where my "most efficient" statement comes from.
All other things being equal, keeping the engine close to max torque should yield best economy.
Various test show that using cruise control is bad for economy, not least because it positively loses kinetic energy by using engine braking on any downhills, leading to it replacing that kinetic energy on the uphill sections.
I'd hazard a guess that best road speed fuel economy (assuming no headwind), is around 50-56mph in 5th, but for any load (weight, speed, headwind or sum of all three), keeping the engine close to max torque should give best economy for those load conditions.
Many have quoted better economy in 5th for example than 6th for the same conditions, mostly this seems down to it lifting the revs closer to 2000rpm than 6th would allow, so the reduced rotational losses from running in 6th are outweighed by the reduced efficiency of the engine at the resulting lower engine speed it seems.
I still get 20mpg round town/commute and 28mpg on a motorway run. Less if heading SW Cheers
Simon
29th Dec 2008 11:44 am
Getafix
Member Since: 13 Sep 2007
Location: Melbourne
Posts: 229
I am feeling ignored
7.7 litres per hundred. Are we all saying I can do better?
(That is 30.5 mpg - if my maths is right)<*(((<<
29th Dec 2008 11:58 am
simonsi
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
Nope, just a measure of consumption which a)doesn't mean anything to someone entirely Imperial-based and b) needs a calculator to turn into real money.
.......I still get 20mpg round town/commute and 28mpg on a motorway run. Less if heading SW
...maybe a bit less around town & 'bout the same on a run as my D3 (06MY - auto box - HSE)
the best long run I have done - towing a HUGE car trailer was from Yorks to London - London to Belfast & then back to Yorks - all up average (brimming tank & using actual mileage) was 28 mpg....the one thing this two day marathon did was it loosened up my D3's engine a whole bunch.
Simonsi - does the JE tune give you any speed / acceleration advantage ? - it clearly doesn't improve consumption.BREXIT - done properly.
Right now ...We need Government - not Politics
Save the Dipstick Flagbearer-keep it simple, less likely to fail campaign-agenda items:Starting Handles, Acetylene Lamps.
Founder: Dipsticks-R-Us Inc
D3 HSE-perfectly formed, passenger friendly...has real DIPSTICK
Jag XK-but sadly no DIPSTICK...HUGE design fault
FL2 has DIPSTICK..."real comfort in rear seats"
VW Golf wondermobile (?)..has real DIPSTICK
Morris Minor..original DIPSTICK technology..and a real KEY.
29th Dec 2008 7:27 pm
captain_sugar
Member Since: 05 Sep 2006
Location: Hradec Kralove
Posts: 1095
Re: Less Fuel in Fifth
norto wrote:
According to the "Scanguage" on a flat road
with the cruise control set on 100kph
my car uses between 1 and 1.5 L/HK less in fifth than it does in sixth
I thought 6th gear was for cruising at 150kph ?!Some people get by
With a little understanding
Some people get by
With a whole lot more
I don�t know
Why you gotta be so undemanding
29th Dec 2008 8:45 pm
simonsi
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
BLFarrar wrote:
Simonsi - does the JE tune give you any speed / acceleration advantage ? - it clearly doesn't improve consumption.
Yes and consumption would be better than normal except I use the extra power quite a bit. Steady 40-50mph on A roads yields 32-33ish mpg but taking advantage of the overtaking power reduces that figure quite a bit...
Overall it seemed 1-2mpg better than standard just after it was done both around town and steady speed....Cheers
Simon
29th Dec 2008 9:08 pm
Shrinky
Member Since: 05 Jul 2007
Location: Cotswolds
Posts: 2515
simonsi wrote:
I think you are missing the point, max efficiency on any engine is at the max torque point, its where the output (torque) exceeds the friction and other losses in the engine.
Whatever you have read (link?) I guess is an approximation to the max torque point. Yes in any driving situation 100rpm is irrelevant but worth understanding the science behind it don't you think...then any reader can apply it to any engine
He is only stating what LR have quoted Global Warming.... I'm luvvin it
29th Dec 2008 9:30 pm
simonsi
Member Since: 14 Oct 2007
Location: Auckland
Posts: 1264
Shrinky wrote:
simonsi wrote:
I think you are missing the point, max efficiency on any engine is at the max torque point, its where the output (torque) exceeds the friction and other losses in the engine.
Whatever you have read (link?) I guess is an approximation to the max torque point. Yes in any driving situation 100rpm is irrelevant but worth understanding the science behind it don't you think...then any reader can apply it to any engine
He is only stating what LR have quoted
Read on Shrinky, it was all sorted earlier, we were BOTH quoting LR.....keep up Cheers
Simon
29th Dec 2008 10:09 pm
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
My Knight in shining spliff armour
Yep we were both at the bottom of the same tree barking at each other it seems
But then again
Its all getting too complicated since Bruce joined though
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