Vehicle & Technical > Discovery
need more noise i think
mentalmoshio sophs V8i:
36 mpg right did it coming home from devon on the m5. havent used it to much lately going on motorways
at 75mph a 3.5v8i should do 21mpg on the motorway according to haynes book. think its 23.4 mpg at 56mph but never got as good as quicker speeds ive found
so u need to average 18mpg on lpg.
change gears at 2750rpm for a start
be relaxed with right foot and cost when downhill.
fit kn filter and lum.... leads . ngk spark plugs and that about it. oh all engine breathing bits secure and clean to breathe.
with bigger boots on u shoulld get 34ish.
make sure the exhuast does leak anywhere .
think also cars with lots of car polish on make less friction with the wind cause u get slight less drag.
and thats about it
DarrenG:
Ah you never mentioned LPG! Even then I still think 18mpg on LPG is over optimistic when it's all but impossible to get that on Petrol even when driving carefully.
Thrasher:
AAAAAAAAAAAAAARGH!
IT IS NOT 36MPG then is it????
It's 18.
And 18 on gas ... I think not. I mean ... gas is WORSE than petrol 99.9% of the time.
You have a roofrack, big tyres etc etc - none of this will *aid* your mpg.
My aero-dynamic (more so than the D1) RR 4.2SC does 17mpg *average* - so I cannot believe a loaded/racked and bigger tyred D1 can beat that?!
I'd say you would be *lucky* to be hitting 13 .....
and that remains THIRTEEN MILES PER GALLON, it doesn't magically double because it is LPG. Otherwise Diesel owners would have to multiply DOWN their mpg readings to compare them with petrol!?!?!?!?!
Evilgoat:
--- Quote from: "steveo4v8i" ---36 mpg right did it coming home from devon this ur on the m5.
at 75mph a 3.5v8i should do 21mpg on the motorway according to haynes book. think its 23.4 mpg at 56mph but never got as good as quicker speeds ive found
so u need to average 18mpg on lpg.
change gears at 2750rpm for a start
be relaxed with right foot and cost when downhill.
fit kn filter and lum.... leads . ngk spark plugs and that about it.
with bigger boots on u shoulld get 34ish.
make sure the exhuast does leak anywhere .
and thats about it
--- End quote ---
Could you PLEASE do something with your sig?
Thats unlikeley I'm afraid. Check your calculations. If it IS right then you need to be speaking to your bank manager about starting a business.
I run an Audi 90Q 2.5 10VT, I run two maps, one for performance, one for day to day use. The standard map yeilds about 170BHP. The car itself weighs in just over a ton. This is a fully electronically managed, turbocharged, modern engine and on the map in question its running better at stock and just about manages 30mpg.
Now look at the lump sat in your engine bay?
You shouldnt coast (out of gear/no clutch) ANYWHERE. Engine breaking is an important part of stopping a heavy car especially in an emergency.
--- Quote ---fit kn filter and lum.... leads . ngk spark plugs and that about it.
--- End quote ---
You will make a difference with these but not THAT much. K&N Filters may actually worsen things as will a free flow exhaust. Think of your engine as a tuned instrument. When the engine takes a lungful of air theres a LOT going on. The plenum chamber and intake headers are (normally) designed to allow as large a mass of air as possible to move, this means after the intake stroke has ended, there's still air piling into the cylinder. Changes in intake characteristics can hamper this. I dont know enough about this engine to say what it will do but on a lot of performance engines you will find that you will loose power. In the exhaust a 'standing' wave is setup which 'pulls' waste gasses out. How well this works depends on lots of factors including expantion boxes, pipe bore and length. A free-flow exhaust or poorly thought out sports exhaust may sound good but again, youre going to hoof the gas flow, emissions and power delivery. Going back to mine. I could have gone for a nice loud 3" system all the way through, instead opting for a system designed for me to match the engine. The result is an exhaust that can be loud but only in the same way as many true performance cars are loud, not the annoying noice of a cherry bomb or chav with a bit of iron drainpipe. Again, the gains here will depend on the car and I'm guessing the stock rover exhaust is pretty poor.
Leads and plugs, yes, but these should be 100% anyway.
--- Quote ---at 75mph a 3.5v8i should do 21mpg on the motorway according to haynes book. think its 23.4 mpg at 56mph but never got as good as quicker speeds ive found
--- End quote ---
You're breaking some cardinal rules here. Most cars have a cruise speed centered at about 60Mph. This seems to hold trud for the 200TDi and I'd expect the V8s too. (theres is a reason haynes manuals are referred to as 'haynes book of lies' btw). Once you start to go about 60 in almost any well designed aerodynamic veihcle the fuel consumption goes up, drastically. Again, the Audi B4 is one of the most aerodynamic cars there has been in terms of saloons. At 61 I get best MPG at around 28ish. 70 its down to 20, 90 and we are into 18 territory and at its top speed, 8. Now this is an aerodynamic car, your disco has all the areodynamic considerations of a house brick. Because of this you'll probobly find your optimum crusie speed is lower and fuel consumption will get scary. As you get into higher speeds the engine has to work significantly harder to overcome drag, on something like a disco this is a big factor. So say 60mph gives you 30mpg, then its logical to expect that 120 would give you 15mpg, well not so. There is a formula but youd be closer to looking at 20MPG at 80 in a car. This is why supercars have to be insanely powerful just to go 20mph faster than the last one. With the power use goes fuel demand.
You *could* run the car insanely lean, heavilly managed with gear ratios that would mean pulling off on a flat junction in low box and you MIGHT just get these figures, although the thing would be undrivable and the lean mix would melt the engine.
Also I REALLY hope you arent relying on the fuel guage for calculations :) Or the Odometer come to that.
Thrasher:
Oh and you must remember that oversized tyres make the ODO read wrong .... so you will be 8-10% out ANYWAY :shock:
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