Thread: Ride Height & fuel consumption???

I don’t know about the effects of ride height and fuel consumption but I would imagine it would be substantial.

I have roof mounted driving lights which I only have mounted during night driving and remove them as soon as it’s light, when doing long drives.

While the lights are in place and I’m driving at highway speeds, I get about a 10% increase in fuel consumption.

Cheers.

Be interesting if anyone actually has measured this. In theory it ought to increase drag simply in proportion to the increased frontal area, but it won't be as simple as that. Because of the changes in airflow the effect could be either larger or smaller. Aerodynamic drag is the major part of resistance at speeds above about 60kph.

A complicating factor is that few people ONLY raise the vehicle - they also usually fit larger tyres, which both increase the frontal area and change the gearing, and often rolling resistance as well. In addition, with a lift the u-joint angles increase, increasing the drive train losses.

John

Add to the fact that Landys are about as aerodynamic as a block of flats to begin with. Id imagine the more you expose of your running gear ie diffs etc. the higher the drag will become. Car companies today go to a great deal of trouble doing analysis of under car drag in wind tunnels to squeeze as much economy out of a vehicle.

A marginal loss of economy is going to be apparent with a lifted vehicle more drag from exposed underbody bigger tyres and more resistance through drag equals a greater mass being pushed through the same amount of air .Even running a lower octane fuel with these factors contributes to even greater loss of economy I ran 95 0ctane 2 full tanks worth and lost at least 50 to 70 kays out of a tank I usually get 300kays out of half a tank of 98 Octane D2V8 but running 95 waranted 250 at a half a tanks worth

I read about this in a magazine once that it can increase fuel consumtions up to 25% for an 8" lift on an F350 V8 diesel but I dont know about a Landy.

When I first did the lift I didnt notice much difference in economy but when I put the taller tyres on it seems to have to work a bit harder and it has lost a bit of economy but I do have the tent on still so when I get the rack off I will check what the economies doing then.

It has to increase it though as turbulence under the body will cause drag as well as the increase in frontal area but I would say only a few % for a mild lift (upto 2") and probably the same for tyres depending on size.

I didn't notice anything with a 2" lift. When I did notice it though, was when changing from hwy to MT tyres, and also when putting a roof rack on. Tyre diameter change didn't make the consumption change much for me, but did make it a lot more inconsistent - though diff gears corrected that.

I doubt if the airflow underneath adds any turbulence with a lift - its pretty awful to start with. To get anything approaching laminar flow underneath you need to either have skirts front and sides within an inch or so of the ground (look at most racing cars) or have very smooth underside, preferably rising towards the back and lower at the sides, together with very close fitting mudguards. No Landrovers come anywhere near either of these ideals, although the current Disco and Rangerovers are closer, at least when the suspension is at minimum height - but probably not close enough. So I doubt that any increase in turbulence will make much difference compared to the increase in frontal area - lifting it does not allow free airflow underneath, so the lift is just a straight addition to frontal area. As someone commented - the streamlining is notably absent, but the large frontal area is probably the biggest problem, even before you lift it.

Sure, the lift would expose the car to more underbody drag but I'm really wondering about the bullbar, more specifically the removal of the original front bumper and air dam - repleat with bib spoiler etc.

I thought my car was terrible with fuel - actually it is, showing avg of 18L/100km. But this is with speedo error of approx 13%, in reality bringing it down to around 15.5L/100km - not bad for a "mid nineties apartment, with a view".
(as opposed to "1950's block of flats")


Hardy