Disco overdrive?

Bear in mind that above 60mph, most of the energy you are using goes to overcome air resistance (which with a Disco is a lot). Whether your engine is turning at 2500 or 3000 rpm to achieve this isn't very important. The higher the gearing, the slower the engine turns, and the more fuel you need per engine cycle to give the power you need to maintain your speed. I accidentally did a large number of miles in D3 (4.6 RR) while towing a caravan in France (I'm too embarrassed to say how many) and it made not a scrap of difference to fuel consumption. Get an overdrive to reduce noise and mechanical stress and wear, but common sense says it can't magically give you more than a couple of extra mpg from the lower friction losses in the engine & gearbox as they run more slowly. It's not like getting a more slippery shape, or losing half the car's weight, or driving downhill, which would give the engine less work to do and therefore use less fuel. You're doing the same work, so you'll need more-or-less the same energy to do it.

My 2p worth. I could be wrong, and I usually am.

In news:7QPVc.510$ snipped-for-privacy@newsfe5-gui.ntli.net, Michael Williams blithered:

IIRC resistance to motion is proportional to frontal area. So solution saw off the roof!

"I've been wondering about some way to increase the fuel economy at high speeds." That is your problem, and your answer. Basic physics I'm afraid. Fuel consumption is directly proportional to Power used. Power used is directionally proportional to drag, and drag is exonentially proportional to speed. In short, quicker you go, more gas you guzzle. You want economy, slow down! There is no 'magic' economy gizmo, and the best you can hope for is a few mpg from efficiency gains - balence those few mpg against the cost to get them, and you will probably find it will take quite a long time to see a real saving Any way, "Obviously an overdrive is one option, though there's scant info on overdrives for Disco's on the net." GKN do one, try Ascrofts or Scorpion, I think Craddocks have advertised them before now, try the 4x4 web for links to the specialists.

Oh, of course. I should have realised that (ex-physics geek). I swear nightsift melts your brain. Apologies for the muppetry.

Ah, well. I've got more than enough to be getting on with anyway, though living in rented accomodation with no garage makes working on the Disco a bit tough (had to use a Tesco carpark at 2am to change the oil one night since I live in SE18 - nice steep hill).

Cheers, Aled.

In article , Michael Williams writes

Although these overdrives will bolt to the gearbox the same as the Defender. There is not enough room under the car to fit them to a Disco. Unless you remove the rear floor and re route the exhaust.