I can probably get a 4.6 rebuild most of it and if it all works out sell my 4.0 and still profit.

More power is cool, but what im interested in in gas mileage. I know for most applications such as bigger engines super chargers and turbo chargers. If you boost the horsepower but dont use most of it the engine runs more effeciently.

Im just wondering what you guys think. I know it wouldn't be much but it would be basicly free and I would have a bigger engine.

Also what all is needed? Engine and Ecu Correct?

 

There are GEMS 4.6 engines that are a direct bolt in swap for the 4.0. I think there are a couple sensors different on the 4.6 but nothing major. I'll get the details on the difference. My buddy has a 4.6 in his 96 D1 and he consistently gets almost 20 mpg around town. He actually ended up with the 4.6 by mistake. He bought a 97 as a parts car and the original engine in the parts car had died under warranty so the dealer installed a 4.6 due to a shortage of available 4.0s at the time.

 

sweet if something like that were true I would be all for it. I can get the engine for dirt cheap and have a buddy who would do all the work for me for free.

 

Save your money, my 4.0 gets better mileage then a lot of my friends 4.6's.

 

You will get more MPG by swapping in a manual gear box.

 

Check out http://www.eastcoastrover.com/RoverV8.html, they have done 4.6 D1 conversions. For a 4.6 gems motor, they sell a fuel chip to compensate for the displacement. Otherwise, a direct bolt in.

They do say the 4.6 will improve fuel economy IF "driven normally"

 

That may be true but I know I struggled to keep up with Will's Disco with the 4.6 in the mountains. That little bit of extra power makes a huge difference at altitude.

 

A local fellow put a 4.6 in his Auto D1 and he said the transmission acted "very funny" as if it didn't know when to shift so he took it out and put the 4.0 back in.

 

You can put a Bosch 4.6 in as well. You will have to swap the front cover, timing set, and file the knock sensors. If you install electric fans or a flex fan, you don't have to mess with the front cover.

Not sure about mileage, but a D1 gets better mileage over a D2 and maybe Mike is thinking of that. I have heard of 2 people swapping a 4.6 and getting better mileage in a D1.