Engine dilemma

[task]

I've reached the stage in the CSK build where I need to start thinking about whet to put under the bonnet.

The 3.9 that came out has done about 160K miles.

Sat in the shed I have a 1994 softdash V8 that was rebuilt before I bought it and fitted it to my last Range Rover, a 1991. This is a serpentine engine and I would say it's only done about 15k miles since a total rebuild, it was very very clean inside last time I had the heads off. It would probably need a bottom end rebuild as it ran for a 20 seconds or so upside down when I rolled the RRC.

I had wondered about building a 4.6 engine, either buy buying a complete bottom end or swapping the crank/pistons in the serpentine engine.

What is the likely cost of building a 4.6?

Is there enough gain from building a 4.6 to warrant the cost or would I be better spending the money elsewhere on the engine?

Any other ideas? (other than fitting a non rover V8 or a diesel)

CSK is manual if it makes a difference.

[Mike Brownlie]

stick with 3.9 and go for turbo or supercharger ??

bigger displacement = thin cyl walls ????

[nicksmelly]

TBH, i'd be looking at a modern V8 like a Lexus LS400, or a BMW 4.4 V8, both of which you can often get for less than £500.

To rebuild any Rover V8 with the intention of power gains you are looking at a lot more than £500 on top of the cost of the engine, and then you are probably nowhere near the 286bhp of either the Lexus or the BMW.

[nicksmelly]

stick with 3.9 and go for turbo or supercharger ??

bigger displacement = thin cyl walls ????

The 3.9, 4.0 and 4.6 have the same bore size = same thin cylinder walls.

[101sean]

Some sound advice here - www.v8forum.co.uk

Stick the non serp timing cover and dizzy on the soft dash engine and use that (will need a spacer on the crank pulley) Most parts are interchangeable. I've just rebuilt my 101 engine from 3 different ones plus new cam and lifters.

[task]

Cheers for the replies,

the question really was, I have to rebuild the bottom end of my late 3.9 engine. Should I convert it to a 4.6 or is the 4.6 not really all that much better for my application than the 3.9 engine?

The Range Rover will be pretty much road use only, probably the odd greenlane etc but no major stuff.

[landroversforever]

Wait a month or so, and wait for Nige to get rid of the Eales 4.5

[task]

I think that might be a little out of my price range when it comes to "for sale" time

[mickeyw]

Wait a month or so, and wait for Nige to get rid of the Eales 4.5

A month! Who's having a laugh

[Range Rover Blues]

Take the sump off the serpentine and check the big end shells, 20 seconds is nothing TBH it could well be fine. The serpentine has a better oil pump and the timing chain housing is very slightly different so I'd fit the serp complete, the drive belt is also better for a big alternator (which is will already have).

If you do rebuild it you should be able to get it cross-bolted too, the block was cast for it but never machined.

IIRC the 4.2 had offset-pin pistons, I don't know how compatible you'd find 4.6 parts but I think it would be cheaper to find a complete short engine.

Money might be better spent on a hot cam and EFi upgrade, more power and better economy.

[task]

Cheers Range Rover Blues, I had wondered if the money would be better spent on improving the engine I own and know was good.

cheers all

[longlandy]

TBH, i'd be looking at a modern V8 like a Lexus LS400, or a BMW 4.4 V8, both of which you can often get for less than £500.

To rebuild any Rover V8 with the intention of power gains you are looking at a lot more than £500 on top of the cost of the engine, and then you are probably nowhere near the 286bhp of either the Lexus or the BMW.

Lexus good thinking about doing one myself, but bmw very bad Must be one of the most unreliable head destroying v8s ever made

[nicksmelly]

More unreliable than a Rover V8... go and pull the other one.

[Range Rover Blues]

Only thing with a posh toyoda Lexus is that they are so reliable if you ever have any problems you'll be looking for another engine. When they get out of warranty there's not so much knowledge about fixing them, that's why prices plumet in the car trade.

[Bowie69]

If I was doing it again, it would be a Lexus V8 without even thinking about it.... they are well used in drift cars and hilux off roaders, there's a huge amount of knowledge out there when you start looking, especially from the aussies.