3.9 into defender???

And not as much of a mystery as a carb for some people

Up to you but rule if thumb is Efi is better than carb

Nothing wrong with carbs as such though...

When its up and running, you'll be glad of EFI. I've not delved into it but the hotwire system isn't massively complex and mine seems to run pretty sweetly. Carbs can be simple but I've read that even a small 390cfm Holley can be a bit over the top for a 3.9 rv8. After all, you find them on mild small block chevy and Ford motors (5 litres or so). I have a feeling that it would need as small a set of jets as Holley provide for that carb and whilst an easy job, that will cost you a few quid to get hold of.
Nothing wrong with twin SUs but you'll never get the mpg, power or reliability in a range of temperatures and conditions as the EFi setup. Even if the EFI went wrong, you can replace all the major components for very little second hand.
People like carbs because there are no sensors and its all mechanical so easier to diagnose a problem, fair enough, but they are an old technology and not as suited to a daily driver as EFI.
Now there is a question over whether a carbed motor sounds better? I have no idea, but some recon they do sound better?

I don't have any first hand experience with these carbs but have been told they are not as good for off road driving. Apparently holly carbs flood easier when on steep gradients whereas you could have efi on it's side and it will still run ok. Just my 5 cents worth.

Try and keep the fuel set up as std as you can (either injection or SU carbs). This will give you the best starting, reliabilty and fuel consumption as they are tuned to work together. If you go for the Holley, you may end up with hot restart problems and almost certainly worse fuel consumption as the jetting will be crude and tends to be rich to ensure there are no flat spots caused by running weak.

noexitroad said:

Apparently holly carbs flood easier when on steep gradients whereas you could have efi on it's side and it will still run ok. Just my 5 cents worth.

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Yep they don't like running sideways whereas the SUs are fine. I've had both and believe it or not the Carb does sound better than an EFi. Don't know why but it does.

EFi will give you more grunt through the rev range than carbs and better economy I think. When running well the EFi seems less hassle and needs little maintenance. For every day I would go for EFi I think.

The only reason I stick to carbs is I know how they work = simples. I only use mine for weekend fun, not every day - try diagnosing an EFi in the middle of a muddy pool!

That's my personal opinion anyway

Good advice from everyone

Efi runs great all the time then one day might go wrong whereas carbs will hardly let you down but probably never run properly perfect!

14cux is very simple and hard to kill

Besides, we should be talking about ignition, fueling is not the biggest problem with rv8 it's sloppy ignition and timing

Fit megajolt as a minimum or do yourself the biggest favour ever and go full MS

It's unreal what it turns your v8 into