3.9 efi v8 into mk5 cortina estate

[mini-mad-nick]

So, my estates been off the road nearly a year and a half after a "light" restoration. I'm going to get a 3.9 efi rover to put into it, what rwd box will i need to use and will be easiest? Is there much cutting invoked to get it to fit? I know i will have to make mounts etc.

To wire the efi in, its 4 wires isn't it?

[sowen]

You need a Rover SD1 LT77 gearbox and manual flywheel as it will have the correct bellhousing, clutch and gear selector and be ready to drop complete. There are other alternatives but don't waste your time on them, complete ready to go LT77 'kit' won't be cheap either. I don't know how well it'll fit or how much chopping would be required, wait for someone with more experience to confirm that.

Is the 3.9efi auto or manual? I've just done an efi conversion on my SD1 and there was a little more to it than just hooking up a few wires.

[ChasR]

What Sowen said sounded about right in all honesty.

A ZF 4HP22 auto will also do the trick. I may soon have a bellhousing complete with sensors to ditch if I swap 'boxes in the Stag.

[sowen]

If it helps, bellhousings tend to go for around £100-150, gear selectors £50+, manual flywheels £50-100 and the bare LT77 gearbox on it's own £50-100 (prices going by roughly average ebay values). They do come up far cheaper than that but you've got to be quick to get the bargains. Buying complete is far easier and often cheaper.

[jikovron]

r380 boxs out of pilots are cheap as billio and tbh the low first gear isnt an issue as unless the cortina rear axle has less than a 3:1 cwp ratio it would be tedious useing first gear with any of the van /car ratios
i note that also from various experiences that the 3.9 is the worst version of the rover as its not a noticeable step up from a 3.5 and yet run on a knife edge between running great and cracking behind the liners unlike the 3.5 which has much more alloy present in that area

[misterbob]

Jul 28, 2014 17:05:38 GMT jikovron said:

r380 boxs out of pilots are cheap as billio and tbh the low first gear isnt an issue as unless the cortina rear axle has less than a 3:1 cwp ratio it would be tedious useing first gear with any of the van /car ratios
i note that also from various experiences that the 3.9 is the worst version of the rover as its not a noticeable step up from a 3.5 and yet run on a knife edge between running great and cracking behind the liners unlike the 3.5 which has much more alloy present in that area

The 3.5 is bullet proof, but the 3.9 is also a brilliant engine.
In fact of all of them, the architecture is the best as it retains the short stroke of the 3.5 with a larger bore.

The worst, IMHO is the 4.6
It's a rough old thing thanks to the long stroke, it's also not fond of revving, like the short stroke engines.
It's a total torque monster though - good for towing and off-roading.

Be careful buying a box without bellhousing.
As I recently discovered, various LT-77 versions exist, some with shorter input shafts.

Going rate for a 2WD V8 LT77 box with bellhousing is 4-500 pounds currently.

[jikovron]

Agreed on that point, the 3.9 is very oversquare and has the highest rev potential breathing and stroke wise

however imho the fitness for purpose transcends the engines characteristics as it depends on what is being sought, a big budget stripped down base to build to a spec with top hat liners, decent heads and replacing the inevitable round bar camshaft then all would have equal merit, but just buying a pulled 3.9 (or similar big bore) engine to fit on spec could massively disappoint as there is a potential for a double whammy of high mileage induced asthmatic performance and a lottery effect with cracks behind the liners.

[mini-mad-nick]

Its going to be used as a daily driven car with towing on the odd occasion. I don't want massive power just something to shift it along quite well when i give it the beans i take it you can put all the "flapper" or "hotwire" efi stuff onto the 3.5? I was going to run a typhoon cam from real steel, along with arp bolts, lightened flywheel, port matched heads, double valve springs and skimned heads to raise the CR.

Thanks for all the input, i shall ponder on it and make a decision when i get round to doing it

[sowen]

Jul 29, 2014 21:56:57 GMT mini-mad-nick said:

Its going to be used as a daily driven car with towing on the odd occasion. I don't want massive power just something to shift it along quite well when i give it the beans i take it you can put all the "flapper" or "hotwire" efi stuff onto the 3.5? I was going to run a typhoon cam from real steel, along with arp bolts, lightened flywheel, port matched heads, double valve springs and skimned heads to raise the CR.

Thanks for all the input, i shall ponder on it and make a decision when i get round to doing it

The early style flapper efi was only available on the 3.5, probably best avoided as the wiring isn't the greatest quality and good spares are hard to come by now.

There is a specific hotwire ecu for the 3.5, as I've got one on my SD1 from a very early Discovery. Some people say the 3.9 ecu runs ok, others say it runs rich on the smaller capacity lump.

If you're going to pep it up then the only things that really matter are the condition of the bores and that the engine has all it's ancillaries and entire efi loom still attached.