3.9 to 4.6 Fuelling?

[Robrover]

I have a new 4.6 short motor which I'm consider swapping into my automatic 3.9 Disco (1995) but keeping the existing heads, standard Lucas dissy, 14CUX Hotwire efi with the 5AM airflow meter and standard Land Rover ERR722 fuel injectors, and fitting a high torque cam (RP4 or equivalent). The 4.6 is 9.35:1 compression whereas the 3.9 (Australian spec) is 8.13:1 with no cats or lamda sensors.

My question is what do I need to do to the 14CUX so it can fuel the higher compression 4.6?

Options seem to be:

1. Add a Unichip to the existing ECU, however Unichip have recently put up their licensing fees and all the local suppiers have ditched them. The Unichip software can only be used by licensed operators who have to install and set it up on a dyno.

2. Add a Haltech Interceptor to the existing ECU. Haltech have one listed for the series 2 Disco but not the earlier model, although I believe Graham Cooper Land Rover in Sydney has done this.

3. Use Mark Adams' Tornado EPROM chipset in the existing ECU - anyone have any experience of this?

I assume it's not within the 14CUX parameters to 'self adjust' for the extra fuelling of the bigger motor. Any other options available, apart from going the full replacement efi route (Megasquirt, Motec, etc) which I'm reluctant to do.

[Teesdale_landrover]

i would recommend the 3rd option

i dont have any experience with the other options which could be made to work, but for plug and play fitment you cant beat the chip.
they do change the engine allot, less throttle needed to maintain speed and noticeably improve sound on stock lump.
get in touch with mark adams direct dont buy off ebay

[CastleMGBV8]

Rob.

If you are keeping the engine standard apart from the high torque cam then the standard hotwire set up should be able to cope with the additional capacity, it is cams with more overlap that cause a problem with the standard system, as the air flow meter cannot cope with the reversion pulses.

Hotwire was used on the 4.2 engines (4.275cc) and the 4.6 engine is 4.552cc. so only 277cc. extra capacity.

You will need to use tin head gaskets to maintain the high compression ratio with the earlier 36cc. chamber heads which should not be a problem.

There may be a marginal amount of tuning available for the standard hotwire system (tune resistors) which I believe adjust the fueling for different capacity engines others more experienced should be able to advise.
I would get it up and running then take it to a rolling road and make sure the mixture is not going too weak at wide open throttle.

As for the price of chips, I used to be able to buy them from BBR for a £100 but the price has gone through the roof, a chip and carrier is £15 and 2 mins time to upload the map = £380 profit, I'm in the wrong business.

Kevin.

[chodjinn]

In my experience piggy-back ECUs aren't worth the circuit borad they're printed on, and since you will have issues setting up the Unichip for reasons stated, personally I'd go with a new standalone ECU, but the mark adams chip will be good as long as it's set up correctly.

[badger]

I use the Tornado chip on my 4.7 landrover (re-linered and rebored), simple to install into the ecu as long as your old ecu has the carrier already in it (some early 14cux types don't) and it runs just perfect, straight out of the box.
My engine has a disco II (Thor) inlet manifold with the 14cux fuelling system grafted into it, and I have the choice of running open or closed loop fuelling with the Tornado by simply swapping tune resistors between "white" or "green". Can't remember off the top of my head which one is which though.
Simple, reliable, quick and effective, gets my vote every time.

[r2d2hp]

And if you opt for 3 let me know.

I have Tornado chipped ECU, 20 AFM Airmeter and Diag unit for sale from my TVR 4.3 engined capri.

[Robrover]

Thanks guys, some great help, looks like I'll give the 14CUX a try on its own first then add a Tornado chip if I feel it needs a bit more.

BTW what's the 20AFM was this the later type? Or the Bosch replacement AFM that I see some TVR owners with the Tornado chip had installed by MA.

[r2d2hp]

20AM is a little larger that the 5AM. Without having the ECU remapped I do not think you will get the best out of the conversion.

The ECU I purchased was for a 4.0 and mine was a 4.3 and to be honest I was disappointed. But after MA mapped it the difference was incredible. Its not so much about top end power as any tuner can sort that out, where it came into its own was in terms of its drivability in top gear throughout the whole rev range.