Hypothetical question (ignition/fuel)
 

Lets say money is no concern, and you have yourself an aftermarket ECU capable of running a V12 with no issues, and a shop ready to build the wiring harnesses aaaannnnd tune it properly so your V12 can actually function as intended.

Assuming professionals will fab up whatever wiring etc is necessary - What product would be best to replace the existing (and failure prone) distributor system, and possibly the injectors as well? I recall reading somewhere that a certain type of Ford injector fits perfectly in the existing holes but it comes in a much finer spray pattern and higher pressure so simply dropping them in without the aforementioned tuning capability would just not work.

Am I silly for thinking the Coil-on-Plug type part off say...an XK8 would work just fine if you have the appropriate harnesses built? Is there a better solution maybe something more universal and reliable?

Well, firstly I'd ditch the dizzy. Full distrubtorless ignition, taken from a X305 V12.

EFI would be something sequential. Maybe two 6 cylinder systems to profit from switching one side off... Probably for me Megasquirt.

My 6.7L will run Ford Denso injectors actually from a 3.0L X Type, They are shorter than the stock V12 injectors and I have made 12 little aluminium extensions to fit in the later V12 fuel rail that is O ringed.

I will be running the Marelli distributor and ignition modules from a MegaSquirt 2 mounted in a Jaguar Lucas ECU case so it will plug into the stock wiring harness. Engine bay harness will be slightly modified to use a couple of old Lucas injectors wires to run ignition to the Marelli (aka Bosch) ignition modules.

The Lucas uses separate wiring for Peak and Hold functions for the injectors. The MS2 will use PWM so 1/2 of the injector wiring from the ECU will be unused.

I do have GM DIS coil packs that I have modified to run directly off the MS2 but I will most likely not use them and keep the distributor. My Marelli distributor is over 15 years old and still good. I know Norm ran the race engines with a Motec ECU and a stock Lucas distributor locked for over 600hp @ 7500rpm

Interesting, I've been talking to the tech ppl at Motec they said their new ECU can do a V12 with Coil on Plug setup no problem, though it would be a few thousand dollars to assemble the parts.

There really needs to be a modernized drop-in replacement kit for these engines.

I doubt there NEEDS to be. Most V12 drivers are hapoy with what they have. And with most I really do mean most. Those crazy few who aren't are a minority. And qith the low numbers of the Jaguar V12 compared to say GM 350CI or Hemi 427CI or what not, the money put into such a project will always remain a loss...

I would tend to agree.

I have no complaints about the ignition and fuel injection systems. They get the job done and virtually all faults and fixes are known.

Everyone here knows (or should, by now) that I love these old Jags and the Jag v12 engines as well. But, in all honesty, I can't see myself spending thousands on modernization/high-tech upgrades. For higher-tech, I rather just go out and buy a more modern car.

That's not a criticism of anyone who takes a different path. In fact, my hat's off to those who do. I'm just getting lazy in my old age....and cheap, too. :)

Cheers
DD

Exactly that. I think a different injection system would be enough. The ignition system is more than sufficient. Even the Lucas/Marelli stuff...

Retrospect
How improved the ECU V12 5.3L
From 6CU to 16CU then 26 CU. Better MPG more stable and additional diagnostic on 26CU. No more power.
Then V12 6.0L 36CU with Marelli on XJ81 and Denso with distless . I do not see big differences between 6.0 may be 1-2-3 ponies and 1mile more on higway.
Hypothetical , you will get high-tech modern ECU.
How many power up you will get? ???
How many Miles per gallon you will get? ???
You will get a headache! You will want to turn to set something, you will think it will give more HP more MPG or something else.
When you have STD ECU you do not think about it and any tuning and do not have headache, just driving.

But I think I need this headache. I like to set, to turn something.

There are smaller choices available, at least for now.

I have a "Superenhanced ECU" from AJ6 Engineering. Haven't gotten around to installing it yet but I'm confident it will work as advertised. I used one, years ago, on my XJS and was happy with the improvement.

Of course, it's a tweaking of the existing technology. Not newer technology. But, it's just $500 and a direct drop-in as opposed to engineering a new system and spending thousands.

Cheers
DD

The biggest improvement would be re-tune the V12 to run on 98RON fuel. The XJS we got in Australia (Lucas ignition ) was tuned to run on 91RON and the Marelli had a strategy link so
it would run on 91 or 95.

Was that just a matter of ignition timing, Warren?

Assuming you use the AJ6 one, what is your old unit? I need a spare DAC6337 or similar to send off and get modified if I choose that route, I'm just abit concerned because (thinking long-term) these 1980s electronics won't last for ever, I've even considered paying a tuning shop to fabricate a interface between the existing wiring harness and the 'new' aftermarket unit to save on headache and cost of rewiring everything. 3D printing makes this fairly easy once you have the design drawn up.

I have two good ECUs; one sent to AJ6 for the magic. The other I'm keeping....for the reason you mention :) I might send that one off to AJ6 for a freshen-up as well !

Cheers
DD

Yes and No,

Yes you could just advance ignition timing and this would increase power, but would not take full advantage of the increase in RON.

Fuel trim and ignition would take better advantage of the advanced timing