Autosport Labs

How about running this system on a V12? Would I have to run two complete MJLJs and edis packs and treat it like two 6's?

Thanks for the input,

Justin

This is for some of the advanced users here. I would image that two EDIS-6 units connected to one Megajolt and two crank triggers might work, <b>IF</b> it is possible to offset one of the crank triggers so that it will fire the other six cylinders at the right time.

Now I don't know anything about V12 engines, if a V12 is two I6 and two cylinders are fired at the same time (i.e. I6_1 and I6_2 fire their cylinders 1 and 1 at the same time) then only one crank trigger is needed.


A nice diagram with the firing order will help a lot.

A V12 can be treated like two six cylinder engines, so in theory you can do it with two EDIS-6 units. A V12 has a firing point every 60 degrees, so you would have to configure your system with two crank sensors mounted 60 degrees apart.

A tweaked V12 would be a beautiful engine. The secret to extracting power increases in the Jag V12 is in the combustion chambers. Harry Weslake worked on the intake ports, so they are very good.

Is it 60 or 65 degrees?

Thanks for the replys 4600cc and Oliver,

4600cc, a V12 is like two I6s but on one the firing order is reversed. Here is the firing order;

1A-6B-5A-2B-3A-4B-6A-1B-2A-5B-5A-3B

Bank A being the righthand side and bank B is the lefthand side.

Two cylinders on the exact opposite sides of the engine fire at the *same* time. Same being as close as possible with a distributor. This is why the V12 does not produce any vibration. They are amazing, it doesnt move or vibrate when running, the only way to tell is by hearing it.

So the question is, can I use one MJLJ to power two EDIS (6) units and fire two cylinders at the same time? With one crank sensor?

How would this be done? Just run two wires from each terminal on the MJLJ to each of the EDIS units?

Thanks for the help,

Justin

From what I understand, and I ask someone else to confirm this, is that you have two I6 engines, firing order the same. (the fact that it is reversed in each bank doesn't count)

That means you can run either one of those engines with an EDIS-6, hooked up to a crank sensor positioned 60 degrees on the crank. In other words position of that sensor does not have to change.

So can you use MJLJ to power two EDIS-6 units and use one crank sensor? <b>Yes.</b>

I would suppose that connecting everything in parallel should work just fine. Run two wires from each terminal on MJLJ to each of the EDIS units. <b>And this is the part that I want someone else to confirm.</b>


Now there is also a different way, instead of using two EDIS-6 units, you could use only 1 and have it run 2 6cyl coil packs. For that, signal off EDIS will have to be amplified. To do this you will have to design (and someone will help you here) 3 amplifiers. Coil packs will be connected in parallel. The effect of this will be same as using 2 EDIS-6 units.

Now for the trivia. How big is the engine and how many HP? I bet all of us will find this info very interesting: <a href="http://www.autozine.org/technical_schoo ... ex.html</a>

For all purposes firing order is the same, yes.

Running one EDIS 6 with double coils per output would be great. How far away can/should I mount the EDIS unit? Can it take the heat in the "V"?

I have the first year of this engine with FI, a 76. It has (for the next couple weeks at least) the Bosch D-jetronic FI. It is very primative and I cannot modify the engine as it cant correct. This is where megasquirt comes in.

The engine is a 5.3L and currently makes almost 300HP and a little more in torque.

Fitting EDIS inside the V won't work. On stock vehicles it is mounted on the firewall in a corner, next to the brake booster, away from the heat. I have mine mounted inside under the dash right next to where I keep my Megajolt. This was done because the engine harness is there.

You will definately have to confirm about the firing order. If firing order is 1A fires then 6B fires then you will have to use two EDIS units, two crank triggers, two MJLJ units. But if 1A fires and 6B fires at the same time, then one MJLJ and EDIS will do. You'd have to get more info on this.

It's starting to look like two EDIS-6 and two MJLJ will have to be used.


<blockquote>

True, the V12 is basically two inline 6:s, but the crank is more or less the same crank as you find in a straight 6. There are 6 crank pins, pairwise parallel, which means that they are spread 120 degrees apart, and in each bank, two of the pistons run in parallel. The banks are spread 60 degrees apart though, so it has an alternating firing order.
One cylinder fire in one bank, then a cylinder in the other bank fires.
This goes on for the entire two crank revolutions. There are no cylinders on one bank that fires at the same time as a cylinder in the other bank.

My friends V12 is an old one with a giant distributor and a single coil.
There is no way that that would have worked if two cylinders fire at the same time.

A single EDIS-6 will not be able to fire two 6 cylinder coilpacks properly on a V12.

A quick google search reveals that the firing order of thye Jag V12 is 1A-6B-5A-2B-3A-4B-6A-1B-2A-5B-4A-3B

This means that cylinder 1 in bank A fires first, 60 degrees later cylinder 6 in bank B fires, and so on.</blockquote>

Ok, some folks at EEC forums had told me it might be possible to run both EDIS-6 units with one Megajolt. Basically you'll have to experiment, we know for sure that it can be done, just a question is how exactly. I'd do this:

1) Intall 36-1 tooth gear, install one crank sensor at 60 degrees, install another crank sensor at 120 degrees.

2) Have the 60 degree crank sensor run EDIS-6 for bank A, and the 120 degree crank sensor run the EDIS-6 for bank B.

3) Let's exclude Megajolt out of equation for now, just do a basic two EDIS unit setup with two 6cyl coil packs. If everything is alright your engine should run smooth at 10 BTDC advance. If something is wrong adjust or check how you setup plug wires for the proper firing order, and then adjust second crank sensor position.


If all works, add Megajolt to the equation, see if one unit can run both of them.

Thanks for the info, I will start rounding everything up. Mega Squirt is going on in a couple of weeks and EDIS is after that. This is a noobie question but when you say to install the sensor at 60 degrees after TDC? Thanks for the help...

<a href="http://picasso.org/mjlj/?q=node/2">http ... =node/2</a>


60* BTDC. That's the required mounting location for EDIS-6's sensor, this particular sensor will feed EDIS-6 for bank A. You also need to mount another sensor 60* BTDC past that to feed EDIS-6 for bank B.

<a href="http://www.austincc.edu/cloud/tc_eec.ht ... eec.htm</a> I recommend you sign up to the two mailing lists listed on that page. I got a lot of information I posted here from those guys.

Will do, thanks again for all the help.

Justin

Hey Mcleodjm,

I have an 86 XJS V12 been eyeing MS/MJ options for this car, maybe we could join forces in development. Here's what my observations are:

- the V12 does not fire two cylinders at the same time, but every 60deg. Look at your distributor - it has a 1-point rotor and 12-point cap.
- it uses distributor with mechanical and vacuum advance, running up to 28-30 deg. My car (HE) has 11.5:1 compression ratio, so it is VERY sensitive to advance.
- it uses 5-pin GM HEI ignition with magnetic pickup in the distributor (rebranded by Lucas), so we may learn something from V8 GM guys.
- going to distributorless ignition would would require two MJs and one trigger wheel with two sensors 60deg apart.

I won't start any work on the care for the next three months or so, but I would like to get some head start on the engineering behind it.

Any ideas?

Bart, Chicago

Hi Bart,

Sorry for the late reply, I have been busy. I am also working with another person, maybe the three of us could team up on this?

For a little background, I have a 76 XJS with the OPUS ignition. When I was thinking the ignition was firing 2 cyl at the same time, I was looking at the marelli ignition, and the dual contact rotor. Even then my logic was flawed.

Is it possible to get away with only one trigger wheel and 2 sensors?

Have you thought yet about where to install the trigger wheel? I have a GM alt in place of my airpump and an electric fan so I have two positions on my crank pully that are unused, I have been looking into haveing a custom pully made for the trigger wheel(s).

Justin