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CDI ?.... MSD ?..... Help please
Posted: Wed Jul 16, 2008 9:42 pm
by mycar
I was hoping that by the time I got to my age I`d pretty well know all I`d need to know about.... well... everything.
B*GGER
A Satuday afternoon at Mike Bainbridges revealed yet another gaping hole in my education...... namely, ignition systems.
So this week I`ve mainly been reading up about coils and capacitors... and I`m making a bit of progress, to the stage where I`d like to ask for some opinions.
Mycar has the original ignition system and my question is should I be thinking of `upgrading` it to a 3 pin CDI.... or even MSD?
I`ve been trawling Pelican and threads like Jamies here on DDK and there seems to be a whole load of pros and cons.... reliability of the later electronics....cost... availability( of the CDI).... and originality issues
It seems reasonable to suppose that, as the 2.0 s engine does it`s best work at the top end of it`s rev band, it seems a shame to ignite it with a system which actually struggles to charge and discharge fast enough when it counts.
Your views would be appreciated.
Regards, Mike
Posted: Wed Jul 16, 2008 10:12 pm
by Bertroex
If I were you, I'd listen to Mike Bainbridge
Bert
Posted: Wed Jul 16, 2008 10:42 pm
by mycar
Bertroex wrote:If I were you, I'd listen to Mike Bainbridge
Bert
Trust me, I did. Mike told me all about it but at the time it all went a bit over my head (a lot). It`s just that now, I`m trying to make sense out of it without bothering him too much.
Mike.
Posted: Wed Jul 16, 2008 11:19 pm
by Barry
Well, I can certainly vouch for MSD: pretty reliable, new (as opposed to 30 yr+ CDI boxes), very easy starting and smoother idling.
Downsides? Not much really, you can still trigger with points, but you should ideally upgrade your HT leads to reduce interferance and leakage. I used Turbo leads and plugs. The MSD intructions say that these leads are essential, but I think we concluded this was for American legal purposes, rather than entirely for performance. You would need a matching coil (as you would for a CDI system also). The only other thing to watch is that you may need a tacho-driver. I gather some tacho's do, and some don't. I did.
Anyway, I put mine on nearly four years ago (I think) and it's still fine (according to James 'TheEasyLife'), certainly don't regret fitting it, and would be happy to do so again.
Charlotte's 911 is now running twin MSD's, and had a single unit before that, and also Steve Wright is also running twin MSD's as well.
The MSD 6A was the basic unit with no (I think) rev limiter, but most people use the 6AL which has plug-in rev tabs, giving a pre-programmed soft-rev limiter. I gather even this has been updated, with a mappable unit now being available.
Posted: Thu Jul 17, 2008 12:09 am
by pb911
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Posted: Thu Jul 17, 2008 6:04 pm
by Mike911scrs
HI Barry
"Charlotte's 911 is now running twin MSD's" is actualy only has 1 MSD box running 2 MSD coils.
regards mike
MSD boxes
Posted: Thu Jul 17, 2008 9:32 pm
by TimB
Mike
PM sent.
Regards
Tim
Posted: Thu Jul 17, 2008 10:57 pm
by Barry
Hi Mike: that's impressive, I didn't know you could do that. Shows how much those units have in reserve.
Nevertheless, I'm pretty sure (for what it's worth

) that Steve Wright is using two systems.
Posted: Thu Jul 17, 2008 11:01 pm
by Ian Donkin
... and I might yet buy another (not that there's anything wrong with how it's working now) to fire each coil from its own MSD box.
The curent setup is how Henry at Supertech recommends you do it, whilst the boys at JB Racing did suggest two MSD boxes.
As you can see, Mike was happy to run the system with just one box.
Decisions, decisions!
Posted: Thu Jul 17, 2008 11:05 pm
by Barry
How does the MSD fire both coils: do you literally split the MSD output to fire the coils in parallel (i.e. loop the output wire into one coil, and onto the next), or are there some MSD's with twin outlet wires?
Posted: Thu Jul 17, 2008 11:09 pm
by Ian Donkin
Neither - split the MSD output and feed each coil from one lead of the splitter (see the white and red wires in the picture from Mike above).
Posted: Thu Jul 17, 2008 11:09 pm
by Barry
Also, if you run two coils from one MSD, does this mean that the Multiple Spark phase cuts out earlier than it would with the system'just' running six plugs rather than twelve?
Or to put it another way, with twin MSD usnits in place, would you get the benefits of the Multiple Sparks for longer / higher up the rev-range?
Posted: Thu Jul 17, 2008 11:10 pm
by Ian Donkin
Pass!
Can I have the next question on Golf?

Posted: Thu Jul 17, 2008 11:17 pm
by Lightweight_911
I opted to go for two MSD Blaster coils fired by two MSD 6AL's for my set-up after discussions with Steve Weiner (of Rennsport Systems in the US) - but mounted on a panel
inside the car (on the rear bulkhead).
In the engine compartment I have two 'dummy' Bosch CDI boxes & two Bosch black coils to preserve the period-original look ...

Posted: Thu Jul 17, 2008 11:18 pm
by Barry
Ian Donkin wrote:Neither - split the MSD output and feed each coil from one lead of the splitter (see the white wires in the picture from Mike above).
Yes, that's parallel then: I'm amazed that the unit can take this, as effectlively it means that the internal gubbins must be 'engineered' (if that's what electronics are) to run either one or two coils with no physical switching, which is either very impressive, or just a worry for their warranty department

.
Nevertheless, I do know that MSD units have a name for operating in some dreadful conditions in some of the U.S. based applications, and doing so for long periods without trouble.
As per the above question (sorry Ian

), I'd love to know what dictates the cut in / out point of the multi-sparking function, before it drops into the big, single spark mode. I.e. whether this is simply a function of revs, or a function of stress upon the unit (more load, less multi-sparking).