MSII vs. MSD for ignition

[twotyerfryer]

I posted on another forum, but realized it would be more wise to post this here. I'm running a Ford 2.3 turbo that makes a little under 400 RWHP. I'm planning on 500 to the wheel in the future. I've been running the EEC IV with an EEC Tuner + a MSD 6AL to control rev limit and improve on ignition. Will I actually benefit very much from using the MSD box along with the MSII? I know of the advantages of using the MSD on my Ford ignition, namely cutting spark instead of cutting fuel for rev limit. Will it help that much with the MSII or will it be more trouble than it's worth?
FWIW, I leave the line at 6700 RPM.

Thanks, Steve

[tebriel]

I believe with the MS2 you can have fuel or spark cut.. Correct me if i'm wrong someone The MSD might be able to get you a stronger spark than your stock equipment. But other than that, probably not any benefits over MS2.
-teb

[Matt Cramer]

The MSD's spark is a bit different from the one supplied by MS-II. The MS-II is a single spark inductive discharge system, while MSD is a capacitive discharge with several sparks per firing event. The MSD box may have a slight performance advantage. Or it may be hype...

[96 Comp T/A]

FWIW, an MSD only provides a multiple spark discharge until about 3500 RPM or so. As RPM goes up the the time between ignition events decreases. There simply isn't enough time during the ignition event to create multiple sparks above that. With today's high output coils and precision fuel metering provided by EFI there is probably little to be gained with one.

[wagon]

I have repaired a couple of MSD boxes over the years - They generate big primary voltages (bigger secondary voltages??) even when they are not multisparking they put something like 200V into the coil primary (they switch coil positive, with the coil negative grounded continuously). They chew heaps of power, and don't get too hot, so it must be going into the coil. But, on an efi motor with good mixture control (and atomisation) they may be of smaller benefit. Maybe. They make lots of RFI, too, so things have to be shielded well to keep noise out.

Perhaps trying it on the dyno would sort this out.

Kendall.

[twotyerfryer]

They make lots of RFI, too, so things have to be shielded well to keep noise out.


Kendall.

I think I'll give the MSD a try. What and How should I shield? Thanks for each input. -Steve

[wagon]

Everything related to an input to the MS should probably be shielded eg. tps, ect, iat, O2 (especially) and crank signals. Keep the MSD box and its wiring away from things. Try experimenting, maybe look at the signals on an oscilloscope and see what noise is there.

[twotyerfryer]

Ok, so how do I shield those inputs? Also, I have no access at all to a scope. If this matters, my MSII is located behind the passenger seat and the MSD can be mounted in the engine compartment in front of the driver. I'm guessing 7-8 feet away (1 1/2 meters). Thanks, Steve

[ChevelleFan]

In their March 2004 article, Car Craft made a point of saying that their MS & MSD were very near each other with the engine on a dyno and they had no problems. Most of my original engine harness ran right past my MSD box and I never had any interference issues. My latest setup (which isn't finished and hasn't run!) will have my MS mounted right next to my MSD box.

http://www.tiresmoke.org/images/megasqu ... iring.html

-Dave

[wagon]

Maybe try it and see, but I would not like to see msd wiring and ms signal wiring right next to each other, for example in the same harness. A distance of, say, 10cm is probably enough (and achieveable in a cramped engine bay).