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High Output Coil Packs for MS


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Hi All,

Been helping a mate sort out his racer, its an old an odd 4.7 Rover V8, and in a serioulsy

silly state of tune :D

Since working on it he reckons its smoother and more useable than ever before :) but lumpy at low rpms and WOT

at Low RPMs and under load, but better than the old flapper system that was on it.

However, he works in USA and has come back with a pair of silly output coils, :

http://parts.bumpstop.com/productDetail.php?pid=31400

he also said he considered these too :

http://www.msdpower.com/product/partno/8241.php?cat=coils

He "Feels" the car is even smoother now, but ran lean so I've upped Fuelling MAP

and now he is vbery happy buny. He has 10mm Magnecor leads and also runs higher octane

fuel due to compression higher than shoyuld be (block decked and heads skimmed to sort warp)

and highly highly modified inlet / trumpet / plemum etc

Q

Is this more a placebo effect, or is there something in this ?

I can understand the weak running, but would massive output coils sort out low end fowling / make any odds ?

Would the vast outputs actually increase the chances of water tracking on the leads and therefore a misfire potential ?

Discuss ?

Nige

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I suspect it depends on what he replaced with them. If he was running a pair of 20 year old fiesta coil packs then pretty much anything is going to be an improvement I'd have thought :)

Land Rover coil packs were a real improvement over the Ford ones on my 3.9 but then the Land Rover ones were brand new and the old Ford ones were of unknown vintage and history so it's difficult to know if the Land Rover ones are better than the Ford ones or not. I wouldn't have expected any increased voltage to cause problems with wet running, the Magnecore leads will insulate that kind of voltage OK, the main cause of arcing is the boots at the coil pack so as long as they are a good seal it should be fine.

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At the risk of being a bit technical on a technical forum...

Under proper running conditions, the actual ignition voltage isn't any higher than with a standard coil. When the ignition fires, the plug voltage rises rapidly until a spark is ignited, then falls quickly back to a much lower sustaining voltage until the stored coil energy is used up.

However, I have seen papers suggesting that quite a large percentage (5-10%?) of ignition events (in a Kettering ignition system) result in some form of partial misfire (late firing, incomplete combustion etc.). The high energy coil might (probably will IMHO) result in an improvement to those events, as if the plug doesn't fire the voltage will continue to rise until a spark is established, and the spark will be of longer duration due to higher available energy.

The effect is probably quite small, but on an engine with sub-optimal chamber design, like the RV8, it might be quite noticeable. I doubt that a high energy system will be that much better than a standard EDIS system though. Remember how much better an EDIS system is than a Kettering one? Thats because it uses up most of the available improvement (coil energy management, high voltage ignition, timing accuracy etc.)

On a system with standard plug leads, it might well be a disaster. Once a spark path has been established, then a low energy path exists for a spark to track. One no-fire event at startup will expose that part of the system to the highest available voltage in the system. If a breakdown occurs and the spark tracks out, it leaves a trail of carbonised oil, plastic etc. which is slightly conductive. This makes it easiers for tracking to occur on this path later, when the voltage is lower, during normal running. Inductive coupling between adjacent cylinders (usually #3 and #5 on an RV8 IIRC) is also likely to be more of an issue with higher energy systems.

I doubt either will be an issue with Magnecor leads - I'm sure you know how hard it is to fire a timing light over magnecor leads.

The next big improvement in ignition is probably ion sensing. Saab and GM spent a deal of money looking at it in the 90s. Sensing the spark current allows a controller to infer a lot about whats happening inside the combustion chamber, and make suitable changes to mixture and timing on a per-cylinder basis. I've not read up on that in a few years though, don't know what the current state of the art is.

D.

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Did you open up the plug gaps to make the most of the high energy coil? If you do, it will raise the ignition voltage of course, and then you find out how close you are to a tracking problem.

Even with standard plug gaps, a high spark energy will tend to mask an engine that fouls it's plugs, or has a hosing injector.

I still think the whizzy high outputs are masking an issue

rather than a magic cure.....but then I am a cynic :lol:

It's an RV8, of course there's something wrong with it!

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