Mallory Performance ignition systems

[campbellju]

I recently got my car mapped and like other people I'm having problems with misfires around 1.7Bar. RC Developments dropped the plug gaps to 0.5mm and replaced my magnecors with standard leads (The rest of the ignition is all new Nissan and well earthed) to help and on the road all looks good which stopped the misfires at high revs.

However, on Saturday around Elvington, I was occasionally getting bad misfires in the mid-range. I'm guessing this is around the peak torque figure where I've got the most boost and pertol getting thrown into the cylinder and either blowing out or drowning the spark.

I don't want to increase the boost anymore, but I don't like being on the ragged limit of the ignition system. I've been looking round the internet at the options available. I quickly ruled out the direct ignition systems as too expensive/complex for my needs though arguably they are the best.

I also ruled out a patch job as after research I can see how ignition components are matched to each other so I need both a coil and amp.

I started looking for alternatives to the usual MSD solution and came across a Mallory system that seems to do the same thing.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=MAA%2D6852M&N=700+0&autoview=sku

http://store.summitracing.com/partdetail.asp?autofilter=1&part=MAA%2D30440&N=700+0&autoview=sku

Its a matched ignition system that should do the same sort of job as the MSD. It uses capcitive discharge to boost sparks power and duration with multi-sparks lower down the range for economy. Doesn't appear to need a ballast resistor and will be around £120 delivered. from what I've read the coil is designed to be effective to around 8Krpm. What am I missing before I decide to place an order.

Also, those who already have aftermarket ignition sytems and running over 400hp, what plug gaps are you using?

Cheers,
Jim

 

[Fusion Ed]

The Mallory system appears to be fine, however it states less current than the MSD but claims a stronger spark.

 

[campbellju]

Thanks Ed. I hear what you're saying, I'm am electrical/electronic engineer but there does seem to be a lot of "black magic" hype with ignition systems between V, I and R etc.

I don't think the Mallory system is the best, I just thought it looked adequate and good value.

I know you have a lot of experience with these sort of things, what gap sizes would you use on a 400hp car with a decent ignition system?

Thanks again,
Jim

 

[stevepudney]

This is what I'll be fitting in the next few days. It just made sence to stick with the MSD kit as I already had the Blaster coil anyway. We shall see.

As a few guys seem to be binning after market, so called Performance/race ignition leads, I will also call Magnecor and ask if they expected there leads to be more efficeint than the stock Nissan leads, if not why not ??

 

[stumo]

I have that Ign box on my Jeep (a 1974 CJ5 with a 6Ltr motor) with a blaster coil. The spark is unreal, you get six fat sparks** that will easily jump an inch (or more) from the lead to earth.

**instead of just one

 

[campbellju]

This is what I'll be fitting in the next few days. It just made sence to stick with the MSD kit as I already had the Blaster coil anyway. We shall see.

As a few guys seem to be binning after market, so called Performance/race ignition leads, I will also call Magnecor and ask if they expected there leads to be more efficeint than the stock Nissan leads, if not why not ??

I think you're right to Steve, the more I read the more it seems the whole ignition system needs to be in balance and the best way to achieve that is to stick with the same manufacturer.

I think its the same with the leads. When I get some more time I'll measure the difference in resistance between the two leads. My guess it the magnecors will be higher resistance making it worse for the standard Nissan system but better when I'm trying to blast 55KV through them to stop them melting. For the moment I'm keeping my magnecors as I believe they will be better matched to the Mallory system.

Stu, I like the sound of that, I'll get a system and see if its any good or not. For £100 its worth a punt.

Thanks for all the comments,

Jim

 

[stumo]

i mean the MSD box, not the Mallory but i guess they will work in a similar manner.

It really is an awesome spark, even more so when compared to a normal setup

Jim, if it was easy to remove the MSD box , you could borrow it but it isn't so you won't. :lol:

 

[MarkTurbo]

I will also call Magnecor and ask if they expected there leads to be more efficeint than the stock Nissan leads

If they are less efficient do you really think magnecor are going to say so :der: They're hardly going to say " no sir our leads are inferior, you'd be better off buying something else" :lol:

 

[AJ4]

Heres the sum total of what I know about choosing ignition systems.

-The voltage is irrelevant, no matter how many 'umpty squillion volts' the adverts claims. The spark will jump at whatever damn potential it needs to
-The best burn is produce by the longest spark, so the duration is the most important figure
-The current should be as high as possible for a hotter spark.
- You trade off spark duration for spark temperature ( I think the duration is supposed to be more important in high boost apps though )

Just ignore the volts and go for the system with the highest output ( Joules ) for the longest duration.

Not really gave it much though to be honest, but what I've read so far is mostly what I quoted above.

thats about it I think...

 

[campbellju]

Thanks Ross

 

[AJ4]

dont take my word for it though, thats only what I've learned from reading up on it, its open to discussion Makes sense from a physics / electronics point of view though. I know for sure the voltage is irrelevant as the spark will cross at the lowest potential possible. A bit like those 'splitfire' plugs that are supposed to 'fire two sparks at once' :lol:

 

[stevepudney]

If they are less efficient do you really think magnecor are going to say so :der: They're hardly going to say " no sir our leads are inferior, you'd be better off buying something else" :lol:

No, of course there not.

I will simply ask them to explain WHY after spending a wedge on there so called "superior" product, in the process of trying to find an answer to a misfire problem a whole load of owners have junked there leads to revert back to standard ones and actually seem to get a better result out of the OEM equiptment, i.e less missfires e.t.c. ............

I mean there must be a reason for it and they are the experts after all...........

 

[AJ4]

definately worth a go, look at what Keiron achieved with the head stud issue ( it was found that the standard ones were better than a certain aftermarket one, purely because they had designed it wrong ).

 

[campbellju]

dont take my word for it though

I didn't ;-) I just agreed with everything you said. The clarity did help though.

I also think energy rather than the V or the I is the most important as fundamentally the spark switches from an electrical reaction to a chemical reaction when it ignites the mixture and no chemist understands V or I.
Some ideas trying to take it forward, my electrical/electronic knowledge is very rusty knowadays... (non geeks beware still!!!)

1. After the secondary coil, there are 4 resistors in series.

Wire from coil to Dizzy
Air gap detween rotor arm and cap
Wires from cap to plug
Air gap on plug

In a DC circuit all the voltage will have dropped to zero at the end of the chain and the relative voltage drop across each could in theory be caluclated. So the system need to be matched to the power you are inducing in the circuit and the relative drop across each so the maximum power is at plugs air gap

2. Doubling the size of the wire means you can transmit more power down them but will also increase their resistance. Ross correct me if I'm wrong but I think this means you will increase the voltage level across the wire but also get additional power loss.

However, if you transmit the power along a smaller (lower resitance) cable, there is a lower limit to the amount of power it can transmit before you overheat and ultimately burn out the cable.

3. The coil is what induces the current into the circuit. I think this is analagous to a turbo in that if you stick a huge turbo on a small engine, it takes forever to spool up and never reaches its maximum potential. Ideally you want the smallest coil possible for the driver to give the fastest response time (needed for rapid changes at high revs) but by being smaller it will not generate as much ultimate current (power) and get hotter in operation than a big fat performance coil giving less life. Likewise, If you stick a bigger engine onto a small turbo, the turbo will be the bottle neck in the same as once once you have saturated your primary coil, you can't saturate it any more. Whilst solving my ignition problems I found the current induced in the OE primary coil was very similar with or without the ballast resistor to drop voltage. (The ballast resistor is bypassed at startup to make sure the primary is saturated but after that its not needed as the primary is saturated already) so the OE system does not need a better coil only or a better driver only as it will either have no effect or make things worse.

4. Given 1, 2 and 3, its why I believe I need a matched coil and ignition amplifier and why the magnecor leads are causing us issues on the standard setup but why I might need them on an upgraded setup.

comments/thoughts etc welcome to help my understanding

 

[campbellju]

Just ordered it, should be about £120 delivered including VAT. It might be rubbish but if it is it won't be the last £120 I've wasted on rubbish fr the car!!!

Fingers crossed its alright

Jim

 

[Odin]

Well I'm feeling very thick right about now .....

The only thing I can add really is that I've never had any problems with my magnecor leads ;-) , I do get problems at the moment but that's due to it over boosting past its mapped point, I got 1.7 bar last night when I was out test driving it after re fitting my new manifold....

I think the manifold is effecting the boost somehow :? .




Rob

 

[campbellju]

Well I'm feeling very thick right about now .....

The only thing I can add really is that I've never had any problems with my magnecor leads ;-) , I do get problems at the moment but that's due to it over boosting past its mapped point, I got 1.7 bar last night when I was out test driving it after re fitting my new manifold....

I think the manifold is effecting the boost somehow :? .

Rob

I shouldn't feel thick, Ross will prbably come on in a minute and tell me I'm talking nonsense :lol: :lol:

Regarding your over boost, I know the 3" downpipes on the 3071R's give a similar problem with the turbo spooling up too fast. Mine and Jimmy's on standard elbows don't

 

[Odin]

turbo spooling up too fast.

That's the first time someone has accused my turbo of spooling to fast :shock: :lol: :lol: :lol: :lol: :lol: :lol: .



Rob

 

[AJ4]

2. Doubling the size of the wire means you can transmit more power down them but will also increase their resistance. Ross correct me if I'm wrong but I think this means you will increase the voltage level across the wire but also get additional power loss.

I think your wrong Current flows more at the surface of a conductor due to more elctrons being free to move in that area than the densely packed ones in the middle. The larger the conductors overall surface area the less resistance. The thicker cable also means more power dissipation before melting, so its a win-win.

I agree about the system being matched. For maximum power transfer you ideally want the four voltage drops to be equal or have equal loads, so its not just a case of whacking on some fancy coloured aftermarket leads with god knows what properties and hoping it all works

I'd buy a completely matched system, from coil to plugs.

 

[Fusion Ed]

Resistance is related to the square area of the conductor (multiplied by its length)! There are factors such as the thermal enviroment you must consider on long wire runs or when its surrounded by insulation material, however neither apply in any significant margin in a car.

Also talking about matched components, its always better to go with a one make system but for max power (energy) transfer the source impedance and the load impedance must both be equal.

In general:

* if you double the length of a wire, you will double the resistance of the wire.
* if you double the cross sectional area of a wire you will cut its resistance in half.

This is why all wires are sized in mm2 not actual diameter etc..