Dyna Ignition Booster -opinions?

[Steph]

I’m toying with the idea of putting a (used) Dyna Ignition Booster on my LM3 that keeps the points & condensers.
I read how it works lessening the current through the points etc.

Any feedback on this unit with the stock coils?

I watched a video on Mike’s Machine YouTube channel where he put a complete Dyna III ignition system on his LeMans V.
He stated that (@3:40) the system over heated his coils.

https://youtu.be/Mgo8CdhEIok

Hmm. Could this happens with the Dyna Ignition Booster too?

[pressureangle]

Yes, it could and probably would, I don't expect the scheme in the dyna box is different from their electronically switched box.

Coil temperature is not a function of current, which is governed by the internal resistance (oms) of the coil. Temperature is a function of the *time* that coil sees the current, and that time is called 'dwell'. Manufacturers control dwell with the grind of the point cam, generally keeping the dwell to the minimum required to provide full coil saturation at maximum RPM. With an electronic box, the dwell can be controlled to provide optimum coil saturation at both idle and max RPM without being too long or too short. BUT with Dyna, the whole point of the exercise is to increase dwell at higher RPM which gives a longer spark, and the stock coils are engineered to tolerate not much more than the stock dwell time. To increase spark energy, the entire system has to support more current/dwell. Dyna sells coils with different ohm ratings; their street coils are 5ohm and the 'race' coils are 3ohm with the expectation that the race coils will have less time between cooldowns and also a shorter service life. The reduced ohms allow a higher current and stronger spark energy.
Even with 5 ohm coils, the Dyna systems use considerably more energy than a point system- I discovered on my '85 LM1000 that the dyna system was what put the charging system in a permanent state of inadequacy.

[John A]

On my modified engines, I power the coils through a dedicated relay. It seems like it helps with reliability as far as coil life and better spark. I don’t have any ideas on why that is but the results of long term use have been trouble free. I’ve not tried it with an ignition amplifier but it’s on a V65 Dyna S along with the coils mounted on heat sinks. On a dual plugged injected big block, the 5 ohm Dyna coils are powered through a relay (diode protected) that is triggered by the original power wire from the ecu.

[Steph]

Ok, sounds like it would need new coils.

Their instructions are somewhat misleading then: “The DYNA Ignition Booster was designed for use with the stock coils”

[John A]

I’d go with new coils. Sometimes it’s hard to find a good spot to mount them if they don’t fit in the original spot, which is usual. Mount them on a heat sink if you can. Never let it spark with the plug lead not grounded or on a grounded plug. I like an amplifier with points.

[Steph]

I’d go with new coils. Sometimes it’s hard to find a good spot to mount them if they don’t fit in the original spot, which is usual. Mount them on a heat sink if you can. Never let it spark with the plug lead not grounded or on a grounded plug. I like an amplifier with points.

I’ve decided to stay with the stock setup for now. It’s been working fine for the last 38 years.
-If I need to get new coils for a used Dyna Ignition Booster box, I’ll be chasing my tail for marginal improvements.

Old bikes modifications are like Newton’s 3rd law
‘every action will have a reaction’. 

[John A]

Well you could try it. Like they said it was designed to work with a stock system. You could keep an eye on the coils for running too hot if you can put a finger on them unless they are buried. Used ignition stuff can be a can of worms if the previous owner damaged them, otherwise I’d try it. If nothing else we’ll learn from it.

[moto-uno]

 ^  I believe you forgot to put the smilie face emoji at the end of your post !  Peter

[John A]

^  I believe you forgot to put the smilie face emoji at the end of your post !  Peter

I’d try it. It’s easy to take it out of the system in case it fails, especially if you consider that possibility as you install it. It must be dual track since there’s points for each side. I ran one on an Ambassador, it was a single track for automotive or tractor stuff. Points lasted longer. It was an Accel,late 70’s 

[pressureangle]

Ok, sounds like it would need new coils.

Their instructions are somewhat misleading then: “The DYNA Ignition Booster was designed for use with the stock coils”

Dyna's opinion of what the stock coils may tolerate may be ... marginal given OEM coil quality control.

In any case, all these ignition schemes are inductive; that is, the spark in any of them only develops as much voltage as necessary to jump the plug gap during the compression/power cycle. Increasing spark energy does not increase spark voltage, it only increases spark duration- and the increased duration covers up a little bit more of the inefficiency of the engine design. The worse your state of tune, the worse your deposit buildup, the worse your timing precision, the more the increased spark duration improves ignition. For contrast, CDI ignitions are designed to force the spark across the gap as quickly as possible with much higher voltage, which also improves ignition with the additional benefit of more closely controlling timing.