BWilcox

Hi Guys,

Recently, an MSD 8226 coil failed in my IROC after 7 years of operation. The last 2 years were run with a MSD Digital 6A. I replaced this coil with an Accel 140011. The Accel coil had great reviews. The MSD 8226 had poor reviews.

Today, in my Son's IROC, a 3 year old Accel 140011 failed.

It seems like brand does not matter any more?

Does anyone make a rock solid 45 KV coil?

Best Regards,

Bruce

cardo0

The coils more than likely overheating from location and current. BTW most coils are oil filled and need to be mounted upright FYI.

Im not going to patronize an EE over an electrical issue. But from ive read lately the MSD CD box is better for very high compression and supercharged/turbo engines to fire the denser fuel/air charge. MSD CD spark is to fast and to short even if has more energy. The MSD coil by itself is fine as 50K volts is enough/max for street type wires - more than that the plug wires insulation wont stop spurious discharge/shorting. And i believe the CD box output is greater than 50K volts. Ive been reading the stock HEI once optimized makes a better spark for street performance use - longer duration. HEI performance module is needed as the stock HEI modules tend to retard at higher rpm and i think affect the spark also - cant recall why now.

I guess what im saying is mount the coil correctly in a cooler location and ditch the CD box. U may need to upgrad the HEI a bit.

And give us feedback if u find different information.

BWilcox

Thanks for the reply.

My Son's IROCZ is very similar to the stock HEI set up. Just a higher output coil has been utilized. Before trouble shooting, I thought the Accel coil went bad. This was based on roughly 20% higher secondary resistance. It turns out the distributor ignition module was the issue.

I am not sure why it failed? Since the hold down screws worked loose, heat might be a root cause? Alternatively. The lower primary resistance of the coil might contribute as well?

I wish I could find a data sheet on this Ignition module. Then, we would know how much current the coil driver is designed to sink during the coil charge (dwell) time.

On my IROCZ, due to the larger engine/cam/compression-ratio, I use the Digital MSD-6A / hotter coil combination. From my ECM tuning experience so far(idle & part throttle), the car runs much better then the stock HEI / hot coil combination.

The coils that I am running do not have oil for cooling / vibration damping. These E-Coils are potted with epoxy. My guess is the potting is great from a vibration viewpoint but poor from a heating viewpoint? The only way for the heat to escape is from the steel core.

I am going to design/build a coil tester. This way, I will be able to characterize the actual performance of the coil under high voltage conditions. This will not cost a lot of money.

The secondary output voltage is a function of the Turns Ratio and the core Permeability. As both rise, the secondary output voltage rise.

Thanks again for your comments and experience.

Best Regards,

Bruce

cardo0

Just a note is that the secondary voltage is a function of the speed the primary coils magnetic flux collapses. U will find the turns ratio of any auto coil does not support 40k volts. Thats why the CD boxes make more output voltage. The CD box "pushes" current (from its capacitors) faster than a OEM system cuts the current source (open points/hall effect/transistor trigger) and the speed of the magnetic field build (or collapse) determines the voltage output. Well the CD box "pushes" more current increasing the field also. IMHO the 60hz system we use is to slow for this effect to boost the voltage at all and the turns ratio is a direct relation, that or maybe a AC current prevents this amplification of the field - but that would be off topic anyways.

Ive been reading the HEI makes a better/longer spark for street engines <7,000rpm but u need to reduce the plug gap from what a CD box uses. More in the 0.30"-0.040" range. But ya know the whole ignition lives longer with that also - cap, rotor, plugs and maybe coil too.

Something else for location is the area below the windshield is a high press area and could possibly be utilized with a little creative duct work.

Good luck Bruce and let us have some feedback of what works for u.