another coil question...

[olie05]

I was looking into high performance coils, since they are cheap... but i started wondering... what will this actually do for me? so my question is what increasing the voltage a coil puts out do for the driveability of the car. Obviously it increases performance a little, but does it also increase gas mileage, i.e. does it burn the fuel more completely than the stock voltage would?

 

I also have 10.3:1 cr with stock everything else (flattops) would upgrading a coil help me take advantage of this cr?

 

-Oliver

[Thumper]

Olie, on my z when I installed my coil and msd 6al there was a very noticeable difference. Actually on all 6 cars I have installed the msd on I have felt a big difference. I know you said just the coil but I have always installed the msd with the coil at the same time so i'm not sure on just the coil.

[zcarnut]

How much voltage a coil can produce is a bogus parameter that has been used to sell aftermarket ignition systems for years.

 

The voltage that a spark plug gap will break down at is mainly determined by the gap size and the pressure inside the cylinder at the instant of the spark. Secondary factors include gap geometry and electrode temperatures. It is not a function of the ignition system. The firing voltage for a typically gapped OEM plug is only 10kV to 18kV. Once the arc forms the voltage across the gap drops to the sustaining voltage necessary to maintain the arc which is no more than a few hundred volts.

 

I have seen claims by aftermarket vendors with ridiculous figures such as 50 or even 60 kV. This is the maximum voltage the test coil generated in a lab on a bench and has little bearing on anything in the real world.

 

There is a limit to the voltage anyways. Too much secondary voltage will deteriorate secondary wires, cause carbon tracing is the distributor and even damage the electronics used in the switching circuitry.

[olie05]

so zcarnut, are you saying stay with the stock system?

[grumpyvette]

http://www.msdignition.com/1ignitions.htm

 

http://www.holley.com/HiOctn/ProdLine/Products/IS/ISD/890-xxx.html

 

while you may only get a slight increase in ignition system effectiveness over the stock ignitions,with just a coil upgrade the MSD or HOLLEY multi strike ignitions like the MSD 6AL which I use matched to a MSD distributor or HOLLEY DISTRIBUTOR (I PREFER THE HOLLEY DISTRIBUTORS MATCHED TO THE MSD CONTROLER AND COIL)THE coil DOES increase spark ,the distributor and MSD controller give you BOTH lower emmissions due to the low rpm multi strike ignition which is more effective at preventing the plugs fouling at low rpms and its stronger spark at higher rpms tends to limit misses in those upper rpms

now you probably will not get any huge power increase, gains in the 2-4 hp range are comon, but upgrading the ignition does tend to make tuning easier and you seldom have ignition problems if you install the complete matched ignition system, something that you can,t say about a points ignition or CHEVYs HEI in many cases

[zcarnut]

so zcarnut, are you saying stay with the stock system?

 

No. The poster was asking about coil output _voltage_. A more important parameter to use when comparing ignition systems is spark _energy_ which is proportional to the gap sustaining voltage times the gap current times the duration of the spark.

 

In general, the more energy that is delivered the longer the duration is. Longer duration sparks ignite the mixture better and can even increase the peak cylinder pressure slightly so that more power is produced.

 

Aftermarket ignition systems can have the potential to increase the spark energy above the stock system. This can be accomplished by increasing the peak primary current in the coil which increases the energy stored in the coil. To handle this increase in current then requires more robust power transistors and an improved coil to handle the current increase without overheating.

 

Also important is the voltage rise time of the gap voltage. It is well known that a fast voltage rise time will fire even a fouled sparkplug (a plug with a lot of carbon deposits on the electrode). The rise time is significant because if it is too slow then the fouling on the plug electrode will drain away the energy before an arc forms. This is why capacitive discharge ignition (CDI) systems were developed.

 

There is a lot of hype and marketing associated with ignition system claims. For additional info I suggest the following web sites:

 

http://www.rmlautomotive.com/ignition.html

 

http://ourworld.compuserve.com/homepages/JET_AV8R/Vision/Ignition/CDI.HTML

[grumpyvette]

more ignition related info links

 

http://www.bgsoflex.com/auto.html

 

http://www.howstuffworks.com/ignition-system.htm

 

http://auto.howstuffworks.com/ignition-system1.htm

 

http://www.familycar.com/Classroom/ignition.htm

 

http://www.motocross.com/motoprof/moto/secontent/seign/ignprin/ignprin.htm

 

http://www.northwestautorepair.com/ignitionsystem.htm

 

http://www.boyleworks.com/ta400/psp/distcurve.html

 

http://www.chevytalk.com/tech/index.html

 

 

heres other options

 

http://www.davessmallbodyheis.com/

 

 

http://www.msdignition.com/

 

http://www.proformparts.com/catalog/distributors_GM.html

 

http://www.atlanticspeed.com/store/MSD%20Chevrolet%20Distributors.asp

 

http://www.holley.com/HiOctn/ProdLine/Products/IS/ISD/ISD.html

 

http://www.performancedistributors.com/gmdui.htm

 

 

Spark plug /ignition info

 

http://www.edelbrock.com/automotive/sparkplugs.html

 

http://www.ngksparkplugs.com/apps/car_truck_suv/default.asp?nav=60000&country=US

 

http://www.strappe.com/plugs.html

 

http://www.applink.net/cct/tips/plugwires.html

 

 

http://www.acdelco.com/html/pi_plugs_ident.htm

 

http://www.atlanticjetsports.com/_techtalk/00000005.htm

 

http://www.ngkspark.com.au/spark_plug_cross_ref_chart_index3.htm

 

 

http://www.strappe.com/plugs.html

 

http://www.babcox.com/editorial/cm/cm59910.htm

 

http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

 

http://www.eric-gorr.com/techarticles/sparkplugs.html

 

http://www.gnttype.org/techarea/engine/plugs.html

 

 

http://www.tsrsoftware.com/sparkplug.htm

 

http://www.racinghelp.com/read_spark_plugs.html

 

http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp2.asp

 

 

http://www.projectbasketcase.com/menus/ignition.html

 

http://www.gofastzone.com/techtips/Spark%20Plugs%20Cross%20Reference/Spark%20Plug%20Cross%20Reference.htm

 

http://www.geocities.com/zgarage2001/advance.html]http://www.geocities.com/zgarage2001/advance.html]http://www.geocities.com/zgarage2001/advance.html

 

http://www.hotrod.com/techarticles/43300]http://www.hotrod.com/techarticles/43300/]http://www.hotrod.com/techarticles/43300

 

http://www.centuryperformance.com/vacuum.asp]http://www.centuryperformance.com/vacuum.asp]http://www.centuryperformance.com/vacuum.asp

 

http://www.custompistols.com/cars/articles/ignition_timing.htm]http://www.custompistols.com/cars/articles/ignition_timing.htm]http://www.custompistols.com/cars/articles/ignition_timing.htm

 

http://chevyhiperformance.com/howto/45673]http://chevyhiperformance.com/howto/45673/]http://chevyhiperformance.com/howto/45673

 

http://www.lmengines.com/Ignition_Timing.htm]http://www.lmengines.com/Ignition_Timing.htm]http://www.lmengines.com/Ignition_Timing.htm

 

http://www.73-87.com/garage/hei.htm]http://www.73-87.com/garage/hei.htm]http://www.73-87.com/garage/hei.htm

 

 

 

 

[image]http://www.73-87.com/garage_photos/disremov/firingorder.jpg[/image]

 

 

OPTISPARK info

 

http://www.gmhightechperformance.com/tech/0310htp_optispark/

 

http://www.charm.net/~mchaney/optisprk/optisprk.htm

 

http://www.fierolt1.com/lt1_95_up_OptiReplace.htm

 

http://www.noid.org/~muttvette/opti.html

 

http://www.gulicks.com/vette/projects/opti/index.html

 

http://www.houston-f-body.org/tech/optispark/

 

 

http://www.dynotech-eng.com/dynaspark.htm

 

http://www.corvetteclinicinc.com

 

http://www.corvettefever.com/howto/16758

[JMortensen]

And if you're lazy, a friend of mine dynoed his brand new L20B a couple months back. He tried stock Nissan EI and MSD back to back and showed a 9hp improvement to the wheels with MSD. 9hp on a NA L20B that I seem to remember ended up at ~140 whp. That's pretty impressive.

[olie05]

wow. Ok I have alot of reading to do! Thanks for the replies and info!

-Oliver

[freakshow]

i have been looking all over for actual info for coil.spark plug gap. I installed a msd blaster 2 coil, and I was looking all over to find out what I could increase my spark plug gap to.

I know that the factory gap on my olds is .050, and if that is that and the compression on my olds is 8.blah-1 and the compression on my datsun is 8.blah-1 couldnt I increase my gap to at least .050?

I run a stock motor, pretty much all of my mods have been to gain mpg, not mph.

I think this would help a lot of people who are just learning the major and minor ins and outs of these engines. I searched all over this site and googled till my eyes were red and still couldnt find what could be done.

Doesnt a bigger plug gap improve combustion??

This part of this stuff kinda has me boggled.

[freakshow]

Nobody answered, so I tryed it. .050 does not work. I gapped the plugs out, ran good at idle, but when revved under load, died. I brought it back home, and reduced the gap to .040, runs smooth, but I didnt notice a difference from stock. The plugs are new plugs, I am kinda just trying things out.