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11.6v to much for coil??!

Started by Canadian1968, September 05, 2013, 07:19:17 PM

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Canadian1968

I sort of touched on this in another post but didn't really get an answer. I am running a street fire coil with a 1 ohm ballast resistor. I get 8.9v at idle but at 2500 rpm I am up around 11.3v and it will still climb after that. Is this much for a coil?? If I
Cruising at 2000 - 2500 rpm the coil is goin to be seeing a min of 11v all the time. ??

I do have a 1.4 ohm resistor but this gives me only 4.8 v that is to low for me!

flyinlow

Remember Canadian, you asked for this.   :rofl:  .

First , the coil does not care about voltage across it . It cares about current...Amps. My MSD ignition runs 300-400 volts thru the primary side of the coil and fires multiple times per power stroke at lower rpms. The coil has never melted.  Your coil should be warm after operating, even too hot to hold on to. Water dropped on it should not sizzle.

The ballast resistor is there to help limit current flow thru the primary side of the coil except during engine cranking. About 3 amps ignition on, engine not running (coil will get the hottest doing this). About 2 amps engine idling. FSM does not list any other numbers at higher rpm. Your coil is an inductor. with a steady dc current ( ignition on ,engine not running)  the coil primary acts like a simple  resistor. Its resistance plus the ballast's resistance controls the current. With the engine running the coil is getting interrupted DC from the ECU and acting like an inductor and making high voltage , low amperage secondary "sparks".  The coils percentage of the total circuit resistance will change with frequency (RPM).

I think your car is OK . 

Canadian1968

Geez why so long! Lol

Basically it's not the voltage but amps I should be worried about If anything !