Spark Plug Wire Resistance?
Thread Starter
Melting Slicks
Joined: Apr 2000
Posts: 3,286
Likes: 8
From: San Jose California
Spark Plug Wire Resistance?
I just received my new plug wire set from Jacobs. I ordered their ceramic boot ultra wires. My previous set of Moroso's best wouldn't last due to the heat of the headers. The boots kept frying. Jacobs are supposed to be good to 2000 degrees. Anyway, I measured the ohms for both wire sets. Each has 8.5mm wires; but the Moroso wires are only about 120-150 ohms (~50 ohms per foot) while the Jacobs are 850-1000!
This is a much greater difference than I had expected. Is this because of the actual conducting wire being different sizes. If so, does a larger wire make a more sluggish electrical charge than the smaller, higher resistance wire.
For example: If you connected an empty 20 foot 4" water hose from your water spicket, it would take longer to fill a glass of water than if you used a 20 foot 1" hose even though the 4" hose has less resistance. This is because the void must be more or less filled with water before it can exit the other end.
Yet even a low resistance wire isn't doing me much good if I loose energy have arcing through damaged insulation. I would be greatly appreciative to hear any comments from those numerous ee's and other experts on the forum.
Thanks,
Chuck
This is a much greater difference than I had expected. Is this because of the actual conducting wire being different sizes. If so, does a larger wire make a more sluggish electrical charge than the smaller, higher resistance wire.
For example: If you connected an empty 20 foot 4" water hose from your water spicket, it would take longer to fill a glass of water than if you used a 20 foot 1" hose even though the 4" hose has less resistance. This is because the void must be more or less filled with water before it can exit the other end.
Yet even a low resistance wire isn't doing me much good if I loose energy have arcing through damaged insulation. I would be greatly appreciative to hear any comments from those numerous ee's and other experts on the forum.
Thanks,
Chuck
Safety Car
Joined: Feb 1999
Posts: 3,631
Likes: 14
From: Fountain Hills AZ
Re: Spark Plug Wire Resistance? (Chuck Harmon)
There was an article about ignition wires several months ago in one of the performance mags. In it, the point was made that there is little advantage to less resistance once it is below a certain point. I don't recall the exact numbers but I think your new wires' readings fall well within the optimum range. The cheapie sets tended to be way above optimum. The spiral core wires way outperformed all of the solid core wires that were suitable for street engines. A couple things that should be considered when buying wires is, 1., many manufacturers make both crappy wires and excellent wires. In some cases they put a fancy "decorative" coating over junk wires and charge a premium price, suggesting to many that they are good wires. The other thing is that, like spoilers on rice cars, bigger isn't necessarilly better. The reason for a thicker cable is to provide better insulation (against current leakage and/or heat) and doesn't have anything to do with the size of the conductor inside that actually carries the current.
