I put a set of Taylor 8mm spiro-pro wires on my 98 Mazda 3.0L (48k miles) and took resistance measurements of the stock motorcraft vs. taylor wires.

I took the longest of each wire (same lengths):

Stock ~7.8 kOhms

Taylor ~3.4 kOhms

About a 56% reduction in resistance, not too shabby. The wires aren't a bad price either, $41 through summitracing.com

As far as a performance gain, I'm not going to tell you I noticed anything. It SEEMS to idle just a tad better and feels a little smoother on the highway, but I did a K&N filter at the same time so I'm not making any conclusions.

Just a friendly FYI

 

Thanks for sharing, it's nice to see some crafty Ford enthusaists around here! Thanks for being honest about the performance difference too, I've even heard Harley Davidson riders talk about how much faster their bikes were after changing the spark plug wires. If spark plug wires actually make your car (or bike) faster, then you were doing something wrong to begin with. The one thing that does make a difference is to overgap your spark plugs, have you given that a shot?

Now it'd be even better if somebody could get just one of every wire on the market and test the resistence through a 3 foot section of them, and also test the dielectric strength. Such is the reason why I read Car Craft.

Thanks again DarkEngineering

(by the way, I love the name)

 

I've thought about doing it, but I'm a little hesitant about increasing the gap without knowing the limits, pros and cons. If I can find some good honest test data on this, I would definitely do it.

Know of any? Thanks!

 

Pro's: quicker starts, smoother idling, less hesitation, the typical. When you increase the gap, you're increasing the voltage required to jump that gap, so as long as it can jump, you're going to get a much hotter spark. Problem is, if you have too much gap, then the spark will find the path of least resistence, which might be to go through the silicone jacket of the wire right into your engine block, or some other nearby accessory. This is the reason why the high dollar wires are so thick, because they have so much dielectric (insulation) strength. The point is, push the gap as far as you can go without the wires arcing. Many things influence how far you can go, including the dielectric strength of the wires, the compression pressure inside the chamber (a denser mixture under more compression creates a difficult path for a spark to jump though- thus the reason why racers usually have to run small gaps), the resistence through the wires, and the condition of your cap and rotor. Cheap ignition parts will not be much of a barrier to electricity trying to get out, and resistence stands in the way of a hot spark getting to where it needs to go. In summary, most Fords do very well with a 0.050" gap, which is up 0.006" from the factory 0.044" gap without any problems, even with stock wires, cap and rotor. MSD ignitions are capable of jumping a 1" gap, but the wires could never handle this much ignition voltage. With low resistence wires and moderate compression ratio (9.0:1 max), you could enjoy a 0.060" gap and probably see a small fuel milage improvement. I personally run 0.055" with a 6A and Blaster 2 coil with a Pro-Billet distributor with brass cap and rotor. One of these days I'll get the MSD super conductors, when I'll step up to a 0.060" gap.

In Summary, gap your plugs as high as they can go without arcing. For most stock or nearly-stock Fords this means about 0.050" gap, which might marginally help performance, but it will help you start a little quicker and idle a little smoother. TK

 

Have you guys ever checked out Splitfire plug wires? It has been several years since I put a set on my 5.0 mustang, but unless my memory is faulty the resistance was 250ohms a foot when I measured it. They still make them and I am getting a set for my I6. JC Whitney has them for around $50 but about a month and a half ago there was also a $20 rebate. When I get mine I will measure the resistance again and let ya'll know.

 

The Splitfire dual core wires are good for 8mm wires, nothing wrong with them. I know a few people who have had them for a while with no problems, unlike their spark plugs. TK