Any reason to use those high dollar plug wires...

[Krooser]

I have used $125+ 8mm plug wires before on a couple race cars. Worked fine.

So now I'm thinking maybe I really don't need to spend that big money when I have a couple new sets of 7mm on the shelf.

If I have header clearance issues I can use some of those hi temp sleeves.

Your thoughts?

[rustbucket79]

Paid for is always a good thing.

[hoodeng]

What kind of spark energy does your system produce? What leads does the ignition manufacturer recommend?

Cheers.

[Monzsta]

They're cheap?

I got a set of wires from Scott Performance Wires for $35 to try them... Cheaper than a set of generics from autozone, and very rugged! I'm definitely going to get the sleeved set next!

https://sparkplugwires.com/

[David Redszus]

The critical factors regarding spark plug wires are conductivity and insulation properties.

Conductivity is a function of conductor cross sectional area. If copper wire is used, count the size
and number of wire strands. More area will reduce electrical resistance. Double check resistance with
an ohmmeter.

Insulation is a function of material and thickness. An interesting test is to visually observe an engine
being run in the dark to see evidence of an electrical storm.

Finally, there is the matter of electrical interference, often called RFI. Spark plug wires act as
broadcast antenna and can send signals that interfere with your 300 watt stereo or ECU.

[hoodeng]

David, all points relevant.
Some years back a guy by the name of Dr C Jacobs wrote a book on optimizing ignition, although modern electronics have bought a new level to spark energy. .

One point he made that was interesting to experience, was to turn lights off and run the back of your knuckles along plug leads and to look for a corona effect, you could not feel anything but the glow would be there on leaking leads.

For new players, just remember to pull a lead from the source not the target when dropping cylinders[if the engine you are working on will allow this]

Cheers.

[Geoff2]

20 + yrs ago when Circle Track magazine was a good magazine, they use to write great tech articles on various subjects related to racing.

One test was on plug wires, specifically conductor resistance. Twelve different brands of wire were tested, all having different resistance [ ohms per foot, commonly used for comparison of wires]. There was a 12 hp difference between the best & the worst. The winner was NOT the wire with lowest resistance. In fact, the winner had the second highest resistance of the wires tested!!! Resistor spark plugs were used for all tests except one, where the manufacturer specified a non-resistor plug be used. It scored the LOWEST hp!!
Too much attention is given to getting the lowest res wires. You have very high series resistances in the circuit, rendering the resistance of the leads insignificant: secondary coil resistance, often 000s of ohms, 3-7kohms if resistor plugs used, high resistance rotor to segment gap & high resistance at the plug gap. Not to mention the effect of capacitance of the leads, or inductance if spiral wound leads are used because they are an inductor.
The effect of capacitance & inductance in the circuit probably explains the result of the above test, where lowest resistance did not translate to the highest hp.

[emsvitil]

Do you remember who made the wire with the highest HP?

[Krooser]

I'm using an analog MSD 6T box. MSD billet dizzy locked out.

I have a set of old but lightly used Mopar Performance wires on the dizzy, another new set on the shelf and a new set of generic daily driver Bosch wires.

We used Ultra 40's on my kids modified, Scott brand on another SBC dirt car and MSD and Accel on my old 351C sportsman car Never an issue.

But I ran junkyard take offs for three years on my dirt modified without problems, too!

[mag2555]

Simple physics will tell that the resistance of the air gap of the plug no less the addition of the very thick Atmosphere that gets created in the chamber at TDC is infinitely more massive then the resistance of even a pig cheap 20 ft long spark plug wire!

Stop wasting cash on low resistance wires and go for the wires with ok levels of resistance, but the best insulation!!!!

[David Redszus]

Simple physics will tell that the resistance of the air gap of the plug no less the addition of the very thick Atmosphere that gets created in the chamber at TDC is infinitely more massive then the resistance of even a pig cheap 20 ft long spark plug wire!

Stop wasting cash on low resistance wires and go for the wires with ok levels of resistance, but the best insulation!!!!

The object of testing wire resistance is not to find wires with the lowest resistance, but to identify broken wires and poor connections. Distributed resistance wires test fine when new but have a habit of breaking with use.

A decent wire will have a resistance of a few ohms per foot.
A connector, at either end, may have a resistance of 1-5K ohms.
The air gap at the distributor will have a resistance of a few mega ohms.

And to make matters even more interesting, chamber conditions of heat and pressure (and gap) will alter
the required firing voltage and spark duration.

[tenxal]

Testing wires on the dyno can be an eye opener.

[rebelrouser]

You only need enough ignition energy to light the mixture in the cylinder, any more is overkill and can actually cause problems. Electricity goes to the path of least resistance, if more energy is in the plug wire than will go across the plug gap to ground, it will seek another path. I am a big believer in using an ignition scope to check the ignition system. You get a measurement of system resistance, burn time, coil operation, and even distributor wear all at a glance under running conditions.



https://4.bp.blogspot.com/-OxA64QjYFiQ/ ... 0/fuel.bmp

[HDBD]

Why not run solid wire with bakelite resistance ends that screw on as used on european cars, assuming the ends can be found that clear headers?

[swampbuggy]

I believe i have heard it stated that real wire ( copper ) is one example , plug wires can interfere with other parts of the ignition system. David ? Mark H.