View Full Version : Spark Plug Wire Life

09-30-2003, 10:40 PM
i am running a turbo motor with efi on alcohol,it makes 1500 hp and i have been down on power from earlier in the year. other guys have told me that they change wires 3-4 times a year because they break down.i don't have any misfiring going on just have lost some power ,can wires make power go away without misfiring? can their be a problem with the coil? i have a 7al-2,msd dist. super conductor wires

09-30-2003, 11:45 PM
Spark plug wires are one of the weaker links in the ignition system. They are beat around from the turbulence inside the engine compartment as the car goes down the track, and they are exposed to high heat from the exhaust system. On a racecar, MSD recommends that the wires be check periodically with an ohm meter to make sure that there is continuity across the entire length of the wire. MSD Spark Plug Wires should measure 50 ohms per foot. As long as you have continuity from one end of the wire to the other then the wire is fine. If the coil has a weak output, then that could be causing a loss of power. Check the coil with an ohmmeter or swap it with a known good coil to see if the power comes back up. Have you done a leakdown on the motor and does it check out ok?

MSD Tech1

10-01-2003, 09:03 PM
i have done a leak down and it checked good,when you say check the coil with a meter what should it read. how close am i to the limit of the 7al-2,i run 16 160lb. injectors with 10.5 comp. and 25-27 psi boost with A .020 plug gap.when i upgrade to another box which would you recommend. thanks for your help

10-09-2003, 10:43 AM
The 7 should fire that with out to much trouble at all. I have personally used the 7 on a blown alcohol motor with 11:1 and 30 pounds of boost. The gap you are running is pretty tight and if the ignition will not fire any wider gap or the fuel consumption does not seem right then I would step up to either an MSD 8 or the MSD 10. Either of these will be able to handle basically anything you want to throw at it. It is not uncommon to replace wires a couple times a year especially if you take the wires on and off allot. If you lose a wire or coil you are going to have some sort of audible misfire. It will not cause the motor to be down on power or flat. With as much power as you are making I would generally recommend checking the cap rotor and wires every few races just due to the fact you are putting so much demand on them.


MSD tech4