spark plug wire question

[sammyg2]

I need to know what the deal is with the metal shielded spark plug wires on my 1980 SC. I noticed a couple days ago that I have an intermittant short on one wire, probably the connection to the boot. But,.....the wires are probably OEM, so they may be due for replacement. Do I need the shielded wires? What is the purpose? Is there a less expensive alternative that works as well?
TIA

[VenezianBlau 87]

I've heard on here that Magnecor makes good wires. Took me awhile to find a place that sells them. I just bought a set of the KV85 (8.5mm) for my '87 for around $133 through http://www.apexperformance.net/magnecor.htm

The 10 mm would not fit my existing wire holders without modification. The 8.5 mm wires are said to fit. Wires are red and really look neat (I'm not ashamed to say that I had to have red).
They are made near Detroit, MI.

Magnecor website is interesting and includes a manual with applications/part numbers.
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Good luck
Bob Sauerteig

[TCGGrafix]

I read somewhere (I think) the shielded wires are not necessary. If I recall correctly, the shielded wires was a result of Porsche trying to correct the blown air box problem due to backfiring. From what I understand it really didn't help. The pop off valve is the only insurance against the infamous exploding air box. Someone please correct me if I am mistaken. Do a search for "shielded wires" or something and you should be able to find the same thread. Good luck!

[TCGGrafix]

OK....It's a bit slow here at the office today. I looked up the thread that backs up my comment. It the 6th post down. Hope this helps. http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=54376&highlight=Ignition+wires

[Superman]

No, you don't need the SS braid. All I needed to fab new wires using the old ends was some 7mm wire and six of those special MB screw connectors. Adam has a related thread right now, and a search will turn up previous detailed discussions on plug wire fabrication (for those who are as foolhardy as I). I could have reused the braided cover, but I did not. It serves little purpose and some say it reduces performance by giving the wires something handy to short against, and it would be hard to see the arc during inspection.

[MoonMotors]

Hi, it's my understanding that the ss wires reduce electrical wave interference. This is supposedly to make the engine run smoother, ie no electrical interference with distributor, CD boxes, and the radio. Yep the radio. I heard this from my boss who's an old German mechanic. It sounded reasonable to me, don't think it makes that big of a difference.

[stlrj]

Yep, shielded cables are so incredible that Porsche opted to leave them out in 84 and never went back.

Maybe they realized that we were not so gullable just because we could afford to be.

Cheers,

Joe

[wckrause]

I think the shielded wires were to help meet EMI (electro-magnetic interference) requirements. There are limits on the amount of radiated emmissions that are allowed. You'll also see that the rear deck is connected to the rest of the body with a short length of braided wire.

I'm not sure why the newer cars were able to run without them, perhaps requirements changed, or changes were made to the ignition system to reduce EMI. Resistive plugs also help reduce EMI by softening the sharp edges of the spark pulses.

[Early_S_Man]

sammy,

You can remove and discard the braided shields. You can replace all of the factory 7 mm neoprene wiring with bulk branded spark plug cable from Belden, Packard, Accel, Magnecore, AC-Delco, etc. The ends unscrew. Plenty of discussion in the following threads:

http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=6058&highlight=spark+plug+cables

http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=32818&highlight=mm+silicone+Beru+wires

http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=7497&highlight=Beru+connector+crimp

[Doug Zielke]

Hey...wait a darned minute!
Can't a guy have his braided wires just because he likes the look of them?
Gives the engine a bit of aircraft-hi-tech look, IMO. In fact, it's the first thing my non-gearhead neighbor noticed, seeing a Porsche engine for the first time.