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Smoothie · Posted: Wed Sep 20, 2006 6:28 am Post subject:

I tried platinums years ago and was unimpressed as well. -Yet all the hype is that they're great and last longer - that auto manufacturers use them to extend service intervals to 100,000 miles or whatever. Maybe it's true only for newer engines with tighter control of air:fuel mix, timing, etc. The Bosch platinums that I tried had the ceramic tip with a tiny pin-like core of platinum.. One thing that happens during ignition is a very small bit of the electrode is vaporized where the spark jumps (true for any plug). This makes me wonder then if that tiny bit of exposed platinum isn't a problem then because even though platinum is tougher than copper, silver or whatever else electrodes are made of, there's way less of it there to absorb the constant erosion caused by the vaporization. Of course that alone doesn't explain things if newer cars actually can run 100,000 miles on them...
Conductivity [both thermal and electrical] may be another issue in favor of copper (and silver which has still higher conductivity than copper) and the self-cleaning characteristics of the plug - maybe conductivity and self-cleaning are more important in older, often oil-burning, cars with looser control of air:fuel and timing...
Iridium plugs are actually platinum with a small amout of iridium. Iridium is even tougher than platinum, so adding it to the mix results in something tougher than platinum. The electrode design is different with a large area of metal exposed as compared to the ceramic-shrouded Bosch platinums, so I'd count that as a good thing (as the electrode wears, you can clean up and restore the sharp edges of the electrodes, re-gap and be happy for a while again). -But they're still inferior to silver and copper in conductivity. (-And I don't know how the self-cleaning characteristics of iridium plugs compare with copper.)

I've been using Bosch silver plugs with no complaints (not because I'm not a cheap bastard - but because they're recommended for the 931 and more importantly I got a bunch on sale some years ago).
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

JB 924 · Joined: 03 Apr 2006 Posts: 606 Location: Hessen, Germany

He just wanted to know what 'plugs to use, not a life story!

johnathan1 · Joined: 08 Oct 2007 Posts: 308 Location: Downey, Ca

I switched out the Bosch plugs that were in my car (looked like they were more than 10 years old) with new Denso plugs, since I have had OEM Denso plugs in my turbo supra, and they just seem to last forever and give great performance. I must say, they really helped the Porsche, it idled MUCH smoother, and now has more power as well.
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-1977 924, 4-Spd...Gone
-1987 Toyota Supra Turbo, Pearl White, BPU, 300RWHP @ 10psi.
-1989 Mercedes-Benz 300SEL

WARNING: MAY CONTAIN TRACES OF AUDI OR VW!

Khal · Posted: Sat Dec 01, 2007 6:28 pm Post subject:

Und hier¿
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'80 924 Turbo

Nobbi · Joined: 24 Aug 2006 Posts: 1396 Location: Germany

I stick with the Bosch W5 DC for my 1977 build.They are recommended in the service manual and i never had a problem with them.
But, it gets hard to find them. I think Bosch replaced them with what ever?

I once tried the 4 Splitfire Boschs, but they didnt get hot enough.After a couple of 100 Km the get oily.

I think that the platinium is only used inside the plug as a electric lead, not on the part that goes into the head...?

Nobbi

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

no...platinum is just a thin layer of material over the electrode.
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Supercharger and EFI kits
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Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

My best results have been with NGK BP7ES that is stock plug on NA. And they worked perfectly with 1 bar of boost also on stock NA engine (9.3 CR).
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
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Ozzie · Posted: Sun Dec 02, 2007 7:37 am Post subject:

2Fast · Joined: 09 Dec 2007 Posts: 459 Location: Klamath Falls, OR

I'am going to put Bosch platnuim plus in my car. I would stick with german parts.
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=====>Alex<=====
1979 Porsche 924 NA 5spd
1979 Parts Porshce 924 NA 5spd

Smoothie · Posted: Mon Dec 10, 2007 11:40 am Post subject:

It's looking like you might have skimmed through this thread too fast, 2Fast. Most of the posts here are about negative results with the platinums.
Try 'em if you must, but let us know how they last.

_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

blargonator · Joined: 22 Sep 2004 Posts: 100 Location: kalamazoo MI

the only good thing about being a parts monkey for autozone is once a quarter i get %30 off parts, and we just started carrying NGKs so i stocked up plugs for my 93' corolla, and i bought 8 plugs for my '77 which we are apparently not able to get anymore, so i got the last of 'em in my area

i had autolites and it wasn't firing on 2 cylinders, swapped out the old fouled out autolite platinum plugs for some plain jane copper densos and i now have spark at 3 cylinders and one cylinder that decided it doesn't want to fire.