patd

Owners manual says WR7DC at .028
Service manual says WR8DS at .028 +/-.004

Which is preferred???

pikey7

I jost got some Bosch Platinum's. They are the '7' model.

I Believe the 7 designates the heat range of the plug.

What you actually need depends on the tune of your engine.

Mike

patd

Somewhere in my travels I read that platinum plugs weren't recommended for 951s.

White951

there should be an emission sticker inside the engine bay. I think its on the fender. Mine says what plugs to use.

John
86 951

Skip

I think the controversy surrounding Platinum plug use is that less of the spark energy is transferred via the platinum center electrode when compared to copper or silver plugs. Platinum plugs were optional for some 951's, which is mainly due to the longer life characteristics, not that it is a better plug or conductor. Platinum plugs work fine in any production Porsche, though they may not be the best choice for high-horsepower applications... they just last longer. At ~$4 each, why compromise quality for life (except for the poor twin-plug flat 6 guys )

booster

I use the +4's with no known problems and they have been in for over a year.

IceShark

The plus 4s are the ones that everyone agrees should not be used in a turbo. I believe even Bosch agrees. Heat on those extra metal tips in cylinder just increases premature detonation chances.

Skip

Bosch or BERU +4?

The BERU is copper core, the Bosch is Platinum. The extra heat from the tips is an interesting concept, is there more information on this. I use the BERU Quad-tips, and used to use the Silverstone's in my 86na, but that ain't no turbo.

Skip

IceShark

It would be any multi-tip plug, Skip.

As far as people saying don't use them on a turbo, that was all over the net. As far as manufacturers, I ran across that on the Bosch Germany site a year or two ago when I was looking for new plugs, but they no longer come straight out and say that. Just touting all the new models of 4 tip offerings.

If you go to the US site (http://boschusa.com/AutoParts/PartFinder/PartFinder.asp) and plug in for the 944 turbo spark plugs there is the following footnote for the +4 and turbo:

"(1) Excluding turbo and supercharged models."

Also noticed something new on NGK's site regarding the 3 tip plug that didn't used to be there, basically saying those are great for turbos and high heat.
http://www.ngksparkplugs.com/product...multipower.asp

I don't know WTF is going on other than the plug guys are making a fortune on premium pricing on the multi-tips and not telling the average Joe and Jill what the real deal is.

I guess if you read the NGK wording closely, I think they are saying it will last longer and perform adequately under hard boosted conditions if you don't care about the other items like detonation and the best performance (since target users won't just change plugs out for new, once in awhile).

There is another interesting item on NGK:

"Multi Power plugs are not for all applications, as they can tend to quench the spark, or hamper the ability of the flame to grow from the initial ignition point."

Now that doesn't sound good, and would apply to your N/A as well.

Unless a spark plug engineer can convince me otherwise, I think multi point is snake oil for just about all circumstances.

Danno

Yeah, I'd like to see a dyno-test comparison between these plugs and your K-Mart $0.95 special. I bet there won't be anymore than a 0.5% difference, which would be in dyno and atmospheric variances anyway.

aka 951

NGK BP8EFS I think - its on my pelican page. Two ranges colder, but special order. They seem to work well.

Mark AW

I agree with eric NGK8's work fine. The higher the number the less likely you are to melt a plug but the worse the cold starting. Mark