Jump to content

Server Lease Renewal/Software Licenses

Our yearly server lease, software licenses, as well as hardware operating costs, ARE due Dec 6th, 2021. Our current donations have fallen far short of the funds we need to renew. Please remember the RennTech.org community is Member supported so please consider a donation to help...  THANK YOU!

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Spark Plug Indexing


RayGT3

Recommended Posts

I would love to see a scientific test on something like this but I think the gains would be so small that they would fall within the margin of error of the dynos. It seems like it might be a waste of time with stock plugs since there are 3 other ground electrodes in the way of the flame anyways. Who knows though. I personally think the gain wouldnt be noticable.

Link to comment
Share on other sites

In years past this was standard procedure in any race type engine, especially high compression motors, re:GT3 (11.8:1). Spark quality and it's relative location was and probably still is important to efficient ignition. If you're just driving to pick up the groceries, the difference is certainly not going to be an issue. But in a racing environment, you take all those little things that don't make much of a difference and add them up, it can make a win or loss difference. It would be interesting to know, of all the folks that finished in GT at Daytona, what type of plugs they were using. It's kind of ironic that folks will spend $6000 for a 10 hp gain but are very quick to discount a very inexpensive possible couple of hp. Maybe I need to go back to school but I have a difficult time understanding the benefit of the multiple electrode over the single. In most cases, if not all, you would only have one spark from the center electrode to the matching ground electrode having the least resistance path, regardless of the number of electrodes. The other ones are only there to get in the way. Color me confused, not the first time and not the last, I'm hoping someone can explain what I might be missing. Please don't think I'm being argumentative, I just like a good, informative discussion. This is how I learn. I'd love to hear everyones comments.

Link to comment
Share on other sites

  • Moderators

Next time I am at RennWerks I'll ask what plugs they use.

With multiple electrodes you are still going to get just one spark, to the electrode with the least electrical resistance. But once in a while someone claims you get multiple sparks. But I was a history major....

The benefit of multiple electrodes is that the plug does not have to be changed as often as a single electrode plug. As the electrode with the least resistance wears then the spark jumps to the next electrode with the least resistance.

The 2.5 Boxster had 2 side electrodes, and were to be replaced at 30,000 miles. When the 2.7 and 3.2 came out Porsche switched to 4 electrode plugs, and increased the change interval to 60,000 miles.

Then you get the platinum debate. Platinum last longer than copper, but does not conduct electricity as well as copper. It is said that the platinum plug with or without multiple electrodes is used to get that 100,000 mile plug.

http://forums.pelicanparts.com/showthread....k+plug+indexing

http://forums.pelicanparts.com/showthread....k+plug+indexing

Link to comment
Share on other sites

  • 3 months later...
  It seems like it might be a waste of time with stock plugs since there are 3 other ground electrodes in the way of the flame anyways. Who knows though.

Read this from PCA.org tech article. The next to last paragraph (though confusingly written) provides some insight.

http://www.pca.org/tech/tech_qa_question.a...F-5CC98AE5EE18}

Link to comment
Share on other sites

  • Moderators

I like the questions in the article. I have suggested that someone with a 2.5 that has 2 side electrodes might want to try the 4 side electrode type plug used on the 2.7/3.2. As pointed out in the question the problem is the 2 electrode plug sold by Porsche has a heat range 7, while the 4 electrode plug sold by Porsche is a 6. Some time ago I searched the net for a Bosch Super plug with 4 electrodes with a 7 heat range for use on a 2.5 and came up with nothing.

The question also points out a question I have had with the Bosch Platinum +4 plug with a part number 4417. What is the heat range. Companies that sell this plug list the same plug for the 2.5/2.7/3.2, but we know the heat range for a 2.5 is different than a 2.7/3.2. I have not been able to verify the heat range of this plug, other than to assume, like in the question, that the 7 at the end of 4417 is the heat range.

As pointed out by Scott, more electrodes does not necessarily mean it is a better plug, rather it is the design of the plug. I do not follow Scott when he mentions indexing, other than as a generic response. If you have a 4 electrode plug in the middle of the combustion chamber and 4 valves per cylinder, then the most electrodes that can face the intake valves is two.

Link to comment
Share on other sites

  • Moderators

That is a handy Bosch chart. I can decode the Boxster oem 2.5 Super plug with the Bosch part number FR 7 LDC4 as an example.

F is the thread size or 14 mm x 1.25 mm.

R is for resistor.

7 is the heat range.

L is the length of the threads.

D is 2 side electrodes.

C is copper.

4 is an extended insulator.

Can't do that with the Platinum +4 plug as the number is simply 4417.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.