Viperbob1

So tracing the spark plug lineage we started out on 997 with Y5DDC plugs. Then Porsche said not to use (technical bulletin posted in couple years ago) these anymore as you needed to use the super special Green Dot edition that were essentially Y5ddc that were hand selected, and then you were to use the 997 RSR plug for Endurance events. Then these endurance plugs became the standard plug. So can anyone tell me how it is possible that these plugs cost $153.00 EACH (down from $280.00 eachI hear)? According to rules these have to be in car for IMSA, but does anyone use anything else for other events like PCA?

tkerrmd

cost of running an IMSA Cup Car??

smf32s

At least you only need six. Life with a cup starts at $1000 it seems like.

Stu

Viperbob1

OK super Porsche tax. Just a standard NGK Racing plug. U can get at A-Tech(for shops) or Summit Racing for under $40 each... Well know for next time.

dass

Bob have you a part no. For a suitable Ngk plug!

Viperbob1

R2349-11 or the 4 digit code 4583

dass

Bob,
Will give them a try .

m42racer

Did someone recommend that plug???

This is a very cold plug @ 11 in the heat range. It will run even colder as its electrode is retracted back into the shell. This plug with its retracted electrode and surface discharge is a plug typically used in high boosted turbo engines. If you have an issue with Piston clearance there are better choices than this plug.

This is a large diameter center electrode , cooper as well I think. It will put more demand on an already over taxed ignition. It takes a lot more ignition voltage to fire that plug.

If you don't have a clearance issue, get the plug out into the chamber more and use a fine wire electrode. This will help the flame kernel and help the ignition of the mixture. The more you open up the plug the hotter and larger the flame core is, which then creates more in cylinder temperature. This burns the mixture quicker and at a higher temperature. You are then extracting more energy out of the fuel.

The surface discharge plug has a very small core as its only around the thicker electrode to the inside of the shell. It only fires at one place on the shell at a time. Which ever side faces the less in cylinder pressure.

Viperbob1

What you say is absolutely correct. But this is what Porsche ships with and to race most of these series anymore you have to run them. They whys you would have to ask them. I know for Club races we will be using different plugs

analogmike

These plugs are used because they won't break. Put one of those fine-wire electrodes out in the combustion chamber and take your chances... A little less power is preferable to a ruined engine.

Viperbob1

That is what seems to be the issue as far as I can tell. KISS (Keep It Simple Stupid). No part to break means no breaking parts and potential damage. I wonder how bad an issue it was. Was it from plugs used too long, or defective plugs. Fine wire ones I would not use, but the Y5DDC has been raced in these motors for many many years.

Red Bear

When you buy a Bosch 997 RSR spark plug from Motorsports they are are individually tested.

Viperbob1

According to the Bulletin they were individually testing the new Sprint plugs and putting a green dot on top of the connector or side of the body. Didnt say anything about individually testing the RSR plugs. I also do not see any marking on body to distinguish as tested or not. Not saying the RSR arent tested, but dont see signs of it.

m42racer

Would love to know what tests they are put through? Resistor measured? Gap measured?

This has all the makings of another way to dictate "only" parts used have to be bought from Porsche.

As for the use of a fine wire plug, the opposite apply's for reliability.

Fine wire plug construction is a lot better than the older plug types suggested. The precious metals used withstand the shock and temps inside the cylinders a lot better than the older types. Any failures of the plugs is not about the plugs but the mapping. If ground straps have failed in the past, that's from overheating and or detonation. Not a plug fault.

A surface discharge plug is the answer? It's hard to believe that anyone with any sort of engineering skills suggested that plug.

Remember the ignition sequence is the most important part of the engines power performance and the spark plug plays a huge role here. You can have all the fancy parts available through the Porsche catalog attached to your engine, but if the ignition is weak and the flame core is suppressed you have paid a lot of money for paperweights.

You have to really know your "stuff" to read a surface discharge plug too. If these engines are run on the edge where a standard plug is at risk the use of a surface discharged plug that is difficult to read is asking for trouble.

I think neither is the reality. Someone that doesn't have clue about engines or spark plugs made the choice of that plug type.

Install a proper choice plug for these engines and see how much better the throttle response is.

JB911

There aren't many choices for Mezger engines any more-Y5DDC has been discontinued-and the surface Racing NGK is only available in heat range 10- 9 and 11 were discontinued:
https://www.ngk.com/search/all?q=R2349

https://www.ngk.com/ngk-6839-r2349-10-racing-plug

https://www.sparkplugs.com/ngk-6839-...10-racing-plug

Or the dual electrode NGKs:
https://www.rockauto.com/en/parts/ng...park+plug,7212
Platinum version:
https://www.rockauto.com/en/moreinfo.php?pk=70033&jsn=7