I use Bosch (non platinum) super 4's, which I have been very impressed with. When I first installed them I could feel the car pulling better and harder, but that is in comparison to an old set of ordinary Bosch plugs that were in moderate shape.

 

I use these, I keep a few spare sets in the garage...

 

I run those as well.

 

NGK's, I just swapped out the old Boschs and she run mucho grande

 

FWIW my local dealer just sold me a set of Beru Ultra plugs, when I asked for stock spark plugs for a 944. I knew about Beru spark plug wires, but hadn't seen their plugs before.

They came in little "Porsche" marked boxes.

 

Aren't these the plugs that got TonyG 10rwhp over stock on a dyno? Maybe that was even one range colder than that?

Edit: I can't find the thread via search. It might be too old. I am thinking they may have been NGK's Iridium plugs. Model # BPR6EIX

 

For you guys in cold climates - be careful about going TOO cold -You'll get a very hard-starting car because of fouling when you get down around freezing unless you lean out your idle.
At 30 degrees F., I am at 12/1 AFR BEFORE the lambda leans it to 18. If I shut off the car at this point, I am cleaning plugs the next day with NGK 6's.

 

Interesting Read on the benefits of Iridium:

http://www.sparkplugs.com/pdfs/iri.pdf

 

I use stock. Also, I'm wondering whether or not a particular plug can really make that much of a difference. There's all this talk about "heat ranges" and so on, but I don't really see what the problem is. Basically you have an air-fuel mixture in the cylinder and need a source of ignition - we use an electric spark. Does it REALLY matter whether that spark is 0.30" long or 0.40" long? I tend to doubt it's going to make THAT much difference; the important thing is there is a spark / source of ignition present and it occurs at the correct time (which is not determined by the plugs, it's determined by the rotor). Yes, you can get fouling and carbon deposits and other nasty things over time that will degrade or in extreme cases even eliminate a plug's ability to fire, but those seem to be functions of air-fuel mixture more than a particular kind of plug. The only way I'm convinced a particular plug makes that much of a difference is with multiple-plug ignition systems, such as are used on aircraft and some very exotic auto engines. This gives (1) redundancy and (2) multiple points of ignition so a more complete burn within the cylinder. This makes sense, but I honestly think a lot of the chatter about "plug heat ranges" and "this plug is better than that plug" is a lot of marketing-driven B.S.

 

[QUOTE=Porsche-O-Phile] Does it REALLY matter whether that spark is 0.30" long or 0.40" long? I tend to doubt it's going to make THAT much difference; the important thing is there is a spark / source of ignition present and it occurs QUOTE]

POP, they say the fuel/air mixture isn't ignited by the spark but by the heat generated by the spark. Too much heat too quickly and you'll get detonation, not enough an you can have a rich/fouling condition.

 

http://www.sparkplugs.com/sparkplug411.asp

This should provide you with about everything you need to know about spark plugs in general. For the 951, most use a copper plug although some have success with Iridium and Silver.

The heat range is dictated by the amount of HP produced so the plug can help control combustion chamber temps and prevent pre-ignition.

Here is a quote from Sparkplugs.com:

As far as designation, they all do it differently. Some count up for cold and some count down. You can get cross reference charts on the site.

Max

 

jeremy, you are referring to something completely different, not normal spark plug operation. more details on the differences here;
http://www.streetrodstuff.com/Articl...ne/Detonation/

 

TonyG swapped plugs during a dyno session and made 10whp more. It's hard to argue with quantitative data.

 

No you're right, I meant to say pre ignition not detonation. Give me the before 9am moron award. The brain isn't fully functional yet.

 

Interesting data. I'll check that out. Wouldn't the spark "hotness" be more a function of coil strength rather than plug design though? Also, some plugs might be more effective by being able to conduct heat away from the electrodes - is this what is meant by "heat range"? Maybe that article will answer the question. I'll check it in any case.