Plug selection has never been easy for me on a semi modded engine. This is a difficult or expensive procedure on the 997.1, I want to be sure on making the right decision once for at least 10K in miles.




With having a factory turbocharged engine, how do you go about the correct temperature selection?
Once the factory condition has been changed by a flash, when is it time to change the range and gap?
How does one measure this range/time to change?


I understand that this is up to the tuner but, many tune tuners have different opinions on the correct range and gap at similar claimed power ranges.


Has anyone changed their plugs to a colder temp to find a "fouling plugs" after the change in temp?
Has anyone kept the stock factory heat range to find a (hopefully not) "Pre-ignition" situation?


I understand that its always safer to go colder when in doubt but, where is the line with these cars to make that switch, if even necessary.


How does altitude, driving habits affect this also?

 

I have tried a lot of different plugs on my 996tt. general rule of thumb is once you tune the car turn the boost up you go to a one range colder plug and decrease the gap. Plug life is something I didnt care about on 996 as it got new plugs twice a year. On 997 plugs are harder to do and I am trying a different plug now and will see how it holds up.

 

I've heard that for additional 100HP you should go with a one stage cooler plug. Last change, I went with one stage cooler plug gapped at .025. I'm currently around 600HP'ish.


Due to the atmospheric change at 1 mile high, I am wonder if this philosophy still holds true. I would think running a hotter plug (not hotter than stock) may be better.


I will be removing my plugs this weekend to see the results of a cooler plug.

 

You might just check with your tuner (Evoms?) and see what they recommend. Evoms recommended Denso Double Platinum PK20PR-P8 every 10,000 miles for my build. Best,

 

We run these: http://www.evoms.com/EVOMS_GT_EVT_Se.../pk20pr-p8.htm in pretty much anything with a stock long block. They're slightly colder than stock, but are the best performing, most reliable, longest lasting plugs we've found for use in the 500-800hp-and-a-little-beyond range. We use them straight out of the box with the .8mm/.031in gap they come with. They're somewhat tricky to find locally through parts stores, but we always keep several sets in stock if needed.

 

ELITE1: "I've heard that for additional 100HP you should go with a one stage cooler plug. Last change, I went with one stage cooler plug gapped at .025. I'm currently around 600HP'ish."


That there is correct & good performance text book information my friend! I have been following that for many, many years in all my cars (all turbos) and it works like a charm!

 

Hey Evoms,


I had this same plug installed at the same time that my 580 ecu tune was flashed. This plug has ran well but, is this the standard for optimal operation at my current atmospheric pressure? Has Evoms considered altitude with this temperature rating?


I will soon see what type of carbon build up I will have after 7K of tracking. (I am having no code issues currently.)


What testing does Evoms do for there recommendations for every scenario? I currently experience a (pulsing air affect during my 5th and 6th gear pulls.) Thankfully the track I attend doesn't see much of 5th gear but, this all has happened after my flash and recommended spark plugs.


I will stand by and promote any vendors along with their input on this forum when it is due. I don't necessarily want to damage anyone's reputation, (not the purpose of this thread.) I would rather want to understand why someone should change their plug temp. and when that time should occur.


Btw, Anthony's car is amazing!!! Thanks for caring for us small track type car guys.

 

Bobby,


Love the info but, I did a google search on "correct & good performance text book" and found nothing. Help me dude, I'll read it!


I'm not looking for more performance but rather, safety for my engine under extreme conditions.


The current weakness isn't the car or track but rather, its the driver!

 

The 'heat range' of a spark plug roughly describes how well it conducts heat from the center electrode to the cylinder head casting (which is cooled by the water jackets) via the ceramic/porcelain. Colder heat ranges are more heat conductive, higher ones are less conductive. The reason we go one step cooler when increasing power within that range is to provide a small safety barrier against detonation--essentially preventing the spark plug electrode from getting to the point where it acts as a glow plug. We don't go too cold, as most cars in that range are street cars, and going two or three steps colder on plugs can result in them easily fouling on cold start or short trips, as the electrode won't get hot enough to burn off any carbon.

Excessively cold heat range plugs can also result in 'soft' response and driveability at low loads, which even high power turbocharged cars achieve all the time when they're out of boost. That being said, on all the 1000hp+ cars, we run a very cold NGK Racing plug gapped down fairly tight, as the heat, temperatures, and spark energy required to safely run 200hp/cyl+ with a difficult-to-burn fuel like C16 require it. You must never let the engine run without getting fully temp with those plugs or they will foul pretty badly, and on a good day they last about 500 miles before they start to misfire under load and require replacement.

We arrived at our particular plug recommendation (power range, heat range, material, and brand) after years of testing different plugs out there on lots of different cars. We've watched knock activity with different plugs on different fuels at different power levels. We've run cars on the road course under racing conditions, track days, street racing, drag racing, daily driving, mile racing, and Sunday Driver Sally driving and found that these behave really well in these engines. They also have the best record in terms of 'install new visually-undamaged plugs in engine and don't have misfires on the first test drive because of a bad plug' of the various plugs available...looking at you, Bosch.

Regarding the driveability concern you're seeing in 5th and 6th gear, shoot me an email at sstone@evoms.com and I'd be happy to assist troubleshooting via that medium.

Sam