I installed the Denso Iridium IK27 (three range colder than stock), but there was a LOT more knock with them, even at low boost. As expected earlier, since the electrode is so small and take less voltage to spark, they seem to spark either stronger or sooner, giving some knock (unfortunately because the timing is not optimised). I went back to NGK V-Power BKR7E (one step colder than stock). I gapped them at 0.035" for now.

 

Isnt 1 heat range per 100hp kind of a rule of thumb for plugs? The copper plugs seem to run the best in the v8 ls series engines. Are you having trouble with the bkr7's?

 

No they run great ! But I found that scaling down too much the MAF signal to run with the 42 lb/hr injectors let the PCM always runs in a section of the MAP where there is too much timing advance. Not good for the knock ...

 

Can someone hear explain spark plug specs?? I always use the mfg recommended OEM replacement because I don't know anything about them. I understand how they work, just don't know about heat ranges etc.

 

Two questions:
How are you planning on using a boost controller on our S/C setup?

Why would you get plugs three ranges colder?

 

Here is some good links about spark plugs :

http://www.stealth316.com/2-sparkplugxref.htm

http://www.maxracesoftware.com/spark_plugs.htm

http://www.strappe.com/plugs.html

 

Manual boost controller is installed and work well ! It avoid the stock by-pass valve selenoid to bleed the extra boost (12 PSI and higher) too fast.

Since Iridium plugs with the same heat range than stock tend to run hotter and I was already running some one range colder copper plugs, I tried some 3 range colder iridium.

 

3 range colder is too much unless you are highly modded, 1 range colder should be efficient if you are modded with maybe a pulley or something like that im only gonna go 1 range colder with a turbo setup unless the manufacturer says different

 

do you see knock with the BKR7E v-power's those are what i have gapped at 0.035

 

did you read his sig.. he is a bit more then modded with just a pully. he already went to a 2.6.. not to mention all the other stuff he has.

 

a quick question how can you have a manual boost controller on a supercharged application i thought the pulley controlled boost only?

 

My knock until now was mainly caused by the timing ...

 

It's easy, it controls the by-pass valve selenoid, this way you can decide at how many PSI the by-pass valve is bleeding the boost.

 

Update : I install back my Denso Iridium # IK27 plugs and gapped them today to 0.026" (tight) , since I run 21 PSI of boost with the 2.6" pulley. Knock retard is way less than when they were gapped to 0.035".

Since I run 91 octane gas, it support merely at least 2 or 3 degress less timing than 93 octane gas.

For your information, each single more PSI of boost need one full point of octane.

It's normal to see some knock retard when running high boost (17 or more PSI) on 91 octane gas.

 

Would one step colder work with a CAI? or is it even neccessary?

 

Yes it will work. Either NGK V-Power BKR7E (great copper plugs) gapped to roughly 0.032" or NGK Iridium BKR7EIX (gapped as provided; no regap if roughly 0.035") or Denso Iridium #IK22 (gapped as provided; no regap if roughly 0.035").

 

Thank you very much^^^^

 

How are spark plugs classified for cars? In airplanes its all about the type of engine, and its operating temp, and power output. It your pushing betwwen 270-300 whp, what kind of spark plugs would you need? This would be running a large amount of boost also.

 

The fact that we cannot gap iridium plugs is purely and simply a MYTH. Are they more difficult to gap ? Yes. But they CAN be gapped if you properly use tools and your brain too LOL.

Scroll down on the following page, you'll see an example of a feeler gauge.

http://www.vespamaintenance.com/tools.html

Here is the gap distance :

http://www.installuniversity.com/ins...p_distance.jpg

You must use the good feeler and GENTLY slide it between the center (round) iridium electrode and the bended electrode. It must be tight. If the gap is too large, you can gently tap on the bended electrode to reduce the gap until the gap is ok. The hardest part is if you tap too much, the gap will be too much reduced, and that's why iridium plug isn't easy to gap, because you will have to use pliers to bend the bended electrode until the gap is larger.

Denso Iridium small center electrode is 0.4 mm in diameter and NGK is 0.6 mm.

In either way, NEVER bend or hammer or even touch the small center round electrode.