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Discussion Starter #1
Since I need to re-gap mine as a result of some changes in my car I figured I'd just put in new plugs. I planned to stick with the stock NGK Platinum's (PFR6J-11).

Just for fun I went to NGK's web site to see what interesting information I might come across.

I found listings for both Iridium plugs and a "new" Iridium IX plug. There wasn't enough data on the web site to make any judgements so I called NGK's tech line.

They told:

1) The Iridium and Iridium IX are the same plugs. Quote- " The web site is a bit confusing on that".

2) They have an Iridium IX that is a cross for the Platinum plug but- they strongly recommend not re-gapping them and the gap is the factory standard .044".

3) There recommendation to me was to stick with the Platinums which I could re-gap to my needs ( I plan to go to .034 or possibly .032).

Chris
1994 VR4
 

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Discussion Starter #2
Well I got a bit more interested in this topic so I went to Denso's web site and then called them on the phone.

Their standard Iridium plug for the VR4 is the IK20 which is the cross to their PK20PR-P11 Platinum plug (same basic plug as the NGK PFR6J-11). This plug has a .044 gap. It could be re-gapped but it is likely to suffer from gap migration (the gap opens back up) because the plug would probably run too hot (you would have gapped it down because you were running more power and you would probably have more heat). You would also run a greater risk of cracking the ceramic, again because of too much heat.

They would prefer to see you go to the IK22 which is the next colder heat range and is pre-gapped at .032.

In Denso's opinion the Iridium plug would be less prone to spark blowout and a better choice for this application than their Platinum plug. They think you could probably even open up the gap some with the this plug.

FYI- they make the HKS Iridium plugs, they do not make NGK's Iridium plugs.

Chris
1994 VR4
 
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