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Denso IK24 compared to NGK BKR8EIX


Old 12-12-2004, 10:48 PM
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Default Denso IK24 compared to NGK BKR8EIX

Before someone says "use the search function", I have and read everything there is to read about them. I propose we start a technical discussion, geared towards the specifics of each. Both are 1 step colder in the heat range compared to stock. I do believe the stock units are too hot and are aimed primarily at emissions, and for FI specifically they're inappropriate. The colder plugs are required. Platinum plugs are not best suited for FI application either, this leaves the trusty copper, requiring more frequent plug replacement, or Iridium which, if tuned properly, would not foul quickly and should last a long time.

The specs on each are.

Denso IK24 ($11.99)
Iridium center electrode= 0.40mm
Ground electrode = U groove
Electrode = tapered cut
Pre-gap = 0.32"

NGK BKR8EIX ($7.60)
Iridium center electrode = 0.60mm
Ground Electrode = flat
Electrode = tapered cut
Pre-gap = 0.30"

From the above I would deduce that the IK24 is technically the better spark plug, but in a FI application, would the smaller gap from NGK make up for some of the difference? Also is Denso's U-grove proven or could it be more marketing than technical advantage.

Essentially my focus is on real world differences and results vs. technical specifications that are often hashed in with marketing.


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Old 12-12-2004, 11:05 PM
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First of all, the gap they come with doesn't mean anything as this should be changed to suit the application.
I used the OEM platinum plugs for about the first year I had the Vortech on and the car ran quite well. The plugs never fouled even at the lower gap.
Then I changed to the NGK copper racing plugs (V-Power, one step colder). Experimented with those for a couple of months. Again, they performed quite well, no fouling during the trial period.
After that, I put in the IK-24s, which are still in the car now.
All plugs were gapped to 0.034".
Performance wise and by "butt dyno" only, I could not tell the difference from one plug to another. I'm going to stay with the IKs simply because these are the last plugs I bought and they were expensive and they work well. I will check them a couple times a year to make sure they are OK and that my engine is not running consistently lean. I am hoping that these will be the last plugs I buy for my car.

Good luck with your thread. If it truly gets "technical", I will move it to "Technical".
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Old 12-13-2004, 07:35 AM
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Originally Posted by Wael El-Dasher,Dec 13 2004, 02:48 AM
I do believe the stock units are too hot and are aimed primarily at emissions
This is a little off topic, but I'm curious. . I understand the principles behind using cooler plugs in FI applications, but is there any data available to support this in NA applications? I've been using the IK-24's in the warmer months and IK-22's in my NA 2.2L during the cooler months, but I can't say that I notice any real difference in performance or gas mileage between the two.

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Old 12-13-2004, 07:53 AM
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Choosing a heat range for plugs generally means getting one that is hot enough to avoid fouling but cold enough to avoid detonation. There will be no performance difference and only a very small difference in head temperature. I have found the IK24's are subject to occasional fouling with repeated cold starts and driving in congested city conditions, so IK22's work better for me, but have used IK24's for highway / track without problem. I do think properly gapped Denso iridium plugs provide good performance and will continue to use them on my NA car.
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Old 12-13-2004, 08:01 AM
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better times and performance with the NGKs as compared to the densos. I ran both of them in my turbo S. The Densos ran a bit too rich.
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Old 12-13-2004, 06:02 PM
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I just installed the IK22's. I really didn't see a big change, maybe a little better idel, but really that's about it for me.
Were they worth it?, in the long run I think so.
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Old 12-13-2004, 07:48 PM
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The IK22 are the same heat range as stock, you shouldn't experience any difference, except that when new, things will be smoother. However that will be the case with any new plug you put in (assuming its the proper heat range for your application). The only advantage of IK22 over stock would be reduced center electrode resistance. The Denso is only 0.40mm, the smaller the better because it reduces quenching and reduces the voltage required to create a spark between the electrode and ground.

Denso is quiet pround of their U-groove design ground claiming it reduces quenching even further. NGK Iridium doesn't have that feature, nor does the stock. I would say the Denso IK22 is a good stock replacement. The IK24's are probably borderline for NA application and somehow my feeling is they were specifically developed for FI applications given their particularly small gap.

If Denso and NGK intended the IK24 and BKR8EIX for NA applications then why wouldn't they pre-gap them larger. If the iridium biggest selling point is the improved spark and elevated melting point, hence they can generate more heat. Shouldn't the gap be larger then to take advantage of that?

I am not sure my logic is correct though because event the IK22 is pre-gapped to 0.32mm. Could the U-groove be a factor when selecting such a small gap on the Denso?

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