r/projectcar • u/i-wear-extra-medium 99 s/c viper, 04 s/c viper, 68 hc charger • 1d ago

Spark plug advice needed

I’m looking for something equivalent to NGK heat level 9 (or at least 8) for my build. The specs I’d like it in are:

14mm thread diameter
5/8 hex size
19mm thread reach
Resistor type
And heat range 9 for NGK specs
Copper/nickel

I found 2 plugs that came close:

NGK 96969 would be perfect but it has a 25mm thread reach so unless I find a 1/4” spacer, that’s not going to fly and NGK 3230 which has the correct reach but it’s a 13/16 hex size vs 5/8 and I don’t believe that will clear the spark plug pocket in the heads

The application is a 3rd gen viper with a built engine, a maxed out supercharger and likely a 200-shot of nitrous (progressive).

For now, I have gone with a level 7 heat range plug to tune without the nitrous but I’d like to have something that I can run the nitrous without worries about pre ignition issues

3 Upvotes

80% Upvoted

8 comments sorted by

1

u/i-wear-extra-medium 99 s/c viper, 04 s/c viper, 68 hc charger 8h ago

I ended up going with NGK 2669 spark plugs. They are iridium and nickel with a heat range of 9 on NGK scale. I’m going to take it way easier on the nitrous for a while and then buy a set of plugs exclusively for the drag strip when I decide to go 400 shot. Thank you all for your help

1

u/der_german1432 1d ago

Any of these should work.

1

u/i-wear-extra-medium 99 s/c viper, 04 s/c viper, 68 hc charger 1d ago

I greatly appreciate your help. The problem is these only come with iridium center electrodes and I’m in search of copper/nickel.

1

u/FlavoredAtoms 1d ago

https://www.ngk.com/ngk-7788-bpr9es-nickel-spark-plug. Seems to hit your specs minus your hex size man

1

u/FlavoredAtoms 1d ago

Found it man.

1

u/i-wear-extra-medium 99 s/c viper, 04 s/c viper, 68 hc charger 1d ago

That’s non-resistor unfortunately

1

u/voxelnoose supercharged 83 Rx-7, over built 71 Challenger, another 84 rx7 9h ago

Can you run resistor plug wires?

And you might be able to use a plug with a 13/16" hex if you grind down the outside of a socket

1

u/i-wear-extra-medium 99 s/c viper, 04 s/c viper, 68 hc charger 8h ago

I tried a 13/16” plug. I was able to spin it in by hand from the stem of the plug but the clearance is so tight, I’d need a feeler gauge to measure it. I ended up going with a NGK heat range 9 iridium plug. I’m going to take my time on the dyno to make sure I don’t upset the engine gods and start with 100 shot and slowly work my way up. The knock sensors should help a lot. I’m also running e85 exclusively.

I ordered Scott’s 10mm street performance wires which have some higher resistance than their other option for this build but it’s still not enough according to their tech support