Upgrading from NGK BPR9ES from BPR6ES.

[Chim55117]

I was doing some reading online and found that with higher boost applications, horsepower, and modification, the stock BPR6ES spark plugs are more prone to detonation.

Sometimes while driving the VR-4, I get backfires around 4-5K RPM. And to some extent this would make sense in relation to my problem (of backfires). I have access to free NGK BPR9ES, and was wondering since I should spring for them and install them.

Is there any any "downside" from me running plugs that are 3 steps colder? There are also the options of BPR7ES, or BPR8ES. I just want to make sure that if I run the BPR9ES it isn't overkill for my application.

The VR-4 has a 20G with full supporting mods and the like and 324 WHP at 18 LB of boost. Relatively low street/daily boost is what it is at now. During the summer I will likely crank the boost and retune with my DSMLink.

Thanks in advance,

- Stephen

[Shane@DBPerformance]

It will be more prone to fouling out the plugs, starting can be harder, more likely to misfire, possible loss of power, part throttle drivability could be worse, gas milage could go down a tiny bit. Or you might not notice anything. 9s are a very cold plugs though, the main problem would be them being prone to fouling out. Most people run 7s on DSMs, you normally wouldn't run 9s unless your running 40+psi and make over 700whp.

[Constant_Project21]

I remember a friend of mine switching to 9's and seeing nothing good (pretty much identical set up as yours). I also went to an 8 for a bit, but my fuel was loading up, and I was shooting 3ft. flames out my exhaust. If ya have access to all of them, why not try going colder and see what works best?

[Swifty1638]

With that setup, I'd run some 7's. Start there.

[Kracka]

7's for sure.

[Constant_Project21]

I shouldve added that I ended up sticking with 7's.

[Halon]

I'd say hell no to 9's. With those mods, i'd stick with 6's or 7's.

[blackrosenova400]

Try running non projected spark plugs, they help prevent pre-detonation as the ground electrode is shorter and is less likely to get hot and pre-ignite the fuel.

Id go with BR7ES's at .026 gap

[jrohner]

I second the BR7ES @ .026.

[blackrosenova400]

Or get a Dynatek Arc-2 CDI :banana:

I just got mine today, I will post a followup how well it runs.