Spark plug for 2017 6.2L w/ supercharger

Mileguru · May 6, 2018

Hello,

I have a 2017 Sierra SLT Crew Cab 6.2L with a Magnuson TVS1900 on it. The pulley and boost are stock from Magnuson, so probably 8psi max boost. I want/need to replace the spark plugs because I get a little bit of ping when really engaging the supercharger. The ping is very short and goes away, but it even does it with around a 94 octane (mixed 91 with 100). It is much, much better with the 94 octane, but it is still detectable.

My questions are:

1) Should I get a one or two step colder plug?

2) Should I lessen the gap to 0.028in or 0.03in?

3) Should I get projected or non-projected tips?

4) THE BIG QUESTION, do I need to get the exact same size plug as the stock ACDelco 41-114 (aka GM part number 12622441)? The REACH is what seems to be different.

I believe the stock plug specs are:

Heat range: 16

Gap size: 0.04in (1.02mm)

Reach: 0.98in (25mm) THIS IS WHERE THE NGK PLUGS DIFFER

Hex size: M16

Insulator height: 0.99in (25.3mm)

Seat: Tapered

The plugs I am considering are Brisk (which have the SAME reach) and NGK (which have a DIFFERENT reach). Eight of the Brisk plugs is way more expensive than NGK.

Brisk RR14YS - two steps colder, projected tip, 0.028in gap, same REACH as stock

Brisk RR14S - two steps colder, non-projected tip, 0.03in gap, same REACH as stock

Brisk RR15YS - one step colder, projected tip, 0.028in gap, same REACH as stock

Brisk RR15S - one step colder, non-projected tip, 0.028in gap, same REACH as stock

NGK BR7EF 3346 - two steps colder, non-projected tip, 0.28in gap, 0.709in (18mm) REACH which is different than stock

NGK BR6EF 3177 - same but one step colder

Doug_Scott · May 6, 2018

I would contact Magnuson to get their recommendation. Who did the tune you are running?

Mileguru · May 6, 2018

Justin at Black Bear Performance did the tune. I wanted to use the Magnuson tune, but they don't give you a hand held anymore to load the tune. It was strange, they didn't even know how I should get the stock Magnuson tune loaded because they didn't know how to deal with the HPTuners credits. I had an EFILive hand held from Black Bear already, so that's why I went ahead and used them for the time being. Because of this, I'm running a conservative Black Bear tune to stay safe until I can get things figured out with Magnuson.

Doug_Scott · May 6, 2018

Most forced induction systems tell you to reduce the gap to 0.025 - 0.028 inches. I would do that, then get a capture log using the device you have and send it to Justin. He should be able to fix the ping issue, or suggest an alternate solution.

Mileguru · May 6, 2018

Thank you. Any advice on going one versus two steps colder? How about matching the exact length of the reach of the stock plug?

It of course seems obvious that I should match the stock reach length, but I want to know for sure because it'll be $20 for the NGK plugs versus $80 for the Brisk plugs. And I'm pretty sure the Brisk plugs only last for 20,000 miles or so (I have to find a definitive answer on that still).

Mileguru · May 7, 2018

10 hours ago, Doug_Scott said:

I would close the gap up on the current plugs you are running first. My first thought is that a shorter reach plug would be a colder plug. I would not change the temp or the reach of the plugs without some legitimate testing being done specifically for the 6.2 engine with the same supercharger. I would trust Justin's opinion.

This is where it gets interesting, as there is a bit of disagreement. Justin said he believes closing the gap won't help, but a colder plug might help.

The Brisk plugs are the only ones that I can find that are the same size as stock (including the reach) and allow for one or two steps colder. The only reasons I would entertain buying new plugs and not just regapping my stock plugs are 1) I can then get colder plugs, and 2) I'd hate to do all of the work of removing and reinstalling the stock plugs only to learn that the smaller gap did not fix it ($80 is worth not having to do the job twice).

What is your opinion on a projected or non-projected tip?

Thank you for all of you help so far by the way. I appreciate your time.

Doug_Scott · May 7, 2018

The problem I have is that I would have already regaped the plugs as the install instructions said for the supercharger. Have you looked at Camaro forums for possible plug options? You will find far more instances of 6.2 with forced induction.

With clearances so tight and fueling so precise compared to carbureted engines I wouldn't play with different reach plugs without some solid dyno testing showing it will not cause any damage. Did you get a capture and send it to Justin?

Doug_Scott · May 6, 2018

I would close the gap up on the current plugs you are running first. My first thought is that a shorter reach plug would be a colder plug. I would not change the temp or the reach of the plugs without some legitimate testing being done specifically for the 6.2 engine with the same supercharger. I would trust Justin's opinion.