Adam Barnes

I've been going through a set of NGK BR8EQ-14's about every year. Is this unusual for an upgraded ignition system? The center electrode gets worn down to the point where my leading ignition no longer fires. Thus the car floods with gas and oil refusing to start. The trailing seem to look almost new at that point, so I just switch them and drive the car a bit longer.

Leading each have a MSD Blaster 2 coil of their own and trailing shares one through the distributor. I think it may be burning the electrode off, but can't verify.

I put between 5000 and 10000 miles on my car in a year, generally less.

I've also had a few plugs where the center core shears off about 1/2 way down inside the plug. NGK told me it is not uncommon on high rpm or vibration engines, but I've been curious if it might not have melted.

Doesn't seem to be a lot of good options when it comes to plugs, so I guess I'll just have to keep buying a set every year and hope for the best?

Adam Barnes

Attaching some images so you can see what I'm talking about...

ft_rt_fl_rl_plugs by falcoln0014, on Flickr

fronttraling by falcoln0014, on Flickr

reartrailing by falcoln0014, on Flickr

rearleading by falcoln0014, on Flickr

frontleading by falcoln0014, on Flickr

mazdaspeed7

Your heat range is too hot. Go up to 10's and you should be fine.

I used to run b11egv's in my ported n/a and never fouled a plug. I started running those after going through a set of stock plugs every 2-3k miles, burning out the center electrode just like your plugs.

Adam Barnes

Correct me if I'm wrong, but the heat range on my current plug is 8? Would a 10 not be hotter and cause more burn to the electrode?

After some googling I see some people like the BR7EIX, but say you need to run a fairly advanced timing to keep it from fouling out. My Weber 34 would probably enjoy that...

I also see reference to an Autolite 2626 which cross references to NGK BUR7EQ that someone claims works great...

Someone else runs 3rd gen plugs as recommended by one of the major rotary aftermarket suppliers...

And several people claiming RX8 plugs are the best they've ever tried...

Too many options. Perhaps I'll burn this new set of plugs into the ground and try one of those out...

mazdaspeed7

Higher numbers indicate a colder plug, because the plug pulls more heat away from the electrode.

Adam Barnes

I've found these in the 9 range:
NGK BUR9EQ - 3.02/ea
Denso 3111 S31A - 3.43/ea
NGK BR9EQ14 - 5.04/ea
NGK RE9BT - 16.88/ea

I've found these in the 10 range:
NGK B10ES - 1.66/ea
NGK B10EV - 6.39/ea

I also see the B11EGV for 4.47/ea

Is there a specific 10 range plug you prefer?

mazdaspeed7

I was running b11egv's in mine. Never fouled a plug, but it was on a tuned fuel injected engine. They may work for you, or may not. I dont have any specific recommendations for other plugs. Maybe someone else can chime in.

BUR9EQ is the FC stock trailing plug. Personally, I dont like the surface gap design of those, I prefer a standard plug that you can gap. Just make sure whatever you get is not longer than the stock plugs. The leading plug hole is open to the chamber, and if it sticks out, it can hit the apex seals.