Spark plugs 6,7,8's

[robains]

I'm going thru the process of testing various NGK plugs

My Plugs

6's (el cheapo)
7's (stock plug for my S)
8's (irridum - stock plug for Cup car??)

Tried the 6's, they seemed ok, can't see any issues on the plugs after 1000 miles, pistons looked good (scope).

Just put the 7's in and am testing now.

Will put the 8's in for Track.

Anyone's opinions on the 6's (ignore box label they are not 7's, used just for cylinder labels 1,2,3,4)??

Cheers, Rob.

[dustylax]

You should run some Denso Iridium IK20's gapped around .030 if you are running a basic supercharged setup.

[robains]

Could you expand on your reasons for Denso and smaller gap?

[dustylax]

well the IK20 is the "7" heat range when it comes to NGK numbers but its Denso's Iridium performance plug which NGK does not offer an equivilent to.

I gap most plugs tighter than that if a car is making decent power otherwise i'll see jagged AFR's on the dyno on most cars in the higher rpm's. On something like a supercharged setup with relatively higher compression and that rev's as high as it does i would do somewhere between 30-34 just to be on the safe side so i know its not breaking up if i was putting a car like yours on the dyno. They should be good enough to drive on the street and the track and give you better performance than an NGK plug since the NGK iridium they offer is more of an "economical" plug and you shouldnt need to mess around w/the other heat ranges.

Some people prefer copper plugs, you could also try some of these NGK's if you do: BKR7E-11, they are good because they run $10 for a box of 4 but the efficiency lifespan wont be as long lasting as the iridium plug.

[robains]

You have me a little confused. The plugs I show in my pics are NGK Iridium BKR8EIX and cost about $10 each ($40 for a box of 4). NGK also offer a BKR7EIX (Iridium) that I could use for street duty.

I'll have to try your gap suggestion and see how that works. Spec is 0.43 and I set mine to 0.40. I'll try IK20 for street use next time around and see if I notice any difference -- I replace plugs pretty frequently.

Rob.

[dustylax]

Originally Posted by robains

You have me a little confused. The plugs I show in my pics are NGK Iridium BKR8EIX and cost about $10 each ($40 for a box of 4). NGK also offer a BKR7EIX (Iridium) that I could use for street duty.

I'll have to try your gap suggestion and see how that works. Spec is 0.43 and I set mine to 0.40. I'll try IK20 for street use next time around and see if I notice any difference -- I replace plugs pretty frequently.

Rob.

simply put:

IK20 would be the "7 heat range" and is a Denso Iridium.

if you wanted to try a Copper plug try the BKR7E-11...some people like copper because its a better conductor, you might get better peformance but shorter life span.

[turbophil]

HEy Rob,

I use the cheapy, non- iridium, plugs for tuning as well. Afterall they seem to make the same or close to identical power.... anyway...

Your 6's look a tad hot as indicated by the 6 or so discolored threads. GEt that down to 3-4. The 7s will probably be spot on as the 6's don't look terribly hot--just a tad hot. I've posted about this before in the big speak plug thread with a bunch of pics as well.... You really need to cut the threads off to see how the plug is reading. Again, your 6's look to be stark white at the tip. You should have "some" color otherwise, your plug is so hot that it's burning off all the carbon and subsequently making the plug diffcult to read (or the mix is too lean at the low rpms, which is doubtful). The 8's will almost certainly be too cold and will give poor plug reading as well but for opposite reasons of the 6s (i.e. too much cabon build up), but that's just a guess, as I don't run 8's myself...

Not to take away from Dusty's comment about the Densos, but it's been my experience that the plugs don't seem to do much of the power side of things in these cars. THey are helpful for reading what's going on the engine and that's about it, IMO... I've ran the ultra $$ densos, Iridium NGKs, and V-groove cheapy NGKs... They all seem to do about (if not exactly) the same...

I've never had the spark "blow out" as some would say from running high boost with the out of box gap, and I do run fairly high boost when compared to the stock SC'ed engines--- although certanily not as high of boost as some others are running... Consequently, I think the stock coil packs are pretty decent for application.

Hope that helps a bit...

Best,

Phil

[dustylax]

i wasnt able to see the pictures that he posted for some reason but like you said phil its not the best way to tell how it looks from the tips like many people think, you can go buy a doctors microscope like they use in ear's with the light on it to see into the plug to really see how the motor is doing rather than cutting the plug's threads off. But like you said also like i mentioned its just better to see how its AFR's are doing when the graph doesnt get choppy on the dyno, its hit or miss on some cars, but your right the stock coil packs are pretty good on these motors already. i usualy only notice a little low end power difference between copper and iridium unless certain motors just do much better on one or the other not 2zz specific.

[robains]

I'll cut the threads off the 6's tonight and post.

7's in the car now and I might pull them before I go to the track and drop the 8's in -- at the very least I'll bring the 8's with me. But I did notice my EGT's were a tad lower with the 7's.

I'm only running a max of 9 psi (post IC).

I don't see any lean issues in my data logs (IQ3 not EFI). I'll do some more testing tonight.

I did a search on "spark plugs" but got 253 pages of results (needless to say I didn't go thru them all) -- maybe it needs to be sticky -- the uberpost didn't say much about plugs.

I'll look into the BKR7E-11 also, worth a try.

Thanks for the responses, Rob.