I went to order more and it shows out of stock now. lol.

 

Thins arent looking so good for my order getting filled then... LOL

 

I ordered 4 from them two weeks ago. They said they would be in stock soon in an email. Got an email from them today saying they shipped the 4 this morning. So, they have some.
Mike

 

There’s a seller on eBay that still has some, I ordered 4 and they shipped today. ~$12/ea.

 

I installed the S29a yesterday from the eBay seller. Didn't get a chance to drive the car, but it fired right up. Will have to look and see how the colder 10s in trailing effect AFRa if at all.

 

I've been pleasantly surprised running 11s in the leading and trailing full time (not surface discharge yet). I expected them to foul in a matter of days on the street.

 

what's your ignition setup? I fouled 7420-11 pretty quickly on the street with stock twins and HKS twin power. went back to 10's and all was good.

 

IGN-1A ignition setup helps, even though the plugs might look dirty the actual spark path will burn clean.
.

 

It is, indeed, a IGN-1A setup.

 

a surface discharge type coupled with the enclosed trailing configuration might concern me more in that regard, but that’s my line in the sand for commenting further on what would only be a theoretical viewpoint …
.

 

OK, so what is everyone running for the leading spark plugs? Sounds like the 6601-11 are great in the trailing spark plugs, has anyone had any luck running them in the leading position with great results? Im asking because I am about to get my car turned with an sxe366 turbo on a half bridge engine on e85. I have been out of the game for a while and am running NGK 7420 on my FC. I felt like the 7420 did not run as well in street driving. Looking to see what is the Hot plug to run now.

 

without specifics beyond a spark plug type/number, it’s just mumbo-jumbo

did you read the last several posts of this thread?

the specifics matter.

what are the specifics of your *entire* ignition system.

because if you think a 6601 will magically transform your engine from a 7420 plug, imagonnastraightupdirectdialthebshotlineonthat.
.

 

I'm running the sakebomb ign1a kit. I agree on specific. The 7420 are on the fc. It crazy to think that spark plug manufacturers haven't created a more modern high hp rotary spark plug considering its a popular engine.in the drag scene and also enthusiasts scene.

 

I have swapped my trailing plugs from 10's to 11's and it still runs exactly the same, if you saw my plug picture posts about 10 posts up. Running a leaned out and timing advanced map on an n/a renesis fwiw.

 

Stupid question: how does one remove the standard crush washer on a plug without just cutting it off, and where would you get new ones and how would uyou replace them (if you had them machined down)?

 

Back in the day, you could often just unscrew them. If that didn't work, you could cut them off and there were replacement crush washers with tangs so you could just screw them on.

 

Unscrew them, takes some finessing

I think I got some generic copper washers from McMaster or Amazon, you can get different thickness.

 

just a short update:

i am currently running on 4 Denso SA31As.

i like the surface gap concept that actually is a return to Mazda's original thinking....

i like the idea that the spark can choose between 360 degrees to find the most efficient path. if you notice the carbon pattern on a conventional plugs porcelain you see ground strap shaded areas. my motor is crisp on startup, happy around town and (yesterday) made 484 and 492 at 19 psi 2560 ft elevation on 93 pump/600 cc of wm AI. no drama.

of course, it still isn't a perfect world in sparkplugland as there are no more SA31s and the NGK item which would be perfect is a bit short on reach. i will be on the dyno sometime in the next 4 weeks and will probably need to evaluate our 3 options:/ R7420s, SA31 and NGK 6601s.

 

Is there a reason to not include the
Denso IRE01? It's should be equivalent if not better then the R7420.

 

"Is there a reason to not include the
Denso IRE01? It's should be equivalent if not better then the R7420."

yes, my mistake on the post. i prefer the Denso IRE01 option as the center electrode is .4 mm versus NGK at .6.

while the larger center might give the NGK an advantage as to longevity that's not my current objective.

i will run the 11.5 heat range.

 

[QUOTE=Howard Coleman;12612534]just a short update:

i am currently running on 4 Denso SA31As.

i like the surface gap concept that actually is a return to Mazda's original thinking....

i like the idea that the spark can choose between 360 degrees to find the most efficient path. if you notice the carbon pattern on a conventional plugs porcelain you see ground strap shaded areas. my motor is crisp on startup, happy around town and (yesterday) made 484 and 492 at 19 psi 2560 ft elevation on 93 pump/600 cc of wm AI. no drama.

of course, it still isn't a perfect world in sparkplugland as there are no more SA31s and the NGK item which would be perfect is a bit short on reach. i will be on the dyno sometime in the next 4 weeks and will probably need to evaluate our 3 options:/ R7420s, SA31 and NGK 6601s.[/QUO

Hey Howard, have you had a chance to dyno and provide more inside on the different spark plugs?

 

Breaking News on the surface gap front.

quick background:

i received advice in an email from Richard Green/Green Brothers New Zealand re the need for surface gap plugs in the top position.
after a few options were identified i ended up running 4. Denso SA31As.

i have been doing a fair amount of 3rd gear pulls and on the last 4 the motor has laid down as it was getting into the higher combustion pressure area. initially i thought it was just a bit rich.

after getting that tuned up i concluded if it wasn't fuel it must be spark.

ignition misfires are easy to diagnose. if you are on the dyno go to zero smoothing and you will see the RPM plot look the teeth of a comb. lots of ups and downs... perhaps 50 or a hundred RPM backups even though the TPS is 100%. often you can't feel it so it is important to look.

if you are logging, set your ECU to the highest cps available... my Link Extreme can log at 1000 cps. here's the plot. notice it appears as combustion pressure ramps.


i suggest it is a good idea to take a look at your RPM plot as you can have modest misfires that you can't feel.

i swapped in a couple of Denso IRE01-32 (10.5) iridiums in the bottom and all misfires disappeared



i will continue to run surface gaps in the top so as to avoid pre-detonation (dented rotor) but am back to more normal plugs in the lead..

 

Howard, that's an interesting result... Intuitively, I would think that if the plug gaps are the same, and all other ignition system factors are the same (coils, wires, etc.), that a 360* surface gap vs. conventional electrode plug would work just the same - and in theory, the surface gap should be even less likely to misfire, since you have more surface area for a spark to jump across (i.e., surface gap should last longer before fouling). Anyway, a couple of questions:

1. Are the plug gap specs for the surface gap Denso SA31As the same as the Denso IRE01-32 (10.) iridiums? If the surface gap Denso's have a larger gap, it may explain the misfires.

2. Is the "reach" spec into the combustion chamber between these different two plug types the same? I would expect the one with the shorter reach to be more likely to misfire, if there is any difference between the two plug types.

 

The Denso S31A's gap is larger than I would like (Gap.055" (1.4mm)), the Denso IRE01-32 gap is better (Gap.028" (0.7mm).
I prefer the surface discharge NGK 6601 (Gap.016" (0.4mm) closer to the 0.02" that I use on gappable plugs) although they're about 2mm shorter in reach. I take out the compression washer and use a slim copper one in its place. Some people have machined them.

 

If you all would look at post 112 where I actually measured a surface gap plug and didn't go by the brochure you can see why they would be having issues with gaps like these as compared to the fine wire iridium plugs we typically use. These gaps are huge, it's irrelevant that they have a 360 degree path when nomater which direction the arc choses the gap is massive. The ideal surface gap plug would have an actual measured gap around .012- .015 not 3 times that.