Spark Plug questions

[Brucelinc]

Stock gaps are .033-.037 so there is very little electrode erosion on SwampRat's plugs.  We shouldn't expect to see much at 18,000 miles.  What we have seen is gaps over .040 by the the time the cars reach 45 - 50,000 miles.  That could cause problems on a car with a tune.

[JagerBomb]

Time to kick an old thread up.
I'm getting ready to do a bunch of go fast parts in the next 2 weeks. It will be getting a 160* T-stat, Catted LMS DP, and LMS tune. I figured I should do my plugs since I have no idea when they were done and I will be doing the MAP.

The question is should I use the Ford MotorCraft SP534 plugs or should I go one step colder (Is it necessary)? If I need to go one step colder what is the part number for it?

[ZSHO]

I would personaly stick with the M.C SP-534 plugs and they also come pre-gapped at 0.30,also with a tune its recommended you change them more often. Z

[BiGMaC]

I would personaly stick with the M.C SP-534 plugs and they also come pre-gapped at 0.30,also with a tune its recommended you change them more often. Z

Ditto... Check with your tuner for the gap... Usually .028-.030

[Skeezixzx9r]

I would personaly stick with the M.C SP-534 plugs and they also come pre-gapped at 0.30,also with a tune its recommended you change them more often. Z

They come pregapped if you get them from your tuner.  I checked the brand new ones I bought and one was .028 and the other 5 were out beyond .034.

[JagerBomb]

I would personaly stick with the M.C SP-534 plugs and they also come pre-gapped at 0.30,also with a tune its recommended you change them more often. Z

They come pregapped if you get them from your tuner.  I checked the brand new ones I bought and one was .028 and the other 5 were out beyond .034.

I never trust pre-gapped anything unless I bought it from a speed shop (LMS, Unleashed, Real Street). Places that actually build fast cars.
Not saying the Techs at the dealership don't know what they are doing (My Brother is one). I just don't believe the guy at the parts counter or store selling it to me.

[Airbornemaikai]

I bought the 534s from Oreileys and even though the website listed them at .34 they were all perfectly gapped at .30 out of the box. Crazy to think I paid LMS $100 for my first set last year, then the dealer another $80 for install. Ended up getting all the plugs and a gap tool for $27 and some change and replaced them all myself in less than an hour

[ZSHO]

I kind of take pleasure taking things apart and putting them back together piece by piece,especially spark plugs,whats the big ordeal pre-gapping plugs to the desired gap that your tuner recommends,it literally takes 7 minutes out of your time to pre-gap them yourself,or you can have them do it for you for an extra 70.00,BTW this will be my 5th set of plugs on my car which i take pride in doing it myself.  Z

[SVTCruz]

So SP-534 are one step cooler than the OEM 2015 SHO spark plugs?

[AJP turbo]

So SP-534 are one step cooler than the OEM 2015 SHO spark plugs?

No

See below
91
General Discussion / Re: SPARK PLUGS
« on: December 27, 2015, 10:38:26 AM »
Yes Z is correct. The SP 534 is the exact plug that NGK calls LTR6CI-11 stock #97177. It is NGK's best plug. It's double precious metal meaning it has iridium on the electrode and the ground strap. Which gives it the 100k service life compared to the single precious metal plugs such as the Iridium IX which is also a really good plug which NGK said is good for 40-50k.

I called NGK recently because I was contemplating changing my plugs. But there is a problem for me.

The stock replacement LTR6CI-11 is gapped by NGK at .032" and is stock heat range. They don't offer 1 or 2 step colder in the laser oem double iridium plug. The 6 designates the heat#, 7 would be 1 colder. the 11 is the gap designation.

If you want 1 step colder you downgrade to the LTR7IX-11 stock 6510. The problem is that plug is gapped by NGK at .044" and NGK told me they recommend only gapping down a maximum of .012" or you risk weakening the weld of the ground strap. Then maybe it breaks off in the cylinder. So that means that they only recommend gapping that plug down to .032"

So anyone running the LTR7IX-11 which is a recommended part for popular 3 bar tunes and gapped at .028"-.030" are running a little less than NGK recommends for that plug.

So if you want to gap down that far I'd run the stock plug but then it's not colder. Or you run the iridium IX line gapped down to a minimum of .032" and you can be colder but also have an inferior plug. But be careful when gapping down you don't go too far and have to go back up...You still over extended it in that case.

[ZSHO]

Here's an excellent discussion related to this thread but giving you a broader spectrum on the Topic followed by pic's,because a thread is worthless without pic's.lol   Z           http://www.ecoboostperformanceforum.com/index.php/topic,5649.msg89426.html#msg89426