I got a 2014 MKS recently. I wanted to change the plugs out. The oem plugs are sp534. I have been reading about and suggested to use sp542 plugs instead. The 534 are used in the 3.5L and the 542 are used in the 2.7L. This is for a stock application, for now. I am going to add an exhaust system to it and possibly a CAI but won't do any kind of tune to it for a few years for warranty purposes.
Was told to use .030 gap for stock and .026 for modified. Does anyone who has an ecoboost know about any of this? Thanks.
The reason you would use them is they are a step colder but the people who I have seem use them are using them in a tuned SHO or MKS. I've been told by multiple people they work better as long as you drive it spirited every once in a while because they tend to foul up if you don't get on it ever.
Just use stock plugs and factory recommended plug gaps. The only reason for a smaller plug gap or colder plug would be a drastic change in cylinder pressure by changing compression ratio or using a power adder (nitrous/supercharger/turbo).
New air filter and exhaust won’t affect cylinder pressures at all. A performance tune will up the boost and lean the fuel mixture some, but they’re all still safe except may a full tilt race tune.
The reason you would use them is they are a step colder but the people who I have seem use them are using them in a tuned SHO or MKS. I've been told by multiple people they work better as long as you drive it spirited every once in a while because they tend to foul up if you don't get on it ever.
Vendors like to sell as much product as possible. I have the Livernois tuner for my 2.7 F150 for 40k miles now set on 91 octane performance tune with stock plugs. It’s run 14.0 at the drag strip and hauled 13k lbs for hundreds of miles with no issues. Even gets 24 mpg unloaded!
The gap they suggest is .028 to .037, which is crazy to have that big of a tolerance as a machinist lol
I'll probably use stock at .030 for now and the 542s at .026 when I tune it. Just considering my options because I know the other ones work too.
Spark plug gap really doesn’t matter as long as it can arc and ignite the mixture. 28 thousands is safer with more boost that a tune will create because the its harder to “blow out the spark” with a smaller gap. More boost = more cylinder pressure = more resistance across spark plug gap. Smaller gap = less resistance. I seriously doubt stock turbos can raise cylinder pressure enough to stop the plugs from arcing but there is no downside to a smaller gap until you get to the point where it will not reliably ignite the mixture, probably less than 15 thousandths.
People like to think a larger gap means a larger spark which means better ignition but that’s not true. Once the spark ignites the mixture it’s job is done, doesn’t matter how big the spark is.