SPARK PLUGS 101 for GT500s
Proper heat range and gap are important to the performance and safety of your car. They're also some of the most mis-quoted and incorrectly referenced pieces of information on automotive forums. That said, here is the VMP Performance guide to spark plugs for 2007-2014 Ford Shelby GT500s.
1. NGK TR6's are NOT recommended for long life on these cars. They are included in a lot of kits because they're a $1.99 plug and it makes people feel like they're getting more for their money. They are not a full step colder than stock and they are a copper plug. If you are racing your car, and you KNOW they are appropriate because you know how to properly read a plug, then they're fine if you change them frequently.
2. Recommended plugs:
Brisk Racing GR14YS for boost levels up to and including 16psi
GR12YS for boost levels 17 psi and up.
We run them in all our race and R and D vehicles including
Christine (GR12YS and .026 gap on her)
Vmpperformance.com carries Brisk Racing in stock
exclusively but other brands are available.
NGK TR7-IX only. This is a full step colder than stock.
These are not pre-gapped and should be clearanced
to .032 for up to 15psi, .028 for 16-19 psi and .026
for 20+ psi. This is a long-life Iridium plug.
Motorcraft SP-471 (AGSF12FM1) This is a Platinum plug and is
another outstanding option and upgrade to stock.
They are one step colder than stock for 07-12 cars
and about a half step colder than stock on 13-14.
Same gap should be used as the TR7-IX and they
are NOT pre-gapped.
These are the ONLY plugs we recommend.
3. From time to time you'll see us tell a 13-14 owner that they can
just re-gap their stock plugs when they do a simple pulley
upgrade. This will depend on the total boost (a 2.40" pulley will
net around 16psi at sea level) and the use of the car. Again, the
13-14 plug will be a little colder than the stock plug in previous
year cars. In this case, we recommend re-gapping to .028
We've found this to be the best gap for this particular car and
this particular configuration. It will also depend on how many
miles are on the original plugs and how they've been used.
4. Do NOT use anti-seize on spark plugs. Simply change them
5. Race gas, unleaded fuels and additives will shorten the life of any
plug, regardless of what the fuel company claims. Be aware of
this and change them accordingly.
6. Learn to read plugs. Go to a manufacturers site for
a reference. Do NOT depend on forum opinions. Why?
Because there is zero control. Manufacturer info is based on a
controlled sample. You can depend on their information.
This information is based on hundreds of thousands of miles in GT500s in a myriad of configurations; mild to wild. It also supersedes any information we have previously offered.