Ford Focus ST Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 · (Edited)
This might be a stupid question. Can I run one step colder spark plugs in my stock car or is that only for once you get a tune? What are the benefits of running one or two steps colder spark plugs?

Thanks.
 

·
Registered
Joined
·
58 Posts
My very limited and basic understanding is that the "colder" plugs keep the hot tip of the spark plug from causing pre-ignition/detonation. I'm sure someone much smarter than I will come along and explain the whys and hows.
 

·
Registered
Joined
·
825 Posts
All spark plugs have a heat range. The various models usually have a set of different heat range.
Usually the heat range is set by how deep the center electrode insulator goes before it connects to the side walls of the plug.
The heat range is chosen based on average driving for that engine.
The heat range which is 'correct' allows the electrode and central ceramic to be hot enough to burn off carbon deposits,
but not so hot it burns up the electrode material.

The pictures of spark plugs showing the correct heat range shows a ceramic with is a golden tan, and the center electrode is clean,
The overhanging electrode is also clean.

Too cold, the ceramic is dark brown, and the electrode is dirty, and the overhanging electrode may have some carbon stuck on it.
Too hot and the ceramic is white, and the electrode is often damaged.. The overhanging electrode is also overly worn, particularly at the tip

SO using a colder plug may be 'good' is and only if you drive the engine hard.. a lot.
Say your average all the time RPM is like 4,500.. FReeway you are staying in 4th or 5th
You are on boost a lot.
Then yeah, a colder plug will be great for YOU.

If you drive the car normally, like in rush hour traffic a lot. Back and forth to work, doing shopping.
average stuff where all you do is drive the speed limit, accelerate average..
And are at 3,000 rpm or under most of the time.Then a colder plug is a big mistake.
A colder plug is not like a free flowing air filter. or using synthetic oil. Putting those in/on no matter drive hard and fast, or slow and sedate.
The difference is a colder plug you MUST drive harder most of the time. (Or at least have a more aggressive tune.)
Or your plugs will get full of crap, and start to misfire and fail to work
 

·
Registered
Joined
·
1,022 Posts
SO using a colder plug may be 'good' is and only if you drive the engine hard.. a lot.
Say your average all the time RPM is like 4,500.. FReeway you are staying in 4th or 5th
You are on boost a lot.
Then yeah, a colder plug will be great for YOU
This is so me....using ngk and tuned
 

·
Registered
Joined
·
1,900 Posts
FWIW I'm Stratified tuned and live in Maine; Stratified recommends one step colder plug with their tunes (NGK 6510), but I'm running a 15-psi-max map slot for the winter to avoid roasting my new snow tires. So I've just gone back to stock heat range plugs (NGK 6509) for the winter. Will pull plugs in 2K miles to see what's what and be sure. Alex is aware.

Hope that helps,
Mark
 

·
Registered
Joined
·
51 Posts
Everyone that is tuned needs to run what the tuner recommends, which is usually 1 step colder. Even stock you aren't going to hurt the car with a colder plug, the risk is fouling a plug. I had to go to a colder plug in my 5.4 when i went from ~6psi to ~14 psi, but I ran the colder plugs for about 1k miles while still stock. They looked great before and after. Learn to read plugs and communicate with your tuner if you decide to tune.
 
1 - 8 of 8 Posts
Top