Race Car Tech Discuss anything related to road racing and auto X.

Spark plug heat range question

Thread Tools
 
Search this Thread
 
Old 01-16-04 | 05:03 PM
  #1  
Thread Starter
Full Member

 
Joined: Oct 2003
Posts: 151
Likes: 0
From: Seattle, Washington
Spark plug heat range question

I have an oval track race car.....an 82.....and i was wondering which heat range would be best for me as i stay up in the upper RPM range.

BR9EQ14 or BR8EQ14 or BR7EQ14

either 7, 8, or 9 heat range

Thanks
Old 01-16-04 | 05:11 PM
  #2  
specRX7_22's Avatar
Rotary Enthusiast

 
Joined: Nov 2002
Posts: 1,014
Likes: 0
From: Eastern PA
arent those the stock plugs?
Old 01-16-04 | 07:18 PM
  #3  
tims's Avatar
Rotary Enthusiast
 
Joined: Apr 2001
Posts: 1,289
Likes: 0
From: North Hollywood, Ca USA
higher the number=lower the heat range. I would try to find some 10's or 11's, but I wouldn't run anything hotter than a 9 in any racing rotary.
Old 01-16-04 | 10:56 PM
  #4  
Thread Starter
Full Member

 
Joined: Oct 2003
Posts: 151
Likes: 0
From: Seattle, Washington
i didnt quite understand that last post......mabye someone could fill me in on even what a heat range is.
Old 01-17-04 | 09:30 PM
  #5  
tims's Avatar
Rotary Enthusiast
 
Joined: Apr 2001
Posts: 1,289
Likes: 0
From: North Hollywood, Ca USA
all spark plugs have a "heat range". for simplicity it is how hot the spark gets. at higher rpm's and at higher intake air temps(like turbos) you want a "colder" spark plug because it does not take much to get these mixtures ignited. to hot a plug can cause detonation and serious engine damage. on a street car I would run what the manufacturer recomends, but for track only cars that will always be run at the high end of the rpm curve colder is better. all race turbo cars can benefit from a colder plug. the NGK plugs are kind of backwards as the number increases the "heat range" goes down. so a 7 plug is "hotter" than an 11. the third and some time fourth digit in most NGK plugs is the heat range. I hope this makes sense.
Old 01-18-04 | 02:21 AM
  #6  
Thread Starter
Full Member

 
Joined: Oct 2003
Posts: 151
Likes: 0
From: Seattle, Washington
Yes that made perfect sense thank you very much for your help..... i think ill get a 9
Old 01-18-04 | 06:37 AM
  #7  
reza's Avatar
Rotary Enthusiast
 
Joined: Dec 2001
Posts: 1,252
Likes: 0
From: Sunnyvale, CA
You can run lower heat range >9.
The problem is higher heat range is hard to start when cold, and you could foul them easily.
What you have to do is have two set of spark plugs.
So you need to use higher heat range <10 for cold start. After engine warm up, switch to lower heat range.
So you could run 11 and start the car with 9 or 8.
Old 01-18-04 | 09:35 AM
  #8  
cpa7man's Avatar
Racing is life!
iTrader: (2)
 
Joined: Jan 2003
Posts: 2,173
Likes: 0
From: Grapevine, TX
Originally posted by reza
You can run lower heat range >9.
The problem is higher heat range is hard to start when cold, and you could foul them easily.
What you have to do is have two set of spark plugs.
So you need to use higher heat range <10 for cold start. After engine warm up, switch to lower heat range.
So you could run 11 and start the car with 9 or 8.
That sounds like a hastle, but that would work. There seems to be so little time to do that kind of stuff like that at the track. The last event I was at the track opened at 7:00 am and we had to be on grid at 8:00 am, and go thru tech as well.

I run about 130:1, 2 cycle oil in my FB with a 12a. I would be worried about fouling out in grid with anything over a 10 rated plug.

Anyone running 10 or higher plug and running high ratios of pre-mix?

Last edited by cpa7man; 01-18-04 at 09:38 AM.
Old 05-08-13 | 10:00 AM
  #9  
1993fd3sracer1's Avatar
Full Member

iTrader: (1)
 
Joined: Mar 2011
Posts: 76
Likes: 0
From: council bluffs
I'm running high premix on high compression and the cold plug starts cold but is a bitch to start after its hot I would recamend 7 heat range for leading and 8 for trailing but I have an fd bridge port and 24psi boost two different cars and set up
Old 05-09-13 | 12:41 AM
  #10  
kc0stp's Avatar
Full Member
 
Joined: May 2010
Posts: 131
Likes: 0
From: Colorado
Im running roughly 50:1 premix (since it comes in nice premeasured bottles) and have NGK 11.5 race plugs for after its warmed up (generally Ill just throw them in after practice)
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
The1Sun
New Member RX-7 Technical
9
03-18-18 11:08 PM
alphawolff
1st Generation Specific (1979-1985)
17
11-17-15 05:57 PM
Joe428
1st Generation Specific (1979-1985)
16
08-19-15 06:24 PM



Quick Reply: Spark plug heat range question



All times are GMT -5. The time now is 04:18 PM.