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Discussion Starter · #1 ·
Question on Plug heat ranges…(ngk)

I confused as to how you know the heat range to pick. Is there a general rule of thumb What are the signs of too hot?

Ie: Nitrous
100-150 shot -8
150-300 shot -9
300+ -10

Based on a 10.0:1 engine vs say a 13+:1 engine
(my case is 10.0:1 bbc aluminum heads basic street strip engine...looking to use 200 shot ten move up if possible)

What is the danger of running too hot or too cold? (is one catastrophic?)

Hope this isn't too basic. I'm trying to understand reading plugs and between timing and heat range I'm confused (both put heat in the plug right?)

oh and who makes the best plug scope for the $$$



Thanks
mike
 

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If you have a good ignition then I would just run 10s and forget about it.
IMO believe running to hot of a plug causes detonation besides burning up the plug. I believe the hotter plug starts to glow red and at this point can cause 2 flame fronts (detonation)

With the motor I now have I cannot tell any difference changing to a hotter plug on a motor (no nitrous) run.
 

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In your case, a -9 would be OK to start with on the nitrous. You may want to run a -8 if your just driving around on the motor.

With nitrous your better off to run a colder plug versus a hotter plug. Remember as we always talk about on here, the first place timing shows up is the tip of the ground strap, right ?? The hotter the plug, the more heat your going to generate on the tip of the plug with a given setting.

The more timing you run, the more heat you see in the end of the strap. As we put more nitrous power to our set up, we take more timing out to take heat out of the strap correct ?? ;)

Talking to most of the plug companies they'll say each heat range is say 90-120 degrees at the tip. If you have say a -9 that is showing a heat/timing mark half way around the bend, it's a good idea to look at the next cooler heat range. In many cases I have went to a cooler plug and been able to add between 1-3 degrees of timing to regain the heat/timing. Putting the timing in, without detonating will make more power....

Sorry to start rambleing... Just thought maybe I could shed a little light on the topic as well as get some of you thinking...;) Thanks for your time.. Steve
 

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Discussion Starter · #5 ·
In your case, a -9 would be OK to start with on the nitrous. You may want to run a -8 if your just driving around on the motor.


Sorry to start rambleing... Just thought maybe I could shed a little light on the topic as well as get some of you thinking...;) Thanks for your time.. Steve


Are you kidding?? The help on here is invaluable and I hope you guys know how much we all appreciate it!

mike
 

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Talking to most of the plug companies they'll say each heat range is say 90-120 degrees at the tip. If you have say a -9 that is showing a heat/timing mark half way around the bend, it's a good idea to look at the next cooler heat range. In many cases I have went to a cooler plug and been able to add between 1-3 degrees of timing to regain the heat/timing. Putting the timing in, without detonating will make more power....

Steve
Steve, just wondering here...while I understand the above, the question I would have is why at the multi system level (3 or more) where motors are generating a lot of heat, do most of the guys/engine builders run say a AR3932 plug or a -10 NGK plug? There is a one step colder plug available from both companies, but I haven't seen anyone use them. Do those plugs have some other qualities that make them undesireable? :confused:
 

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I have always used the AR3932's without any problems and I'm hosing a fair amount on three. I bought a bulk load of them so I doubt if I'd be switching soon. I run that plug (or equivalent) in all the motors that i work on.

Steve, does that imply that with a healthy 3 system tuneup, one could STILL add 2+ degrees of timing because of the colder plug? Don't think I'm froggy enough to jump at that one. :rolleyes: Most think I'm off my rocker for the timing I run as it is, but it doesn't hurt parts and is faster with the timing in it. I just creep up on it and keep a watchful eye (pull the pistons fairly often for a checkup).
 

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Steve, does that imply that with a healthy 3 system tuneup, one could STILL add 2+ degrees of timing because of the colder plug? Don't think I'm froggy enough to jump at that one. :rolleyes: Most think I'm off my rocker for the timing I run as it is, but it doesn't hurt parts and is faster with the timing in it. I just creep up on it and keep a watchful eye (pull the pistons fairly often for a checkup).[/quote]

I'm not saying change plugs and just throw timing at it.... :-Daw But I am saying I have changed over to the colder plugs, started and the same point, and added timing as it looked like it could stand it. That being said, I have been able to add between 1-3 degrees on average.... Hopefully this is a little more clear now.. Thanks, SJ
 

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Thanks for the info steve.

Im loading up my r5671a9's when cruising around for extended peroids of time. any suggestions on how i can get away from this? If I run one step hotter should i back the timing down 1-2 degrees?

Its a 565 big chief 62cc chambers, 14.5:1 single 1250 dommy.1000 hp on motor, 350 nitrous max.

I have not tried sand blasting or bead blasting my loaded up plugs, is this an okay thing to do?
 
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