# Why is colder better on spark plugs?



## JunioR_VW (Jul 30, 2002)

What is the deal with colder heat ranges on spark plugs? The NGK BKR7EIX is one heat range colder. What is the benefit if any?
These seem to be the plugs that everyone raves about on the turbo vw's
http://www.parts4vws.com/catal...R7EIX


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## chewbacca5017 (Apr 20, 2007)

*Re: Why is colder better on spark plugs? (JunioR_VW)*

I'm no scientist here... But it appears that this mainly becomes an issue when you chip your car... Running higher boost = higher temperatures = higher chance of detonation (air/fuel igniting under the intense heat before the spark plug sparks). For the same reason we only run premium fuel in our turbo engines (to ensure that the air/fuel only ignites by spark, whereas 87 octane would probably detonate in our turbo'd engines), we'd also want to run a cooler spark plug once we chip our cars for the added comfort of avoiding detonation.
There might be more to it, but I think that's the general idea.


_Modified by chewbacca5017 at 10:07 AM 7-8-2008_


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## Uber-A3 (Feb 23, 2002)

*Re: Why is colder better on spark plugs? (chewbacca5017)*


_Quote, originally posted by *chewbacca5017* »_I'm no scientist here... But it appears that this mainly becomes an issue when you chip your car... Running higher boost = higher temperatures = higher chance of detonation (air/fuel igniting under the intense heat before the spark plug sparks). For the same reason we only run premium fuel in our turbo engines (to ensure that the air/fuel only ignites by spark, whereas 87 octane would probably detonate in our turbo'd engines), we'd also want to run a cooler spark plug once we chip our cars for the added comfort of avoiding detonation.
There might be more to it, but I think that's the general idea.

_Modified by chewbacca5017 at 10:07 AM 7-8-2008_

you got it


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## Revo Technical (Jan 9, 2003)

It transfers more heat from the combustion chamber to the cylinder head.


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## JunioR_VW (Jul 30, 2002)

*Re: (Robin @ Revo Technik)*


_Quote, originally posted by *Robin @ Revo Technik* »_It transfers more heat from the combustion chamber to the cylinder head.

The plug does?


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## CanadianJetta2.0T (Sep 14, 2006)

*Re: Why is colder better on spark plugs? (JunioR_VW)*

Do these plug needs to be gapped or are they "plug and play" ?


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## walkingfool (Mar 24, 2008)

*Re: (JunioR_VW)*

Take it from an old geezer, a "colder" plug is designed to operate properly in a hotter engine. I know, it seems wackbards.


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## Revo Technical (Jan 9, 2003)

*Re: (JunioR_VW)*


_Quote, originally posted by *JunioR_VW* »_
The plug does?

Yes. The heat range has nothing to do with the actual spark.
















And all plugs should be gapped, regardless if they come pre-gapped or not.


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## brandon0221 (Mar 7, 2007)

*Re: (Robin @ Revo Technik)*

21K on my NGK's and no problem. Yes they were plug and play.


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## gtiiiiiiii (Mar 6, 2004)

*Re: (brandon0221)*

1 heat range colder in these motors with tuning for the stock heat range have been causing problems in many people's cars.
With older cars it was common place to put a heat range colder spark plug in a motor making more power.
I'm against the use of them in these motors with just a chip and exhaust, etc. Since "everyone" does it on the 'tex though I'm sure it's the safest, best bang for the buck, absolute right thing to do however.








Let's be honest, your motor shouldn't be to the point where 1 heat range colder spark plug is what separates you from running okay and detonation...
So even though it's a common misconception that they're "better" nobody has ever shown any sort of improvement other then "it runs much smoother now!" or "idles SOOO good now." Which is funny because my car already idles great and is smooth. My favorite is "I really picked up some midrange power." As if somehow new spark plugs added 10 hp =/
Definitely a placebo mod in my eyes.
Seeing as the big turbo kits use stock heat range injectors and they're not detonating, there is no reason for colder spark plugs with minor bolt ons.
In fact, I've seen people have misfires and a rougher engine after installing the incorrect (colder) spark plugs.
If someone has some data to show me a benefit and that I'm completely wrong, then sweet I'll go swap out my plugs, but that hasn't happened yet.

_Modified by gtiiiiiiii at 4:14 PM 7-8-2008_


_Modified by gtiiiiiiii at 4:15 PM 7-8-2008_


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## Revo Technical (Jan 9, 2003)

What are stock heat range injectors?
Cooler plugs can smooth out a timing curve if you're running more aggressive timing with more boost.
I've built 3 motors w/ big turbos (not just VW) and they all run cooler plugs.
Your mileage may vary, but it doesn't cost much at all to experiment.


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## rippie74 (Sep 26, 2007)

*Re: (Robin @ Revo Technik)*

With all my mods I am running stock plugs without any issues so far & my car has 8500 miles on it. (All my mods were complete @ around 2500 miles). I don't see the need to change my plugs.


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## JunioR_VW (Jul 30, 2002)

*Re: (rippie74)*


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## magilson (Apr 18, 2005)

*Re: (JunioR_VW)*

There's a little bit of truth in all these posts, really. Robin's got the technical down and I agree with some of what gtiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii said. A lot of people swap in new plugs and feel better idle, smoother power (really?), etc. I'm willing to bet all of those things can be attributed to the simple fact that they've installed new plugs.
That being said I ran Revo stage 1 and now APR stage 1 and in both cases I've had no issues running the NGK BKR7EIX plugs. I inspect them at a reasonable interval to make sure combustion looks good with them and it appears that they are doing just fine. Spark plugs shouldn't be treated as an install and forget mod. They should be checked to make sure they are working right for your modifications.
Here are pictures of my plugs after 13k miles:
http://forums.vwvortex.com/zerothread?id=3865163


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## gtiiiiiiii (Mar 6, 2004)

*Re: (Robin @ Revo Technik)*


_Quote, originally posted by *Robin @ Revo Technik* »_What are stock heat range injectors?
Cooler plugs can smooth out a timing curve if you're running more aggressive timing with more boost.
I've built 3 motors w/ big turbos (not just VW) and they all run cooler plugs.
Your mileage may vary, but it doesn't cost much at all to experiment.

Yeah, but big turbos create a lot more power and I would totally agree with different plugs at that time, just not so much with a stock turbo


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## JunioR_VW (Jul 30, 2002)

*Re: (gtiiiiiiii)*

SO what is the best replacement plug out there for me?


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## magilson (Apr 18, 2005)

*Re: (JunioR_VW)*


_Quote, originally posted by *JunioR_VW* »_SO what is the best replacement plug out there for me?

If you couldn't determine that from what was said here then you should probably just stick with stock.


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## JunioR_VW (Jul 30, 2002)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_
If you couldn't determine that from what was said here then you should probably just stick with stock.

vortex sincerity...


_Modified by JunioR_VW at 5:11 PM 7-17-2008_


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## Michael S. (May 5, 2006)

So what is the correct plug gap? I just installed new OEM plugs (NGK) from my local dealer and they were definitely gapped wider than the plugs I removed from the GLI... The ones coming out were somewhere between 32 and 35 thousandths... The new ones were close to two times that... What's right?
I re-gapped to 35 thousandths and the car is running fine... I just want to make sure I gap them correctly.


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## blackvento36 (Mar 17, 2003)

*Re: (gtiiiiiiii)*


_Quote, originally posted by *gtiiiiiiii* »_1 heat range colder in these motors with tuning for the stock heat range have been causing problems in many people's cars.
With older cars it was common place to put a heat range colder spark plug in a motor making more power.
I'm against the use of them in these motors with just a chip and exhaust, etc. Since "everyone" does it on the 'tex though I'm sure it's the safest, best bang for the buck, absolute right thing to do however.








Let's be honest, your motor shouldn't be to the point where 1 heat range colder spark plug is what separates you from running okay and detonation...
So even though it's a common misconception that they're "better" nobody has ever shown any sort of improvement other then "it runs much smoother now!" or "idles SOOO good now." Which is funny because my car already idles great and is smooth. My favorite is "I really picked up some midrange power." As if somehow new spark plugs added 10 hp =/
Definitely a placebo mod in my eyes.
Seeing as the big turbo kits use stock heat range injectors and they're not detonating, there is no reason for colder spark plugs with minor bolt ons.
In fact, I've seen people have misfires and a rougher engine after installing the incorrect (colder) spark plugs.
If someone has some data to show me a benefit and that I'm completely wrong, then sweet I'll go swap out my plugs, but that hasn't happened yet.

_Modified by gtiiiiiiii at 4:14 PM 7-8-2008_

_Modified by gtiiiiiiii at 4:15 PM 7-8-2008_
I don't know man...........
These logs were taken back when I had EIP software, and I've seen pretty similar occurrences posted here from people running the original Revo tune. Only difference is the plugs (stock vs NGK bk7eix or whatever they are)
















Correction factor logs only show where the ECU had to pull timing to prevent detonation. If colder plugs meant less timing pulled........well, it may or may not add up to 10hp, but you get the idea. 


_Modified by blackvento36 at 4:09 PM 8-11-2008_


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