Spark plug replacement
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Teching In
Joined: Apr 2013
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From: Killeen, TX
Spark plug replacement So I'm replacing the spark plugs in my 01 TA, and from reading on the forums it seemed most recomended NGK TR55's for a lightly moddded LS1 (mine has headers and a cat back). Went to the store and happened to get into a conversation with one of the guys there, and he recommended to go with the TR6 plugs. From what I had read, those plugs were best suited for a nitrous/FI setup. Long story short, I ended up going with the TR6's after this conversation. Wondering if ended up buying the wrong plugs...anybody with a little more knowledge care to point me in the right direction?
From what I researched the tr6 is one step colder than the tr5(stock recommended), the tr55 is half step colder than the tr5 (stock recommended). I currently have the tr55s on my car but did buy tr6's because I went turbo. Just haven't had time to swap em out and so far the the tr55's are holding up and haven't had any problems. Someone correct if wrong.
The TR5 and TR55 are the same heat range but have different gap. The TR6 is a step colder than the previous. This has been my research and say a thread that had info from NGK's site confirming this. I cannot say that the TR6 plugs are right or wrong for you as I have only used TR55's with what's in my sig.
^^^^^^corrected on the gap for tr5 and tr55's
https://ls1tech.com/forums/generatio...r5-vs-tr6.html
https://ls1tech.com/forums/generatio...k-tr5-tr6.html
https://ls1tech.com/forums/generatio...r55-plugs.html
http://www.ls1gto.com/forums/showthread.php?t=243764
https://ls1tech.com/forums/generatio...-ngk-tr55.html
https://ls1tech.com/forums/generatio...r5-vs-tr6.html
https://ls1tech.com/forums/generatio...k-tr5-tr6.html
https://ls1tech.com/forums/generatio...r55-plugs.html
http://www.ls1gto.com/forums/showthread.php?t=243764
https://ls1tech.com/forums/generatio...-ngk-tr55.html
Thread Starter
Teching In
Joined: Apr 2013
Posts: 38
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From: Killeen, TX
From what I researched the tr6 is one step colder than the tr5(stock recommended), the tr55 is half step colder than the tr5 (stock recommended). I currently have the tr55s on my car but did buy tr6's because I went turbo. Just haven't had time to swap em out and so far the the tr55's are holding up and haven't had any problems. Someone correct if wrong.
TR5 and TR55 are the same heat range. The second "5" designates a larger gap. Since GM changed the gap via TSB on some plugs, I wouldn't run the TR55 anyhow.
The TR5 and TR6 are the same gap, but the TR6 is one step colder.
I wouldn't worry about them too much. Run them for a while and if the car runs OK, pull one of the front easy to reach plugs and see if it is getting too much carbon on it.
Better one range too cold than too hot.
The TR5 and TR6 are the same gap, but the TR6 is one step colder.
I wouldn't worry about them too much. Run them for a while and if the car runs OK, pull one of the front easy to reach plugs and see if it is getting too much carbon on it.
Better one range too cold than too hot.
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So I'm replacing the spark plugs in my 01 TA, and from reading on the forums it seemed most recomended NGK TR55's for a lightly moddded LS1 (mine has headers and a cat back). Went to the store and happened to get into a conversation with one of the guys there, and he recommended to go with the TR6 plugs. From what I had read, those plugs were best suited for a nitrous/FI setup. Long story short, I ended up going with the TR6's after this conversation. Wondering if ended up buying the wrong plugs...anybody with a little more knowledge care to point me in the right direction?
TR-55 Stock heat range .059 gap
TR-6 1 step colder
-Stock, Full bolt-on, or H/C/I cars up to 11:5.1, the TR-5 is fine.
-High compression 11:5.1 +, Forced induction, or small shot of Nitrous(100 or less)... TR-6
-Big shots of Nitrous( 150 or larger), and high boost FI setups, the BR non projected tip plugs are advised.(BR7EF-BR8EF-BR9EF depending on power level).
Thread Starter
Teching In
Joined: Apr 2013
Posts: 38
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From: Killeen, TX
TR5 and TR55 are the same heat range. The second "5" designates a larger gap. Since GM changed the gap via TSB on some plugs, I wouldn't run the TR55 anyhow.
The TR5 and TR6 are the same gap, but the TR6 is one step colder.
I wouldn't worry about them too much. Run them for a while and if the car runs OK, pull one of the front easy to reach plugs and see if it is getting too much carbon on it.
Better one range too cold than too hot.
The TR5 and TR6 are the same gap, but the TR6 is one step colder.
I wouldn't worry about them too much. Run them for a while and if the car runs OK, pull one of the front easy to reach plugs and see if it is getting too much carbon on it.
Better one range too cold than too hot.
*Edit*---What is the stock gap for plugs on the LS1? Shame on me for not knowing but it's just not coming to me at the moment
Last edited by macattack0821; Aug 23, 2015 at 11:50 AM.
Thread Starter
Teching In
Joined: Apr 2013
Posts: 38
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From: Killeen, TX
TR-5 - Stock heat range .039 gap
TR-55 Stock heat range .059 gap
TR-6 1 step colder
-Stock, Full bolt-on, or H/C/I cars up to 11:5.1, the TR-5 is fine.
-High compression 11:5.1 +, Forced induction, or small shot of Nitrous(100 or less)... TR-6
-Big shots of Nitrous( 150 or larger), and high boost FI setups, the BR non projected tip plugs are advised.(BR7EF-BR8EF-BR9EF depending on power level).
TR-55 Stock heat range .059 gap
TR-6 1 step colder
-Stock, Full bolt-on, or H/C/I cars up to 11:5.1, the TR-5 is fine.
-High compression 11:5.1 +, Forced induction, or small shot of Nitrous(100 or less)... TR-6
-Big shots of Nitrous( 150 or larger), and high boost FI setups, the BR non projected tip plugs are advised.(BR7EF-BR8EF-BR9EF depending on power level).
You cannot go by what kind of mods you have done entirely, you have to visually inspect the plugs. Generally speaking you can determine how hot your plug is getting just by looking at the threads and the tip. Like all metal, when it reaches a certain temperature it begins to change color from heat, you should only see discoloration of the metal at the closest point to the firing end where heat is greatest. If the plug is starting to discolor (turning yellow or straw color) beyond the first 3 threads, the plug itself is getting very hot. Another way, but slightly less accurate is to look at the ceramic around the firing tip, if the ceramic remains bright white, then it is running hot as well, the ceramic portion should begin to change to a slightly darker shade of off white towards the very very light brown/tan color on the proper heat range after a couple of passes.
That being said, if your not getting detonation, its better to run the plug as hot as the car will handle not only for emissions reasons but youll get a nice clean burn. Often times guys go to the TR6's, like I had to do because we just can't get around the KR once the plug gets hot on track passes. There is always a trade off depending on what heat range you go with, just like there are always trade off's with running bigger cams.
Cylinder temperature is the only direct way to determine what plug heat range you need correctly, but since we can't measure that, we can only speculate based on the gradual increase of horsepower, and increases in horsepower are direct increases to combustion pressure and temperature.
That being said, if your not getting detonation, its better to run the plug as hot as the car will handle not only for emissions reasons but youll get a nice clean burn. Often times guys go to the TR6's, like I had to do because we just can't get around the KR once the plug gets hot on track passes. There is always a trade off depending on what heat range you go with, just like there are always trade off's with running bigger cams.
Cylinder temperature is the only direct way to determine what plug heat range you need correctly, but since we can't measure that, we can only speculate based on the gradual increase of horsepower, and increases in horsepower are direct increases to combustion pressure and temperature.
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From: Schiller Park, ILL Member: #317
Stock gap for the factory platinum tip plugs was .060". I've used TR55s with gaps in the .050-.060" range without any issues, stock internal + bolt-ons or mildly cammed. The TSB that calls for a smaller gap (.040") was specifically for the GM iridium tipped plugs released around ~2003 as a service replacement for the platinum plugs.
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From: Bucks County, Pa.
Stock gap for the factory platinum tip plugs was .060". I've used TR55s with gaps in the .050-.060" range without any issues, stock internal + bolt-ons or mildly cammed. The TSB that calls for a smaller gap (.040") was specifically for the GM iridium tipped plugs released around ~2003 as a service replacement for the platinum plugs.
this what I run, but I chose them for the higher compression. I chose 035, because I didn't want to risk blowing the spark out. Not necessarily one size fits all, but it fits quite a lot.
Joined: Nov 2001
Posts: 34,629
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From: Schiller Park, ILL Member: #317
"A new spark plug has been released for use in the above vehicles. The new spark plug has an Iridium tip instead of the current Platinum tip. Due to the different tip design, the gap of the spark plug has also changed. The new spark plug, ACDelco Part Number 41-985 (12571164), is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed to the gap required with the Platinum plug, or damage to the spark plug may result."
No updated plug gapping requirement was ever listed/issued for the engines themselves, only a change in gap for this specific new plug itself.
Having said that, another bulletin was released in May of '13 (13D-070) stating that platinum plugs would again be offered in place of the iridium tipped versions for 2006 and older applications that were previously serviceable with said iridium tip. Reading the document, this seems to have more to do with price concerns rather than any "improvement" by going back to the platinum tip. No mention was made of gapping in this bulletin.
IMO, for those using conventional tipped plugs in the stock heat range (such as NGK TR55), the majority of stock to moderate applications will benefit from using something close to the larger original gap size.