General LSX Automobile Discussion - NGK tr55 to tr6 plug change on H/C LS1. Any difference? Yes..

Yesterday, I swapped out the NGK TR55 spark plugs gapped at .055 with one heat range colder NGK TR6 spark plugs gapped at .045, recommended by Fast Motorsports might I add (shop that previously tuned the car). Thought I'd share the very noticable difference it made incase this may be helpful to others. The plugs were in, and are in a 430whp & 400wtq 346ci LS1 C5 Corvette with ported heads, cam, intake, headers, etc. with a compression ratio of 10.8:1. First, the TR55 plugs I removed were gapped at .055, had approximately 7k miles of use and looked excellent when removed. With the TR55 plugs the engine made a not loud but noticeable ticking noise (what I always thought was valvetrain noise due to the Torquer v3 cam & dual springs) and the car surged very little at lower rpm's. With the TR6 plugs gapped at .045, the difference was very noticeable. The noticeable ticking noise is gone, completely. I mean with the engine running I had to concentrate to hear any ticking from the valvetrain. And the best part, there is no more bucking at lower rpm's. In lower gears I had to get rpm's down near 1k or under to get any bucking out of it. I'm surprised at the difference it made.

I wonder how good the TR6 plugs would be on a cammed LS3. I am thinking the colder plug would be better in the Arizona heat.

Wonder if the ticking you heard was a loose plug allowing compression to escape the cylinder, or arching of some sort, or even a cracked/hairline defect in a plug causing a low rpm misfire; any of which could also cause the bucking. I've never had issues like that with TR55s, even with modified internals and more aggressive tuning than stock.

Wonder if the ticking you heard was a loose plug allowing compression to escape the cylinder, or arching of some sort, or even a cracked/hairline defect in a plug causing a low rpm misfire; any of which could also cause the bucking. I've never had issues like that with TR55s, even with modified internals and more aggressive tuning than stock.

Idk RPM. None of the TR55 plugs were definitely not loose at all. I inspected all 8 plugs when I removed them, just habit on my part. Brandon, tuner & owner at Fast Motorsports, told me he recommends TR6 plugs w/ .045 gap for my application, now I know why. Also not long ago I coincidently came across a thread (either here on tech or on Corvette Forums) about some fellow who had a very similar set-up as mine and he also experienced a little surging/bucking. His thread mentioned when he changed TR55 plugs with TR6's, his surging pretty much completely went bye-bye.

If you ask me, it only makes sense the TR6 plugs are the better plug in my case. Concidering my engine has nearly a full point bump in compression and nearly 150hp over stock. I can't say TR6 plugs are always going to be better then TR55's, but this time in my case the TR6's definitely helped my car run better.

Idk RPM. None of the TR55 plugs were definitely not loose at all. I inspected all 8 plugs when I removed them, just habit on my part. Brandon, tuner & owner at Fast Motorsports, told me he recommends TR6 plugs w/ .45 gap for my application, now I know why. Also not long ago I coincidently came across a thread (either here on tech or on Corvette Forums) about some fellow who had a very similar set-up as mine and he also experienced a little surging/bucking. His thread mentioned when he changed TR55 plugs with TR6's, his surging pretty much completely went bye-bye.

If you ask me, it only makes sense the TR6 plugs are the better plug in my case. Concidering my engine has nearly a full point bump in compression and nearly 150hp over stock. I can't say TR6 plugs are always going to be better then TR55's, but this time in my case the TR6's definitely helped my car run better.

It sounds like you did a pretty comprehensive check of the old plugs to rule out looseness or damage issues, so it seems that TR6s really are the right plug for this application. Glad to hear that it worked for you. :cheers:

So would these plugs help a stock ls1 with bucking issues at lower rpm? Or would it depend on mods.

So would these plugs help a stock ls1 with bucking issues at lower rpm? Or would it depend on mods.

I can't see any reason why a stock, NA LS1 would need a colder heat range and smaller gapped plug. The OP has higher compression and is making much more power than stock, so this is not a comparable situation IMO.

If there is anything wrong with your plugs, then stock heat range replacements should cure the issue for a stock engine. If not, then your problem likely lies elsewhere.

Alright thanks. I'll have to do those when I install my headers and poly MM.

Newb question: I just ordered an NGK kit for my stock LS1. Was there a different brand that could have been better (or made a difference) on my stock engine?

No, NGK's are what pretty much everyone runs. I run tr-6's in mine.

So would these plugs help a stock ls1 with bucking issues at lower rpm? Or would it depend on mods.

RPM WS6 is right. Colder spark plugs are needed for either one or a combination of increased power, higher compression and tuning. So yes, it depends on mods.

Newb question: I just ordered an NGK kit for my stock LS1. Was there a different brand that could have been better (or made a difference) on my stock engine?

Certain brands being better then others is debatable. The bottom line, NGK is a very good brand spark plug that will work well as long as the correct heat range plug is used and with the proper gap.

TR6 reminds me of nitrous...?

I ran TR55's in my Z06 with the H/C setup and no issues. It was very quiet and no drivability issues. The only reason why I switched over to the TR6's was because I added a nitrous setup to the car.