SilverSmoke

I read as many posts I could from different forums, and it seems like it is still bit of a debate on which plug to use, the TR55 or TR6 with aftermarket heads with increased compression.

I'm looking at using maybe the iridiums unless someone can sway me away from them (as in not needed or will break, issues, etc). But I did read the iridiums allow more energy to pass through for better spark production.

the heads will bump compression to approx 11-11.5:1 for good DCR.

What has everyone used with good success for heat range with higher compression on aftermarket heads?

Thanks for any insight and experience!

WeathermanShawn

iTrader: (1)

Hi there:

Many will tell you the heat range of the TR-55's can be used with no issues. I have no argument against that.

I'm running about 11.1:1 CR and went with the TR-6 heat range. Colorado's highest octane gas is 91 and with the higher compression I wanted to play it safe on the plugs and mitigate any detonation.

In a 100% subjective view, the engine seems to run a little "rougher" with the colder plugs the first few minutes, but I am keeping myself out of any detonation issues.

I followed the masses and went the copper plugs. I am always curious whenever somebody tries something new or different. You can always run an iridium or any plug for a while, pull it and check it and see how its working for you.

Good luck..WeathermanShawn..

DaddySS

When you are at higher compression and using colder plugs, do you gap them the same?

davered00ss

iTrader: (4)

I used the NGK TR55IX plugs before I had my heads and liked them a lot. Their gap did seem larg when I pulled them. I run TR55's now. Also thinking about TR6's. I always thought you had to run colder pluge any time you bumped up hp.

vettenuts

iTrader: (4)

NGK recommends one heat range lower for each additional 100 hp. The TR6's are relatively inexpensive and actually a better plug because they are copper core (at least from a performance standpoint, the Iridium doesn't require replacement as often). I am running the equivalent Denso right now and plan to run the TR6's when I install my new heads in the spring. If you error on heat range, best to error on the cold side as well.

DaddySS

Any help on the gap for TR6s with 11:1 compression or do I use the standard 055?

Viper

iTrader: (6)

Try .042, they come out of the box at around .039-.040. You don't want to bend the electrode all the way to .055. I'm running .042 at 11:1

DaddySS

OK, thanks for the help.