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Discussion Starter · #1 ·
We have been getting some calls about this lately asking what spark plugs we are using in the supercharger kits and what we recommend. Since 2007 we have been using the NGK LTR6ix-11 plugs in all of the forced induction 2.4L Ecotec forced induction kits we have sold, supercharger and turbo. These plugs hold up really well to boosted cylinder temps and we have several customers that have gone over 100K miles on the plugs boosted. They come pre-gapped at 1.1mm (around .043") and that gap works well with most boosted applications under 12psi, above that boost we usually have to close the gap down to around .035".

We sell the sets for $40 -

Slingshot Turbo / Supercharger NGK Spark plugs

If you look around though they can be found for a little less on Amazon, etc.

If you have a turbo kit and did not replace the spark plugs, these will give you a little more protection from knock with the 1 step cooler heat range. Usually the recommendation is that for every 75-100hp you add you should go one step colder on the heat range of the spark plugs.

Hope that helps and let us know if you have any questions about them.
Dave
 

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Thanks for the hint. Have you tried the Brisk plug equivalent? Looks interesting but unsure about it being snake oil...
 

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Dave, I haven't tried them yet, but after speaking extensively with an NGK engineer, it was his opinion that if we're running less than 10 pounds of boost, he would recommend using that plug as a second choice. His first choice would be the LTR6BI-9 (stock # 92182). The point that both he and I agreed upon is that these plugs come out of the box gapped to .036 and should be used that way. Taking the LTR6ix-11 which is designed to have a .044 gap, would not be optimal if the gap had to be tighten down as the ground electrode to center electrode angle would not be proper. Have you tried these in the 2.4 ecotec before and if so what were your experiences with them?

Thank you
 

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Discussion Starter · #4 ·
Thanks for the hint. Have you tried the Brisk plug equivalent? Looks interesting but unsure about it being snake oil...
We have not ran the Brisk plugs on the Ecotec, all of our experience with those come from the MINI cooper world. Over there, some people swear by them, others have had issues with them, kinda a mixed bag. We did test a bunch of spark plugs on the dyno with the MINI back several years ago and none of them made more power than the others, when comparing to new sets installed and ran. MINI's are also really rough on plugs though, so the stock plugs can get ate up in a short time if ran hard, and once a plug is starting to misfire because of gap wear, then of course putting any new plug in will make it run more smoothly, gain power, etc at that point. That is what we have seen over there numerous times, customers with old original plugs putting new "X" brand plugs in and swearing they are so much better than the old 100K miles plugs that they pulled out.

We will get a set of the Brisk plugs though and test them here on the dyno for power difference vs stock ones, it would be pretty easy to do. Also we can put some other plugs into the test that we have ran and post up the dyno graphs to see if there is any power difference. With the Solstice/Sky we can monitor misfires at idle also, but I do not think we can do that with the Mefi software from Bob, I will talk with him though and see if there is a way to record that info also, since power and misfires are going to be the 2 main indicators we would check. Probably will not happen before SSITS though as we are starting to get everything ready for that, but it would be interesting to see how the Ecotec responds to the Brisk and other plugs.

We will post it up once we do it.
Hope that helps,
Dave
 

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Discussion Starter · #5 ·
Dave, I haven't tried them yet, but after speaking extensively with an NGK engineer, it was his opinion that if we're running less than 10 pounds of boost, he would recommend using that plug as a second choice. His first choice would be the LTR6BI-9 (stock # 92182). The point that both he and I agreed upon is that these plugs come out of the box gapped to .036 and should be used that way. Taking the LTR6ix-11 which is designed to have a .044 gap, would not be optimal if the gap had to be tighten down as the ground electrode to center electrode angle would not be proper. Have you tried these in the 2.4 ecotec before and if so what were your experiences with them?

Thank you
We have not ran the LTR6BI-9's on the Ecotec, since the LTR6ix-11's work for almost all of the installs we do with the supercharger/turbo setups we run. It is very rare that we have to close down the gap on the -11's and the larger gap is better at preventing them from fouling out, better idle quality and also closer to the stock gap. If we had to close the -11's down a lot the -9's would be the better option though. The -11's have gotten us above 300hp at the wheels on the Solstice without touching the gap and 280hp at the wheel on the Slingshot so far without touching the gap also, we should know pretty soon, but it looks like over 300hp on the Slingshot will be fine with that gap also. At those power levels we are about 150hp over the stock power and really another heat range colder is going to start to have an advantage also.

What did you put in with you HAHN kit?
 

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Bill recommends running the NGK 4306 only, with a tighter gap. Thus my concerns of using a plug designed to have a wide gap being tightened down and no longer having a 90 degree ground electrode to center electrode interface. I was holding off on going to the -11 plugs until my ecu comes back from Bob. I'll know more before SSITS though

hope you meet you there and check out your SC ride
 

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Discussion Starter · #7 ·
The 4306 come gapped at 1.3mm from my understanding and are stock heat range (5), is that what you are running just re-gapped? What boost pressure and gap are you running? I would run what Bill told you, just can not figure out why it would be a stock heat range plug on a forced induction 2.4L that has a larger gap than stock, but I am sure he has his reasons.

All of us here are really looking forward to the SSITS this year, we were not able to make it up there last year since it conflicted with another event, but it will be really nice to put some names and faces together this year and see all the rides, sounds like it is going to be really big this year!
 

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The 4306 come gapped at 1.3mm from my understanding and are stock heat range (5), is that what you are running just re-gapped? What boost pressure and gap are you running? I would run what Bill told you, just can not figure out why it would be a stock heat range plug on a forced induction 2.4L that has a larger gap than stock, but I am sure he has his reasons.

All of us here are really looking forward to the SSITS this year, we were not able to make it up there last year since it conflicted with another event, but it will be really nice to put some names and faces together this year and see all the rides, sounds like it is going to be really big this year!
It is at least gapped at 1.1 out of the box (.043) if not larger, and he wants to get away from the iridium plugs and use the 4306. I guess he has more faith in the copper plugs in this engine. That's what I've been using for over 15K miles, but after doing my research, will be making a change. I've gone down a tad in boost to 7 PSI from 8.5 and really don't see any difference until speeds over 80 or so when you can get full use of the extra power. To me it's a small trade off to have a little extra margin of safety and a little less chance of being accepted into the Kenny_H club of super speeders.
 

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Discussion Starter · #9 ·
With the built engines we have been installing recently we have been able to do some more testing with other forced induction kits. @MACAWS Slingshot came in with the HAHN turbo kit on it and as most are aware @rabtech also has a HAHN turbo kit installed on his built DDMWorks engine. While we are installing and testing @MACAWS engine on the dyno we saw some slight differences with the air/fuel ratio on the wideband compared to @rabtech and wanted to look into it further. Both of the builds were almost identical, except for the spark plugs that were being used in the engines. @rabtech was using the stock spark plug that ships with the HAHN kit which is a LZTR5A-13 and @MACAWS we installed the spark plugs that we use on all of our forced induction kits - LTR6ix-11. The LZTR5A-13 is a nickel plated, stock heat range of 5, 1.3mm gap spark plug. The LTR6ix-11 is a iridium tipped, 1 step cooler plug (heat range 6) with a 1.1mm gap. Both plugs use a copper core.



So what we wanted to know is if there would be any difference in the power produced on the dyno and if air/fuels would change with the different plugs, here is the dyno -









On the dyno, there are 2 lines, a orange one and a green one. They are both on the same vehicle with exactly the same setup, just different spark plugs. We installed the spark plugs as they were delivered in the package at the stock gaps, we did not change anything on these plugs, just installed them. The graph shows that the power is very consistent between both spark plugs at this power level between the 2 different spark plugs, the lines almost overlap. We were also monitoring air/fuel ratio's during the run and they were also almost identical, with the HAHN plugs being just a tick richer on all the pulls, around .1-.2 difference on the air fuels. We are hoping to have another test session with a turbo setup soon and will try some more plugs out on that setup hopefully to see how the power and air/fuels perform on that setup also.



Hope that helps,

Dave
 
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