Spark plug selection for high compression 5.7 stroker

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RockinRobin

RockinRobin

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I'm getting close enough to having my Gen III Hemi 5.7 based 414 stroker done to think about getting spark plugs. I've been told to go 3 numbers colder than stock.
The motor is 12:1 compression and will run a carburetor on 110 race gas.
I don't want to spend the money on Brisk plugs, at least not at first. Any recommendations on brands and numbers??
Thanks!
 
Copied and pasted from Lxforums. Can't speak to the accuracy, though it looks right.

NGK-5306 (stock heat range) Heat range 4
NGK-4306 (1 Step) Heat range 5 (up to 150)
NGK-2315 ( 2 Step) Heat Range 6 (150-200)
NGK-6510 (3 Step) Heat Range 7 (200+)

6.1 Hemi
NGK-4306 Copper Stock Heat Range 5
NGK-2315 (1 Step) Colder Heat Range 6
NGK-6510 (2 Step) colder Heat Range 7

http://www.lxforums.com/board/f287/nitrous-spark-plug-help-guide-340694/

I've got 2315's in my 11.6:1 forged 5.7. $109 shipped from Rock Auto. I'm sure you could get a similar deal on the 6510's, which are 3 steps colder for a 5.7.
 
Uhcoog1 said:
Copied and pasted from Lxforums. Can't speak to the accuracy, though it looks right.

NGK-5306 (stock heat range) Heat range 4
NGK-4306 (1 Step) Heat range 5 (up to 150)
NGK-2315 ( 2 Step) Heat Range 6 (150-200)
NGK-6510 (3 Step) Heat Range 7 (200+)

6.1 Hemi
NGK-4306 Copper Stock Heat Range 5
NGK-2315 (1 Step) Colder Heat Range 6
NGK-6510 (2 Step) colder Heat Range 7

http://www.lxforums.com/board/f287/nitrous-spark-plug-help-guide-340694/

I've got 2315's in my 11.6:1 forged 5.7. $109 shipped from Rock Auto. I'm sure you could get a similar deal on the 6510's, which are 3 steps colder for a 5.7.
Click to expand...

Thanks, I'll look into it this week!
 
Uhcoog1 said:
Copied and pasted from Lxforums. Can't speak to the accuracy, though it looks right.

NGK-5306 (stock heat range) Heat range 4
NGK-4306 (1 Step) Heat range 5 (up to 150)
NGK-2315 ( 2 Step) Heat Range 6 (150-200)
NGK-6510 (3 Step) Heat Range 7 (200+)

6.1 Hemi
NGK-4306 Copper Stock Heat Range 5
NGK-2315 (1 Step) Colder Heat Range 6
NGK-6510 (2 Step) colder Heat Range 7

http://www.lxforums.com/board/f287/nitrous-spark-plug-help-guide-340694/

I've got 2315's in my 11.6:1 forged 5.7. $109 shipped from Rock Auto. I'm sure you could get a similar deal on the 6510's, which are 3 steps colder for a 5.7.
Click to expand...

Checked into plugs today. It seems that the motor's compression ratio is too high to get reasonably priced plugs. NGK said I need heat range 8, and they only make those in $100 a piece racing plugs, so will be going with the Brisk plugs. ER12S is what they recommend, they also have ER10S that is a heat range colder than 12S, but they said they might foul if they are too cold. We'll see.....
 
Alright, so I needed to re-visit my spark plug selection now that I'm putting nitrous on the car...

I spoke with 3 groups, Nitrous Outlet, NGK, and Brisk:

Nitrous Outlet suggested the RR14S for my power level (415 rwhp on mustang) plus a 150 shot. RR12S for anything above a 150 shot.

NGK said they don't have a plug for me for 150-250 hp nitrous shot. He said my N/A power and compression is at the upper end of what the 2315 is good for.

Brisk said the RR14S for my power plus 125 shot. And a RR12S for my power level plus a 250 shot. I asked if I would foul the plugs, and he said it was possible in a daily driver, but as long as you run it hard fairly often you're fine. Shoot, I'm at full throttle as soon as the oil temps are up every time I drive, so he said I'd be perfectly fine.

ALSO- a search on LX forums showed that a number of guys run the RR12S daily without fouling problems.

** I have the old style 03-08 5.7 heads. What heads do you have RockinRobin? Your part numbers are different
 
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