Spark gap vs BOOST ?
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From: Alaska
Spark gap vs BOOST ? Newb question(s):
In LOW boost, pump gas applications I have had no problem with TR6 plugs gapped.035" up to 180kPa.
At what point, as I turn up Boost PRESSURE will I need to shrink my spark plug gap?
Is water/methanol injection also a factor in maximum usable spark gap ?
At what point will I need to consider going to a BR7EF heat range ?
In LOW boost, pump gas applications I have had no problem with TR6 plugs gapped.035" up to 180kPa.
At what point, as I turn up Boost PRESSURE will I need to shrink my spark plug gap?
Is water/methanol injection also a factor in maximum usable spark gap ?
At what point will I need to consider going to a BR7EF heat range ?
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Ran tr6s up to 12 lbs , about where you are at now then switched to br7s to be safe. Now at 15.5 lbs with br7s at .024 , recently put in a new set after about 25k miles and the gap on the old ones grew to .034 , still ran fine as far as I could tell but haven't gotten back to the track to see if the larger gap was hurting it .
Thread Starter
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From: Alaska
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My Belt drive magnuson makes 11 PSI on 4.8 Liter
VSR 78/75 goes 12 PSI into 5.3 Liter. Both using TR6 so far, but the Turbo tune really HATES 90 octane pump gasoline. Had to take spark back to 6 degrees advance in the 4000- 4400 rpm torque peak area, back out to 11 degrees at higher rpm. Working on install of water+Methanol now- MAY be time to give a colder spark plug a try tho.
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Hopeful that I can run up to 15 PSI with Methanol PLUS shitty nominal 90 Octane pump gas. IF you guys think BR7ef will help at that level, I will dmn sure give 'em a shot.
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My Belt drive magnuson makes 11 PSI on 4.8 Liter
VSR 78/75 goes 12 PSI into 5.3 Liter. Both using TR6 so far, but the Turbo tune really HATES 90 octane pump gasoline. Had to take spark back to 6 degrees advance in the 4000- 4400 rpm torque peak area, back out to 11 degrees at higher rpm. Working on install of water+Methanol now- MAY be time to give a colder spark plug a try tho.
.
Hopeful that I can run up to 15 PSI with Methanol PLUS shitty nominal 90 Octane pump gas. IF you guys think BR7ef will help at that level, I will dmn sure give 'em a shot.
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I switched from TR6 to a BR7 above 18-ish psi. 0.035 gapped on both.
The TR6 worked fine, but I was concerned about them contributing to pre-ignition type events if things weren't running as well as I wanted. So, I switched to the BR7. I didn't really notice any change in drivability, etc... so I think it is just a better plug to use for most boosted applications. I run a 0.035 gap out of the box on the BR7 plug with a D580 ignition coil which isn't as strong as the D510C (or equivalent) that most folks run today. I've run this up to 24 psi without any ignition issues.
The TR6 worked fine, but I was concerned about them contributing to pre-ignition type events if things weren't running as well as I wanted. So, I switched to the BR7. I didn't really notice any change in drivability, etc... so I think it is just a better plug to use for most boosted applications. I run a 0.035 gap out of the box on the BR7 plug with a D580 ignition coil which isn't as strong as the D510C (or equivalent) that most folks run today. I've run this up to 24 psi without any ignition issues.
Last edited by NoGo; Jul 9, 2025 at 01:51 PM. Reason: Fat fingered 510C
I switched from TR6 to a BR7 above 18-ish psi. 0.035 gapped on both.
The TR6 worked fine, but I was concerned about them contributing to pre-ignition type events if things weren't running as well as I wanted. So, I switched to the BR7. I didn't really notice any change in drivability, etc... so I think it is just a better plug to use for most boosted applications. I run a 0.035 gap out of the box on the BR7 plug with a D580 ignition coil which isn't as strong as the D150C (or equivalent) that most folks run today. I've run this up to 24 psi without any ignition issues.
The TR6 worked fine, but I was concerned about them contributing to pre-ignition type events if things weren't running as well as I wanted. So, I switched to the BR7. I didn't really notice any change in drivability, etc... so I think it is just a better plug to use for most boosted applications. I run a 0.035 gap out of the box on the BR7 plug with a D580 ignition coil which isn't as strong as the D150C (or equivalent) that most folks run today. I've run this up to 24 psi without any ignition issues.
I'm running the D585 truck coils at the moment, they seem to be working fine but have been toying with the idea of stepping up to a more powerful coil.
Are the connectors all the same you think?
Yes 510C. I fat fingered it. Will fix.
I think your fine with the D585. If you do want to swap to the D510C you'll need to change the connector at coil or change the harness from the coil pack plug to the coil (ie "LS3 coil pack harness" and a bunch of stuff will pop up). You'll also have to figure out a bolting scheme to get them onto your valve covers - different bolt spacing on the D510C's vs the older coils.
If you are ****, you can adjust the dwell vs. the D585. The D510C has a pretty quick dwell recovery and doesn't require as much. On my personal car and friends that I tune, I just leave the dwell alone - but if you are particular about it, I would transpose the LS3 coil dwell tables but leave the dwell multiplier tables alone.
Lastly, the D510 coils do slide a little more towards the headers - probably not an issue on most setups, but if you are one of those turbo setups where your plug wires *barely* don't touch you may have to shorten the wires a smidge.
I'm actually swapping to D510C's this summer. Sourcing OEM D580/D585 is hard and they are pretty old now - I prefer the OEM stuff vs. aftermarket coils. Also, the valve cover bolting pattern is a pain in my *** with the older coils - no one makes a higher clearance valve cover with the old spacing.
Coil guide for folks that haven't seen it:
I think your fine with the D585. If you do want to swap to the D510C you'll need to change the connector at coil or change the harness from the coil pack plug to the coil (ie "LS3 coil pack harness" and a bunch of stuff will pop up). You'll also have to figure out a bolting scheme to get them onto your valve covers - different bolt spacing on the D510C's vs the older coils.
If you are ****, you can adjust the dwell vs. the D585. The D510C has a pretty quick dwell recovery and doesn't require as much. On my personal car and friends that I tune, I just leave the dwell alone - but if you are particular about it, I would transpose the LS3 coil dwell tables but leave the dwell multiplier tables alone.
Lastly, the D510 coils do slide a little more towards the headers - probably not an issue on most setups, but if you are one of those turbo setups where your plug wires *barely* don't touch you may have to shorten the wires a smidge.
I'm actually swapping to D510C's this summer. Sourcing OEM D580/D585 is hard and they are pretty old now - I prefer the OEM stuff vs. aftermarket coils. Also, the valve cover bolting pattern is a pain in my *** with the older coils - no one makes a higher clearance valve cover with the old spacing.
Coil guide for folks that haven't seen it:
Last edited by NoGo; Jul 9, 2025 at 02:52 PM.
Thread Starter
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From: Alaska
Let's drift the thread a little further:
Will a COLD plug , ie BR7ef allow MORE Spark Advance than a TR6 run on the edge of KR ?
ie, specific example of my Turb0-Pig 5.3 Suburban:
my "advertised" 90 Octane pump gasoline puts me into KR in the 4000-4400 rpm torque peak zone, I can avoid Knock ( mostly) at 6 degrees spark advance in that area, running back up to 11 degrees above 4800 rpm.... Is it "Likely" that I'd get a couple more degrees advance out of a heat range 7 plug ?
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I have just installed Methanol spray last night, 6 gallons per minute nozzle is underzied., ( Brings AFR down by about 0.8 ) ordered a 10 GPH nozzle should be here around next week. Goal is to be able to safely run 15 PSI on our shitty local gasoline, and start ( progressive control ) spraying 70% Methanol around 8PSI.
Will a COLD plug , ie BR7ef allow MORE Spark Advance than a TR6 run on the edge of KR ?
ie, specific example of my Turb0-Pig 5.3 Suburban:
my "advertised" 90 Octane pump gasoline puts me into KR in the 4000-4400 rpm torque peak zone, I can avoid Knock ( mostly) at 6 degrees spark advance in that area, running back up to 11 degrees above 4800 rpm.... Is it "Likely" that I'd get a couple more degrees advance out of a heat range 7 plug ?
.
I have just installed Methanol spray last night, 6 gallons per minute nozzle is underzied., ( Brings AFR down by about 0.8 ) ordered a 10 GPH nozzle should be here around next week. Goal is to be able to safely run 15 PSI on our shitty local gasoline, and start ( progressive control ) spraying 70% Methanol around 8PSI.
Last edited by Full Power; Jul 18, 2025 at 03:35 PM. Reason: clarity
Thread Starter
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From: Alaska
Another COLD plug question for the gang:
Anybody have trouble with BR7ef spark plugs daily driver service in WINTER ?
ie Cold starts, long-ish idle periods while waiting for De-Froster ?
Typical start-up + warm-up in Alaska: Go out start engine, shovel snow off hood, roof, and around vehicle for 10 minutes, go back inside and get wife moving, load up dog, load empty fuel jugs, water jugs, other crap needs hauling to town... finally get moving up the driveway after 18- 20 minutes. And than we follow a bunch of SLOW-Pokes driving 35 miles per hour for 20 more minutes...
Ya think I will carbon up BR7ef under such conditions ? ?
Anybody have trouble with BR7ef spark plugs daily driver service in WINTER ?
ie Cold starts, long-ish idle periods while waiting for De-Froster ?
Typical start-up + warm-up in Alaska: Go out start engine, shovel snow off hood, roof, and around vehicle for 10 minutes, go back inside and get wife moving, load up dog, load empty fuel jugs, water jugs, other crap needs hauling to town... finally get moving up the driveway after 18- 20 minutes. And than we follow a bunch of SLOW-Pokes driving 35 miles per hour for 20 more minutes...
Ya think I will carbon up BR7ef under such conditions ? ?
I don't think so. Been running the BR7 plugs for a few years now. I don't drive in as cold as conditions as that (I usually call it quits in the low 40's, maybe touching 30's in spring and fall). I do let the car idle for a pretty long time (5/10 min) before taking it out all the time because I prefer it warmed up before heading out. I also run a/f a little richer because I think it makes the car drive nicer - usually around a 13.5.
So, in conclusion, 5+ min of idling every time out, richer a/f than normal, and 40-ish weather, the plugs look fine. Also, the cold fall weather is usually the last driving condition before the car goes under the knife in the winter (for whatever I can come up with) and I have not noticed the plugs having any abnormal fouling. Not exactly the same as you, but possibly a good proxy data point.
So, in conclusion, 5+ min of idling every time out, richer a/f than normal, and 40-ish weather, the plugs look fine. Also, the cold fall weather is usually the last driving condition before the car goes under the knife in the winter (for whatever I can come up with) and I have not noticed the plugs having any abnormal fouling. Not exactly the same as you, but possibly a good proxy data point.
Feel like you are looking at it wrong. The only thing a colder plug does is run cooler. It doesn’t make more or less spark energy. It just runs at a cooler temperature and dissipates heat more quickly.
So if you are currently melting plugs or detonating due to the “glow plug effect” caused by running too hot of a plug.... then yes. A colder plug will allow you more timing on the same tune.
Couple issues I see here.
#1) You are running the incorrect plug design. U shouldn’t ever run an extended tip plug (tr6) in a turbo application. It’s just asking for trouble as the plug is too far into the CC and retains more heat than is ideal. It will also read “hot”. That doesn’t mean guys that run a TR6 will instantly melt down a motor either. It just means you get a hotter running plug than is ideal and won't be able to correctly read the plug for timing adjustments.
#2) You are going about this backwards heat range wise. You start with a cold plug. Get a read, and then move hotter if you are fouling the plug. Starting with a hot plug of the wrong design is a recipe is asking for trouble.
#3) Run the correct recessed BR7 plug with your conservative tune. Make a full 1/4 pull with as little run time as possible, and then shut the motor off immediately at the end of the ¼. Pull the plugs and read the heat line on the ground strap. THAT is the only thing that will tell you if you can add or pull timing.
So if you are currently melting plugs or detonating due to the “glow plug effect” caused by running too hot of a plug.... then yes. A colder plug will allow you more timing on the same tune.
Couple issues I see here.
#1) You are running the incorrect plug design. U shouldn’t ever run an extended tip plug (tr6) in a turbo application. It’s just asking for trouble as the plug is too far into the CC and retains more heat than is ideal. It will also read “hot”. That doesn’t mean guys that run a TR6 will instantly melt down a motor either. It just means you get a hotter running plug than is ideal and won't be able to correctly read the plug for timing adjustments.
#2) You are going about this backwards heat range wise. You start with a cold plug. Get a read, and then move hotter if you are fouling the plug. Starting with a hot plug of the wrong design is a recipe is asking for trouble.
#3) Run the correct recessed BR7 plug with your conservative tune. Make a full 1/4 pull with as little run time as possible, and then shut the motor off immediately at the end of the ¼. Pull the plugs and read the heat line on the ground strap. THAT is the only thing that will tell you if you can add or pull timing.
This thread just reminded me of some jackass youtube vid I recently ran across where the guy claimed you should start with a 10 heat range ngk on an ls motor with 8lbs of boost, lol. I only changed from a 6 to a 7 when I went over 10lbs, and that was just because I wasn't sure how much more boost I planned to run.
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From: Alaska
Maybe the YouTube motor surgeon mistook the NGK Iridium spark plug "X" term to be a roman numeral heat range 10 ?
What motor uses heat range 10? Have to be 14:1 compression natural gas motor?
What motor uses heat range 10? Have to be 14:1 compression natural gas motor?
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Nitrous engines mostly. I ran a TR7IX on my 14.5 compression NA engine. It was pretty snappy with that plug in it. When I switched to 10s for the nitrous, it really calmed it down.