NGK TR6 (4177), BR6EF (3177), BR7EF (3346) users?

MNwe4

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Sep 29, 2008
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Minneapolis, MN
Any of you guys ever use these with E85 and what are your thoughts? I've been using the originally recommended Autolite 103's with my GN1 heads for years. They seem to be working ok, but would like to try a NGK. Compression is 8.5:1, boost is limited to 21 psi due to fueling, timing is 23* and maybe would go up. Car is 90% street, but looking at hitting the track next weekend. The TR6 seems to be pretty popular over the internet, but the recessed tip of the BR6 or 7 EF seems like a good choice for the track. How about the street?
 

MNwe4

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Sep 29, 2008
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Minneapolis, MN
I use NGK 5238 for strip and street w/TA alum heads.

A colder version is NGK 5820.

Also, my WOT timing is 19 degrees running high 9's.
Thanks for the info. Looks like that plug is a heat range 9. Good to know that it doesn't foul quickly on the street. I've never ran a non projected tip plug so I wasn't sure if they'd last long idling and cruising around. Maybe E85 is more forgiving? I'm also on a stock ECM so I have to stick with resistor plugs, but any advice is helpful since I can just look for the same plug with a resistor.
 

20psiofevil

Active Member
Feb 10, 2013
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Tr6 is a good plug but the gap opens up over time. Every single one I've installed in my car have done this. I switched to the br7ef when I added nitrous to the car and they work great. I've had no misfire issues to speak of. I did foul one while on the dyno last winter though when the car went pig rich.
 

MNwe4

Member
Sep 29, 2008
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Minneapolis, MN
Thanks for the reply. I went to the parts store last night and compared a few. Ended up buying the BR7EF (3346). See attached pic. Left to Right - NGK BR7EF, NGK TR6, Autolite 103. From seeing this doesn't it appear that the TR6 is hotter than the 103? I've never had any issues with driveability on gas or E85 with the 103's, so I definitely didn't want to go hotter. Wish they had a TR7 (if that exists) for comparison purposes. Regardless, with the 7 heat range and the recessed tip I should have a little more safety margin. As an extra bonus they all came pre-gapped at a tight .028 according to the feeler gauge.

plugs.jpg
 

Ttype6

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Aug 17, 2004
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Looks like that plug is a heat range 9. Good to know that it doesn't foul quickly on the street.
I don't think this plug would handle too much idling and low speed driving on the street in Minnesota. Nick lives about a mile from the sun. A cold spark plug doesn't foul suddenly. The electrode is relatively cold so it won't do a good job of burning the crap that will build up on the tip,so it builds up more and more. The first sign that this is happening will be some misfires/stumbling while the engine is idling at a stop sign. You'll notice this at this time because everything in the combustion chamber is the coolest at this time. All that is necessary to burn the crap off of the plug tips is to heat them up to a temperature that will accomplish this. If you pay attention,you will notice the misfiring at an idle. When you do,give it a full throttle blast or two. If it idles like a dream at the next stop light you will have the proof that you need. If you do notice the misfiring after alot of low speed driving and idling,you can consider it a good sign that you have a good plug for racing. This is what I notice with my BCR8ES plugs here in Michigan. Heat range 8,non projected tip,cut back ground strap.
 
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MNwe4

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Sep 29, 2008
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Minneapolis, MN
Good suggestion there TType6. I went with the 7 heat range, non-projected tip, gapped at .028". Sounds from what you're saying it should drive around in the northern climate reasonably well. As mentioned the Autolite 103 has done me good for years, but I wanted to try a non-projected NGK in case I decide to up the timing a bit more. NGK specifically told me that the 103 crosses over to their TR6, but from the picture you can see it protrudes a bit more. Not that it wouldn't work fine, but was in the opposite direction I'm looking to go. I have read a lot of you guys liking the BCR8ES, but those need to come from special vendors, correct?

The car always fires instantly and idles as smooth as expected. I'll keep my eye on how it does with the new plugs. It's looking like I may be installing the plugs Friday night and then driving 1.5 hours to the track on Saturday, making a few passes, and driving home. We'll see how it goes. I'll keep some 103's as a back up, haha.
 
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Ttype6

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Aug 17, 2004
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Good suggestion there TType6. I went with the 7 heat range, non-projected tip, gapped at .028". Sounds from what you're saying it should drive around in the northern climate reasonably well. As mentioned the Autolite 103 has done me good for years, but I wanted to try a non-projected NGK in case I decide to up the timing a bit more. NGK specifically told me that the 103 crosses over to their TR6, but from the picture you can see it protrudes a bit more. Not that it wouldn't work fine, but was in the opposite direction I'm looking to go. I have read a lot of you guys liking the BCR8ES, but those need to come from special vendors, correct?

The car always fires instantly and idles as smooth as expected. I'll keep my eye on how it does with the new plugs. It's looking like I may be installing the plugs Friday night and then driving 1.5 hours to the track on Saturday, making a few passes, and driving home. We'll see how it goes. I'll keep some 103's as a back up, haha.
l wouldn't focus so much on projected verses non. The more important thing is keeping the tip temps cool to avoid pre ignition. I wouldn't focus too much on advancing timing. Advancing the timing speeds up the flame front. It's a bad idea to speed it up if it doesn't need to be. Your plugs will tell you if your timing is good. If your ground straps are clean from the tips to the curved part of the strap,your timing is good. If the straps are clean from the tips to where they are welded on,your timing is advanced too much and needs to be retarded. As you increase boost,the flame front will speed up and the line on the straps will move toward the welded end. Start with low timing and make your objective more boost while keeping an eye on your ground straps. Let your heads cool as much as possible before removing spark plugs. Aluminum gets softer with heat faster than iron.
 
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Nick Micale

Tech Advisor
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May 26, 2001
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Nick,what compression ratio and boost are you running with the 19 degrees?
The compression is 9.5:1, and boost is 18-20 psi to run 9.80 and the "normal" track DA is about 3500.

The turbo is HPQ-70 with a ,69 exhaust housing which spools extremely fast, maybe the 4500 stall 8" converter helps a lot when launching!!
 

MNwe4

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Sep 29, 2008
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l wouldn't focus so much on projected verses non. The more important thing is keeping the tip temps cool to avoid pre ignition. I wouldn't focus too much on advancing timing. Advancing the timing speeds up the flame front. It's a bad idea to speed it up if it doesn't need to be. Your plugs will tell you if your timing is good. If your ground straps are clean from the tips to the curved part of the strap,your timing is good. If the straps are clean from the tips to where they are welded on,your timing is advanced too much and needs to be retarded. As you increase boost,the flame front will speed up and the line on the straps will move toward the welded end. Start with low timing and make your objective more boost while keeping an eye on your ground straps. Let your heads cool as much as possible before removing spark plugs. Aluminum gets softer with heat faster than iron.
Thanks for the good explanation. I agree keeping timing low and increasing boost is a better way to go, but unfortunately I'm limited to 21 psi due to my 80lb injectors and walbro 430 fuel pump. I was hitting 100% DC at the track last year and that's with a base FP of 50 psi. I won't go too crazy on timing. The car doesn't "need" to be any faster I guess.
 

MNwe4

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Pulled my existing plugs last night which turned out to be Autolite 3923's, not 103's. Cylinders 1-6, left to right. Forgot I put those in before the track last year. They're the same, but with gaskets. Thought I'd share for anyone who wants to move away from the tapered seat style. The condition of these is racing/cruising on E85 last fall, cruising and a few pulls this year on gas, then a cruise or two on E85 again just now before removal. They look ok, yea? Question, can gasketed plugs be reused???

IMG_20170815_201001679.jpg
 

turbo nasty

Turbo Dojo / MNTR
Jul 19, 2001
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Cant read plugs accurately after being driven that much. The plugs could be perfect and the next start up from cold and your tune could be a bit rich on cold start and that condition puts a slight fuel foul on plugs and then that doesnt burn off and skews reading. Best way...at track fresh plugs...make pass...shut off at big end..coast to return road...pull plugs and read them. FWIW on flame speed Optimal timing is based on the AFR/fuels burn speed. Dont look at timing itself affecting the flame front speed rather look at timing as starting the combustion event based on the fuel your using burn rate which is going to burn at a set speed based on its chemical make up. Timing......... the start of the combustion event cycle based or your fuel and compression so that peak cylinder psi happens at the proper place in pistons movement to get max benefit from the combustion process. Too early timing to burn rate for the fuel and peak cylinder psi happens at wrong timing...bad. Happens too late for fuels burn time and...bad. Timing is a bed partner to flame but AFR and compression are the two components that are looked at for flame speed.
 
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Paul69camaro

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Mar 24, 2009
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Thanks for the good explanation. I agree keeping timing low and increasing boost is a better way to go, but unfortunately I'm limited to 21 psi due to my 80lb injectors and walbro 430 fuel pump. I was hitting 100% DC at the track last year and that's with a base FP of 50 psi. I won't go too crazy on timing. The car doesn't "need" to be any faster I guess.
I hit the limit of the walbro 430 at about 22-23 psi on my 249 CI (9:1) motor with 160 lb injectors. I added a Kenne Bell boost a pump and have gone as high as 28 psi with now issues. My base fuel pressure is set at 35 psi...


On the spark plug topic, I have been running the BR7EF plugs for about 8-9 months now on a street driven car. I have them gapped down to .022 since I was having spark blow out issues. The car is set between 20-21 degrees of timing depending on ethanol content and runs 25-27 psi boost. I cruise the car a lot and have not had a single issue with these plugs. I'd recommend them to anyone.
 

MNwe4

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Sep 29, 2008
428
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Minneapolis, MN
I hit the limit of the walbro 430 at about 22-23 psi on my 249 CI (9:1) motor with 160 lb injectors. I added a Kenne Bell boost a pump and have gone as high as 28 psi with now issues. My base fuel pressure is set at 35 psi...


On the spark plug topic, I have been running the BR7EF plugs for about 8-9 months now on a street driven car. I have them gapped down to .022 since I was having spark blow out issues. The car is set between 20-21 degrees of timing depending on ethanol content and runs 25-27 psi boost. I cruise the car a lot and have not had a single issue with these plugs. I'd recommend them to anyone.
Awesome. This gives me a little boost of confidence as I drive 2 hrs to the track tomorrow morning. Haven't fired the car yet since I installed the plugs since its been raining all week. I am using a Caspers volt booster and see 15.1v on the logger during WOT. Previous gap was .030, so these at .028 should work out. Thanks for sharing your experience. Based on how tomorrow goes I may need to take a look at some of the 1000cc high imp. injectors. They're spendy though.
 
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