Lesson on Plug Gap for High Boost!!

RRRR03Cobra

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After debating on whether to increase the boost or not, I decided to slightly increase the boost to about 19.5 lbs on the Whipple! :pop:So I dropped the upper pulley size to a 3.2 from a 3.5. I already have a Metco 4 lb lower. Since I wasn't able to get the car to Rick yet and get his advice on this thing, I added sum fuel and checked the A/F and MAF counts. I just wanted it to be safe until I can get it back to the shop!! I noticed in lower first gear when I would hammer it, it would sputter a little and almost misfire. So yesterday morning, I went and bought some new TR6 plugs and installed them and gapped them at .034. Just like before. I took it to a dyno yesterday and it acted the same way on the dyno. The graph looked like a sine wave off of a heart monitor!! Hmmmmm. So Matt and Rock H. asked me what the plug gap was set at. I replied .034. They both agreed with the amount of boost I was running, that it was waaay to much. So I sought out some of our respected SVTP family members and asked for their opinion. They all agreed that it should be set to .025-.029. And that .034 was waaaaay to much gap for that amount of boost! Thanx Hissman, Posi, Iron Terp, XtremeJC :beer:. So this morning, I reset the plugs to .028. I allowed the car to warm up and headed to HWY 178 for a test run. Rolling about 2500 rpms in 1st, I nailed the car and wooooooow nelly!!!! She blew the 315 M/Ts slam off!!!! :burn:When I shifted to 2nd, it smooked em again throughout the entire gear and into 3rd!!! It's like a totally different animal!!! The M/Ts hooked up decent with the 17lbs of boost. Not any more!!!! All I can say is WOW! I am blown away!! Literally!!!!!!! New numbers coming soon! Thanx SVTP family:thumbsup:
 
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Posi

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No need to thank me because I learned from the same guys you did lol. It's just now I can pass on a little info from personal experience also. And the guys I've pm'd over the years know exactly who they are!:rockon::beer::lol:

Good luck with your car and with some new numbers.:beer:
 

black 10th vert

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without forums like these, I wonder where we would all be?! Nothing like sharing experiences to broaden everyone's knowledge, which saves time, money, and makes for better cars!
 

thomas91169

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.032 for me on anything less than 15psi. on cars over 15psi, i recommend .028, especially on stock ignition systems.
 

02reaper

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I got two questions for you. First, are you one of Amazons helper posters? I see that your username is [email protected]? Second, at that boost level, don't you think the TR6's are too hot of a plug?
 

RRRR03Cobra

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I got two questions for you. First, are you one of Amazons helper posters? I see that your username is [email protected]? Second, at that boost level, don't you think the TR6's are too hot of a plug?


Yes, I try to help Linn and Rick out on the boards! He stays very bz in the shop! I will help out in the areas that I have knowledge about! I have read mixed reviews about TR6s and TR7s! I also like to get several opinions about things pertaining to these cars!! Some of the guys on here have been modding these cars from the beginning and have "Been there, done that":beer:
 

Posi

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I got two questions for you. First, are you one of Amazons helper posters? I see that your username is [email protected]? Second, at that boost level, don't you think the TR6's are too hot of a plug?


He has a good question here I think. I was told and I'll be double checking (because I can't remember) that a good plug is the NGK BR7ef's. They're copper and the ix's are iridium and the iridium has been accused of breaking off and that's not good. Per Rick @ Amazon too.

We just changed my tr7ix's and they already had a miss and they've only been in since January maybe. So I'm going to double check on the BR7ef's for sure.

I'll be double checking on the heat range also.
 

black 10th vert

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He has a good question here I think. I was told and I'll be double checking (because I can't remember) that a good plug is the NGK BR7ef's. They're copper and the ix's are iridium and the iridium has been accused of breaking off and that's not good. Per Rick @ Amazon too.

We just changed my tr7ix's and they already had a miss and they've only been in since January maybe. So I'm going to double check on the BR7ef's for sure.

I'll be double checking on the heat range also.


please update on this issue, Brian. I'm going to be doing my stage 5 with 2.93/4# very soon, and was leaning toward the TR7ix for that. The BR7's would be WAY cheaper, though, so maybe I'll go with those. I was leaning toward the irridiums because most people say they are smoother running, and last longer (which is important when you only have 3 threads!), so you don't have to mess with the threads too much!;-)
 

02reaper

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I have the br7ef's on my whippled cobra with 15psi. I haven't had any trouble with them. I had them on the car with the eaton and upper 2.8 pulley also with no problems.
 

BWH2003

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I use br7ef's as well and im running a whipple at 25 psi. I run them at .028 and everything seems fine
 

Posi

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Alright just got off the phone with Brandon @ NGK and took as many notes as I could.

The TR7ix's are iridium and the BR7ef's are copper and also they are a non projected plug. Which means they do not protrude into the combustion chamber and they also come factory with a tighter gap.

So they have less chance of actually overheating and less chance of spark blowout because it's non projected which is good for a high boost app. He also said they are a good plug for Nitrous applications.

The TR7ix's are actually a projected plug and the tip goes into the combustion chamber.

The BR7ef's are one range cooler than the Tr6's also.

I think that's about all. I was writing notes as fast as I could.
 
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XJRGUY

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He has a good question here I think. I was told and I'll be double checking (because I can't remember) that a good plug is the NGK BR7ef's. They're copper and the ix's are iridium and the iridium has been accused of breaking off and that's not good. Per Rick @ Amazon too.

We just changed my tr7ix's and they already had a miss and they've only been in since January maybe. So I'm going to double check on the BR7ef's for sure.

I'll be double checking on the heat range also.

NGK iridium's to my knowledge didn't have a history of breaking.

It was the DENSO IRIDIUM plugs that had breakage problems.

I've been running NGK TR6-IX for 10,000 miles with no problems on my Cobra, and also run them in my Viper, Volvo C70 HPT and motorcycle. I also installed them in my wife's FX35.

Just trying to prevent mass hysteria about NGK iridium plugs.
 

CobraBob

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This thread should be copied over to the "How To" section. Spark plug/gapping questions come up all the time. I might even add some of the content on this thread to my FAQ page. Great job guys!
 

Posi

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NGK iridium's to my knowledge didn't have a history of breaking.

It was the DENSO IRIDIUM plugs that had breakage problems.

I've been running NGK TR6-IX for 10,000 miles with no problems on my Cobra, and also run them in my Viper, Volvo C70 HPT and motorcycle. I also installed them in my wife's FX35.

Just trying to prevent mass hysteria about NGK iridium plugs.

Easy now I just said "accused" lol. Sorry but after mine have only been on for about 6 or so months and it had a miss at 5,500 rpm's and up I switched. Then again they only had 1,000 miles on them too and a lot of that with Racegas or a mix.
 

mgmustang1

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i just put a gen II on with stock upper, metco 4# lower. max boost was 19.2, then dropped to 18#. i have my tr6's at .030. mustang dyno 609hp 593tq. 93 octane 1 can of torco
 

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