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WHOLE lot of spark plug convo right here

27K views 158 replies 35 participants last post by  tunerlover3 
#1 · (Edited)
OK soo i decided to go on a WILD search and fine ALL standard NGK spark plugs that will work for us, all of them are th 3 dollar ngk v power spark plug.

I heard alot that iridium’s are NOT what u wanna be running on E85 OR high boost applications, tips braking, etc SO i wanted to make a whole thread on the standard v powers.
Now first of all, they don’t make a lot in the 25mm .985 inch reach, (standard reach size 4306 and all the 9 dollar iridium plugs) which puts the tip right in the end of the head, Im kind of concerned about this, but a lot of guys run the 19mm ¾ reach with out issues? But if you ever looked the spark plug its a lot higher recessed into the head. But I guess under compression it doesn’t make a huge difference. Any info on that please chime in spark plug gurus.
So on to what I found Here’s a full list of all v power ngk plugs with there Heat Range (HR)
Hot to cold

Popular 4306 HR5

this is the only 25mm reach plug they make in the v power standard But it’s a standard heat range. Some say doesn’t madder, but ive been noticing a lot that are 500-600 horse seem to like the 1-2-3 step colder plugs. Rule a thumb is 100 horse over stock 1 step colder. Here’s the list by PN of all 19mm reach plugs, and you may need slim socket for a lot of these.

NGK 4306 HR 5 2.89 14mm thread 25mm reach
NGK 4291 HR6 2.89 14mm thread 19mm reach
NGK 6962 HR6 2.89 14mm thread 19mm reach
NGK 4644 HR7 2.89 14mm thread 19mm reach
NGK 4091 HR7 2.89 14mm thread 19mm reach
NGK 5791 HR7 2.89 14mm thread 19mm reach
NGK 4554 HR 8 2.89 14mm thread 19mm reach
NGK 7173 HR8 2.89 14mm thread 19mm reach
NGK 7405 HR9 2.89 14mm thread 19mm reach
NGK 5238 HR9 2.89 14mm thread 19mm reach
NGK 5820 HR10 2.89 14mm thread 19mm reach
NGK 7942 HR10 2.89 14mm thread 19mm reach
NGK 6596 HR11 2.89 14mm thread 19mm reach



Wanted to see if anyone has RAN any of these and what they have experienced. I’m about to try the 4554 or the 7173 being shooting for 30-32 pounds on a 61mm turbo running E85.
For 12 bucks they are worth trying different heat ranges/gaps
So there ya go guys, bunch of research trying to find out 14mm and heat ranges. Again I don’t LIKE the 19mm reach but again, I know a lot that run the 19mm with no issues. You can get on sparkplugs.com to take a gander at the plugs too if ya want. SOOO lets DISCUS !!!!

currently on a set of 06s gapped to .20 3-4k miles startng to see blow out on 30 pounds Need changed O yes, but thats why im lookin at trying some colder vpowers.
 
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#3 ·
Ok here are the pics of what I have in stock.

From left to right...4306, 6962, 4291, 4554, and 7405


4306:


6962:


4291:


4554:


7405:


Now for some measurements.

The 4306's from seat to electrode tip is about 1.26 inches.
The 6962's from seat to electrode tip is about 0.90 inches.
The 4291's from seat to electrode tip is about 0.980 inches.
The 4554's from seat to electrode tip is about 0.80 inches.
The 7405's from seat to electrode tip is about 0.875 inches.

The 4306, 6962, 4291, and 5791 are considered regular V power plugs.
The 4554, 7173, 7405, and 7942 are considered racing V power plugs.
 
#155 ·
Ok here are the pics of what I have in stock.

From left to right...4306, 6962, 4291, 4554, and 7405


4306:


6962:


4291:
Tuner, What are you running for plugs in your car and the gap? Does the E1 require anything diff than stock heat range etc?

4554:


7405:


Now for some measurements.

The 4306's from seat to electrode tip is about 1.26 inches.
The 6962's from seat to electrode tip is about 0.90 inches.
The 4291's from seat to electrode tip is about 0.980 inches.
The 4554's from seat to electrode tip is about 0.80 inches.
The 7405's from seat to electrode tip is about 0.875 inches.

The 4306, 6962, 4291, and 5791 are considered regular V power plugs.
The 4554, 7173, 7405, and 7942 are considered racing V power plugs.
Tuner, What are you running for plugs in your car and the gap? Does the E1 require anything diff than stock heat range etc?
 
#4 ·
yes i noticed the "racing' plug part on the site, guessing because of how COLD they are.

thats crazy the size differnce because on sparkplugs.com they said they where ALL 19mm reach, and ovbiosuly they are a tad different.

4291 looks like a good choice for one step colder.
7405 aint to bad ethier, but its a HR9 lol we talkin 700-800 horses there.

I wanna try a HR7 or HR8 Have any 5791 or 7173? thanks for the pics thats awsome bro.
 
#5 ·
I've on this forum of the infamous irridium tip breakage, but it was never posted by anyone. It was always someone posting that they "heard" about the irriduim tips breaking.

All I can say that for my combination, the 2 step colder irriduim plugs work best. my car idles better and pulls through the RPM's smoother than with the 4306's.

This is like the oil and tranny debates. Use what ya want if it works for your combination.
 
#6 ·
picked this up off of car craft.com


One of the things we learned the hard way while testing our first E85-fed small-block was that cold spark plugs are absolute necessities. In our normally aspirated tests, we melted a plug. Later, Bosch Product and Technical Support Manager, Matthew Hallis, told us ethanol is particularly sensitive to pre-ignition. In other words, it doesn't take much of a heat source to initiate combustion. Pre-ignition is caused by a heat source in the combustion space that begins the combustion process before the spark plug fires. Any kind of hot spot, like a glowing spark-plug ground strap for example, can light off the intake charge during the compression cycle long before the spark plug is supposed to fire. This creates dangerous cylinder-pressure spikes and can cause massive engine damage in the form of melted pistons. In our first test, we were lucky the only damage was a bunch of nuked spark plugs and two warped intake valves.

The solution to this E85 pre-ignition problem is to run a minimum of three heat ranges colder than the heat-range that spark plugs would normally survive on gasoline. Cold plugs are designed to transfer as much heat as possible away from the spark plugs so they won't melt. Supercharged, turbo, or nitrous'd engines demand a nonprojected-nose spark plug, which minimizes the length of the spark-plug ground strap. While platinum and iridium plugs are very popular for mild street cruising, they should be avoided when pushing an E85 engine hard, such as on the dyno, since these materials tend to retain heat and could cause pre-ignition problems.

Also, because the supercharger boosts cylinder pressures, we knew a smaller plug gap of 0.030 inch would help to get the fire lit. Very cold plugs tend to not want to start as well as hotter plugs on a cold engine, so if you decide to build a similar package, you will need to experiment with heat ranges by starting out cold and going warmer until you see excessive heat evidence in the plug.



Read more: Using E85 Pump Gas - Tech - Car Craft Magazine
 
#11 ·
4091 is a HR7 v power 19mm reach

and 6596 most likley knowone will use with a HR of 11!!!! lol thats once cold ass plug. also 19mm reach vpower

Gonna update the top list with these few i just found this morning.
 
#13 ·
I shoulda took a shot when i had my head off, but never did :/ but ovbiously think about it being flush, and the19mm is about 1/4 inch up in the head. But again, alot run these type in our heads, and dont have issues.
 
#15 ·
with all that pressure, i dont see how a 1/4 of a inch is gonna madder, correct me if im wrong guys?

I have run the 19mm plugs before, with no issues, back when i was on pump gas, ran good too. Now that im on corn, and ive read soo many articles on running colder plugs PERIOD with corn, im gonna get a 2-3 step colder set.
 
#18 ·
ordering some 4644s and 7173 $2.50 at orileys :) soo gonna try the 7s and 8s and ill get back to u guys, ill gap them the same most likley .25 -.20 range. on a 61mm 30+ psi and corn. But untill than cause it will be two weeks or better, lets see if anyone else has used any of the above plugs.
 
#20 · (Edited)
By the looks of it all but the 4306's are gasket seat plugs.I thought our head required a tapered seat like the 4306 and the iridium plugs use.
My setup does fine with the colder heat range iridium,for some reason i just don't like how the car runs on 4306's....its just not as smooth.
Chief i would stick with a projected tip plug that's in the heat range you need.The racing plugs are non projected tip and with the plug being recessed as far as it is might be a problem.
 
#21 ·
Im gonna get the 4644s and just see how they perform, at 9 bucks worth a try. And yes i know what you mean by the gasket seated plug. But i know many that have ran them, inluding my self with no issues.

I just dont like irdiums with E85 and high boost.
 
#23 ·
i guess for one they do have a hotter spark than the standard plug, and i read else where they would be prone to pre ign with running alky.

Im gonna pick my 4644s today, and get a pic of them compared to 4306s. Cant wait to get a snail back in the neon!!!
 
#25 ·
i read that with alky there are problems with pre-ignition running them, because they are a hotter spark, and they retain heat like you quoted. why i wanna try the standard 2 step colder.
 
#26 ·
4554s to 4306s Got them gaped to a .20 for some high boost, As you can see the eletrode is recessed into the plug, and its about 1/4 shorter, ill get back to you all on idle drivablity and wot performance. It will be harder to start, i hear 2-3 step colders PLUS E85 which is already hard cold starts, sounds like be fun starting, but ill get back to you all, heres some pics.



 
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