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Discussion Starter · #1 · (Edited)
So I was reading on the VT forums and someone posted about NGK plugs with our cars and also using their race plugs since the are recessed. He talked to a rep there and this is what he found out

Copied from Velosterturbo.org

"I spoke with a technical rep at NGK last Friday about using these plugs on our car. The reason for the call was to confirm I had the proper gap and to find out what could be causing the carbon fouling I had after only a month of use. He literally LOL'd when I told him I was using them for my daily driver. He went into great detail explaining why their website does not offer a plug for our car and also why their racing plugs should NEVER be used on a daily driver. The absence of the projected ceramic tip completely prevents the plug from being able to self clean and combined with low speed driving, the expected life you should see out of this plug is around 100-300 miles, depending on how much stop and go driving you do. I can't tell you how much he was stressing THIS PLUG IS NOT INTENDED FOR DAILY DRIVING USE! Its for racing ONLY! Quarter mile and circuit races where the engine will be used very aggressively is where it shines. Any slow/low speed engine use on these plugs causes them to foul out, fast, after which they recommend throwing them away. The fouling has caused lots of spark related problems for people trying to use them as daily driver plugs. I can't remember exactly what they all were, but they were NOT GOOD. These plugs cannot be sandblasted and reused safely, and he stressed the point that I was not being told that because he was not trying to sell me some other plug to replace it with because NGK does not recommend the use of their plugs on our car. He repeated that one a couple times as well because I told him our cars come with NGK plugs, but he would not recommend even reinstalling the stock plugs. He just kept saying they DO NOT offer a plug that is appropriate for our car, they do for the N/A, but not the Turbo. He also mentioned that the race plugs do not have the reach into the chamber the the OEM plugs have, so even in the case that I wanted to use a set of racing plugs on our car, these are not the right length and they do not offer a race plug with that reach. I will be either going with the Autolite XP570(1, 2 or 3...still trying to find an Autolite spec with the actual heat range for these, I want 8) or the HKS M40XL plugs after that conversation."

So after reading this I got a bit worried since the guy said we shouldn't be using any NGK plugs in our car. Well I have been running the NGK 1422's for a while now. So this got me thinking about them because on cold start I always have misfires and can hear it popping out the exhaust. It has done this since new with the stock NGK plugs also. Well I searched around and found out the Autolite XP5701 is their cold plug that is comparable to the NGK 1422. For those on stock setup with no tune you can use either the XP5702 or XP5703.

Since I put these in my car I have no misfires on cold start and my car runs so much better. Mine are gapped to .028 and is running great. Today was my first day on the fwy with them and the car gets up to speed a lot better and is super smooth when crusing and if I have to get into the throttle it just pulls harder now. I would recommend these for the price. They were $27 at the local auto parts store

Edit:

Here is a description of what plugs work with what...

XP5703 Stock replacement
XP5702 Mildly modified to full bolt ons (i.e intake, dp, exhaust, fmic, 60mm tb, ect)
XP5701 Tuned to highly modified

Heat Range Explanation
Typically the heat range for NGK Spark Plugs varies from 2-11. This number indicates the thermal characteristics of a spark plug, or how ‘hot’ or ‘cold’ a spark plug is. The term hot/cold is commonly used to describe whether a spark plug heats up easily (hot) or whether it provides resistance to heating up (cold).

Generally, low power engines such as lawn mowers don’t produce a large amount of heat, hence use a low heat range (or hot) spark plug such as a 4 heat range. This means the spark plug will heat up easily and reach its optimal operating temperature. High performance engines on the other hand produce a large amount of heat, hence a high heat range (or cold) spark plug such as a 10 heat range needs to be used to resist the heat developed by the engine.

Several factors influence the heat range of a spark plug, although typically the insulator nose design provides an indication of the heat range of a spark plug.

When a spark plug absorbs heat produced from combustion, the heat is transferred through the center electrode and insulator nose to the metal shell, which then transfers the heat into the engine casing and circulating coolant.

View attachment 1317

A low heat range (or hot) spark plug typically has a long thin insulator nose which will heat up easily however will not dissipate readily to the metal shell (above left). Conversely, a high heat range (or cold) spark plug has a short thick insulator nose which will dissipate heat much easier (above right).

When the heat rating is too high:

The spark plug temperature remains too low and causes deposits to build up on the firing end; the deposits offer an electrical leakage path that gives rise to loss of sparks.

When the heat rating is too low:

The spark plug temperature rises too high and induces abnormal combustion (pre-ignition): this leads to melting of the spark plug electrodes as well as piston seizure and erosion.

NGK Spark Plugs pioneered the use of a copper cored electrode in 1958, which enables a spark plug to heat up quickly and also dissipate heat quickly giving an ultra wide heat range. It is essential to use a spark plug that fits a specific engine and its conditions of use.

As spark plugs are positioned in the head of an engine, their analysis can give a good indication of how your engine is operating.

Directly from the Technical Information page at NGK
 

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After reading this I did a little searching around and looks like the Autolite XP 5703 will work for our car. I'm wondering if I should wait to replace the spark plugs until after I get the tune. Good read and find btw!
 
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Discussion Starter · #3 ·
After reading this I did a little searching around and looks like the Autolite XP 5703 will work for our car. I'm wondering if I should wait to replace the spark plugs until after I get the tune. Good read and find btw!
The XP5703 would be for stock tune. It depends on when you plan on getting the tune. If it won't be for a while then I would say for the $27 for all 4 of them would be good insurance to do now or later
 

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Discussion Starter · #4 ·
So took these for a good drive yesterday and noticed on the fey the car runs so much smoother and less throttle input. My mpg actually went over 34 which was amazing because I have never seen that. So far these plugs are way better than ngk.

Also make sure your spark plug gapper isn't worn. I found out mine was a tad worn and was off by about .03. Or get a feeler gauge instead
 

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So after reading this I took a drive down to the local O Riley s. I walked up to the guy at the counter and asked for a set of Autolite HKS 5701 plugs. He of course said he didn't list those. I said HKS instead of HK. He then asked if I new a different number I said how about NKG 1422. He looked that up as well. He didn't have those, but the HK 5701 Came up listed as the only option . He had 6 HK 5701 plugs in stock. I put them in and Forte 5 was correct my car runs better with those plugs. Thank you Forte 5. You helped me pick the correct heat range I needed 5701 cause I'm tuned. I was Confused with the N K G plugs heat range .
 

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So to summarize,

Ngk doesn't recommend the plugs for our car that we have stock.

Auto lite XP5703 are a better stock replacement

Auto lite XP5702 are 1 step colder good for those with mild tunes and pushing slightly more boost or timing than stock

Auto lite XP5701 are 2 steps colder than stock and best for those tuned

Sound about right?
Obviously that's generalizing a bit.
 

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Welp, adding spark plugs as the next thing to do to my car. At least it's cheap and can be taken care real soon.
 

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Will be giving these a try today but using XP5702 for the few mods that are done.
 
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Discussion Starter · #9 ·
So after reading this I took a drive down to the local O Riley s. I walked up to the guy at the counter and asked for a set of Autolite HKS 5701 plugs. He of course said he didn't list those. I said HKS instead of HK. He then asked if I new a different number I said how about NKG 1422. He looked that up as well. He didn't have those, but the HK 5701 Came up listed as the only option . He had 6 HK 5701 plugs in stock. I put them in and Forte 5 was correct my car runs better with those plugs. Thank you Forte 5. You helped me pick the correct heat range I needed 5701 cause I'm tuned. I was Confused with the N K G plugs heat range .
Your welcome! Glad I can help and your car is running better! I noticed after driving with them for a while that it got smoother in time and my mpg went up.

So to summarize,

Ngk doesn't recommend the plugs for our car that we have stock.

Auto lite XP5703 are a better stock replacement

Auto lite XP5702 are 1 step colder good for those with mild tunes and pushing slightly more boost or timing than stock

Auto lite XP5701 are 2 steps colder than stock and best for those tuned

Sound about right?
Obviously that's generalizing a bit.
That's about right. The xp5702 can be ran in a modded car with no tune or in stock form. I have read that the stock plugs burn a bit to hot for some people and they go 1 step colder and notice a nice increase of smoothness and power

Will be giving these a try today but using XP5702 for the few mods that are done.
Get those suckers in there! I think you will like them. not sure how they will match up to your HKS plugs but these are better than the crappy NGK plugs. I don't have on cold start anymore the popping out the exhaust which is really nice lol
 

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so what is the 1 step colder plug for the car?
 

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Discussion Starter · #11 ·
1 step colder is the xp5702 plugs. The xp5701 are 2 steps colder than stock.

I also gapped mine to .028 and it's running perfect
 

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HAHAHAHAHAHAHA, it cost less for all 4 then I spent for one HKS. Still have to install the plugs but hey for $25.52 for all 4 I will give it a shot (they have a 7 year warranty on them against going bad) since I am on my 3rd set with only 20K miles.
 
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Discussion Starter · #13 ·
HAHAHAHAHAHAHA, it cost less for all 4 then I spent for one HKS. Still have to install the plugs but hey for $25.52 for all 4 I will give it a shot (they have a 7 year warranty on them against going bad) since I am on my 3rd set with only 20K miles.
Exactly! I got mine for $27 and they are cheaper than the ngk 1422 plugs I had!
 

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Replaced my plugs, not sure if placebo effect, or if they are actually better, but car does seem to run better. I had 10K on factory plugs, and I gotta say, they where a little dirty for only having 10K on them. Oh well, I'll put some miles on the car and let you know if it still seems to be better.
 

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Replaced my plugs, not sure if placebo effect, or if they are actually better, but car does seem to run better. I had 10K on factory plugs, and I gotta say, they where a little dirty for only having 10K on them. Oh well, I'll put some miles on the car and let you know if it still seems to be better.
What plugs did you use?
 

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Okay... So for the un-initiated such as myself to turbos, what does "going a step colder" mean?

Why can't you run XP5701's on a stock motor?

Does running "colder plugs" improve performance?

And finally... I am making a list of "essential mods" that I want to do lol, so from what I have read in this thread, the stock plugs are junk, yes?

Thanks so much
 

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I read something on the NGK website

"A good rule of thumb is, one Heat Range colder for every 75–100hp added."

Soooooo unless I get a tune and full bolt on I can run stock plugs right? Won't colder plugs build up junk on them? Please enlighten.
 
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