# Spark plugs for e85.



## jacobm (Aug 5, 2011)

So I was having some stuttering/mis-firing at high boost on the spark plugs so I switched to the NGK BKR7E with a .028 gap. Right away I noticed a huge improvement but I can't help but feel it could be better. I know these are the best choice for normal stage 1ish cars but are there better options for an e85 set up? Im running a e85 tune with about 20-22 psi boost, 3'' exhaust no cat and some other mis minor mods. Anyone have any suggestions on plugs?


----------



## warranty225cpe (Dec 3, 2008)

jacobm said:


> So I was having some stuttering/mis-firing at high boost on the spark plugs so I switched to the NGK BKR7E with a .028 gap. Right away I noticed a huge improvement but I can't help but feel it could be better. I know these are the best choice for normal stage 1ish cars but are there better options for an e85 set up? Im running a e85 tune with about 20-22 psi boost, 3'' exhaust no cat and some other mis minor mods. Anyone have any suggestions on plugs?


 Id like to know the answer to this one as well. Im pushing 25-27 psi on my E85 tune. Id like to know if I should be running a tighter gap. Im going to check them out tonight. I think my gap might be a little too big.


----------



## 20v master (May 7, 2009)

warranty225cpe said:


> Id like to know the answer to this one as well. Im pushing 25-27 psi on my E85 tune. Id like to know if I should be running a tighter gap. Im going to check them out tonight. I think my gap might be a little too big.


 Are you misfiring? What makes you think your gaps are too big? I'm consistently getting random misfires on plug 1 and 3 since I've been playing with E85, so I'm going to pull them tonight and check gaps. 

Before Max gets in here, there is no universal plug and/or gap for engines/fuel type. You have to play with gaps and temp ranges, but I'd say a 7 is fine for moderate boosted E85 setups.


----------



## warranty225cpe (Dec 3, 2008)

20v master said:


> Are you misfiring? What makes you think your gaps are too big? I'm consistently getting random misfires on plug 1 and 3 since I've been playing with E85, so I'm going to pull them tonight and check gaps.
> 
> Before Max gets in here, there is no universal plug and/or gap for engines/fuel type. You have to play with gaps and temp ranges, but I'd say a 7 is fine for moderate boosted E85 setups.


 Because I think my gap is at 30-32 right now. And sometimes I can feel a misfire. I thought it would be a better idea to go with a heat range warmer (since E85 burns cooler) and a small decrease in gap (from .28).


----------



## 20v master (May 7, 2009)

warranty225cpe said:


> Because I think my gap is at 30-32 right now. And sometimes I can feel a misfire. I thought it would be a better idea to go with a heat range warmer (since E85 burns cooler) and a small decrease in gap (from .28).


 Well then if you are feeling misfires, then a good place to start is the plug gap. But are these misfires under WOT and have you logged AFR under WOT? Under Max's wide knowledge he says misfires can happen on E85 at anything richer than 0.82 lambda. I don't see why everyone wants to run huge gaps if it's not helping anything (this started with the FSI coil conversions). It puts more load on the coilpacks and makes them more likely to fail. Close your gap up, and see if the misfires go away. There isn't a benefit to the larger gap IMO.


----------



## jacobm (Aug 5, 2011)

Talked to a friend of mine whos running e85 in his vrt and hes running a .20 gap. Guess I'll try gapping to .24 still undecided about heat range though.


----------



## 20v master (May 7, 2009)

jacobm said:


> Talked to a friend of mine whos running e85 in his vrt and hes running a .20 gap. Guess I'll try gapping to .24 still undecided about heat range though.


 The gap that a VR is good with has nothing to do with a 1.8T. Like I said, a 7 should be fine for all but the most extreme setups/climates.


----------



## Marcus_Aurelius (Mar 1, 2012)

20v master said:


> Before Max gets in here, *there is no universal plug and/or gap for engines/fuel type.* You have to play with gaps and temp ranges, but I'd say a 7 is fine for moderate boosted E85 setups.


 Statement in bold should be stickied on top of the 1.8t technical section! I don't how many time I've explained this in details over there, just to see 4 thread titled "what gap should I run" pop up the next day. 



warranty225cpe said:


> Because I think my gap is at 30-32 right now. And sometimes I can feel a misfire. I thought it would be a better idea to go with a heat range warmer (since E85 burns cooler) and a small decrease in gap (from .28).


 It's either you know you have a misfire or you don't. Diagnostic of WOT engine break up can be sketchy because it could be coming from a host of things (fueling, ignition, charge pressure leaks etc.), and blaming it on something when you're not sure is the perfect approach to have one those tail-chasing sessions. 



20v master said:


> Well then if you are feeling misfires, then a good place to start is the plug gap. But are these misfires under WOT and have you logged AFR under WOT? Under Max's wide knowledge he says misfires can happen on E85 at anything richer than 0.82 lambda. I don't see why everyone wants to run huge gaps if it's not helping anything (this started with the FSI coil conversions). It puts more load on the coilpacks and makes them more likely to fail. Close your gap up, and see if the misfires go away. There isn't a benefit to the larger gap IMO.


 Misfire is not a feeling! If it's not logged, more often than not, what feels like a misfire is a result of something else. Like you mentioned Adam, AFR on the rich side (more like richer than 0.80 lamda) is very prone to breaking up at WOT on E85. In the evo/DSM community we call it "rich-knock", the symptoms are very similar to a misfire, but will show up in the knock sensor instead of the misfire counter. 

You are correct, there is a trend in the 1.8t world to look for too wide of a gap for the ignition system strength. The gap should be tuned to match the application (I run different gap for track and street because it's two very different use of the same motor). What I don't totally agree with is when you say " There isn't a benefit to the larger gap" - if the ignition system is strong enough, there is actual benefit to a wider gap (bigger arc, allowing a better burn via a fuller flame front), but it's not the case with our cars. Something like an amplifier or plain stronger coils like the GM ones (dwell tweaks are needed) will allow and benefit from wider gap and better performance. :beer: 

Plug range and gap data dump coming up!


----------



## 20v master (May 7, 2009)

Marcus_Aurelius said:


> What I don't totally agree with is when you say " There isn't a benefit to the larger gap"


 ......on a stock 1.8T ignition system. Happy now?


----------



## Marcus_Aurelius (Mar 1, 2012)

20v master said:


> ......on a stock 1.8T ignition system. Happy now?


 Happy Max! :laugh: 

I know it, you know it ... but when the average vortexer read the previous uncorrected statement, they'll assume that, in general, there is no benefit to widening the gap (regardless of ignition strength). Not for you, or the other technically inclined members, but what we should say is: 

Ideal gap (independent of ignition strength) is the widest possible gap without getting misfires under load (full boost and heat soaked). To be noted, there is also the other end of the spectrum, where having too small of a gap creates misfires at idle (especially at cold start and E85). I ran into this with the TT (before replacing my aged coil harness), at WOT I needed 0.18" - 0.22" gap or it was a misfire party - but at idle, the small gap that prevented breakup under load, gave me constant idle-misfire that sounded like lumpy cams. So, there is a happy medium, or in certain cases, the need to run two gaps for street vs track/spirited driving.


----------



## 20v master (May 7, 2009)

Marcus_Aurelius said:


> but at idle, the small gap that prevented breakup under load, gave me constant idle-misfire that sounded like lumpy cams.


 Careful now, you'll start a new ricer trend. :laugh:


----------



## jacobm (Aug 5, 2011)

Thanks Max. That's some good knowledge to have. I'm fairly new to the whole working on my car/ mod myself scene so its definitley good to know. I also wanna say I picked up a Mad Max Dv a little while ago.... holy crap that thing is amazing. Great work its one of favorite mods :laugh:


----------



## Marcus_Aurelius (Mar 1, 2012)

PART 1 (heat range) 

Spark plugs heat-range selection and gapping should be done in accordance with your specific application. With that said, here are a few guidelines that will help you E85 guys set things up properly: 

-*Heat range selection* 

The ideal way to select your heat range is to know or measure your combustion chamber pressures and resulting temperature. Since this is out of reach for most, there are a few other ways of measuring your specific in-cylinder conditions. 

1. Plug reading 
This was the most popular way back in the day. But unfortunately it's becoming a lost art nowadays with the emergence of the internet (where one or two guys does the leg work and their findings are shared and copied by the rest). The price and availability of EGT probe/gauge as well as wideband AFR monitors also doesn't help the art of plug reading. To stay specific to our TTs, normal temperature range is between 450* C and 850* C in our engine. At low operating temperature conditions (cold start, warm up, idle), a plug that's too cold for the application will show sign of carbon fouling (visible in the insulator nose). While a plug that is too hot will have overheating signs. The most common and visible sign of plug overheating is electrode erosion and deterioration. This should not be taken lightly, as it could result in a hot spot that leads to pre-ignition and engine failure. 

2. EGT monitoring 
Despite popular misconception, the plug range (cold or hot) does not have any bearing on the combustion temps... it's the in-cylinder pressure that dictates the operating temperatures. The heat range is the ability for the plug to operate optimally within the operating range (no cold carbon fouling and hot overheating). Monitoring exhaust gas temps is an effective and reliable way of knowing the combustion temperatures. A probe placed before the turbo will give valuable data that could be used to know the min/max operating temp range and select a plug range accordingly. My personal rule of thumb is (zero science behind it, just empirical experience and data collection), #6 plugs for EGT temps in the 600s - #7 plugs for EGT in the 700s - and #8 plugs for max EGT in the 800* C. 

Follow these simple guidelines and you should be in good shape with selecting your plug heat range. It's worth mentioning that rich AFR and over advanced ignition timing (especially with the properties inherent to E85) can trick you into thinking that your cylinder pressures and temperatures are lower than they are. Extra fuel dumped in the cylinder will cool down the EGT readings a bit, even if the combustion pressures are high. Same thing with aggressive advance, take that into account when running E85 and selecting plugs using this method (I selected my plug heat range from the base timing without any advance to give me that extra safety cushion). On E85 and lots of timing advance, my EGT are low considering the amount of boost I run (mid 700* - low 800*). However, I still use an 8 range plug because I know that without the timing advance, the cylinder temp can be much higher than they seem from EGT readings (plug reading confirmed it). So, be wise with your plug heat range if you're going run rich AFR, lots of boost, and aggressive timing advance on E85. 

Part 2 (plug gapping) to follow :beer:


----------



## Marcus_Aurelius (Mar 1, 2012)

jacobm said:


> Thanks Max. That's some good knowledge to have. I'm fairly new to the whole working on my car/ mod myself scene so its definitley good to know. I also wanna say I picked up a Mad Max Dv a little while ago.... holy crap that thing is amazing. Great work its one of favorite mods :laugh:


 Thanks, I'm glad you enjoy the performance benefit that the modified valve provides!


----------



## Marcus_Aurelius (Mar 1, 2012)

*Spark plug gapping* 

A spark plug is nothing more than a flame igniter that uses electrical current (from the coil) to create a spark in the combustion chamber. Problem is, each combustion chamber, even the same motor, will be subjected to different operating pressure depending on several factors. Things like boost level, combustion temperature, compression ratio, timing, pre/post turbine restrictions will determine and drive the cylinder pressure up or down depending of the level of the tune or specifics of the setup. What does this mean to our discussion? The cylinder pressures specific to your engine setup and application is what determines what the optimal gap will be, nothing more, nothing less. There is no magic numbers here, and people who blindly use gaps given by others on their car are uneducated fools. 

The technical term that deals with in-cylinder pressure measurements is the Mean Effective Pressure (MEP), and the type of MEP measurement most relevant and commonly used for things like plug gapping is the Brake Mean Effective Pressure (BMEP). The BMEP values of the application is what dictates the ideal plug gap. The higher BMEP values you have, the tighter the gap has to be to prevent spark blow-out under load/WOT. Spark blow-outs, although having the same symptoms as a misfire, isn't technically one - it's just the BMEP values that are too high for the plug gap (but most people just call it a misfire by mistake or to keep things simple). Turbo cars can have BMEP values ranging from anything from 12 bar to 30+ bar on some extreme applications (mine is an example). 

Since we don't even have (AFAIK) the typical stock BMEP values for the 1.8t, it's hard for the average joe to go by that to estimate proper gap for their specific setup. The practical way to do it is to start with a small gap (say 0.22") and go for some hotlapping at various gears and uphill if possible. If no blow-out happens, go to 0.24", 0.26", 0.28", and so on until you have some, then back down to the previous working gap to give yourself a safety cushion. It is to be noted that plug gap will grow over time, and coil/harness health are also a factor on how much gap you can get away with, therefore take these things into consideration as well. :beer:


----------



## tedgram (Jul 2, 2005)

opcorn:


----------



## All_Euro (Jul 20, 2008)

Good info Max :thumbup: 

An important side-note about a plug's heat range is that this can vary between different plug manufacturers. For example, I run a Bosch heat range 5 - which is colder than their heat range 6. 

Sorry I can't find the chart I had that compares different heat ranges/plug types but here is a printed list of some… 


*Autolite*: 

Autolite indicates the Heat Range with the last digit of the part number. For example, 3923 has a Heat Range of 3. The higher the number, the hotter the plug. The lower the number, the colder the plug. 

For example, starting with part # 24 (Heat Range 4), If you want a colder plug you would use part # 23 (Heat Range 3), for a hotter plug you would use part # 25 (Heat Range 5). 



*Bosch*: 

Bosch indicates the Heat Range in the middle of the plug number. For example, FR6DC+ has a Heat Range of 6. Bosch plugs get hotter the higher the number, colder the lower the number. 

Starting with part # FR6DC+ (Heat Range 6), a colder plug would be # FR5DC+ (Heat Range 5), a hotter plug would be # FR7DC+ (Heat Range 7). 



*Champion*: 

Champion indicates the heat range in the middle of the plug number. For example, RV15YC6 has a heat range of 15. (The 6 at the end of this part indicates the Gap setting.) Champion plugs are hotter the higher the number, colder the lower the number. 

Starting with part # RCJ7Y (Heat Range 7), a colder plug would be # RCJ6Y (heat range 6), a hotter plug would be # RCJ8Y (Heat Range 8). 



*Denso*: 

Denso indicates the heat range in the middle of the plug number. For example, SK20PR-A11 has a heat range of 20. The number at the end of the part indicates the Gap. 

Denso Iridium Power plugs feature the Heat Range at the end of the part number. For example, IK20 has a Heat Range of 20. Denso plugs get colder the higher the number, hotter the lower the number. Starting with part # IK20 (Heat Range 20), a colder plug would be # IK22, a hotter plug would be # IK16. 



*NGK*: 

NGK indicates the heat range in the middle of the plug number. For example, BCPR6ES-11 has a heat range of 6. (The number after the “-“ is the Gap.) NGK plugs are colder the higher the number, hotter the lower the number. 

Starting with part # BKR6E-11 (Heat Range 6), a colder plug would # BKR7E-11 (Heat Range 7), a hotter plug would be # BKR5E-11 (Heat Range 5). 



EXCEPTION: NGK Racing Plugs: (Any NGK plug that begins with the letter “R”) 

For NGK Racing Plugs, the Heat Range is located AFTER the hyphen. 

Example: R5671A-10 has a Heat Range of 10. A colder plug would be # R5671A-11 (Heat Range 11), a hotter plug would be # R5671A-9 (Heat Range 9). 

Some NGK Racing Plugs are also available in half heat ranges. These are displayed as a 2 or 3 digit number after the hyphen. For example, R6120-85 has a 8.5 Heat Range and R6120-105 has a 10.5 Heat Range. 



*Pulstar*: 

Pulstar indicates the Heat Range by the number "1" or "2" in the plug number. 

Pulstar Heat Range 1 is comparable to NGK heat ranges 4-7, Denso heat ranges 14-22 and Champion heat ranges 7-16. 
Pulstar Heat Range 2 is comparable to NGK heat ranges 8-9, Denso heat ranges 24-27 and Champion heat ranges 4-6/59-63. 
At this time the colder Pulstar Heat Range 2 is only available in 2 racing plug designs, BE-2rT and HE-2rT.


----------



## All_Euro (Jul 20, 2008)

Courtesy of boschsparkplugs.net...


----------



## jacobm (Aug 5, 2011)

Great info guys, looks like I know what I'm playing with this weekend.


----------



## spydox (Apr 4, 2013)

*plugs*



jacobm said:


> Great info guys, looks like I know what I'm playing with this weekend.


 
Im no expert like others here but I did go round and round with plugs and paks. I ended up with non-iridium . I tried the denso IK20 and had nothing but misfires. My NGK Pt plugs have been super..


----------



## Marcus_Aurelius (Mar 1, 2012)

All_Euro said:


> Courtesy of boschsparkplugs.net...


 :thumbup:


----------



## Marcus_Aurelius (Mar 1, 2012)

spydox said:


> Im no expert like others here but I did go round and round with plugs and paks. I ended up with non-iridium . I tried the denso IK20 and had nothing but misfires. My NGK Pt plugs have been super..


 There is nothing wrong with iridium plugs. They have much longer service intervals and the gap don't grow out of spec overnight. Unless you love changing/servicing plugs very often, or have a weak ignition system (bad coils or harness), iridiums plugs work just fine.


----------

