spark plug guide

[touge_ae101]

hey guys, did a search and found a bit of info but not too much so thought i would ask for knowledge on spark plugs. want actual knowledge not spam/opinions.

i haven't paid much attention to the spark plugs i'm running up till now and i think it may be an area where i should be refining it a bit.

these are the two sets of plugs i have run in my car since i got the engine in, the original denso's (PK20R11) and then some NGK BKR6E-11's


so from what i've read the NGK suffix '11' means they are gapped to 1.1mm. is this about right for a NA 20V? how would changing compression affect the gap i would want to run? i know smaller gaps are better for turbo applications due to the lower compression.

now i know there are ways to tell how healthy your engine is running by looking at the tips of the plugs. to me it looks like there has been detonation going on with my NGK plugs as the end is quite white and looks burnt. as you can see above.

so what are the advantages of different tip designs and what is the best for each scenario?i notice the denso plugs have a pointed tip and the NGK plug has the valley down the middle of the flat tip.

i talked to a real interesting salesman once who explained everything but i have since forgot so thought i would ask for a bit of info.

[1I1]

Plugs going white like that is from them getting too hot? Change heat range (for Denso plugs go to a 22, NGK up to a 7)

Oh and: http://www.globaldenso.com/en/products/ ... /qa_3.html

[Bazda]

I would be running a 7 heat range in your car.

Personally id go with NGK V-power plugs. Pretty cheap if you have a trade account. I used to use the normal ones and didnt notice a difference with these but the design is meant to help.

[touge_ae101]

cheers guys. yeah getting a bit hot sounds about right it gets an absolute thrashing. you can also see heat marks up the thread of the plug, indicating there has been a lot of heat generated (car has never been hot or overheated though but does run pretty rich)
what does changing to a higher heat range mean for driving around town though? can i expect the plugs to take slightly longer to get up to operating temperature? i.e. possibly a bit more cold hesitation?

i'd like to know the differences between designs of the tips and how each one is better/worse if anyone knows anything about it?

so is 1.1mm the correct gap to be running on a NA 20V? i'm running a MSD igniter coil and std dizzy so that should have a bit more punch to 'jump the gap' of a larger gapped plug than the normal 0.8mm gap?? what would be the biggest gap you would recommend?(is bigger even better??)

[QikStarlie]

wouldnt be too worried about plug gaps and fancy plugs. just some normal ones as other have said. plug gap, should only need to gap them down if it starts misfiring. temp range, also agree on going to a 7. shouldn't notice any downfalls to it. plugs too cold will start to foul. but not likely in your situation.

[allencr]

The 1st thing to know is that any plug should be set by you only, not some hit or miss BS from the factory that should never to be trusted.

Gordon Jennings, more stuff then you'll ever need to know- http://www.strappe.com/plugs.html
Drag racing only- http://www.dragstuff.com/techarticles/h ... plugs.html
Pitchers- http://www.dansmc.com/Spark_Plugs/Spark ... talog.html

[AE86fan]

Hey just a couple of things in your post that you might want to know...

You are right in saying that turboed engines have closer spark plug gaps but it isn't because of lower compression ratios. While most turboed or supercharged engines do have lower static compression ratios, on boost the cylinder pressures are way higher than N/A which makes it harder for the spark to make the jump, hence the closer gap.

If your engine is running rich, it shouldn't be running hot, if anything a rich engine should run cooler (and make less power unless its a diesel) and be less likely to detonate. It might not make sense but unless you are getting the correct ratio of air into your cylinders (14.7 parts) when you increase the fuel (1 part) the fuel wont burn at its optimum. A lean engine will make more power but at the risk of higher cylinder temperatures and this is where detonation will usually occur.

Often, if the engine has been detonating, the spark plug will be one of the first things to be damaged.

As for spark plugs, don't be too worried about spending $100 on platnum plugs or similar unless you cant be arsed changing them every 80,000 ks which is their main advantage over any real performance gains in n/a applications.

[touge_ae101]

thats an interesting point that you make about running lean. i have been running short trumpets open for a couple of weeks now and my oxygen sensor is a bit bung so it is possible that this has caused it to lean out at mid-throttle scenarios and the ecu has no way of knowing this.

thanks allencr those pages are quite interesting i think i may need to look at my timing again. it was at about 20deg adv but i pulled it back to about 14deg but could possibly bring it back a bit more. although it seemed to go better on 20deg than it does now!

[Quirky]

thanks allencr those pages are quite interesting i think i may need to look at my timing again. it was at about 20deg adv but i pulled it back to about 14deg but could possibly bring it back a bit more. although it seemed to go better on 20deg than it does now!

Did you short the terminals?
at idle the ignition timing is all over the place from 15-20 degrees.
Its almost impossible to read infact.

How high is your idle also?

[touge_ae101]

yeah shorted them whatever they are. can't remember right now.

it idles fine just below a grand once its warm.

[Bazda]

I thought the initial is meant to be 10 deg... with the points shorted..

v-power plugs ftw. Around $5 each on trade. Cant go wrong with that!

[touge_ae101]

I thought the initial is meant to be 10 deg... with the points shorted..

v-power plugs ftw. Around $5 each on trade. Cant go wrong with that!

yeah manual says 10-12 but they run quite well on anything up to about 14deg apparently.

awesome will have to hit mark up to get me a hold of a set. its missing really bad at low revs now. suspect knock sensor too but going to check codes etc tonight.

[Bazda]

I wouldn't run that timing unless I was on 100 octane..

[Quirky]

Id put it back to 10deg just to be safe...

[touge_ae101]

mark (whynot) came around to check timing tonight and it was 5deg retarded...hmm that might be why it hasn't been running well.

have lost all trust in mechanics doing any sort of work on my car! they couldn't even set the timing correctly.

that would explain the plugs getting hot and sluggishness down low. getting some plugs off mark next week that will hopefully rectify the poor state of the ones currently in there.

[allencr]

Forget that timing light unless you've verified that the factory marks are correct to begin with AND its got an emissions test to pass, otherwise it's almost useless except for checking the ECU/mechanical/vacuum advance. Its for the factory setting of a compromise between economy & performance & emissions. It's tough to get within 3-4 degrees with that small pully, crude marks and variable viewing angle.
Advance the timing as much as possible for a fast & smooth idle with the octane you wanna burn, so that it will only ping/detonate/spark knock when it's abused by trying to accelerate in 3rd/4th from 2500RPM.
Knock sensor's be good.

[RomanV]

Disagree, as knock sensors are reactive not proactive obviously.

Maximum advance without knock does not mean the greatest torque production possible, so it's pointlessly creating intermittent detonation events for your engine having the timing cranked up.

[nzhogrider]

It's also important that you don't get tunnel vision and focus on the sole subject of ignition timing or spark plug heat range when both of them are largely affected and interrelated with the air:fuel ratio and fuel maps for ECU programming etc.
e.g. when tuning engines using spark plug colour examples, you generally go for the coldest plug you can run for your ability to tune the air:fuel ratio to the best you can obtain and maintain for the envirinment you are operating your engine in (i.e. tuning based on plug colour when at the track isn't going to be the same for commuting in traffic). The reason you go for the the coolest plug you can is so you are able to keep combustion temps as low as possible and maximise thermal efficiency. There is a point where if you go too cold then you won't have enough spark energy to burn all the fuel properly in your combustion chamber. A hotter plug is more forgiving, meaning that you can dump more fuel in and have it burn properly but chances are you will be running too rich or too much fuel for the same amount of air which significantly produces less power per stroke than the correct 14.7:1 A/F ratio can, however you will be running on the safe side of the A/F ratio and reduce you exposure to the risk of detonation from running too lean.
Ignition timing also plays a huge part in how well the combustion charge of air and fuel will burn, by obviously altering the point at which you begin the combusion process in relation to the piston being in it's top dead centre (TDC) of the compression stroke. This in turn will change the combustion temps and can lead to the plug choice being different for the exact same fuel maps/tune, A/F ratio etc. with only a change in ignition timing.
Lastly when it comes to mapping ignition timing in the ECU for maximum torque (which is what a good tuner should do) it has to be achieved simultaneously with obtaining the correct A/F ratio for any given load point, once all this has been properly completed then you can use the spark plug tuning guide by colour/condition etc. since you know for sure that all other variables are dialed in.
As has already been mentioned, I think you will be best with a fairly standard plug, gapped properly and returning the ignition base timing to around 8 to 10 deg before top dead centre (BTDC) depending on which fuel you run. i.e. 8 deg BTDC for 95, 9 deg BTDC for 98 and possibly 10 deg BTDC if you run a high octane race fuel. Knowing that higher octane fuels burn slower therefore you need to start the combustion process slightly earlier to fit with the mechanical properties of your cam/valve timing and allow for complete conbustion.

[levinguy]

Forget that timing light unless you've verified that the factory marks are correct to begin with AND its got an emissions test to pass, otherwise it's almost useless except for checking the ECU/mechanical/vacuum advance. Its for the factory setting of a compromise between economy & performance & emissions. It's tough to get within 3-4 degrees with that small pully, crude marks and variable viewing angle.
Advance the timing as much as possible for a fast & smooth idle with the octane you wanna burn, so that it will only ping/detonate/spark knock when it's abused by trying to accelerate in 3rd/4th from 2500RPM.
Knock sensor's be good.

are you serious???

[touge_ae101]

factory marks are in the right place as everything has been assembled following the manual. it goes a lot better now than it ever has i actually have power before 6000rpm now. i don't even rev it all the way out to 8200rpm most of the time now as it wants to change a bit earlier.

yeah i know what you mean nzhogrider ignition makes SFA difference at the end of the day. all i want is my engine to be running healthy so i don't end up snapping a rod or putting a hole in a piston cause i am quite hard on it. but only cause its a 20V and can handle it

/need to get O2 sensor $$$$