Sparkplug technical information.

[John Orchard]

l'd like to confirm something with regard plugs...

A 'projected electrode' plug is stated as hotter than a similar heat range non projected electrode, is the plugs temp range totally related to the distance from the plug gap to where the porcelain meets the outer casing?

So, would say a '9' (NGK) projected electrode be equal to an '8' non projected?

Or would l have to measure down from the gap to the point where the porcelain meets the outer casing, and would a similar distance mean a same hest range?

Anyone know where this topic is explored?

[sleepy]

Not heard that stated from a plug maker.
As I understand plug heat range it is related to the length of the porcelain. The shorter the porcelain the quicker the heat can get away from the electrode. Meaning a hot plug has a short porcelain and a cold has a long.
The length of the earth electrode also has an effect as well in it ability to stay cool enough not to melt or cause detonation.   

[John Orchard]

Not heard that stated from a plug maker.
As I understand plug heat range it is related to the length of the porcelain. The shorter the porcelain the quicker the heat can get away from the electrode. Meaning a hot plug has a short porcelain and a cold has a long.
The length of the earth electrode also has an effect as well in it ability to stay cool enough not to melt or cause detonation.   

On a projected electrode plug the porcelain might be longer?

Is the length the porcelain the only dimension that effects heat-range?  ....... or maybe the distance to where the porcelain meets the outer casing from the start (combustion chamber end) of the outer casing (thread)?

A projected electrode plug may have a longer porcelain section because it protrudes into the combustion chamber further? More of the porcelain/centre electrode would be exposed to combustion heat.

To me, the distance down from the leading edge of the metal casing (thread) to where the porcelain meets it will determine heat-range?  If the porcelain is longer from projecting into the combustion chamber further, would that make it hotter?  Is the porcelain the only channel for heat to transfer to the head?

Hmmm, I guess the length of centre electrode (including porcelain) does determine heat-range, regardless as to whether it protrudes further into the combustion chamber or not?

Still not sure on all this!  I did read somewhere that a projected electrode plug is a 'hotter' plug, I wondered why?

Well I have B9ES, B8ES, BP8ES & BP9ES plugs, I will start measuring length of porcelains.  I might have to send a letter to a plug manufacturer for clarification of this  ;-)

[sleepy]

Just use what works and don't think about it too much.
Protruding plugs are to put the spark further into the combustion chamber not to change the heat range.
Manufactures give a plug a heat number and as far as I know they compensate for the amount of protrusion in the length of the porcelain. 

[ralph311]

Any help?

https://www.denso.com/global/en/products-and-services/automotive-service-parts-and-accessories/plug/pdf/t-manual.pdf

[pokey]

There's a bit to plugs when you get into them but basically your correct. Short porcelain is a cold plug  and long porcelain is a hot plug.  The gap around the porcelain  stays hotter. as for the short 8 being the same i dont think I could agree with that.

[John Orchard]

Any help?

https://www.denso.com/global/en/products-and-services/automotive-service-parts-and-accessories/plug/pdf/t-manual.pdf

lnteresting, thanks.

[Dungar Pilot]

Not heard that stated from a plug maker.
As I understand plug heat range it is related to the length of the porcelain. The shorter the porcelain the quicker the heat can get away from the electrode. Meaning a hot plug has a short porcelain and a cold has a long.

Short porcelain is a cold plug  and long porcelain is a hot plug.  The gap around the porcelain  stays hotter.

Someone must be right?

Can someone confirm which?

I get confused when it is time to change the clock for Daylight saving!

[John Orchard]

Not heard that stated from a plug maker.
As I understand plug heat range it is related to the length of the porcelain. The shorter the porcelain the quicker the heat can get away from the electrode. Meaning a hot plug has a short porcelain and a cold has a long.

Short porcelain is a cold plug  and long porcelain is a hot plug.  The gap around the porcelain  stays hotter.

Someone must be right?

Can someone confirm which?

I get confused when it is time to change the clock for Daylight saving!

Depends whether you put your left or right boot on first.

[sleepy]

Not heard that stated from a plug maker.
As I understand plug heat range it is related to the length of the porcelain. The shorter the porcelain the quicker the heat can get away from the electrode. Meaning a hot plug has a short porcelain and a cold has a long.

Short porcelain is a cold plug  and long porcelain is a hot plug.  The gap around the porcelain  stays hotter.

Someone must be right?

Can someone confirm which?

I get confused when it is time to change the clock for Daylight saving!

Sorry, I must correct my earlier statement. Short porcelain is a cold plug.
I recon they got the terminology wrong, I would have said a hot plug goes in a hot motor and a cold plug goes in a cold motor.
Still the facts are quite clear in that a plugs porcelain needs to work at the correct temperature to keep the carbon/oil burnt off and the electrode at correct temp. So in a low compression engine with a low BMEP the plug needs to have a long porcelain to stay hot enough to work long term and the opposite applies to a high compression race engine with higher combustion temperatures. The "hot" motor needs a cold plug with a short porcelain to dissipate the heat faster so that the electrode doesn't over heat. 
Always used to have a laugh when people told me that a hot plug made the motor start better in cold weather, almost like they think the plug make a hotter spark or somehow generates it's own temperature.   

[matcho mick]

projected plugs are dual purpose,(old wives story??)all early aircooled Vdubs used them,hot when chugging along,but up the pace & incoming cool intake calmed things done heatwise, likewise early Yamaha 2 valve motors SR/XV seemed to like them too,BP7ES std fitment, KLG FE65P my fav in my velo around town,but FE100s for interstate pub crawls BITD,so to original question, BP7ES would sorta even out to B8ES,(by now everyone refers to their plug charts to tell me i'm wrong, lol),cheers

[John Orchard]

l agree that a longer porcelain will run hotter, a short porcelain will transfer the heat of combustion into the cylinder-head so that the piston crown does not melt.

My question, for the same given length of porcelain, is it a hotter plug if more is protruding into the combustion-chamber (exposed to more flame)' or a colder plug (exposed to cooling mixture before ignition).

:-)

[Nebo]

  HI John.  Champion and NGK has released some very good Tech articles over the years . Make very good reading.

   One interesting article is on  Surface Gap Plugs, No Heat Range. Hard to foul.

   Made for 2 stoke outboards, Nitro engines . Used by Porsche,F1 and in other race cars using mechanical Fuel injection. Do not know if there still used. Except Drag cars.

   Also Oem Spark plugs on the early Kawasaki Mach 1.   Requires a very High energy ignition System to fire the plug.

    BuY the way . Supercheap NGK BR9EG $13.95. A good Price.

   

[ralph311]

My question, for the same given length of porcelain, is it a hotter plug if more is protruding into the combustion-chamber (exposed to more flame)' or a colder plug (exposed to cooling mixture before ignition).

Well my 2c opinion is  8's is 8's and 9's is 9's regardless of construction. Protruding or not if its been labeled an 8 by ngk then that's what it is. :-)

If you look at a plug heat range conversion chart it will for example, tell you an ngk 8 is a denso 24. No mention of any other factors.

You might choose a different construction tho because of considerations other than heat range.

[John Orchard]

  HI John.  Champion and NGK has released some very good Tech articles over the years . Make very good reading.

   One interesting article is on  Surface Gap Plugs, No Heat Range. Hard to foul.

   Made for 2 stoke outboards, Nitro engines . Used by Porsche,F1 and in other race cars using mechanical Fuel injection. Do not know if there still used. Except Drag cars.

   Also Oem Spark plugs on the early Kawasaki Mach 1.   Requires a very High energy ignition System to fire the plug.

    BuY the way . Supercheap NGK BR9EG $13.95. A good Price.

 

Yeh l run "surface discharge" plugs in my race GSXR1000 Superbike.

[Momus]

My question, for the same given length of porcelain, is it a hotter plug if more is protruding into the combustion-chamber (exposed to more flame)' or a colder plug (exposed to cooling mixture before ignition).

Well my 2c opinion is  8's is 8's and 9's is 9's regardless of construction. Protruding or not if its been labeled an 8 by ngk then that's what it is. :-)

If you look at a plug heat range conversion chart it will for example, tell you an ngk 8 is a denso 24. No mention of any other factors.

You might choose a different construction tho because of considerations other than heat range.

We ran surface gap plugs in rotaries; around an 11 in NGK and had to use a 6 or 7 to warm up or they would foul.

[tony27]

  HI John.  Champion and NGK has released some very good Tech articles over the years . Make very good reading.

   One interesting article is on  Surface Gap Plugs, No Heat Range. Hard to foul.

   Made for 2 stoke outboards, Nitro engines . Used by Porsche,F1 and in other race cars using mechanical Fuel injection. Do not know if there still used. Except Drag cars.

   Also Oem Spark plugs on the early Kawasaki Mach 1.   Requires a very High energy ignition System to fire the plug.

    BuY the way . Supercheap NGK BR9EG $13.95. A good Price.

 

Yeh l run "surface discharge" plugs in my race GSXR1000 Superbike.

When the first Sherco 450s came out the importer at the time loaned me his personal bike as way of getting them seen & he was running a surface discharge plug out of the 600 supersport kit for GSXRs, I'm pretty sure it had come out of 1 of the WSS bikes he'd worked on in Italy. He told me the cost of each plug in the kit & it was scary

[Nebo]

    Yes Momus i forgot about Rotary Engines.   Very hard on Plugs.  Especially  if it has been Ported and Turbo charged  and a big Weber Carb.

     Another Engine hard on Plugs. The Honda CX650 Turbo. Even B9EGV NGK,s would not last more than 5000 to 7000KM,s.  A friend had one.

    It would just burn the end of the Electrodes.  I think this happened because there was no intercooling. Causing Very High Combustion Tempertures.

     Even tryed special Turbo Porsche/Bosch  racing plugs .  Both Silver and Platinium.   Cost a heap.  Lasted about 10K.

     May be Surface gap plugs would have lasted longer.  He still Loved the Bike .  100HP Claimed.  260kg Claimed.  Comstar Wheels. Did not handle great.

 

[John Orchard]

So, I have been measuring plugs .....

Between a B8ES and a B9ES, the porcelain on an 8 travels 3mm further (longer) down into the metal casing than a 9.

The difference between a B8ES and a BP8ES, the porcelain is the same length, on a BP the porcelain protrudes 2mm further into the combustion chamber but also travels 2mm less down into the outer metal casing.

Now my interest is; would one or the other (projected v non projected) run hotter or cooler for the same given porcelain length (quoted heat-range)?  Exposure to either cooling incoming fuel/air charge or more exposure to combustion flame-front?

My testing continues  :-)

[ralph311]

Now my interest is; would one or the other (projected v non projected) run hotter or cooler

The heat range of both is 8, regardless of design parameters. Not sure what you're chasing?

[Tomas]

I would say BP would run hotter than B in the same engine. Two are designed for different applications.

[John Orchard]

Now my interest is; would one or the other (projected v non projected) run hotter or cooler

The heat range of both is 8, regardless of design parameters. Not sure what you're chasing?

ls it porcelain length alone denoting heat-range then?

[pokey]

HEAT refers to the encapsulated zone. IE depth not length, The porcelain is an insulator not a heatsink and not a conductor. While the fresh cooling fuel charge washes over the exposed plug the VOID is mostly unaffected so it stays hotter. Longer the Void the Hotter it remains. Make sense?

[John Orchard]

HEAT refers to the encapsulated zone. IE depth not length, The porcelain is an insulator not a heatsink and not a conductor. While the fresh cooling fuel charge washes over the exposed plug the VOID is mostly unaffected so it stays hotter. Longer the Void the Hotter it remains. Make sense?

An angle l've not considered, thanks, this is why l ask the question here :-)

[sleepy]

Have you read this from NGK
https://www.ngk.com.au/technical_info/heat-range/
Doesn't answer your question on protruding plugs.
In my past life as a car Dyno operator plugs of different design were often tried and I can't say we ever noticed any differences between protruding and not of the same heat range. Did used to run BP5ES in my Bultaco trials bike to help stop fowling at low revs but never did a back to back with a B5ES probably because I had boxes of the BP5ES for my car. 

[80-85 husky]

i fouled an "R" plug in my 2000 kato 250 and replaced it with a plain jane B8ES but a month or two later i noticed it breaking down at high revs?? cleaned filter carb etc with no change then got told "you need a racing plug" and bang, sorted... i was suprised it made that much difference

[sleepy]

i fouled an "R" plug in my 2000 kato 250 and replaced it with a plain jane B8ES but a month or two later i noticed it breaking down at high revs?? cleaned filter carb etc with no change then got told "you need a racing plug" and bang, sorted... i was suprised it made that much difference

The R stands for resistor not racing.