Spark plug recomendation

[jackb_ms]

Hello All

Which are the best spark plug for a K series VVC pushing 180bhp?

The car is mostly used on the road.

Cheers

Jack

[tangomikeromeo]

Not sure if ‘best’ but I’ve used NGK BCP7ES for a few years in a similar spec engine (both with and without VVC mechs) with no issues. 

If you want an expert’s view a call to DVA would be my recommendation for the last word on the matter.

I use NGK in everything that needs a spark plug and had no issues either. 

Horror stories of fake plugs abound but a reputable retailer should cover that off (I.e. not pence from eBay)

[Paul Mason]

My K, just taken out aforementioned NGK's and replaced with the same at a 0.8 gap following various bits of advice and research. Car ran spot on with them, only changed as part of general winter fettling

[revilla]

My VVC is around 170bhp. Never used anything other than OEM Rover NLP100290 and never had problems.

[elie boone]

The NGK BCPR 7 ES with 1mm gap runs much sweeter than the OEM plug on a EU3 engine 

[revilla]

@elie boone: Interesting ... when you say "runs much sweeter", what difference should I notice? Never tried anything else because I didn't have a problem but if there's a benefit to be gained I may give the NGK BCPR 7 ES plug a try. Is the 1mm gap standard as supplied or do you adjust to that?

[elie boone]

I do adjust the gap, the engine has a better response to the throttle this on a EU3 non VVC

[revilla]

I'll give them a try then!

[anthonym]

NGK BCPR 7 ES is standard in my 2000 R500 K 235bhp  (.9 gap) aiui they are quite "cold" plugs.

edit: I now gather from later in this thread that the hotter the engine, the colder the plugs required.

 

 

previously:

NGK BCPR 7 ES is standard in my 2000 R500 K 235bhp  (.9 gap) aiui they are quite "hot" plugs.

 

[7 wonders of the world]

NGK 7 grades are not a hot plug on the country they are a grade or 2 cooler than most OE plugs  - these being 5 or 6.

& should be fine unless your running something hairy but of older design like a well tweeked Crossflow then you might consider an 8 grade - but spec this in EV form  at with the precious metal electrode as these burn off deposits more efficiently than the convention electrodes.

 

[anthonym]

what's EV? Sounds like I should be interested.

[7 wonders of the world]

Here you go....

https://www.sparkplugs.com/Data/uploads/Charts/NGK_Plug_Chart_1.jpg

 

[anthonym]

 I always get hot/cold wrong. So cold means the engine has to get hotter to burn off the crud? Hot means the plug burns hotter in a colder engine? Not the other way round?

I can't see EV in that chart ... no still can't see it, unless it's 19mm reach 1mm fine wire gold platinum c.e. ? (istr my mondeo uses platinum plugs)

[revilla]

Yes I think that's the way to think of it. Hot plugs naturally run hotter, so suit an engine that doesn't hear the plugs so much. Cool plugs naturally run cooler so suit an engine where the plugs otherwise tend to get hit. I do have to think about it each time though!

[elie boone]

The Hot Spark Plug is a better heat insulator and keeps more heat in the tip of the spark plug. Whereas, a Cold Spark Plug conducts more heat out of the spark plug tip and lowers the tip's temperature. A great surface area exposed to the hot combustion gases. Heat transfer to the engine head is slower. ( shameless copy )

[anthonym]

so... the hotter the engine the colder the spark plug (requirement) - I'll edit my above hot to cold.

[7 wonders of the world]

That's correct otherwise you run the risk of the plug overheating as it cannot conduct the heat from combustion away fast enough which results in the tip glowing incandescent and you suffer detonation......... and from there its a slippery slope to a holed piston.

[7 wonders of the world]

Just to confuse matters even more Champion number their plugs the opposite way to NGK  

[anthonym]

now edited to change to the opposite

NOW it becomes crystal clear - hotter engines need LESS insulated (i.e. colder) plugs so the plug doesn't over-heat.

I guess also that cooler engines (less horse power meaning less heat) need plugs to get hot enough sooner to clean themselves, so the plug is MORE insulated ("hotter")

wonder how long my clarity will last 

edit: I think the idea of hotter engines needing LESS insulated plugs is what makes NO sense (thanks to shameless copier above) to me, because I am very accustomed to my far too hot engine needing insulation in and on everything to prevent (well, at least slow down) everything getting fried. Everything does get fried in the end, but takes longer.

and cooler running engines needing MORE insulated plugs makes sense vice versa.

I suppose I need less warm clothing the warmer it is.. the plug needs less insulation the hotter the engine

 

all the above completely edited to the opposite of what it was.

 

 

PREVIOUSLY

NOW it becomes crystal clear - hotter engines need more insulated (i.e. colder) plugs so the plug doesn't over-heat.

I guess also that cooler engines (less horse power meaning less heat) need plugs to get hot enough sooner to clean themselves, so the plug is less insulated ("hotter")

wonder how long my clarity will last 

edit: I think the idea of hotter engines needing more insulated plugs is what makes sense (thanks to shameless copier above) to me, because I am very accustomed to my far too hot engine needing insulation in and on everything to prevent (well, at least slow down) everything getting fried. Everything does get fried in the end, but takes longer.

and cooler running engines needing less insulated plugs makes sense vice versa.

[revilla]

Anthony ...

 

It's the other way around! Hotter engines need LESS insulated plugs. Cooler plugs conduct the hear away more readily.

 

Cooler engines need MORE insulated plugs. Hotter plugs don't the hear away so well and therefore naturally run hotter.

[anthonym]

I surrender.

[revilla]

You're thinking that a "more insulated" plug, i.e. one which conducts heat less well, will be somehow insulated from the heat?

The thing is, the insulation isn't between the plug and the source of heat, it's between the plug and the thing which is cooling it, i.e. the surrounding metal. So reducing the ability to conduct heat reduces the plug's ability to cool and it therefore runs hotter.

You're thinking of it like a person standing in front of a fire, insulation between the person and the fire stops them getting hot.

But it's more like a person on a cold day. Insulation between the person and the surrounding cold air, like thick clothing, keeps them warmer, not cooler.

The nose of the plug is always exposed to the same level of heating, however well the plug conducts heat. The only question is how well it can get rid of that heat.

[anthonym]

I need a drink...

[revilla]

Hot drink or cold drink?

[anthonym]

hoho! 

 

now edited to fix it https://www.lotus7.club/comment/2280623#comment-2280623