Sparkplug with or without resistance
Discussion
andy43 said:
I'd just check with the suppliers to be 100% sure.
They look very similar to the Accel 9002 ceramic leads I've got - I have resistive plugs.
Just goes to show how TVR Parts Ltd follow the Piston Heads TVR forums, then take the products discovered and tested by TVR enthusiasts only to re-brand them as a genuine TVR part so they can charge a premium for it, its almost a licence to print money and I guess was motivation behind the deal RG struck with Les Edgar, having the rights to use the genuine TVR part designation and TVR logo is really just a licence to improve the margin made on every product sold.They look very similar to the Accel 9002 ceramic leads I've got - I have resistive plugs.
Genuine TVR part my arsh, just because TVR Parts Ltd claim it to be a genuine TVR part and give it a TVR part number doesn't mean anything. I'm not commenting on the quality of the Accel 9002 ceramic leads which I'm sure are great, just making people aware when we contribute on this forums its not just us TVR enthusiasts reading with interest. The so called TVR specialists are reading these pages just as avidly and using them to profit from the good ideas they spot.
Saying that, as we know imitation is best sort of flattery, it just makes me chuckle when something like the American made Accel 9002 ceramic leads that were never original TVR equipment are suddenly now a genuine TVR part
If TVR Parts Ltd are listening I'd challenge them to give their definition of a genuine TVR part, is it...
A: A genuine made for TVR part in a TVR Parts Ltd box, properly tested by TVR with a TVR Parts Ltd quality guarantee?
or
B: Just a generic part they've decided to apply a TVR Parts Ltd part number to so they can call it a genuine TVR part?
I'm not down on people making a profit, but just taking a generic part then branding it as a genuine TVR part without it seeing much specific TVR testing is rather misleading marketing practice, I know these cars were very much parts bin specials anyway but if you sell a part as genuine TVR equipment people might understandably assume they are paying the premium for some sort of type approval process as you see on all other car maker's OEM parts.
It's all a bit of a con if you ask me, a marketing con built around allowing their customers to think the designation "genuine TVR part" actually means something, which of course it doesn't
If the engine is standard then NGK BPR6ES (R = resistor) or if you want to fit iridium tipped ones that will last for 60,000 miles then NGK BPR6EIX (more expensive but used by Lexus so says it all).
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
ChimpOnGas said:
andy43 said:
I'd just check with the suppliers to be 100% sure.
They look very similar to the Accel 9002 ceramic leads I've got - I have resistive plugs.
Saying that, as we know imitation is best sort of flattery, it just makes me chuckle when something like the American made Accel 9002 ceramic leads that were never original TVR equipment are suddenly now a genuine TVR part They look very similar to the Accel 9002 ceramic leads I've got - I have resistive plugs.
busted bang to rights. They are accel aren't they? Don't forget these come from accel needing cutting and crimping - for the doubling of the accel price the 'genuine' parts are fully assembled/plug n play.I like the installed photo they've used as well, the leads fitted on the drivers side look great without the clearance problems against the two steel heater pipes most of these cars have....
Edited by andy43 on Wednesday 23 November 07:59
N7GTX said:
If the engine is standard then NGK BPR6ES (R = resistor) or if you want to fit iridium tipped ones that will last for 60,000 miles then NGK BPR6EIX (more expensive but used by Lexus so says it all).
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
I could just look this up I know but for the benefit of others considering changing plug GRADE including myself, http://www.pistonheads.com/gassing/topic.asp?h=0&a...
So is a 6 a hotter plug?
Less fouling because the plug gets hotter so assists detonation at slower engine revs !
How will this plug effect detonation at hotter engine temps and higher revs?
My car uses MBE, mapped on 7's will this plug change effect my ign or fuelling at all.
For those with aftermarket ECU's will the Ecu detect anything and adjust timing or is it not an issue?
Is pre detonation a possibility using a hotter plug?
ClassiChimi said:
N7GTX said:
If the engine is standard then NGK BPR6ES (R = resistor) or if you want to fit iridium tipped ones that will last for 60,000 miles then NGK BPR6EIX (more expensive but used by Lexus so says it all).
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
I could just look this up I know but for the benefit of others considering changing plug GRADE including myself, http://www.pistonheads.com/gassing/topic.asp?h=0&a...
So is a 6 a hotter plug?
Less fouling because the plug gets hotter so assists detonation at slower engine revs !
How will this plug effect detonation at hotter engine temps and higher revs?
My car uses MBE, mapped on 7's will this plug change effect my ign or fuelling at all.
For those with aftermarket ECU's will the Ecu detect anything and adjust timing or is it not an issue?
Is pre detonation a possibility using a hotter plug?
Just scroll down to find each type of plug and the nice people at NGK have listed the specs for each. You can compare the Iridium ones, BKR6EIX, against the B7ECS which are in the Competition and Racing Types section.
http://ngkntk.co.uk/wp-content/uploads/2011/04/588...
and the NGK spark plug code: https://www.ngk.de/fileadmin/Dokumente/EN/download...
HTH
Edited by N7GTX on Friday 25th November 10:55
Edited by N7GTX on Friday 25th November 11:06
At its simplest the plug grade should run hot enough to burn the combustion carbon off and no more and 6 grade is a mid value plug that will run clean enough for normal road use. If you go for 7 grade the tip cools faster between combustion cycle, so can take more heat, but conversely will carbon up if the engine is not running hot enough, and that's obvious by having black plugs. Leave it too long and the carbon will eventually build up and give a path for the HT that will kill the spark, so you need to keep an eye on the plug colours. One thing being forgotten here is we are dealing with a 50 year old engine design thats only producing about 60bhp per litre, so its not exactly a high stress environment for your plugs- no specialist fuels, (LPG noted!) turbo chargers (on the whole)or ultra high compression ratios, so I doubt you could ever get near a point of pre detonation being and issue with 6 grade plugs. Pre detonation basically occurs at high engine temps when something is hot enough to ignite the incoming fuel, and that could be a red hot spark plug, if the plug was too "soft" (a lower heat number).
On the issue of resistance- you need some somewhere, but its far from precise just how much. After all each plug lead is a different length, so its resistance will be different- double the length, double the resistance. You could go from say 5k ohms to 40 k ohms between the coil and plug tip by whatever means and not notice any difference in real terms. If the overall resistance is too low, it can glitch the tacho and produce surrounding radio interference, and may upset some electronics (although the 14CUX is pretty bullet proof). If you go too high, you could produce a misfire as the engine RPM goes up and the coil dwell time becomes very short on a V8. This makes the available HT drop off quite rapidly above about 5000 rpm, so the extra resistance added to this could kill the spark. Id say as a rule of thumb unless you are running very low resistance "inductive" leads like magnecore then the HT leads should have enough resistance to do the job. Id only add extra if aftermarket electronics was affected.
On the issue of resistance- you need some somewhere, but its far from precise just how much. After all each plug lead is a different length, so its resistance will be different- double the length, double the resistance. You could go from say 5k ohms to 40 k ohms between the coil and plug tip by whatever means and not notice any difference in real terms. If the overall resistance is too low, it can glitch the tacho and produce surrounding radio interference, and may upset some electronics (although the 14CUX is pretty bullet proof). If you go too high, you could produce a misfire as the engine RPM goes up and the coil dwell time becomes very short on a V8. This makes the available HT drop off quite rapidly above about 5000 rpm, so the extra resistance added to this could kill the spark. Id say as a rule of thumb unless you are running very low resistance "inductive" leads like magnecore then the HT leads should have enough resistance to do the job. Id only add extra if aftermarket electronics was affected.
Edited by blitzracing on Friday 25th November 12:29
Ok so re visiting the code structure, 6 isn't a huge change.
That's interesting re resistance Mark, I'm only using resistive plugs because I have the odd neighbour complain my car effects their TV so more an experiment on their behalf.
I'm liking the iridium ones too.
I'll consult with Jason at Powers and go from there
Cheers guys
That's interesting re resistance Mark, I'm only using resistive plugs because I have the odd neighbour complain my car effects their TV so more an experiment on their behalf.
I'm liking the iridium ones too.
I'll consult with Jason at Powers and go from there
Cheers guys
blitzracing said:
Pre detonation
Sigh.Blitz, I hold you in high regard for your obvious expertise on the RV8. But I've noticed before that the subject of detonation and pre-ignition is an area where you are confused, or you at least use a mixture of terminology that makes little sense. We all have our areas of confusion (I have many), and it seems that this one is yours. Please forgive me for humbly trying to correct your misuse of terminology.
There is no such thing as "pre-detonation".
The phrase "pre-detonation" is a contradiction, because the phenomenon of detonation takes place after the spark has fired. I'll say that again: detonation happens after the spark. As I'm sure you know, detonation is where the mixture burns explosively in an uncontrolled manner, and is caused by a variety of things (weak mixture, excessive compression, high temperature, wrong fuel grade, and others). But detonation is NOT spontaneous combustion. Detonation is initiated by the spark in the normal way (although the timing of the spark itself may be part of the problem); it is the subsequent violent burn that characterises detonation and causes cylinder pressure to rise far too quickly, and hence reach a much higher peak than it would otherwise because the piston is still high up in the cylinder.
The other phenomenon that people frequently mix up with detonation is pre-ignition. Often people seem to treat them as the same thing, but they are not. Pre-ignition happens before the spark has fired. It is caused by some other ignition source: perhaps a bit of carbon crud that's glowing hot, or a bit of metal swarf, maybe a damaged spark plug electrode or something like that (or, as you mention, the wrong grade of plug - although I reckon it would have to be grossly wrong to cause pre-ignition, except perhaps if you're really caning it on the track). This causes the mixture to ignite well before the spark, perhaps when the piston is still quite early in the compression stroke or even during induction - the resulting pressure rise due to combustion adds to the rising pressure due to compression, and you get extremely high pressure (typically much higher than you'd get with detonation).
The key difference is: detonation happens after the spark; pre-ignition happens before the spark. And they have very different causes.
Pre-ignition is way more damaging than detonation. Pre-ignition will destroy an engine in moments, whereas detonation typically doesn't. Detonation is usually only damaging over a longer period of time, and light detonation is unlikely to do much harm at all - in fact, modern engine management systems flirt with detonation all the time. By contrast, I don't think a "safe" level of pre-ignition can ever exist!
Lets banish the term "pre-detonation". It doesn't exist, and makes no sense once you understand the key difference between pre-ignition and detonation.
Edited to add: From the context of your post, you're clearly describing pre-ignition.
Edited by Dr Mike Oxgreen on Saturday 26th November 07:41
Dr Mike Oxgreen said:
.... There is no such thing as "pre-detonation".
When the phrase 'pre-detonation' is used I think what is actually meant is 'uncontrolled combustion', defined here on page 174:Edited by Dr Mike Oxgreen on Saturday 26th November 07:41
https://www.scribd.com/doc/207939150/Advanced-Engi...
So usage of the term 'pre-detonation' is kind of right.
Edited by davep on Wednesday 30th November 09:42
As recommended by LPG-man, I have been running Iridium 6 plugs for the last 30,000 miles and loving them. Only minor drawback is you have to remind your service centre that they are iridium 6s, or they will just swap them for standard 7s at the service..
So should I be moderating my advice and saying..... ".......except on turbo or super charged engines"?
So should I be moderating my advice and saying..... ".......except on turbo or super charged engines"?
QBee said:
As recommended by LPG-man, I have been running Iridium 6 plugs for the last 30,000 miles and loving them. Only minor drawback is you have to remind your service centre that they are iridium 6s, or they will just swap them for standard 7s at the service..
So should I be moderating my advice and saying..... ".......except on turbo or super charged engines"?
Reading the NGK guide, it would appear the Iridium ones are good for standard engines. B7ECS would suit turbo or supercharged engines as NGK state:So should I be moderating my advice and saying..... ".......except on turbo or super charged engines"?
"Racing spark plugs are generally constructed
with higher heat ranges due to the production
of more thermal energy from racing and
performance modified engines.
Different designs offer varying projection into
combustion chamber to match engine design
and performance characteristics.
Ground electrode designs vary to offer better
engine flexibility or resistance to damage by
high levels of combustion vibration and high
temperatures."
Powers fitted B7ECS on my turbo and I've fitted the same at the last service and she still performs well. So I think you are right Anthony.
davep said:
So usage of the term 'pre-detonation' is kind of right.
No, it really, really isn't.The terms are "detonation", and "pre-ignition".
There is no such thing as "pre-detonation".
The thing you've quoted is talking about 'bubbles' of the mixture sort-of spontaneously combusting as the flame front advances during a detonation event. But crucially, this is after the spark has ignited the mixture - overall, detonation is not a spontaneous combustion - it is initiated by the spark in the normal way. There is nothing about detonation that justifies sticking the prefix "pre-" in front of it.
What Blitz was talking about was simply pre-ignition.
There is no such thing as "pre-detonation". Unfortunately, his use of that term makes him sound foolish to anyone who isn't familiar with him, when quite obviously he isn't a fool.
Edited by Dr Mike Oxgreen on Saturday 26th November 16:59
Blitz obviously knows this, his problem is more likely to be answering questions to numptie's like me who confuse terminology in the first instance.
I ask some daft questions, possibly because I'm a fool or because at a late stage in life I've re kindled a very basic knowledge of mechanical engineering and find the technical answers rewarding to read and indirectly helps me understand my Tvr better.
I do now remember a distant lesson off a clever engineer who also explained the difference between pre ignition and detonation, I wish I'd not asked now
I ask some daft questions, possibly because I'm a fool or because at a late stage in life I've re kindled a very basic knowledge of mechanical engineering and find the technical answers rewarding to read and indirectly helps me understand my Tvr better.
I do now remember a distant lesson off a clever engineer who also explained the difference between pre ignition and detonation, I wish I'd not asked now
ClassiChimi said:
Blitz obviously knows this
For sure.And I hope it's clear that I'm only trying to clarify the terminology - because although Blitz undoubtedly understands the subject and is merely getting his terminology slightly wrong, unfortunately the confusion will spread to readers of this thread who don't understand that detonation and pre-ignition are two different beasts.
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