RogerH Posted February 10, 2015 Report Share Posted February 10, 2015 Hi Folks, I think the similar plug for a TR4/4A would be a BP6HT or BPR6HT. Does anybody know who may sell these. - I'm seeking that extra 50BHP. Roger Quote Link to post Share on other sites
Peter Cobbold Posted February 10, 2015 Report Share Posted February 10, 2015 (edited) If we knew how they work then we'd be on sounder ground. The improved feel to the engine that others report is probably due to less cycle-by-cycle variation in combustion. AKA 'coefficient of variation' or COV. These multilelectrode plugs, which do use edge-to-edge discharge, show improved cov: http://www.e3sparkplugs.com/combustion-analysis.php I cant find any COV data for the NGK plugs. The multielectrode design contrasts markedly with the 'wire plug' approach that opens up the gap to the mixture as widely as possible, reducing the quenching of the early flame on metal electrodes. The small diameter electrode (0.4mm) allows much leaner mixtures to be ignited reliably, as has been known since the '80s. http://www.globaldenso.com/en/products/aftermarket/plug/power/features.html http://www.globaldenso.com/en/products/aftermarket/plug/topics/2005/pdf/SAE-Manuscript.pdf (note fig 3) This ability of 'wire plugs' to ignite lean mixtures reliably might be useful in overcoming the pinking that some Lucas PI engines encounter upon sudden throttle opening, caused by a lean spike*. Has anyone tried wire plugs as a cure for that pinking? Peter *https://supertrarged.wordpress.com/2013/06/12/the-lucas-pi-lean-spike/ Edited February 10, 2015 by Peter Cobbold Quote Link to post Share on other sites
Guest ntc Posted February 10, 2015 Report Share Posted February 10, 2015 Just put a Viagra tablet in the tank same result :lol: Quote Link to post Share on other sites
Peter Cobbold Posted February 10, 2015 Report Share Posted February 10, 2015 (edited) More on cyclic variability using photos of the spark kernel and the flame progression: http://www.tvu.com/PCycleByCycleweb.html note the comment that "... the ground strap is both an obstruction and a heat sink for the new born flame". The triple electrode plugs must suffer badly from that, or is it a deliberate design feature? Maybe this is clue: "This looping of the spark is caused by flow through the gap that carries the low inertia ionized gas column away from its original location. As the arc moves and its channel length increases, the voltage needed to drive the arc increases until it becomes large enough to break down a new arc across the original gap. This characteristic voltage rise and sharp drop is a common characteristic of inductive sparks in engines." Perhaps the triple electrode arrangement forms a chamber that deters the escape of the ionised gas and so keeps the inital arc running without the need to strike a new arc. Edited February 10, 2015 by Peter Cobbold Quote Link to post Share on other sites
TR NIALL Posted February 10, 2015 Report Share Posted February 10, 2015 Just put a Viagra tablet in the tank same result :lol: Put the Viagra in your Tea for even better Results. Quote Link to post Share on other sites
RogerH Posted February 10, 2015 Report Share Posted February 10, 2015 I swallowed one the other day without a drink and it got stuck in my throat - I've now got a stiff neck. Roger Quote Link to post Share on other sites
Alec Pringle Posted February 10, 2015 Report Share Posted February 10, 2015 Just don't try using one as a suppository . . . . . . Someone mention daffodils ? Cheers Alec Quote Link to post Share on other sites
astontr6 Posted February 11, 2015 Report Share Posted February 11, 2015 Dear Peter, I am using the wire type plugs and have used the 3 electrode types. Both these designs are not new but the deference today is that the spark plug manufacturers are able to make them last much longer by using exotic materials. I did suffer from pinking in the late 1990's when I went unleaded ( Cyl Head Conv.) and had to retard my ignition to 7 degrees static, to cure it. But as the formula for unleaded changed during the 2000's, the pinking problem went away and also it has to be realised that both these types of plugs are designed for modern CD systems of 50 to 60 Kv on lean burn engines. Therefore in my mind, both types of plugs would have to be tested on a Dyno. to see which one performs best when used on an old Lucas Ignition system and old design plug leads. I personally believe that you will not get the best out of these two plug designs unless the ignition system is up dated. As stated before, I have up dated my electronic ignition of 20+ years old, to the latest Pertronixs Ignitor2 along with their special coil 45Kv. and wire plugs. I noticed a major difference straight away on start up let alone in the upper rev range. But I have not tried this system with the 3 electrode type. Bruce. Quote Link to post Share on other sites
Peter Cobbold Posted February 11, 2015 Report Share Posted February 11, 2015 (edited) Bruce, Wire plugs dont need high HT, the small diameter central electrode 'concentrates' the electrcial field ionisation and breakdown will occur at a lower HT than a conventional plug. That said more HT will help too. But for my application I am wary of going for more HT because of the risk of cross-firing in the disy cap - if that were to happen then a boost-filled plenum could blow itself apart from the backfire. With PI or carbs a cross-fire would not be so damaging. The test should be done as you say with new standard plugs run first, then replace with fancy ones: wire, triple whatever. A rolling road might have difficulty in picking up the difference in running. The improvement can be felt by drivers, but its response to transients that gets better and smoother part-throttle running, while RRs are best at picking up wot changes and not transient behaviour. The power gain may be trivial perhaps a percent point. But economy could improve more since part-throttle mixtures are more difficult to ignite reliably every cycle. Indeed your wire plugs with 45KV should allow you to lean out the mixture more than most, until the lean spike intervenes. I am puzzled why plugs from either end of the spectrum of design - more shoruded than standard versus a more open gap - should both improve running. Peter Edited February 11, 2015 by Peter Cobbold Quote Link to post Share on other sites
Peter Cobbold Posted February 11, 2015 Report Share Posted February 11, 2015 (edited) A description of the influence of electrode diameter on the initiation of the spark i.e. the ionisation, aka breakdown, phase: http://www.weaponxperformance.com/technicalPDF/SPARK_PLUG_TECH_V1.pdf It shows how the iridium electrode diameters of 0.5 to 0.6mm were found to be optimum, and how smaller diameters are better :- -by requirng less voltage ( figs 2 , 5) -at igniting lean mixtures down to AFR 17 ( fig4) The NGK iridium plugs with heat range recommended for supercharged TR6 engines also have 0.6mm diameter central electrodes. (see blog). Group of 6 graphs summarising the factors that influence the voltage needed by plugs: http://www.stealth316.com/2-sparkplugtech.htm#j4c Edited February 11, 2015 by Peter Cobbold Quote Link to post Share on other sites
poolboy Posted February 12, 2015 Report Share Posted February 12, 2015 Two hundred and fifty miles: Am I on the Edge of Destruction ? Quote Link to post Share on other sites
Peter Cobbold Posted February 12, 2015 Report Share Posted February 12, 2015 (edited) Two hundred and fifty miles: Am I on the Edge of Destruction ? Looks fine to me! Why these plugs should work better then standard while being so dfferent from wire plugs, which also work better than standard, is a puzzle. They're fresh plugs so nothing to do with the much longer service life of both types. Odd. And Nick Jones reckons these prechamber plugs are better too: post12: http://sideways-technologies.co.uk/forums/index.php/topic/6251-spark-lifetime/ Peter And for the ultimate plug, the Fan Flame: http://www.mtfca.com/discus/messages/257047/317694.jpg Edited February 12, 2015 by Peter Cobbold Quote Link to post Share on other sites
marki Posted February 12, 2015 Report Share Posted February 12, 2015 I take it these plugs are preset ie plug gap ? Cheers Mark Quote Link to post Share on other sites
stephen cooper Posted February 12, 2015 Report Share Posted February 12, 2015 When i was at the rolling road I did a run with plasma plugs (black line) and then with new NGK BP6ES (yellow) Quote Link to post Share on other sites
Peter Cobbold Posted February 12, 2015 Report Share Posted February 12, 2015 When i was at the rolling road I did a run with plasma plugs (black line) and then with new NGK BP6ES (yellow) Cant find those plasma plugs - what do they look like? Clearly not good above 4500rpm.! Peter Quote Link to post Share on other sites
stephen cooper Posted February 12, 2015 Report Share Posted February 12, 2015 Hi Peter, They are the ones in post 12 on the other forum you referenced. Of course an RR does not give a full picture, I ran them in my old 2.5pi saloon first. Seemed a bit better at running from cold in that. My weber 6 is very smooth right from cold. The only other thing I tested was K&Ns, mine are quite soiled and cost 2 BHP at the top end over running no filtration. May go again this year, see how its doing Quote Link to post Share on other sites
Peter Cobbold Posted February 13, 2015 Report Share Posted February 13, 2015 (edited) Hi Peter, They are the ones in post 12 on the other forum you referenced. Hi Stephen The idea with that type of prechamber plug is to extent the lean misfire limit, to improve fuel economy and lower NOx. Many have smaller holes that prevent flame passing through, like a Davey lamp. They work by spraying, not flame, but precursor chemical radicals that initiate flame outside the plug. So the flame starts over a much bigger volume, improving the probabilty of getting a lean mixture to fire. At higher rpm there may be insufficient time to refill the chamber with ignitable mixture, hence the fall off. The major application is in low speed large capacity gas engines so refilling not an issue there. I speculate that the triple electrode plugs may, likelwise, improve firing by cooling the kernel locally within the electrode gap and generating a bigger volume of those precursor radicals , whcoh dont get blown away as fast as from a conventional plug. So, as the kernel expands out of the gap the intiation of a flame front away form the plug is aided by the cloud of accumulated radicals. The design will have to be a compromise between trapping radicals in the gap and refilling the gap with fresh mixture. Some designs of riple electrode plugs have more extensive earth elctrodes that will create a bigger restricted space. They are modern designs where lean burn, lower NOx and long service life are important. Peter Edited February 13, 2015 by Peter Cobbold Quote Link to post Share on other sites
Peter Cobbold Posted February 14, 2015 Report Share Posted February 14, 2015 Prechamber spark plugs, state of the art: Peugeot-Citroen: http://www.freepatentsonline.com/7104245.pdf Mahle: http://www.greencarcongress.com/2010/10/tji-20101027.html They both spray several ca 1mm jets of cooled unstable precursor chemicals , not flame itslef, to intiate autoignition of the main chamber mixture over a big volume. This reduces burn time and has 'green' benefits: better thermal effciciency, lower NOx, higher octane. Peter Quote Link to post Share on other sites
JohnG Posted February 14, 2015 Author Report Share Posted February 14, 2015 (edited) Prechamber spark plugs, state of the art: Peugeot-Citroen: http://www.freepaten...com/7104245.pdf Mahle: http://www.greencarc...i-20101027.html Have to say, I'm impressed. Getting away from a "spark plug" and igniting, a much higher % of the mixture more quickly and more efficiently has to be the aim with our engines. Better fuel economy, improved power curve & reduced emissions. Peter The question is; are they available and if so where, otherwise, when? John Edited February 14, 2015 by wjgco Quote Link to post Share on other sites
Peter Cobbold Posted February 14, 2015 Report Share Posted February 14, 2015 (edited) Peter The question is; are they available and if so where, otherwise, when? John John, I think there will be a plug revolution that will eventually be usable in TRs. The Mahle plug needs its own fuel supply, a tiny volume about 3% of main charge, so I see big problems with delivering that outside of a lab environment. The Citroen plug wont allow running at high rpm, indeed they suggest its target applciation is boosted engines where the boost refills the prechamber. So neither route is realistically a retrofit for TRs. But a plug that reliably ignities a big volume of mixture more rapidly than conventional plug. will do the job better. Why? A conventional plug.spark kernel around 1mm long and a volume of ca 0.1 cubic millimetre has to fully enflame a 30ml chamber of mixture - that's 300,000-fold bigger volume - in about 45crank degrees. At 3000rpm it has about 2.5 msec to do that.( Because a full rev takes 20 msec. Spark timing 30BTDC, peak pressure at 15ATDC). That 300,000fold volume rise varies a lot in its time course cycle by cycle with the mixture velocity and richness in the plug gap and a mm of so beyond having big influence. Turbulence in the combustion chamber has a scale of roughly around 1cm, so we can imagine a spark occurring either at the fastmoving edge or in the stagnant centre. Fast leads to rapid flame expansion, but a spark in the stagnant mixure greatly delays it. The mixture wil vary locally too; lean burns slower So the rise in pressure varies cylce by cycle: http://getadomtune.com/galleria/var/albums/Lessons/CombustionDifference.jpg?m=1362881043 As a result spark timing can never be perfect, however hard we try. The solution is to ignite a big volume fast. The most practicable ignition for doing that seems to me to be corona discharge, with ionisation streamers centimetres long: And BorgWarner too: http://www.beru.com/download/produkte/whitepaper_ecoflash_en.pdf We'll know when beemers and the like fit them. I can see them working in TRs too. Peter This article describes the events occurring in the plug gap - shows the importance on cyciic varaition of turbulence and mixture is the very earliest stages of flame intitiation: http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=164442&fileOId=625828 ( the first 5 pages of the pdf are useful, then it gets too complicated ) Edited February 14, 2015 by Peter Cobbold Quote Link to post Share on other sites
Peter Cobbold Posted February 14, 2015 Report Share Posted February 14, 2015 More Russian prechamber plugs,like in posts 12 and 114. https://www.drive2.ru/b/1634049/?page=2 ""Pre- combustion chamber jet engine or why prechamber spark - do not work " Quote Link to post Share on other sites
marki Posted February 14, 2015 Report Share Posted February 14, 2015 Right I've bit the bullet and bought some. Has anyone fitted them with a standard PI system ? Haven't had the balls to fit them yet......Mark Quote Link to post Share on other sites
Peter Cobbold Posted February 14, 2015 Report Share Posted February 14, 2015 Mark, Which plugs? Wire- iridium? I think John Jervis has fitted them recently: https://supertrarged.wordpress.com/2015/01/19/john-jervis-fitting-a-moss-supercharger-kit/ AFAIK the gap is not adjustable, but the electrodes wear so slowly that they are fit and forget. Peter Quote Link to post Share on other sites
marki Posted February 14, 2015 Report Share Posted February 14, 2015 Hi Peter NGK BUR6ET. Mark Quote Link to post Share on other sites
JohnG Posted February 14, 2015 Author Report Share Posted February 14, 2015 Mark Hi I have them fitted to my PI. They have provided smoother tick over and cold running. A great improvement over the standard fit plugs, although there seems to be a wide range of opinion as to why they should. It's all good educational stuff. I just wish I understood all of it! Put 'em in and give them a go John Quote Link to post Share on other sites
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