Spark plugs

Spark plugs

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ClassiChimi

12,424 posts

149 months

Sunday 4th December 2016
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I should have known getting into things like iridium would open up the world of science to me hehe
Freaked out now yikes
Do they omit radiation I've i drop em laugh

Ok so if the gaps 0.6 I'll be happy with that then, special tool, I've got a small screw driver I was going to Wedge in there.

I take the point they are gapped correctly by NGK
So should be plug in and play. I'll check them anyway smile

ChimpOnGas

9,637 posts

179 months

Sunday 4th December 2016
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ClassiChimi said:
I should have known getting into things like iridium would open up the world of science to me hehe
Freaked out now yikes
Do they omit radiation I've i drop em laugh

Ok so if the gaps 0.6 I'll be happy with that then, special tool, I've got a small screw driver I was going to Wedge in there.

I take the point they are gapped correctly by NGK
So should be plug in and play. I'll check them anyway smile
Alun, here's the history and evolution of the spark plug ending with the use of iridium and why:

https://www.youtube.com/watch?v=7N-7WGfnKHo

Now learn more about amazing iridium:

https://www.youtube.com/watch?v=cuovE4OQi2g

By the way you really shouldn't use traditional copper core plugs once you've upgraded to distributorless ignition as with your MBE system, ideally you want to fit platinum fine wire or better still iridium.

Both platinum & iridium materials were only really chosen as a direct response to the specific needs of EDIS, but others still running a distributor can also benefit from these newer technology plugs, the Denso TT twin iridium tips are the latest development and apparently they do offer benefits.

SILICONEKID345HP

14,997 posts

231 months

Sunday 4th December 2016
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I thought Iridium were used for stomach ache .confused

WokingWedger

Original Poster:

1,030 posts

205 months

Sunday 4th December 2016
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[quote=SILICONEKID345HP]I thought Iridium were used for stomach ache .confused[/quote

Look out Dave they may stop your gas!

ChimpOnGas

9,637 posts

179 months

Monday 5th December 2016
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WokingWedger said:
Just ordered the Denso iridium twin tip.

I will report back !
Great stuff Peter, lets have a review of the Denso TTs when you've fitted them.

At this point its worth reminding ourselves of the dreadfully inappropriate shrouded electrode no 7 (too cold rated) NGK B7ECS, and how they normally look when you pull them out.



Compare this with the much more suitable extended electrode BPR6ES, but sitting next to the even better new for 2015 Denso TT with its twin fine wire electrode plugs.



Kind of makes the original B7ECS chosen by TVR look archaic, which of course it is!

On the Denso TT only the centre electrode is iridium with the earth electrode being platinum, this is the same recipe as my very expensive NGK LPG Laserline plugs which add a special anti-corrosion coating for longer life when burning propane.

The main difference is the platinum earth side on the Denso TTs is a second fine wire construction like the iridium centre electrode, so it too sits projected out of the electrode. The platinum on my NGK LPG Laserline plugs is a chip that is set into the earth electrode so it retains the traditional earth electrode shape.

I really like the look of the Denso TT design, I saw benefits when I moved to iridium plugs and the Denso TTs could be the next step in the development of the fine wire concept which definitely works, car manufacturers adopted the technology some time ago and they don't fit snake oil.

While I appreciate a lot of the benefit is longevity and service life we all know from school by physics that electricity prefers to conducts through sharp pointy shapes rather than flat ones. Lightning is often used to demonstrate this in a very dramatic way, the reason is that for an electrically charged object the electric field at the surface is inversely proportional to it's curvature radius. When an object is very sharp, the electric field is higher and can induce a lightning channel by attracting air then repelling the electrons in the air.



This is why lightning rods are pointed, lightning rods typically have a sharp & pointed tip because electric lines of force are more highly concentrated around pointed objects for the reasons already given. And lets be honest if lightning strikes you want it to strike the lightning rod and not the structure the rod is there to protect, for many years the tallest buildings in our towns & cities were churches, this is why church spires are typically pointy.

In the case of a spark plug you want the spark to jump in a controlled way using the least voltage possible so it stands to reason anything you can do to help with this like making your electrodes sharper and more pointy will only be a good thing. If using one sharp and pointy small radius fine wire electrode as with my iridium tipped LPG Laser Lines offers clear benefits, then using the same well accepted rules suggest having two opposing pointy electrodes (live & earth) as with the new Denso TT will deliver twice the benefit.



Let us know how you get on with them mate thumbup

blitzracing

6,387 posts

220 months

Monday 5th December 2016
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Ummm--I appreciate all the theory about the ionisation tip on a modern plug, but we are dealing with a 50 year old engine design here, long before you could computer calculate things like the flame front path or even where to put the spark plug for the best flame front in the cylinder head. Also you do hit the spark plug gap with a very big hammer, it takes a great deal to stop 15kv in the first place what ever shape the electrode, and the arcs only function is to ignite the mixture once reliably. The issue is here is we have absolutely no documented evidence for combustion improvements on the rolling road that I have seen and the one test I've seen of new stock plugs against the iridium equivalents, the results where exactly the same. This does not tally with "improved combustion" as you would see a power increase or reduced emissions. I don't have an issue with increased service intervals or general reliability, but lets have some real facts other than the "bum" dyno for this engine before we empty our wallets.

SebringMan

1,773 posts

186 months

Monday 5th December 2016
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The combustion may not be any different but the reliability will be improved and while some may less you're being lazy leaving the plugs in for longer there is less chance of coming across a duff batch of spark plugs.

I know I did with the Triumph Stag (NGKs). Because they were new I chased everything else, only for the new NGKs to be the problem.

ClassiChimi

12,424 posts

149 months

Monday 5th December 2016
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Would these exotically tipped plugs put more or less strain on the ignition system or is it so small as to be negligible


One tip which sounds like good sense, don't leave them in there too long as they can be very hard to remove after 30,000 miles.
As part of a normal service it must be a good idea to check the gaps/condition anyway.

ChimpOnGas

9,637 posts

179 months

Monday 5th December 2016
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blitzracing said:
Ummm--I appreciate all the theory about the ionisation tip on a modern plug, but we are dealing with a 50 year old engine design here, long before you could computer calculate things like the flame front path or even where to put the spark plug for the best flame front in the cylinder head. Also you do hit the spark plug gap with a very big hammer, it takes a great deal to stop 15kv in the first place what ever shape the electrode, and the arcs only function is to ignite the mixture once reliably. The issue is here is we have absolutely no documented evidence for combustion improvements on the rolling road that I have seen and the one test I've seen of new stock plugs against the iridium equivalents, the results where exactly the same. This does not tally with "improved combustion" as you would see a power increase or reduced emissions. I don't have an issue with increased service intervals or general reliability, but lets have some real facts other than the "bum" dyno for this engine before we empty our wallets.
Well, you'd need to pay me a lot of money to go back to NGK B7ECS, a distributor and a single coil... things have moved on mate and while you may choose not to believe I've enjoyed some very real benefits from iridium plugs even when I was running the factory ignition system, I'm here to tell you I most definitely did.

My recent experiments show this engine likes a lot more advance at idle than the distributor could ever hope to deliver without ending up way over advanced as engine speed increases, I've settles at 24 degrees on LPG and 23 degrees on petrol and with a 13.3:1 AFR target the engine is clearly happier this way as the idle is way smoother and when you pull away you can immediately feel the new bubble of torque that wasn't there before making slow speed manoeuvring of my TVR as smooth and controllable as any modern car.

When I fitted the iridium plugs some years ago to what was at the time a very standard Chimaera the effects were very similar to advancing the timing, and if you think about it this makes perfect sense, if the iridium plug is more effective at starting the burn it will be just the same as advancing the timing. With the iridium plugs the car immediately became easier to reverse park and idled smoother too, this has got progressively better as I added the Canems engine management system, MSD coil packs, MSD super conductor HT leads and finally advanced my timing at idle to 23/24 degrees.

The other thing that definitely helped were the elimination of all the tiny vacuum leaks that existed and went unnoticed especially around the crankcase ventilation pipes that attacked by corrosive crankcase fumes go baggy over time, pipes that are just a push fit and really benefit from hose clips. Actually if we look at the crankcase ventilation system it's really just a controlled vacuum leak itself, and not a very well controlled one at that. The idle control circuit is then plumbed into all this for good measure so the poor old stepper motor is trying to regulate idle speed using dirty turbulent air taken from immediacy in front of the throttle butterfly, none of this makes for a smooth idle or smooth driving progress at small throttle openings. If you look at more modern crankcase ventilation systems or even better designed ones that are contemporary to the 14CUX equipped Range Rovers & TVRs you'll see a PCV valve that shuttles back and forth between full plenum vacuum and atmospheric pressure ahead of the throttle butterfly.

The way Range Rover regulated all this was to simply use hose diameter, by placing a brass restriction in the hose to the plenum where there's a strong depression and using a larger bore hose connected just ahead of the throttle butterfly they hoped to create the right balance between the two. But this is a very crude system that doesn't even deploy a check valve let alone a proper PCV valve so there's nothing to stop a pulse of back pressure creating a sudden pressure shift right in front of the throttle butterfly with the inevitable unwanted drivability issues it will promote. Right opposite all this is the point they chose the idle control valve (stepper motor) should take it supply of air from, its really no surprise these cars can get into a cycle of shunting at small throttle openings with a system like that.

Even if you don't have a fancy engine managements system that allows you to dial in more advance and a richer mixture at idle, with decent HT leads, the deletion of those dreadful plug extenders, a set of iridium plugs, a simple check valve in the PCV hose and a handful of hose clips you can make a standard Chimaera idle and drive massively better. Let the stepper motor breath clean still air at atmospheric pressure, block the now open steel pipe on the throttle body and it'll idle better still, reset your base idle and its job done.

If you regularly go to TVR events and you have an ear for such things you'll hear a lot of Chims and Griffs that idle and run like total krap, it really is super common. Why people put up with this is beyond me but I guess they just think that's how they are, the truth is if your RV8 hunts and has a nasty miss/flat spot just off idle you really don't need to put up with it.. nono

And the good news is it doesn't need to cost a King's ransom to put right. wink




ChimpOnGas

9,637 posts

179 months

Monday 5th December 2016
quotequote all
ClassiChimi said:
Would these exotically tipped plugs put more or less strain on the ignition system or is it so small as to be negligible
That's the point Alun (no pun intended), these plugs put less strain on your coil packs not more because less voltage is required for the spark to jump the gap.

If people are still running cats they should delete these too as they're just a great big restriction for the exhaust gasses to pass through. You wouldn't fit such a restriction by choice, cats are only there to clean up exhaust emissions so if you can do away with them do so tomorrow or sooner.

Linked to the cats is the necessity for the narrow band lambda sensor equipped 14CUX to be configured to try and achieve the cat friendly and way too lean at idle 14.7:1 AFR. Narrow band lambda sensors work well but only in the very narrow window of 14.2:1 to 15.0:1 AFR, this is fine for most situations but it most definitely isn't the AFR this engine likes to idle at. If you could choose a nice smooth idle AFR is would be in the much richer 13:1 to 13.5:1 range, and after market ECU with tfar superior wide band lambda sensor feedback allows you to achieve just that. So it should really come at no surprise that 14CUX equipped TVRs hunt at idle as they lurch around the 14.7:1 AFR point at 10-12 degrees of timing, worse still many of them are sucking more air than they should via a host of tiny and difficult to detect vacuum leaks, the poor old 14CUX desperately tries its best to correct this to the already too lean target of 14.7:1 target but burdened with two narrow band lambda sensors cant hope to do so effectively.

That's why anything you can do to improve the way the your Chimaera engine breaths like ditching the very restrictive cats, or burns its fuel by fitting a set of plugs that promote better combustion, will definitely be translated to a smoother idle and the response you feel at that moment you start to squeeze the throttle pedal. These iridium plugs aren't magic, but it's just because all the systems on the Chimaera don't really promote a nice idle in the first place that when you do fit a set iridium plugs you can actually feel the difference, a difference you might not even notice on any other car.

Try a set for yourself, then and only then tell me I'm wrong. wink

WokingWedger

Original Poster:

1,030 posts

205 months

Monday 5th December 2016
quotequote all
Will I need to adjust the timing using Denso iridium twin tip ?

I guess I try it, and see if it 'pinks'.

If yes, then I may have a decision to make !

ChimpOnGas

9,637 posts

179 months

Monday 5th December 2016
quotequote all
WokingWedger said:
Will I need to adjust the timing using Denso iridium twin tip ?

I guess I try it, and see if it 'pinks'.

If yes, then I may have a decision to make !
No timing changes required, the effects of these plugs may be similar to adding a few degrees of timing at idle... but you'll only really notice it at idle. You're not really changing your timing by fitting these plugs, just improving combustion at idle a little which can have a similar effect, they're completely safe and there's no timing adjustments needed when fitting these plugs.

Its important to point out the improvement these plugs make is quite small, but if you're properly in tune with your engine and how it currently runs and drives you should notice an improvement at idle and just above idle as you pull away or manoeuvre the car at slow speed (reverse parking ect).

If you want to hear the difference 8-10 degrees has on your idle quality simply suck hard on your vac advance pipe and hold the vacuum by letting the end of the pipe stick to your tong, watch your timing markes with a strobe to watch the 8-10 degrees you're adding. If your vac advance module doesn't have a split diaphragm and your base plate in the distributor isn't seized you should achieve a 150-200rpm rise in your idle speed. This increase in idle speed will mask what you really want to hear, so screw your base idle back down to 900rpm and your engine should idle much nicer than you're used to, of course as soon as you let the vacuum go the engine will stall.

This would work better if you could also dial in a richer AFR at idle (13.0:1 to 13.5:1) which is tricky on the 14CUX as it always wants to be at 14.7:1, just make sure you don't have any vacuum leaks as your 14.7:1 could easily be a very hunty 15.5:1 which can only be properly corrected by eliminating the tiny overlooked vacuum leaks these cars very often suffer from (check baggy push fit PCV hoses at barbed "T" joiner and use hose clips).



N7GTX

7,855 posts

143 months

Monday 5th December 2016
quotequote all
blitzracing said:
Ummm--I appreciate all the theory about the ionisation tip on a modern plug, but we are dealing with a 50 year old engine design here, long before you could computer calculate things like the flame front path or even where to put the spark plug for the best flame front in the cylinder head. Also you do hit the spark plug gap with a very big hammer, it takes a great deal to stop 15kv in the first place what ever shape the electrode, and the arcs only function is to ignite the mixture once reliably. The issue is here is we have absolutely no documented evidence for combustion improvements on the rolling road that I have seen and the one test I've seen of new stock plugs against the iridium equivalents, the results where exactly the same. This does not tally with "improved combustion" as you would see a power increase or reduced emissions. I don't have an issue with increased service intervals or general reliability, but lets have some real facts other than the "bum" dyno for this engine before we empty our wallets.
Agree with Blitz. I would be very surprised to see anything near 15kv on a single coil and distributor engine especially on a V8. I regularly use a spark tester to measure each cylinder. It tests the spark duration and the KV and on the shorter plug leads the KVs may be 8-10 KVs. On the longest leads, the KVs will be as low as 5 or 6.

Increasing the gaps will mean more energy to jump the electrode and on long leads this could become unreliable on a single coil system. That is why older plugs such as the B7ECS, BPR6ECS and so on are factory set to 0.6mm (lower resistance to jump the gap).

On later plugs fired by pencil coils and coil packs which deliver a much higher and far more reliable spark, the gap is typically set at 1.1mm on platinum tips. The KVs are often up to 25 so this energy can jump the electrodes easily. The downside is the higher heat and burning will tend to erode the electrode and a copper cored plug would burn away relatively quickly. Hence the use of much stronger metals such as platinum and iridium to prolong life. Removing platinum tipped plugs from say a Ford Focus after 40,000 miles and the wear is negligible and even at 60,000 miles on an S type, it is hard to tell the difference.

But for those with forced induction, refer to NGK and your installer, as the B7ECS is highly recommended as a plug for racing and hard use situations. wink

I would tend to follow the advice from NGK as in this link:
http://ngkntk.co.uk/wp-content/uploads/2011/04/588...

Edited by N7GTX on Monday 5th December 18:50

blitzracing

6,387 posts

220 months

Tuesday 6th December 2016
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Heres the roller results for iridium plugs:

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

As for the available HT applied to the plug it works this way- The plug gap is open circuit, but as the HT rises a small amount of ionisation occurs, as a precursor to the arc being established. At some point the insulation affect of the air gap breaks down and an arc is established that now looks much like a short circuit, so the HT wont rise any further and will start to fall as the coil discharges. The big point here is the HT will simply keep rising into an open circuit as the magnetic fields collapse in the coil- you could see 30kv if the plug gap was big enough, but you don't because the arc will happen before this point is reached. In the case of the single coil on the RV8, you simply don't have the dwell time available to allow the coil to reach magnetic saturation between cycles as the RPM rises, so the peak HT available starts to drop of quite sharply, and the plug gap is small enough to ensure a reliable arc at whatever RPM. I will certainly consider that using a pointed electrode with a wider gap will allow a better combustion point to initiate a flame front - but measuring the effect may prove difficult. Id think the real results would be reduced HC in an exhaust gas test, as this would show the mixture had burnt more effectively. It would be a nice easy test to do with stock vs iridium plugs as apart of an MOT test.

WokingWedger

Original Poster:

1,030 posts

205 months

Tuesday 6th December 2016
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Not looking for more power, just a bit less fouling and smoother running.

I now have the plugs but need a few days before fitting and reporting

ChimpOnGas

9,637 posts

179 months

Tuesday 6th December 2016
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WokingWedger said:
Not looking for more power, just a bit less fouling and smoother running.
And that you will for sure yes

Sometimes people spend a lot of energy trying to prove someone is wrong, when all they really need to do is accept moving on from the dreadfully inappropriate NGK B7ECS can only be a good thing rolleyes

All the text book babel could never convince me my ears and senses were wrong, my car idled better when I fitted iridium plugs and thems the real world tried and tested facts folks yes

blitzracing

6,387 posts

220 months

Wednesday 7th December 2016
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I totally agree that B7ECS is a very bad choice and anything that reduces fouling is a good thing, but I've never seen a fouling issue on the BP6ES plugs on an engine that runs correctly. Im very happy however to be a test guinea pig on the gas test next MOT (March next year) to see if the HC drops with Iridium as a definitive test. As a side issue if you do get uneven colouring on the stock plugs it can be due to blocked injectors, where the fuel does not atomise correctly and effectively washes one side of the plug insulator as it enters the combustion chamber, so its time for a bottle of injector cleaner.

ChimpOnGas

9,637 posts

179 months

Wednesday 7th December 2016
quotequote all
blitzracing said:
I totally agree that B7ECS is a very bad choice and anything that reduces fouling is a good thing, but I've never seen a fouling issue on the BP6ES plugs on an engine that runs correctly. Im very happy however to be a test guinea pig on the gas test next MOT (March next year) to see if the HC drops with Iridium as a definitive test. As a side issue if you do get uneven colouring on the stock plugs it can be due to blocked injectors, where the fuel does not atomise correctly and effectively washes one side of the plug insulator as it enters the combustion chamber, so its time for a bottle of injector cleaner.
Don't get me started on those old Lucas disc type injectors used on the 14CUX equipped Rover V8s, they're in need of updating as much as the dreadful B7ECS plugs.

I'll avoid telling my MA injector cleaning scam story rolleyes

The truth is there are so many little things you can do (using better & newer parts) that will improve the way your TVR runs its a crime not to do them, and best of all it doesn't need to cost the earth either.

blitzracing

6,387 posts

220 months

Wednesday 7th December 2016
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Like you I did not believe the MA story about the injectors, but to be fair to the man, I did have uneven colouring to the plugs, that has now gone after a full injector clean. You should know me well enough by now that I always like to double check the facts--- smile

Edited by blitzracing on Wednesday 7th December 10:37

ChimpOnGas

9,637 posts

179 months

Wednesday 7th December 2016
quotequote all
MA has some very specific knowledge on the 14CUX for sure, but for way too long he's also held & profited from his unique position as the only person able to map the system.

I watched him at work (and at sleep), what I got for my chunk of money was:

1. A rather basic health check that yielded nothing because I'd already done it myself

2. A period where he plugged in his laptop, sat in my car on the rollers, had a little snooze on my time, but made no changes to the fuelling because that would have involved burning me a new chip which he most certainly didn't do

3. An insistence I needed my injectors cleaning when I'd only recently fitted a set of far superior and flow matched Seimens (Vectra) injectors

Not content with this MA went on to tell me he couldn't solve my hunting, so I asked if he felt my catalytic converter was partly to blame, MA said absolutely not. A week later I removed it anyway and resolved 90% of the hunting in a stroke.

The final test for me came when an old Healey 100/4 turned up idling about 300rpm too high and an owner unable to resolve the issue. Now I cut my teeth on these basic things so I asked MA what he thought and stood back to see if he really knew his onions, he stumbled and struggled to deliver a convincing diagnosis.

Now I know a set of SUs are very different to the skills needed to tune the 14CUX system but if he couldn't diagnose an obvious issue on such a basic machine it was clear to me he shouldn't be working on my car. So with the owner of the Healey claiming he's just had his carbs rebuilt, ignoring this I simply reached for the throttle spindles and gave them a wiggle, "there's your problem mate" I said, "ask whoever rebuild these SUs for your money back, the spindles and bushes are totally shot, its inducting air via the wear so you'll never get your idle down until the wear has been resolved".

MA looked at me open mouthed clearly astonished by what is after all is the very first thing any half competent mechanic worth his salts would check on a high idling pair of SUs, I just looked at him and shook my head.

My experience of MA was not great, I'm not saying he's a complete charlatan because there are clearly things he knows about the 14CUX that are still being discovered to this day, but I can 100% grantee you he never served as an apprentice in a proper workshop under the supervision of time served mechanics, and without this grounding and basic knowledge of simple fuel, ignition systems and diagnostic skills he at best can be described as a very one dimensional 14CUX one trick pony.

That sounds harsh, but I feel people should know the truth about MA as many are still paying him lots of their hard earned money for his services in the misguided belief he's some sort of engine tuning Svengali, which as I witnessed with my own eyes he most definitely isn't nono

MA and his performance that day was one of the many reasons I chose to wave goodbye to my distributor ignition and 14CUX fuelling system, I recommend that anyone wavering on the decision to move to a more modern engine management system should stop procrastinating over misguided engine bay originality aesthetics... and do the same.

Freeing yourself from the 14CUX isn't cheap but neither is MA, once you've taken the plunge and installed a more modern fuel and ignition engine management system you will never look back... and I include you in that Mr Blitz wink

Deep down you know it makes sense mate yes




Edited by ChimpOnGas on Wednesday 7th December 11:14