HT Leads Tested

HT Leads Tested

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ChimpOnGas

Original Poster:

9,637 posts

178 months

Thursday 21st August 2014
quotequote all
Taken from some tests done in the States:

Granatelli wires (2 OHMs)
Here we have the Granatelli wires. These wires were the lowest wire OHM resistance wire we have ever tested, at 2 ohms of resistance. Granatelli uses a stainless steel core, wrapped in silver plated copper wiring. This is the highest quality wire we have ever carried, and the wire that we strongly recommend.


MSD wires (33 OHMs)
In second place, we have the MSD wire set. Compared to the Granatelli wires in first place, these wires are red in color, and come in at 33 ohms of resistance to the Granatelli wires's 2 OHMs of resistance. The MSD wires are still good quality though. Msd states on their boxes that they use a copper alloy conductor for their wires.


ACCEL wires 124 OHMs
In third place, we have Accel wires. These use a copper/alloy wire core, and are has a 8mm silicone jacket. These wires had a cheaper feel, and look compared to the other wires, but still had a great, low resistance.


Mopar wires 390 OHMs
Fourth place belongs to the Mopar Performance spark plug wires. We measured these wires to have 390 OHMS of resistance which is quite high, but still acceptable.


Magnecor wires 1548 OHMs
Fifth place place belongs to the Magnecor wires. Magnecor wires had the highest resistance out of all of the wires we tested, coming in at 1548 OHMS of resistance. (In Magnecor's defense, they claim that low OHM resistance wires are not a measure of quality).


The results on the Magnecor & MSD leads come very close to my own, the Granatelli leads perform the best but I prefer to trust MSD as they have a very long history in the US performance ignition market with an excellent reputation for quality & customer service.

I've been running MSD Mustang performance coil packs on my TVR for some time, these are very popular in the States with guys fitting turbos to their fox body Mustangs who suffer spark blow out on standard coil packs.

I dont want to provoke a debate on MSD vs standard coil packs, all I can say is after thousands of miles they've proved to be 100% reliable on my LPG TVR that will definitely be putting more load on the coils than the same car burning petrol.

spitfire4v8

3,990 posts

180 months

Thursday 21st August 2014
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blitzracing said:
Sorry mate- wrong way around I think
banghead
paperbag

Pupp

12,206 posts

271 months

Thursday 21st August 2014
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And just for balance, I run MSD coil packs and Magnecor leads. Never had an issue with the leads in 120k + miles but I did have a new coil pack die. Not sure that proves anything at all

blitzracing

6,387 posts

219 months

Thursday 21st August 2014
quotequote all
Please guys- stop getting hung up on DC resistances- a coiled type HT lead might become the equivalent to 10k ohms when presented with the HT spike- this value depends on how many turns the spiral core is and what its wrapped around. This is how some radio suppression is created, other wise we might as well all use copper cores if you want 100% spark energy.

Sardonicus

18,928 posts

220 months

Thursday 21st August 2014
quotequote all
Pupp said:
And just for balance, I run MSD coil packs and Magnecor leads. Never had an issue with the leads in 120k + miles but I did have a new coil pack die. Not sure that proves anything at all
120k since fitting eek .... now there's a man who gets to enjoy his TVR bow I have a set of these spiral wound steel core and those trick bendy plug ends to avoid the ex primaries and decent thermal socks and no plug extenders wink


Edited by Sardonicus on Thursday 21st August 12:07

SILICONEKID345HP

14,997 posts

230 months

Thursday 21st August 2014
quotequote all
Sardonicus said:
20k since fitting eek .... now there's a man who gets to enjoy his TVR bow I have a set of these spiral wound steel core and those trick bendy plug ends to avoid the ex primaries and decent thermal socks and no plug extenders wink


Edited by Sardonicus on Thursday 21st August 12:07
I thought you did only 500 miles a year rolleyes My old man uses the old copper leads for his Cresta ,why not use them ?


Edited by SILICONEKID345HP on Thursday 21st August 14:30

Sardonicus

18,928 posts

220 months

Friday 22nd August 2014
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You can't Daz no suppression/resistance with copper your ECU would spit it's dummy

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 22nd August 2014
quotequote all
Sardonicus said:
You can't Daz no suppression/resistance with copper your ECU would spit it's dummy
Simon mate, can you foresee any Canems ECU issues for me on the MSD leads?

Sardonicus

18,928 posts

220 months

Friday 22nd August 2014
quotequote all
ChimpOnGas said:
Simon mate, can you foresee any Canems ECU issues for me on the MSD leads?
Probably not Dave so long as you keep the resisted spark plugs , EDIS ignition is proper fussy with this stuff and I have had no issues with my Accel leads (metal cored) but with resisted plugs.

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 22nd August 2014
quotequote all
Sardonicus said:
ChimpOnGas said:
Simon mate, can you foresee any Canems ECU issues for me on the MSD leads?
Probably not Dave so long as you keep the resisted spark plugs , EDIS ignition is proper fussy with this stuff and I have had no issues with my Accel leads (metal cored) but with resisted plugs.
Thanks Simon thumbup

Mark Adams

356 posts

259 months

Friday 22nd August 2014
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This topic comes up regularly, and it seems that nearly everyone has an opinion on spark plug leads! However most of the people who express those opinions do not use (or even have) an ignition analyser, which is a bit like choosing wallpaper in the dark. When I am on the rollers tomorrow, I shall try and get a couple of printouts from the ignition analyser and annotate them, so that you can see what I am talking about.

Here are the basics. There are two distinct phases to the ignition cycle, which impose different demands on the system.

Current does not flow in the system until the arc across the plug electrodes has initiated (been "struck"). The resistance of the plug leads is only important after the spark has been initiated and current flows, so in this initial phase the insulation is what matters. So there are two distinct phases - initiation where voltage and insulation are important, and then the burn where the resistance of the circuit matters.

When the spark is required the current supply to the ignition coil primary circuit is switched off. The resultant collapse of the magnetic field in the core of the coil is what induces the rapid rise in voltage in the secondary windings.

The voltage required to strike the arc is dependant on many factors, which basically boil down to how difficult it is to ionise whatever gas is between the electrodes of the spark plug.

Some factors that affect the secondary voltage required are the cylinder pressure (increases with load, higher load requires higher voltage), spark plug gap, spark plug electrode size (thinner pointy electrode creates higher electrostatic field, so requires less voltage), fuel used (LPG is more difficult to ionise than petrol), etc. Hence this phase of the cycle just requires good insulation in the secondary side of the system!

Incidentally the above reasons are why many ignition secondary faults and misfires show up under load only. Hence the best place to find them is on a rolling road.

Once the arc is struck, the energy stored magnetically in the core of the coil starts to discharge in the form of current flowing into the secondary system. At this point some resistance (i.e. leads, plugs, suppressors) is necessary to maintain a decent spark. If there is no resistance, then most the spark energy is dissipated in a very short time. This effectively makes it self-extinguishing.

Over the years I have removed a lot of low-resistance leads which were causing nasty idle and light-throttle running issues, so my personal opinion is that they are a bad thing. Burn times are often as low as 0.14 to 0.25 milliseconds. There is also another nasty byproduct of low resistance leads, and that is that they leave quite a bit of energy in the coil, and produce a very large kickback voltage on the primary circuit as the spark is extinguished. Typically the regular kickback from low impedance leads can be of the order of 350-400 Volts, against the more normal 150-200 volts of a correctly-specified system. This produces lots of unpleasant consequences especially where the coil(s) are driven by an ECU. Sometimes it will spike the ECU, and sometimes cause premature failure of the ignition drivers.

Where there is resistance in the circuit the full voltage is still available to ionise the mixture and start the arc. The resistance ensures that the energy is not all dissipated at once, and thus a longer burn time will follow.

Conversely if the resistance of the secondary circuit is too high, then the current flow through the secondary system will not be sufficient to maintain the arc. The arc will then be extinguished, probably resulting in a misfire.

There are two schools of thought on the subject of ignition, since nobody really knows how the process occurs. The burning process is simply an exothermic chemical reaction, which is initiated by the spark. The American aftermarket seem favour the short spark, and hence their leads etc., are generally minimum resistance. Values of 100-500 Ohms are not uncommon. Everyone else goes for resistance of around 5,000-15,000 Ohms, which gives a burn time approaching two milliseconds. Rover V8 systems commonly like 10,000-20,000 Ohms (coil lead plus one plug lead).

In these days of modern lean-burn engines and either wasted-spark or coil-on-plug ignition systems, secondary resistance is commonly higher - around 20,000-25,000 Ohms. This is coupled with more energy stored in the coil to give longer burn times, nearing three milliseconds. On a typical Rover ignition system, burn time would be between 1.1 to 1.4 milliseconds at idle (according to plugs etc.). There is an enormous quantity of research information available on this process for those who are interested, such as proceedings from various SAE Automotive Engine Management conferences for example.

The standard TVR (Land Rover) leads are OK when new, but don't generally last all that long. They are jolly cheap so it’s recommended to change them every 25-30K miles. The leads that we have found meet every requirement are those by Magnecore, and we have used thousands of them over many years with only three problems. One important point when using Magnecore leads is that they are so good at what they do, that they often expose weaknesses in other areas of the ignition system. However this doesn't mean that there aren't any other good leads around, and I have tested many other brands that give perfectly good results.

Leads with an inductive core (such as Magnecore) introduce a different dynamic to the system. The inductive nature of the lead core tends to extend burn time, by offering resistance to transient current flow (in simple terms). This means that resistance alone for this type of lead gives very little information about the effect of this technology on plug lead and burn performance, so is wholly misleading as Mark (Blitz) has pointed out several times...

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 22nd August 2014
quotequote all
Thanks for your contribution Mark and very informative it is too.

So in summary, the opinions on the benefits of low resistance leads still seems divided and is very much depending on what side of the pond you live on.

In your words "the American aftermarket seem favour the short spark, and hence their leads etc", TBH that's good enough for me. As we all know the Yanks certainly have never had a problem making big power from pushrod V8s.

The bit about spark plug electrode size is of particular interest to me as I'm running LPG, like you say a thinner pointy electrode creates higher electrostatic field so requires less voltage, which I guess is why the NGK Laser Line LPG range of plugs look like this:



This one is straight out of my engine, I can confirm after 10,000 miles these plugs work brilliantly even though people told me the tips would fall off and destroy my engine hehe

NGK make the best spark plugs in the world bar none, and they didn't get to where they are now by producing products that destroy engines wink

Back in the day I had an old Champion spark plug tester, you would hook it up to an air line and put the connected plug into a sealed chamber with a little window. The machine had a 12v coil so you could get the plug firing as you wound up the pressure, eventually when the air pressure got high enough you could put the spark out and watch it happen before your very eyes.

The idea was to test for a bad plug, but it also showed the effects of increased compression or forced induction can have on the spark. And that's why when our American cousins go forced induction they often need to upgrade their ignition systems with capacitive discharge coils, close their plug gaps and fit better HT leads.

With our antiquated Sun Tuner machine and this prehistoric spark plug tester we could pretty much diagnose any ignition fault, its just a shame I dont have accesses to them now frown

Your point about LPG being more difficult to ionise than petrol is very true, those NGK plugs certainly made an improvement for me so now lets see if (following American thinking) the MSD leads will work well too.

With all this technology out there I still believe in listening, smelling & driving to tell if an engine is healthy. A bit like when that Austin Healey came into Mech Repairs when you had my TVR on the rolling road, you may recall I went straight to the SU throttle spindles wink

Oh and the hunting on my car we couldn't solve during that £600 morning disapeared the moment I removed the main cat that you told me was such good quality, I put my money on a blocked exhaust and won that bet too.

I have to say ditching that big cat made almost as much improvement as ditching the 14CUX wink

And for completeness, my reconditioned Vectra injectors you insistent on removing and then found to be perfect like I said they would be, are indeed still perfect now I'm on the fully mappable by anyone Canems system.

Best regards, Dave byebye


blitzracing

6,387 posts

219 months

Friday 22nd August 2014
quotequote all
Mark Adams said:
This topic comes up regularly, and it seems that nearly everyone has an opinion on spark plug leads! However most of the people who express those opinions do not use (or even have) an ignition analyser, which is a bit like choosing wallpaper in the dark. When I am on the rollers tomorrow, I shall try and get a couple of printouts from the ignition analyser and annotate them, so that you can see what I am talking about.
Any printouts would be great. I made the mistake of looking at the primary ignition spike on copper leads with a very nice little Hamec 'scope but it blew up the input as it was only rated at 300 volts. I also destroyed two rev limiters in the process- I learnt a lot in a short and expensive time. eek

SILICONEKID345HP

14,997 posts

230 months

Friday 22nd August 2014
quotequote all
ChimpOnGas said:
Thanks for your contribution Mark and very informative it is too.

So in summary, the opinions on the benefits of low resistance leads still seems divided and is very much depending on what side of the pond you live on.

In your words "the American aftermarket seem favour the short spark, and hence their leads etc", TBH that's good enough for me. As we all know the Yanks certainly have never had a problem making big power from pushrod V8s.

The bit about spark plug electrode size is of particular interest to me as I'm running LPG, like you say a thinner pointy electrode creates higher electrostatic field so requires less voltage, which I guess is why the NGK Laser Line LPG range of plugs look like this:



This one is straight out of my engine, I can confirm after 10,000 miles these plugs work brilliantly even though people told me the tips would fall off and destroy my engine hehe

NGK make the best spark plugs in the world bar none, and they didn't get to where they are now by producing products that destroy engines wink

Back in the day I had an old Champion spark plug tester, you would hook it up to an air line and put the connected plug into a sealed chamber with a little window. The machine had a 12v coil so you could get the plug firing as you wound up the pressure, eventually when the air pressure got high enough you could put the spark out and watch it happen before your very eyes.

The idea was to test for a bad plug, but it also showed the effects of increased compression or forced induction can have on the spark. And that's why when our American cousins go forced induction they often need to upgrade their ignition systems with capacitive discharge coils, close their plug gaps and fit better HT leads.

With our antiquated Sun Tuner machine and this prehistoric spark plug tester we could pretty much diagnose any ignition fault, its just a shame I dont have accesses to them now frown

Your point about LPG being more difficult to ionise than petrol is very true, those NGK plugs certainly made an improvement for me so now lets see if (following American thinking) the MSD leads will work well too.

With all this technology out there I still believe in listening, smelling & driving to tell if an engine is healthy. A bit like when that Austin Healey came into Mech Repairs when you had my TVR on the rolling road, you may recall I went straight to the SU throttle spindles wink

Oh and the hunting on my car we couldn't solve during that £600 morning disapeared the moment I removed the main cat that you told me was such good quality, I put my money on a blocked exhaust and won that bet too.

I have to say ditching that big cat made almost as much improvement as ditching the 14CUX wink

And for completeness, my reconditioned Vectra injectors you insistent on removing and then found to be perfect like I said they would be, are indeed still perfect now I'm on the fully mappable by anyone Canems system.

Best regards, Dave byebye
You and Mark have something in common ! You both write very long posts tumbleweed

rigga

8,727 posts

200 months

Friday 22nd August 2014
quotequote all
SILICONEKID345HP said:
You and Mark have something in common ! You both write very long posts tumbleweed
Was there any need to quote the whole fking lot rolleyes

TV8

3,118 posts

174 months

Saturday 23rd August 2014
quotequote all
ChimpOnGas said:
The extender shows 0.3 on the 20k setting so 300 Ohms which is nothing when you look at the resistance of the CI leads and even the Magnecors. But if we're looking at the super low 130 Ohm MSD leads the extenders more than double the resistance from coil to plug. Extenders can definitely be a source of failure but many may argue they are essential. Personally I think at best they are a necessary evil and removing the extenders has to be a good thing if it can be done without compromising the reliability & longevity of the HT lead.
Hi Dave and other contributors, please see my other topic on the ratings of plug extenders if you have any knowledge here.

Thanks