HT Leads Tested

HT Leads Tested

Author
Discussion

ChimpOnGas

Original Poster:

8,968 posts

127 months

Wednesday 20th August 2014
quotequote all
To satisfy my own inquisitive mind and for the benefit of others I decided to test three different brands of HT leads, the leads tested were:

1. Commercial Ignition - These should be considered as bog standard off the shelf every day leads at the lower end of the market

2. Magnecor kv85 competition 8.5mm - An expensive performance orientated lead

3. MSD 8.5mm Super Conductor - A well respected American made performance lead (cheaper than Magnecor kv85)

"ALL LEADS TESTED WERE AN ALMOST IDENTICAL 3' LENGTH"


First off lets look at the Commercial Ignition lead without the plug extender (measured using the 20k setting)



And now with the non resistor plug extender






So with the nothing special every day Commercial Ignition lead as our control lets see what the hugely more expensive Magnecor kv85 competition 8.5mm give you for all that extra money (again measured using the 20k setting)



For completeness I tested a second Magnecor lead of the same length proving they are indeed very consistent






Finally here's how the MSD 8.5mm Super Conductor leads perform, IMPORTANT This time it was necessary to drop the meter right down to its lowest 200 Ohm setting





So there we have it, if resistance genuinely is the measurement of HT lead performance we now have the figures to help choose HT leads.

The MSD 8.5mm Super Conductors were purchased from Summit Racing in the USA and arrived within a week of ordering, they are obviously a lot more expensive than the every day quality CI leads but do actually work out cheaper than Magnecor even when you factor in shipping & duty using Summit's excellent IParcel duty pre-pay option.

MSD claim 40-50 Ohms per foot, this was supported by my tests where I saw a very consistent & extremely low 44 Ohms per foot, & this was with the measurements taken with both coil & plug ends fitted.

The construction of the MSD 8.5mm Super Conductors also seems of extremely good quality, as soon as I've fitted them I'll report back here on how they perform on the car.

Dave.

spitfire4v8

3,086 posts

129 months

Wednesday 20th August 2014
quotequote all
How is resistance a measure of HT lead performance? You need to consider the whole system not the lead in isolation. Have you measured the resistance of the air gap on the spark plug? and the drop as the air ionises? What does your aftermarket ECU think of running low resistance Ht systems? Most ecus throw a wobbler if you run low resistance, hence the need for resistor plugs for example. What resistance are you trying to target and why?

Edited by spitfire4v8 on Wednesday 20th August 08:56

blitzracing

5,744 posts

168 months

Wednesday 20th August 2014
quotequote all
Im with this man- the DC resistances are of little use considering the HT waveform is AC, so the true resistance is very different. You need to 'scope the primary and secondary waveforms to really see what's going on, and the ethos that low resistance is good is very misplaced on stock road engines (LPG and full race high CR engines excepted).

ChimpOnGas

Original Poster:

8,968 posts

127 months

Wednesday 20th August 2014
quotequote all
spitfire4v8 said:
How is resistance a measure of HT lead performance? You need to consider the whole system not the lead in isolation. Have you measured the resistance of the air gap on the spark plug? and the drop as the air ionises? What does your aftermarket ECU think of running low resistance Ht systems? Most ecus throw a wobbler if you run low resistance, hence the need for resistor plugs for example. What resistance are you trying to target and why?

Edited by spitfire4v8 on Wednesday 20th August 08:56
That's why you'll find my caveat statement above:

"So there we have it, if resistance genuinely is the measurement of HT lead performance we now have the figures to help choose HT leads

Don't confuse my results with me making any spurious claims, re-read and you'll see that's not what I'm doing here.

All I've done is posted the results after testing a range of leads so people can make their own minds up.

The facts are MSD Super Conductor leads have been used extensively in the States for years & years with a multitude of different engine management systems, and from my research with absolutely no issues whatsoever.

The American performance market is massive, making what goes on here on our little island look like a joke, so honestly if these low resistance MSD leads give trouble I'm sure we'd all know about it.

But hey lets see what happens on my car first, which is why I included this:

ChimpOnGas said:
As soon as I've fitted them I'll report back here on how they perform on the car.
I knew this post would provoke the age old debate on HT lead resistance which is why I specifically didn't make any claims that a lower resistance lead gives benefits, and no doubt that debate will rage on eternally with sound arguments either way.

Lets not use Piston Heads as an opportunity to snipe, lets share information and politely debate after fully understanding whats been presented.

ChimpOnGas said:
So there we have it, if resistance genuinely is the measurement of HT lead performance we now have the figures to help choose HT leads. Dave.
The important word here is IF

spitfire4v8

3,086 posts

129 months

Wednesday 20th August 2014
quotequote all
I await this test and results and evidence with interest, but i suspect that whatever you come up with as a result will be clouded by the true picture of what happens in a full ignition system . Even the way the HT lead is wound (assuming said lead has both straight and wound wire within it) has an impact on its conductivity profile and electromagnetic radiation. I went through this when I had some bespoke HT lead wire made for my own ecu installs. Funnily enough though the actual conductor used in my HT lead when decided upon was imported from the USA ..

ChimpOnGas

Original Poster:

8,968 posts

127 months

Wednesday 20th August 2014
quotequote all
spitfire4v8 said:
I await this test and results and evidence with interest, but i suspect that whatever you come up with as a result will be clouded by the true picture of what happens in a full ignition system . Even the way the HT lead is wound (assuming said lead has both straight and wound wire within it) has an impact on its conductivity profile and electromagnetic radiation. I went through this when I had some bespoke HT lead wire made for my own ecu installs. Funnily enough though the actual conductor used in my HT lead when decided upon was imported from the USA ..
Interesting, so in the spirit of the PH forums being about the open sharing of information by non-traders, what brand of American leads did you find were best?

I doubt my results will be seen as credible by the group because I freely admit I don't have access to the test equipment to make this possible.

What I will be able to report on after fitting the MSDs is subjective but simple:

1. How well my LPG powered TVR idles & runs

2. LPG & Petrol economy improvements if any

3. Durability & longevity of the leads

4. Any indication of EMI interference

Pretty basic stuff I admit, but dare I suggest.... important all the same wink

TBH I'm quite sure I'll see or feel zero power improvement so I haven't included this in my evaluation list, actually my little lead swap project had nothing at all to do with outright performance gains, it's just everyone here is obsessed with horse power so they immediately assume that's my goal too.

However with LPG proven scientifically to be way harder to strike than petrol it is possible there may be a small improvement in idle quality as there most definitely was when I ditched the ridiculous TVR OEM shrouded No7 plugs and fitted a No6 plug with an extended electrode.

Mostly though for me its about the durability & longevity of the leads as I'm burning propane which most definitely puts more load on the whole ignition system, leads very much included.

Perhaps these leads will prove more durable, perhaps they wont, perhaps they'll send my Canems dual fuel ECU into an EMI induced tiz?

Lets see scratchchin

One thing is for sure, those cheapy Commercial Ignition HT leads have lasted longer than the expensive Magnecor KV85s operating in exactly the same high temp environment of number 7 & 8 cylinders & while burning LPG.

In fact I went back to the Commercial Ignition HT leads when the Magnecors failed and the bouncing tacho needle immediately disappeared, this has nothing to do with the catastrophic failure of the Magnecors either as the needle bounced from the day I fitted the brand new Magnecors.

Obviously replacing the completely feked Magnecors with anything would deliver a significant & immediate improvement, but what I can genuinely report is those cheap old Commercial Ignition leads do a better job than my Magnecors did even when they were brand new.

The CI leads instantly gave me a smoother idle & no tacho bounce, this makes me suspect some of leads Magnecore made me weren't the full ticket from day one.

I'm using those old CI leads right now and the car is running great, so I probably don't even need to make the switch to the MSD Super Conductors?

But for me this is a hobby not a business, so I'm just having fun trying stuff out, and I'll for sure share the honest subjective results whatever the outcome.

After all I haven't got any commercial reasons to hide my findings.

Edited by ChimpOnGas on Wednesday 20th August 12:01

spitfire4v8

3,086 posts

129 months

Wednesday 20th August 2014
quotequote all
I didn't import american leads dave just the central conductor core was imported. The actual lead was made in the uk. i say lead singular because it's on a large reel (just under a kilometer of wire was what i had to buy and i've probably used less than half of it but it was a god-send when making bespoke length leads up before you could buy such stuff on ebay etc). I went to the manufacturing plant which was something like 50m long and the machine doubled back on itself to fit all the manufacturing process in.
They had a clever system of being able to change reels midway through manufacturing so they didn't lose many meters of part made wire every reel change. My leads were a full silicone but I also bought a part reel of blue wire at the same time which was one layer silicone one layer epdm which i've never really used much of. Maybe I should ebay it. Must be a few hundred meters of the stuff on it gathering dust ..

Edited by spitfire4v8 on Wednesday 20th August 13:42

ChimpOnGas

Original Poster:

8,968 posts

127 months

Wednesday 20th August 2014
quotequote all
spitfire4v8 said:
I didn't import american leads dave just the central conductor core was imported. The actual lead was made in the uk. i say lead singular because it's on a large reel (just under a kilometer of wire was what i had to buy and i've probably used less than half of it but it was a god-send when making bespoke length leads up before you could buy such stuff on ebay etc). I went to the manufacturing plant which was something like 50m long and the machine doubled back on itself to fit all the manufacturing process in.
They had a clever system of being able to change reels midway through manufacturing so they didn't lose many meters of part made wire every reel change. My leads were a full silicone but I also bought a part reel of blue wire at the same time which was one layer silicone one layer epdm which i've never really used much of. Maybe I should ebay it. Must be a few hundred meters of the stuff on it gathering dust ..

Edited by spitfire4v8 on Wednesday 20th August 13:42
Ok and thanks for all the info, your experience in these matters is respected & valued, I'll test the MSD leads on the car unless you genuinely feel I may damage my ECU in any way.

What sort of symptoms would I experience as a result of leads that were too low in resistance, could they overload the spark drivers damaging them or is it just a case of experiencing a temporary misfire until I go back to higher resistance leads because the low resistance confuses the ECU?

Does the ECU need to see resistance in the ignition circuit before it'll fire the coil packs, or will it still fire the coils but put too much load back to the spark drivers or overheat the coils themselves?

I'm currently running NGK LPG Laser Line No2 which work very well and have a very long service life, TBH I'm not sure what resistance they run at as NGK list them as a direct replacement for both BP6ES (non-resistor) & BPR6ES (resistor), amongst many many others:

http://ngkntk.co.uk/wp-content/uploads/2011/04/LPG...

Thanks again, I freely admit I don't really have a grasp on how my Canems ECU relys on resistance in the leads & plugs to function correctly.

What I don't want to do is cause any ECU damage as I did when I experimented with the rather excellent but extremely low impedance Keihin LPG injectors that eventually over heated the peak & hold injector drivers in the dual fuel ECU if I drove it for longer than 2 hours in one sitting (works perfectly now with the 2 Ohm Magic Jets BTW).

Thanks in advance for your advice, Dave.



spitfire4v8

3,086 posts

129 months

Wednesday 20th August 2014
quotequote all
On the emeralds ecus I use I know that having too little ht resistance can interfere with uploading of info to the ecu when mapping, it's an electrical interference issue more than anything in this case, the same reason they tell you to route ht leads and crank signal wires well away from each other..
I don't know what impact it has on the drivers in the ecu, but as the drivers control the low tension side of the coils I would imagine you would be fine, but check with canems first smile
Lower resistance changes the duration of the spark once ionisation occurs and makes it longer .. what they call long thin spark at college learning stage. More resistance makes a short fat spark. I'm not an ignition expert by any means and this stuff is probably in intricate detail somewhere on the www. I just know that every ecu manufacturer i've spoken to says put resistor plugs in !

spitfire4v8

3,086 posts

129 months

Wednesday 20th August 2014
quotequote all
incidently my wire was made by madison wire in blackburn, they have a website but not a lot of detail about construction differences etc

ChimpOnGas

Original Poster:

8,968 posts

127 months

Wednesday 20th August 2014
quotequote all
Ok & thanks again.

I'm guessing lower resistance could potentially equate to higher EMI and that could interfere with the operation of the sophisticated electronics within the ECU?

Everything I've read about MSD Super Conductors suggests their double silicone wall construction is extremely good at limiting EMI and as I've not had any ECU issues or radio interference arising from the NGK Laser Line LPG plugs (only benefits) in the last 10,000 miles I feel its safe to consider them proven.

But assumption being the mother of all f-ups, I will double check on these super low resistance leads with David Hampshire at Canems.

thumbup

SILICONEKID345HP

14,741 posts

179 months

Wednesday 20th August 2014
quotequote all
Did you test the genuine bog standard Bocshe /lucas HT leads ?


http://www.ebay.co.uk/itm/LAND-ROVER-Range-Rover-I...

http://www.ebay.co.uk/itm/LAND-ROVER-DISCOVERY-1-3...

I bet the Boscsh leads are just as good !

blitzracing

5,744 posts

168 months

Wednesday 20th August 2014
quotequote all
spitfire4v8 said:

Lower resistance changes the duration of the spark once ionisation occurs and makes it longer .. what they call long thin spark at college learning stage. More resistance makes a short fat spark. I'm not an ignition expert by any means and this stuff is probably in intricate detail somewhere on the www. I just know that every ecu manufacturer i've spoken to says put resistor plugs in !
Sorry mate- wrong way around I think- ,the low resistance leads give a very short fat spark at goes out almost as soon as it starts as there is little resistance to control the discharge rate of the coil. For the same reason the rapid collapse of the magnetic field in the coil causes much higher spikes in the coil primary so you spike the switching electronics- typically the spike with resistive leads can be 300 volts, but if you use copper HT leads it will go to nearer 600 volts, with resulting failure of switching semiconductors. Another side effect is the spike oscillates as the coil discharges (called a ringing signal), so lets say the tacho needs a 300 volt pulse to trigger it, if you have a 600 volt pulse, it could be followed by a 300 volt pulse as the coil rings- so the tacho gets two triggers instead of one- hence the erratic behaviour. You also increase the amount of radio frequency radiation from the HT leads, that again glitches electronics.

The coiled type of HT leads create a magnetic field around the wire as the HT spike passes down them, and this acts like a generator that generates a voltage that pushes back against the HT spike, so this reverse voltage looks like the lead has resistance to any current flowing down the wire, but what you are doing is holding power back in the coil. As the spike reduces, the reverse voltage reduces, so the lead resistance appears to drop, so you can wring out that last few joules of energy from the coil, instead of wasting it in a simple resistive lead. This is why DC resistance tests are of little use.

More generally- You have to consider just how much head room is available in your ignition system- typically the Bosch coil can produce about 30kv if you leave the HT side open circuit- but connect it to a plug, and it will only reach 5-10kv before the plug fires and the voltage stops rising. The resistive leads simply means the coil voltage has to rise a bit further before the plug fires- but its no big deal when you have plus 20kv to spare. For those hoping that better leads will liberate horsepower or better running, all you have to do is ignite the mixture to create a stable flame front, and after that any extra spark just erodes the plug tips as you cant ignite the mixture twice.

The issue of how you use the coils available power depends on what you are trying to ignite- a rich mixture, high compression ratio, or LPG take a higher voltage to start the arc, but then once the flame front is established it will keep burning easily, and the plugs job is done- so a short hot spark is fine. On the other hand if the engine is leaner burning, or lower compression its harder to get a decent flame front with a short duration spark as the mixture does not burn so readily, so a lower voltage, with a longer burn time will ensure a proper flame front is established. So for HT leads- go ahead and use low resistance for special fuels and race engines,(short fat spark) but for road engines stick to resistive leads to maintain the spark duration.

SILICONEKID345HP

14,741 posts

179 months

Wednesday 20th August 2014
quotequote all
uote=spitfire4v8]I didn't import american leads dave just the central conductor core was imported. The actual lead was made in the uk. i say lead singular because it's on a large reel (just under a kilometer of wire was what i had to buy and i've probably used less than half of it but it was a god-send when making bespoke length leads up before you could buy such stuff on ebay etc). I went to the manufacturing plant which was something like 50m long and the machine doubled back on itself to fit all the manufacturing process in.
They had a clever system of being able to change reels midway through manufacturing so they didn't lose many meters of part made wire every reel change. My leads were a full silicone but I also bought a part reel of blue wire at the same time which was one layer silicone one layer epdm which i've never really used much of. Maybe I should ebay it. Must be a few hundred meters of the stuff on it gathering dust ..

Are these the one`s you were talking about ? they are spot on ..I purchased the ends from fleabay


Edited by SILICONEKID345HP on Wednesday 20th August 19:42

ChimpOnGas

Original Poster:

8,968 posts

127 months

Wednesday 20th August 2014
quotequote all
Sounds like a low resistance lead may well be beneficial on my LPG burning TVR then assuming it doesn't cause ECU issues.

Blitz's post supports all the results of many discussions I've had with recognised LPG specialists, LPG is harder to strike but once its lit it burns beautifully well.

My simple resistance tests above seem to prove the MSD Super Conductors are very low resistance indeed, so have the potential to deliver that short high powered spark needed to start the LPG burn.

watch this space wink

TV8

2,732 posts

123 months

Wednesday 20th August 2014
quotequote all
How about the plug extenders? Do they change anything given that they are in- line to it all? Also, do they go wrong and if so, can they be tested? Dave's showed a small change in resistance in the pics above. Is that right?

Sardonicus

16,481 posts

169 months

Wednesday 20th August 2014
quotequote all
ChimpOnGas said:
Sounds like a low resistance lead may well be beneficial on my LPG burning TVR then assuming it doesn't cause ECU issues.

Blitz's post supports all the results of many discussions I've had with recognised LPG specialists, LPG is harder to strike but once its lit it burns beautifully well.

My simple resistance tests above seem to prove the MSD Super Conductors are very low resistance indeed, so have the potential to deliver that short high powered spark needed to start the LPG burn.

watch this space wink
Dave I dont need to tell you that as lower resistance as possible is the way to go without causing interference/noise etc you want as much energy reaching the plug as possible hence the take up of pencil/direct fire coils and engine mounted coils and shorter & shorter HT leads in recent years smile I am happy my American Accel leads biggrin

ChimpOnGas

Original Poster:

8,968 posts

127 months

Wednesday 20th August 2014
quotequote all
TV8 said:
How about the plug extenders? Do they change anything given that they are in- line to it all? Also, do they go wrong and if so, can they be tested? Dave's showed a small change in resistance in the pics above. Is that right?
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.

ChimpOnGas

Original Poster:

8,968 posts

127 months

Thursday 21st August 2014
quotequote all
Sardonicus said:
ave I dont need to tell you that as lower resistance as possible is the way to go without causing interference/noise etc you want as much energy reaching the plug as possible hence the take up of pencil/direct fire coils and engine mounted coils and shorter & shorter HT leads in recent years smile I am happy my American Accel leads biggrin
Precisely Simon and some excellent examples there, just one look at a Chevy LS says it all, they didn't make it that way for fun.

The 3' Commercial Ignition lead showed a huge 12,700 Ohms and the Magnecor a far better 4,200 Ohms.

But with the MSD Super Conductor lead showing just 130 Ohms on a 3' lead I'd need to shorten the Magnecor lead to just an inch long to see similar levels of resistance.

Or put it another way I could run a 30' MSD Super Conductor lead and its resistance would still be lower than a 3' Magnecor lead.

Whether this will all translate to something that can be felt is yet to be proved but the MSD super low 43 Ohms per foot can't be a bad thing assuming the EMI is still well supressed.

Watch this space wink

ChimpOnGas

Original Poster:

8,968 posts

127 months

Thursday 21st August 2014
quotequote all
Bobby Shaftoe said:
Would summat like this be any good: http://www.ebay.co.uk/itm/331296262956?ssPageName=...

Seems to be the same spiral would stuff as Magnecor use and low resistance but a fair bit cheaper. The normal carbon string ignition cable doesn't seem to last two minutes in the red hot engine bay on my wedge.
Looks the same & performs the same are two different things, the spiral wound MSD Super Conductor leads look a lot like Magnecors too but have a resistance that's a massively lower!

The best thing to do would be to order a foot of it and test its resistance, they say 350 Ohms per foot in the EBay ad but you've really got to test the lead yourself to be sure.

350 Ohms is still a long long way off the MSD Super Conductor 43 Ohms per foot but I doubt you'd feel it.

There's a host of HT lead test results on the net originating from the US if you go looking, every time what the Yanks call plug wires get tested the MSD leads come out as having the lowest resistance.

But I also found comment on how a respected magazine did a back to back dyno test on a host of HT leads and the results showed zero power gains.

That doesn't surprise me at all, this whole HT lead thing has nothing to do with power gains for me.

But there is a chance the MSD leads could give me an even smoother idle on LPG and this better idle combustion will likely show up on my mate's gas analyser as lower emissions, I dont give two ships about emissions by the way but it's nice to know the gas I put into the engine at idle is getting burnt as effectively & completely as possible.

At the end of the day I needed to change two burnt Magnecor leads anyway so I'm just experimenting, there's also a very good chance the MSD leads will make fek all difference I can feel.

But at least I'll have the new leads I need and they'll be good quality ones that last (I hope).