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Best Ignition Leads to compliment the Classic Retrofit CDI+ box


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Following on from Ian Comerford's "New Ignition Leads" thread which ended in 2019. I would like to get up to date thinking on the best leads available for a 930 with Jonny's CDI+ box fitted.

There were mixed views on Beru last time and the belief a dodgy batch of China made items had made their way to the UK market.

What should I be considering replacing my 32 year old Porsche original set with ?

 

Edited by carrpet
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13 hours ago, Ian Comerford said:

If they’ve lasted 32 years then ca£400 for a new set doesn’t seem to bad.  Buy Porsche.

Now (as of today) £500 with discount post brexit price increase !

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3 hours ago, mean in green said:

Magnecors fit well, KV85.

How long have they been installed ?

Edited by carrpet
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1 hour ago, carrpet said:

Now (as of today) £500 with discount post brexit price increase !

Wow, well done the Brexiteers......

4 hours ago, mean in green said:

Magnecors fit well, KV85.

There is probably a discussion to be had about the merits of the Porsche screened wires vs other, unscreened ones.  Do we understand benefits or otherwise?  A older thread from Pelican here, a couple of different versions of the “benefits” including one I hadn’t heard of.....

http://forums.pelicanparts.com/porsche-911-technical-forum/328528-braiding-sparkplug-wires-why.html

Jonny might have something more factual on the subject, calling Jonny!

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1 hour ago, Ian Comerford said:

Wow, well done the Brexiteers......

There is probably a discussion to be had about the merits of the Porsche screened wires vs other, unscreened ones.  Do we understand benefits or otherwise?  A older thread from Pelican here, a couple of different versions of the “benefits” including one I hadn’t heard of.....

http://forums.pelicanparts.com/porsche-911-technical-forum/328528-braiding-sparkplug-wires-why.html

Jonny might have something more factual on the subject, calling Jonny!

Yes Jonny is probably the person best qualified from a technical perspective to give us a expert view on this ?

Screened v unscreened - what is the screen there for ?

Is it to stop radio interference

Is it to enhance the performance of the HT leads

Is it to protect the HT leads

Is it a safety feature ?

I had a 928 S4 with very long HT lead runs and they were not screened !

Have there been relevant technological advancements made since the Porsche Original leads were designed ? The latest "high performance" leads all appear to have silicone insulation which I am sure was not part of the OP spec'n

The highest specification (3 levels) set of Magnecor leads (8.5mm) are on sale for £200 delivered, so 40% of the price of the Original Porsche leads.

The Pelican thread that Ian has provided a link for is 13 years old but provides a range of insights as to why the braided screening was included. It also refers to 10mm Magnecor which does not appear to exist now as a Porsche variant !

It is possible that silicone is such a good insulator that the explosion risk referred to, which I assume was from external arching causing ignition in the wrong places, is no longer relevant, as Porsche do not appear to use braiding on later cars.

If it is to stop interference between two adjacent leads causing cross-firing then that is something completely different !

 

Edited by carrpet
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I made my own using screened wire. I can't see how anyone can justify £500 for a set of plug leads.

What's wrong with these 

https://type911shop.co.uk/epages/de867ca1-377e-432e-84fd-bdccf2206766.mobile/en_GB/?ObjectPath=/Shops/de867ca1-377e-432e-84fd-bdccf2206766/Products/655

Or am I missing something?

 

 

Edited by Phill
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4 hours ago, Phill said:

I made my own using screened wire. I can't see how anyone can justify £500 for a set of plug leads.

What's wrong with these 

https://type911shop.co.uk/epages/de867ca1-377e-432e-84fd-bdccf2206766.mobile/en_GB/?ObjectPath=/Shops/de867ca1-377e-432e-84fd-bdccf2206766/Products/655

Or am I missing something?

Possibly missing some information ? Do you know who made these HT leads ? 

There are aftermarket sets all over the place, some under the brand "retro line" which no doubt are OEM. I bet Beru are one of the OEM suppliers and there are a number of people who have had a problem with Beru branded items  "not fitting very well" and not lasting very long, on both sides of the Atlantic.

Ignition HT Lead Set. Porsche 911 SC / 930 Turbo | eBay

Ignition HT Lead Set. Porsche 911 SC / 930 Turbo - 91160901007/2 | Design 911 (design911shop.com)

 

 

Edited by carrpet
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1 hour ago, carrpet said:

 

All Matt, I'm sure he can tell you how many be has sold and if there have been any complaints. Mind you there is nothing like over thinking things ;)

To be fair I wouldn't buy eBay junk and nor would I buy from design911.

Edited by Phill
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12 hours ago, flatsix777 said:

I’ve been running Clewitt leads on my 930 with a MSD box. Think I fitted around 2012 with no issues since. 
David

Hi David

Are the Clewitt leads screened/braided ?

Regards

Peter

Chris at GCR Leicester (just rebuilt Ian Comerford's engine) recommends and fits Magnecor 8.5mm

Edited by carrpet
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There were a few problems with Beru (which is what Porsche sell) a few years ago, the ends were bigger for some reason and they didnt fit all dizzy caps. Havent had this problem for over a year at least so maybe there was a duff batch.

The aftermarket ones however we have had a 100% failure rate! Complete crap, made by Uro, we dont list them anymore, best avoided.

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I would also suggest from experience that the Beru ones are not the same as the ones Beru make for Porsche, as with lots of other items.  I figured that the leads are critical to good running and couldn’t reconcile the possibility that ones that are 90% of the Porsche ones (in terms of quality) might result in 90% running performance.  Mind you, that was when they were a different price......

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2 hours ago, carrpet said:

Are the Clewitt leads screened/braided ?

 

Yes, the spec said they had exterior braiding and noise suppression. I purchased from Pelican and think I paid about $150, although it was a while ago and part of a much bigger order. 

Regards

David

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I looked at Magnecor when I did my conversion. They did not get the best reviews at the time and they are very expensive especially when you can make your own to the same spec.

Also, what's wrong with your existing leads?

Also, I can't imagine Jonny would make a product that would require a change of leads at the same time?

Edited by Phill
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2 hours ago, Phill said:

I looked at Magnecor when I did my conversion. They did not get the best reviews at the time and they are very expensive especially when you can make your own to the same spec.

Also, what's wrong with your existing leads?

Also, I can't imagine Jonny would make a product that would require a change of leads at the same time?

Hi Phill,

The leads in my car are 32 years old, which is the main reason for asking the question. There must be some degradation in performance over that period of time in the flexible conducting cores. The CDI+ change is not the trigger here more a coincidence. I am interested in what Jonny has to say because no one has yet contributed from a technical theory perspective and Jonny has the capacity to do this because of his background. On a Pelican thread Jonny has referred to the MSD box that David has, which delivers voltages >500V, in relation to plug lead life.

Peter

4 hours ago, Type911 said:

There were a few problems with Beru (which is what Porsche sell) a few years ago, the ends were bigger for some reason and they didnt fit all dizzy caps. Havent had this problem for over a year at least so maybe there was a duff batch.

The aftermarket ones however we have had a 100% failure rate! Complete crap, made by Uro, we dont list them anymore, best avoided.

Thanks

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4 minutes ago, Busybee said:

Sounds like you need to ask Jonny directly ? 

I think you are right !!

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I think judging by his answerphone message Jonny is on holiday and will be back in 2 days time !

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I bought Beru ones a while ago.  They were a bar steward to fit, the only way to get them onto the cap was with silicon lube.   I would say the quality isn't as good as the originals. 

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I run the non-braided Beru ones and probably 8 years old now.  They were bought before the distributor cap end sizes went 'wrong'.   When I got them, I unscrewed the plug caps and made sure the brass 'screw' was in the centre of the lead touching the conductor( they weren't).  I don't run the braids because they encourage degradation of the wire insulation (which acts like a capacitor dielectric) and you end up with lots of stray sparks in the engine bay.

Regarding solid core versus carbon, basically solid lasts longer (than carbon) and carbon produces less EMI (interference) on newer cars.  

The resistance of the lead is irrelevant on an SC, since it has 5kOhm in the rotor arm and another 3kOhm in the plug cap.  Those resistors are doing the EMI suppression so you don't need resistive wire.

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