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Ignition leads - 8mm vs 10.5mm

Ron Burgundy

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Just looking at NGK leads

They have 8mm blue leads and also 10.5mm black leads

The price difference is about 30 bucks.

Worth getting slightly thicker ones or stick with 8mm ?
 

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07GTS

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with normal leads ive never noticed any difference as the core is most likely the same just the shielding increases diameter, only time i could hear a change in the engine note was when i fitted the zero ohm leads
 

Ron Burgundy

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with normal leads ive never noticed any difference as the core is most likely the same just the shielding increases diameter, only time i could hear a change in the engine note was when i fitted the zero ohm leads
What's an example od zero ohm leads ?
 

Trevor loves holden.

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According to ngk all there leads are rated to 1,300 ohms per metre so its the insolation is the only change which stops RFI to your radio too much resistance reduces sparking and ignition energy.
 

Fu Manchu

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I ran 10mm leads on my old VP with MSD coils. Went better.
 

Skylarking

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The thicker leads simply have thicker insulation and the same core conductor material when I looked some years ago.

Since the leads can’t short to earth when operating, the thinner leads must by design have enough insulation to prevent such arcing. Thicker insulation simply won’t reduce arcing since it’s not a problem to begin with.

So I ’d save the few dollars and put it towards something else unless it’s the aesthetics of coloured leads you’re after ;)

(edits follow) Also want to add that the ignition system is designed for a specific resistance in the leads and within the plug itself. If they are changed to zero ohm leads, there must be some impacts to the spark timing and RFI (not in a positive way). In any case, zero ohms conductors are usually described as (near absolute zero degree) superconductors which would make such a zero ohm room temperature conductor worthy of a Nobel prize. So i think it’s a marketing term more than something real. I also doubt they have RFI test report to back up the other marketing guff. Basically if gains were so easy, vehicle manufacturers would have been using such leads years ago.
 
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07GTS

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The thicker leads simply have thicker insulation and the same core conductor material when I looked some years ago.

Since the leads can’t short to earth when operating, the thinner leads must by design have enough insulation to prevent such arcing. Thicker insulation simply won’t reduce arcing since it’s not a problem to begin with.

So I ’d save the few dollars and put it towards something else unless it’s the aesthetics of coloured leads you’re after ;)

(edits follow) Also want to add that the ignition system is designed for a specific resistance in the leads and within the plug itself. If they are changed to zero ohm leads, there must be some impacts to the spark timing and RFI (not in a positive way). In any case, zero ohms conductors are usually described as (near absolute zero degree) superconductors which would make such a zero ohm room temperature conductor worthy of a Nobel prize. So i think it’s a marketing term more than something real. I also doubt they have RFI test report to back up the other marketing guff. Basically if gains were so easy, vehicle manufacturers would have been using such leads years ago.
only thing i noticed besides a change in engine note was my windscreen mounted gopro gets a small static interference i believe from the leads, there gains im not sure of as i never done back to back tests and dynos can vary to easily, and there price now is crazy back when i got mine they were same cost as stock replacements i wouldnt get them at what they are now best spent on other areas
 

BlackVXGTS

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10.5mm leads (red or blue) look better, but are rather wasted on the short leads used for the VT2/VX/VY/VZ/VF V8s (unless you've relocated the coil packs). Look better on the good old Aussie V8 engine:
 

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