bigger spark leads

[aznsiko]

hey fellas just wondering if any one knows.. if i install bigger spark plug leads.. is it compulsory that i adjust and redo my timing..

[bennjamin]

bigger ? As in , longer actual leads ? AFAIK Resistance changes over the length of a lead - but i will go out on a limb and say NO.

[Eclipsor]

If by bigger you mean thicker. The reistance will decrease. If longer the resistance will increase. The electricity won't "travel any slower" though. Not taking into account differences different cables might have in capacitance and other effects.

[**Ghost**]

so it thicker better?

[Eclipsor]

Ya. Well from an electrical sense it is. Smaller resistance the higher the current (from I=V/R) and the larger the spark I assume. Not sure of any other factors in an engine there is though.

Found the formula. R = (pL)/A

where L is length, A is cross sectional area, p is resistivity and R is resistance.

So if p or L increase R will increase and if A increases R will decrease. Resistivity depends on the material the lead is made out of.

[ah8118]

wow.. this is becomin like a maths/physics lesson....

[wynode]

I thought a good spark is dependant on a high potential differnce as opposed to a high current?

[gambate]

I thought a good spark is dependant on a high potential differnce
yes, AFAIK

[Eclipsor]

yeah you're probably right. or a combination of both. either way smaller resistance in the lead will increase current and increase the voltage across the spark plug. Because there will be a smaller drop across the lead....I think ;)

[tinkerbell]

wanna answer the guys question perhaps?!?!?!

no - it is not compulsory UNLESS you move the distributor...

[robbo_is_mad]

So wat type of millimeter is the best?

8.5 mm 7.0 mm or 12.0 mm

someone told me the thicker the leader the more youll get out of it!!!

is this truu

[DLO01]

To answer the topic starters question: No need to as stated above.

Yes thicker is generally better.

But it not just the thinkness that your should look for

Resistance also depends on Materials used, length, Heat and also Insualtion of the leads.

[JohnnyVtec]

Gday M8,

Honda's need a certain amount of resistance unless your leads are going on a full blown race car that will never or not likely see much of the street. You have to consider that there are many different types of thick wires as well as thin wires. The main thing to concentrate on is the ablity to capacitate the voltage desired by the resistance desired. An easier approach to selecting proper leads is to research all the wires you may have in mind as candidates. then check their RFI compatablity and the ohms per square foot resistance.

In short, I'd be looking for something within the 500-800 ohms per square foot resistance. as well as having 6 core and preferably kevlar+silicone jacket.

I do have to somewhat agree with Ben and say that in some cases the spark can be efficient enough/overly-efficient that the total spark advance may need minor reduction. However your ecu should quickly adapt to the changes and prevent problems from occurring.


Hope that helps,

[fatboyz39]

Is your motor stock? If it is then leave the leads stock. Nice and simple.

No need for thicker leads.

[tinkerbell]

i will back to back test a set of MSD 8.5mm leads VS stock OEM leads (180'000KM old) once i am near a dyno...

[eg92b16a]

I have read that the best leads for a honda vtec engine are the honda leads.
It's not just about the size of the lead, but the suppression of noise and the resistance of the leads.
Just think that if you get larger leads with less resistance, that means that more current is flowing, therefore dizzy components are working harder to supply the extra current.
From personal experience with 8.8mm leads, don't go there. I fowled plugs more regularly and ended up cooking the igniter in the dizzy.
You have to think about the whole ignition system not just parts of it.
As Fatboyz39 said, stock engine = stock leads.