Resistor Plugs

[landon]

Any problem with resistor plugs WR8dc instead of W8dc? I use a Bosch red coil w/ pertronix and std. wires / connectors.

Thanks for any feedback!

[c.d.iesel]

only W6DC, W7DC, and W8DC (depending on yer state of tune )

you can order from any BMW dealer for the real thang

[fwardell]

Hmmm. cd, I'm using WR8DCs which seem to work well on my stock '76 '02 with a plug gap of 0.035" and blue coil. What's the downside here?

[Napes]

c.d. - are you saying that Bosch Super W8DCs are still available from the dealer? I've been being told they are NLA.

Bob Napier

[c.d.iesel]

i'll get you the numbers on friday - remind me then

[TobyB]

Where you run into trouble with R plugs is where you have

resistor wires, resistor coil, resistor rotor, resistor cap... and maybe resistor butt

to go with it.

Some rotors are marked R5, meaning they have a 5k resistance.

Some wires are resistance wires. Most, in fact...

I don't think any 2002- style caps have resistance in them...

Anyhoo, the resistances add up, and if they're too much, you'll have hesitation

or misfiring at moderate to hard acceleration. Did that once...

changed to a non- resistor rotor, and then non- resistor plugs at the next change.

No problems since. (on that car!)

t

[Guest Anonymous]

Toby, as usual, is correct all that resistance adds up and may be counter productive. The easy thing to do is take an ohmmeter to each component and measure it - if in doubt.

I do not believe the stock wire is resistance wire. It is solid copper strands as opposed to carbon impregnated radio (interference) suppression wire. The boots/plug connectors have built in resistors. In the very older versions, you could disassemble the boots and actually find a fuse-like resistor. Adding to the resistance might be unseen corroded contacts. Resistor plugs might be an acceptable idea when used with non-resistor wires and plug connectors/boots.

P.

[Guest Anonymous]

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,305765/

[bevans6]

Resistor plugs, caps, rotors etc are there to modify the way the spark duration and strength happens when the plug is fired. A resistor plug will have no effect on when the spark happens, but it will increase the duration of the spark while reducing the size of the spark - same energy, longer time. This has the effect of reducing the RF energy created by the spark, so resistor plugs are required in cars that have computer ECU's, radios, GPS systems, all the modern stuff. You can still get non-resistor Bosch plugs, I buy them from my Formula Ford guy who imports them from Europe directly. They are NLA in North Amercia.

The coil sees near infinite resistance (the air gap) until it fires. It creates the plasma in the gap with a burst of high energy, and the plasma has low resistance so the remaining energy in the coil is drained quickly. the resistor simply causes the energy to drain more slowly while still maintaining the plasma path within the spark. If you wanted to experiment with resistor plugs and you had a decent coil, you could open up the plug gap. That would have the effect of increasing the initial voltage hit for sure, and making the spark run at a higher voltage, maybe...

If you don't go over 5K in resistance and use a quality wire, no problems using resistor plugs.

Brian

[Napes]

Does your Formula Ford guy have a web link or email he'd be willing to let us use for contact?

Bob Napier

[ingraham]

I'm an EE being curious, not contrary: If the total resistance is correct, what difference does it make where it's located (wire, boot, or plug)? Is there a secondary effect at work?