What's the coldest resistor plugs one could get?

[xxobuick]

With all of the modern data acquisition end engine control now a days what are you guys running for resistor plugs?  A lot of the racing cold plugs out there by NGK and Champion don't offer a super cold plug that has a built in resistor in a 14mm thread with the shorter reach of 3\8" like a lot oh the vintage engines. I can get a champion 8 heat range in a rj8c but anything colder is non resistor. Any suggestions?  This motor they are going in, is 15-1 compression and don't wanna turn the spark plugs into glow plugs!  When I run a non resistor plug on the dyno I loose communication because of the RF noise. I run rf canceling wires but its not enough.   I have seen resistor caps that replace the plug wire boot that goes on the plug but have never tried them.   

[RichFox]

You might contact Rick Gold at ERC. I get my weird plugs from him and he delivers to the salt at his fuel truck.

[jacksoni]

This chart shows at least one step colder than your RJ8C in that size but also one with a 3/4" ( ) hex in a 4 range. Might not fit!!

http://aftermarket.federalmogul.com/en-US/Technical/Documents/Champion%20Spark%20Plug%20Copper%20Plus%20Heat%20Range%20Chart.pdf

[RansomT]

Is the only reason you don't want to run non-resistors because of the dyno?

[Stainless1]

With all of the modern data acquisition end engine control now a days what are you guys running for resistor plugs?  A lot of the racing cold plugs out there by NGK and Champion don't offer a super cold plug that has a built in resistor in a 14mm thread with the shorter reach of 3\8" like a lot oh the vintage engines. I can get a champion 8 heat range in a rj8c but anything colder is non resistor. Any suggestions?  This motor they are going in, is 15-1 compression and don't wanna turn the spark plugs into glow plugs!  When I run a non resistor plug on the dyno I loose communication because of the RF noise. I run rf canceling wires but its not enough.   I have seen resistor caps that replace the plug wire boot that goes on the plug but have never tried them.   

OK, what communication are you losing?  What data system are you using... The biggest problem I have with the dyno is finding a computer with a hard drive that will survive the acoustic vibration.... Solid State hard drives solved that problem, was easier than putting it in another room.
Maybe you need an overshield on your data wiring.

[xxobuick]

The dyno data acquisition is the same one we are going to run in the car.  We are running a Megasquirt MS3-PRO, to control the motor and for data-logging.  The Non resistor plugs can also cause resets for the on board computer, which is what I am trying to avoid.  I contemplated wrapping a lot of the wires and the ECU in lead sheet to see if that would help stop the interference. 

[manta22]

EMI/RFI (electromagnetic interference/radio frequency interference) is a pretty severe problem with high power ignition systems with fast rise times. There are only two ways of minimizing problems with close- by electronics-- filtering & shielding.

 Filtering really involves getting inside the electronics itself so that is not an option open to most racers. It seems to me that manufacturers of race electronics devices should do a far better job of making their products more immune to EMI/RFI in the first place. However, shielding is something that can be done external to the electronics. Shielded cable goes a long way toward solving the problem, especially on analog sensor data inputs. An alternative to shielded cables is simply wrapping the existing wires in aluminum foil, aluminum foil tape, or copper foil tape. Copper is easier to deal with since you can solder a short pigtail to ground the shielding.

Grounding all electronics to the chassis with short, direct connections will help. Don't forget to ground the metal cases of any electronic devices as well.

Finally, moving the ignition box away from sensitive circuits is desirable but if that can't be done, move the wiring of the box away from everything else and cross the ignition wiring over other wiring at right angles to minimize coupling noise into sensitive wiring.

EMI/RFI consists of magnetic field coupling and electric field coupling. Magnetic shielding is accomplished best by ferrous metal-- steel. Electric field shielding is relatively easy-- a thin metal shield is very effective. Copper & aluminum are best because of their conductivity. Running a wire through steel brake line tubing is very effective!

Regards, Neil  Tucson, AZ

[hotrod]

You also might take a look at adding ferrite chokes to the wires as close to the unit as possible the right ferrite choke will strongly attenuate high frequency spikes on the wires.
you can also use shielded wire like RG58 coax for data lines that need to pass near the ignition.

https://en.wikipedia.org/wiki/Ferrite_bead

http://k0bg.com/rfi.html  <-amateur radio  view of the issue, you might ask around the local ham radio groups to see who the local RFI guru is they work with this stuff all the time.

http://www.amazon.com/Handbook-Practical-Cures-Frequency-Interference/dp/0872596834/ref=sr_1_1?s=books&ie=UTF8&qid=1406486089&sr=1-1&keywords=rfi+handbook

1967-1974  corvettes had shielded ignition wires as I recall, you might talk to your local Chevy parts supplier to see if any of their ignition wire kits can be adapted to your system.

Accessory spark plug resistor caps and special low emissions wires are available
http://www.magnecor.com/magnecor1/main.htm   (checkout their faq THE TRUTH ABOUT IGNITION WIRE CONDUCTORS)



Polyphaser is one of the leading manufacturers of surge protection devices and they have a whole line of protectors intended to suppress spikes and transients on data line.
http://www.smithspower.com/brands/polyphaser/products/data-line-surge-protection
http://www.smithspower.com/brands/polyphaser/services/media-library/white-papers

Don't forget your surges can be coming into the equipment on the dc power supply line, that can be clamped with a combination of MOV's and ferrite beads along with shielding of the line so it won't pickup the surge in the first place.

http://www.smithspower.com/SiteMedia/SiteResources/WhitePapersandTechnicalNotes/1457-001.pdf?ext=.pdf

It is a very complex subject and it often has to be solved by experienced trial and error elimination of possible paths for the transient and figuring out an effective filter to suppress the surge in that specific configuration, a solution that works on one car might be totally useless on another due to differences in the surge path or method of induction of the surge into the wiring.

Rules of thumb
Place high voltage ignition wires as far as possible from other wires (especially data wires)
If the ignition wires must pass close to another wire bundle put metallic shielding around the wire you want to protect and if possible arrange the wires so that the ignition wire is as near as possible at 90 degrees to the other wire to minimize the electrical coupling between them.

Assume you are getting spikes on you DC power supply and put filter components right next to the data system you are trying to protect with high efficiency grounding (not some slender little wire but a proper braided ground strap to a substantial ground) I would start with a MOV and transorb protector if you can find a data line protector that is compatible with your system wiring. (ie the right end connectors if you are using RJ45 data lines or coax lines to pass your signals)

Distance is your friend keep low voltage sensitive lines as far as possible from high voltage systems and if possible shielded by metallic shields that cover the wiring (or place on the other side of a fender panel etc. so a grounded metal sheet is between the two)

There are two types of coupling for high voltage surges, electrical and magnetic. A low conductivity shielding like copper or aluminum works best for electrical RFI, a steel or other magnetic material is best to shield against magnetic coupling. Best protection is a little of both a steel tube covered with aluminum foil for example to pass the wire through, and well grounded.

Use single point grounds if you can so that all electrical equipment is grounded near the same location on the chassis.

[saltracer1]

used some ferrite cores on a CNC machine at work last week and they worked wonders to eleminate some weird noises. I bought ten of them here mouser.com and put them on every encoder lead.

http://www.mouser.com/Search/ProductDetail.aspx?R=ZCAT3035-1330virtualkey52130000virtualkey810-ZCAT3035-1330

[manta22]

Ferrite beads are good for conducted RFI/EMI on a wire; they're cheap, convenient to use, and effective on HF interference. Don't forget that you can not only string a wire through the center hole of a ferrite bead, if it is large enough, you can make two or more turns around the bead and back through the hole. This increases its filtering capability.

MOVs and other transient protectors are meant to prevent damage from overvoltage spikes, not to reduce EMI/RFI.

Regards, Neil  Tucson, AZ

[Seldom Seen Slim]

Be careful when you use shielded wire or a coax cable for wiring in the car.  At some frequencies - like perhaps ignition, maybe data from a sensor - the capacitance of the inner conductor to the shield can farkle the signal.  If you do try shielded - look carefully for unintended effect of the new shielded cable.

Jon/WA8GDW/SSS

[jauguston]

XXO,

You mentioned resistor plug caps as a possibility. Ultralight aircraft engines like my Rotax 503 use them. They screw into solid wire plug wires and attach to plugs that have a threaded on plug end on the plug. The screw end is removed to use them. A source is Mark Smith at Trikite.com or most avation supply places.

Jim

[hotrod]

MOVs and other transient protectors are meant to prevent damage from overvoltage spikes, not to reduce EMI/RFI.

True in some cases but not all.

By design they are used to protect against worst case conditions like a lightning induced voltage spike on household wiring with the typical 300 v clamping voltage, they would never activate under normal conditions in a 12V DC system. In those rare worst case conditions such as a mistake made doing a jump start, and accidental shorting of a battery terminal with wrench or a 30,000 volt ignition wire that gets loose due to vibration and finds its way to some place that gives a path to the 12V supply or inductive coupling between ignition wires and power supply wires you can have repetitive spikes in the hundreds of volts enough to kill or disrupt digital systems.

That is one of those worst case conditions that when you need it, you really need it. The capacitance of MOV's is low enough they would not be of any consequence on a 12V supply but would be inappropriate for a high speed data line. For those applications you want something like the transorbe (back to back zener diode) which are designed for digital systems. Transorbe or just old fashioned back to back zener diodes can take a lot of high frequency noise off a line by clipping peaks. That makes other built in filter systems in the digital device more effective and make expensive digital hardware live longer in a hostile environment.

https://en.wikipedia.org/wiki/Transient_voltage_suppression_diode

http://www.vishay.com/docs/88301/15ke.pdf    (turn on clamping voltages available ranging from 7v - 550 v)

They can be used to clip peaks on severe noise conditions. Voltage spikes can add if they arrive along with RFI/EMI. Interference that would not be a problem with out riding on top of a spike produced by another component can transform into a big problem due to the merging of multiple forms of electronic noise on the lines, and push digital systems over the edge. A clean power supply is one of the first things you want to look at so several noise sources do not reinforce each other and create problems.

Peak voltage surges on a 12v system power supply line can reach hundreds of volts (spikes up to 300 volts have been detected in some systems)
Most 12v DC systems assume the power never goes above about 35-50 volts but that can be easily exceeded due to transients caused by jump starting and other high load power applications. Damage due to such over voltage spikes is additive and although the digital system might avoid damage or upset by a single spike of that level, repeated exposure will eventually degrade components and cause failure of capacitors and solid state devices which have limited ability to cope with out of spec voltages

http://www.eetimes.com/document.asp?doc_id=1272768

Like I mentioned above there is no one size fits all each system is different and you have a tool box of suppression techniques for different problems.
Understand the problem and understand the too box then pick the right tool for that particular situation.

[Esslinger Eng]

If needed, we had some custom 12mm thread x .750" reach, 5/8" hex, RESISTOR, surface gap (roughly .028" gap) sparkplugs made for our midget engines that are equivelant to a 10.5 or 11 NGK plug.  There is no ground wire to fracture, and we have had really good luck with them over the last six months of use.  We've sold over 500 of them in this time, and I have yet to hear of a failure.  We are even using them on the F/BGMR and F/GL we sent to Bonneville this year.  In all our dyno time with them on these GAS burning engines I have yet to see one load up either, but that is definitely a possibility when using a sparkplug this cold.  Both of these engines idle at an indicated 10.5:1 AFR or so...