Ignition Information

Last updated: April 27, 2003

Spark Plugs

Date: Tue, 23 Sep 97 00:40:00 EST
From: "Houseman, Carl W. x1323"

Use only NGK platinum BUR7EQP and BUR9EQP, which is also the definition of Mazda's OE replacement plugs for the 3rd gen. Some have found these at a decent price at chain auto parts stores.


Date: Tue, 31 Mar 1998 14:55:58 -0500 From: rotary@mediaone.net (Carlos Iglesias)

>I appreciate your response. the way it was explained to me was, if I run
>colder plugs, the plugs do not retain as much heat. With a cooler plugs,
>the combustion cycle is not as complete. With an uncomplete combustion
>cycle there is more gas left over, there by cooling the engine with the
>unburned fuel.

Not true as I understand that heat ranges to affect plugs. The temperture range of a plug has to do with how much of the combustion heat the plug literally retains in it's the section exposed to the combustion chamber. The more the heat (range), the less the plug fouls, but also the greater the liklihood that the hotter (literally) plug could cause detonation/pre-ignition. In other words, plug heat ranges have nothing to do with the ignition systems ability to ignite the air-fuel mixture (as long as the plug is not fouled). The only way that a colder plug could lower engine tempeture (or EGT) is if it fouled enough to significantly miss fire and thereby allow lower temps, but this would be an ad hoc reasoning in any performance minded endevour.


Date: Thu, 9 Jul 1998 10:05:43 -0400
From: rotary@mediaone.net

>I am getting ready to purchase a new set of colder plugs and wanted to
>know what your recommendation would be (not that I would follow it :-).
>I am considering the NGK 10.5 all the way around. What other benefits
>would I see if I mixed them up a little bit. Maybe running 11.5 with
>10.5 trailing.

Funny you should ask. Just this weekend I was visiting my local domestic speed shop for some fitting and race gas, and the NGK Florida Sale Manager (Carlos Sezumaga) had driven up from So. Florida to close a deal with the shop. The shop owner asked me what type of plug my RX used so he could stock them. I told him I use BUR9EQP's for the street, and 13's for the track. Well, the NGK guy was suggesting something else, and I somewhat dismissed him not realizing with whom I was talking.

Turned out that I really hit it off with him (must have been the Spic Connection) and he gave me some advice and THREE PACKAGES (of eight) of discontinued 10.5 and 11 plugs. He did this after I told him how much we (the RX community) pay for race plugs. Well, he told me that the plugs that he gave me had been discontinued about 2-3 years ago, and they were every bit as good as the newest itieration, but back then they were about about about a 1/4 the price of the new plug. Nice to see that the new models are little more than a device for profit maximization ;-)

Well, we talked a little about plugs in general, and he confirmed that changing a plug's heat range has NOTHING to do with the quality of the spark (assuming that the plug is not fouled), and only effects the amount of heat that the plug retains, which in-turn directly effects the plug's contribution to the detonation profile of the engine. After reading Dr Jacobs book, this only validated what I already knew. For a long time, I've heard the misconception that certain heat ranges work better (ie spark quality) than others. This is wrong. Heat range ONLY effects the amount of heat that the plug "head" reatain and also the plug propensity to foul.

So to make your answer a quick one, buy the HOTTEST (i.e. least suceptable to fouling) range plug which will not contribute to you car's detonation. Like many of my answers to technical question, it not a simple pill to swallow, but it is the most effective medicine.

Personally, I think that I'll stay with BUR9EQP's for the street, and buy 13's for the high boost application. BTW, I buy 13's because they're (literally) half the cost of the 10.5' or 11.5's as priced by Mazda Comp.

>Is NGK the brand to go with?

NEVER, NEVER buy any other type.... if you get my drift.


Date: Fri, 31 Jul 1998 18:29:02 -0400
From: "Houseman, Carl W. x1323"

> The leading and trailing sparc plugs fire a different number of times?

Leading plugs share a single coil so both fire at the same time. When one chamber is at TDC, the leading plug in the other chamber is mostly through the power "stroke". The extra or 2nd firing of the non-TDC plug does very little if anything, but it saves the cost of an additional coil and electronics to manage it.

Trailing plugs each have their own coils and only fire at TDC in each chamber.


Date: Tue, 29 Dec 1998 06:12:28 -0500 (EST)
From: tferragame@webtv.net (Terance Ferragame)

Just a note on the '+4'. SCC or one of the mags had an article on the +4 a month ago. According to Bosch engineers, you can't use the plugs in a rotary engine. Something about an inherent vibration that causes the electrods to break. They also said that considering the number of rotary engines in the world, they are NOT going to correct the problem.

So stay away from the Bosch Platinum +4 for your 7.

Plug Wires


From: "David Ieroncig"
Date: Tue, 8 Apr 1997 22:20:45 -0500

I'm sorry for the long article, but I thought that some of you would like to read up about Spark Plug wire sets. I got the article as part of a response I received from Magnacor directly.

I had mentioned to the person who answered me that I was going to ask you guys about what you thought about the wire sets before actually going ahead and purchasing them.

So... I'm waiting to hear from those who already have them. How about the Racing Beat wires.. better?

Meanwhile, I went through the article that he has sent, and I figured it was worth posting to "The List", given that its content ended up being more technical than commercial.

FWIW... Given the recent "Vendor on the list" saga, I want to make clear the fact that I have no affiliation to Magnacor and I do not and will not benefit from this post (besides your input on the subject). In consequence, I think I deserve and wish to remain "flame-free".

I hope you'll find this useful.

David Ieroncig.
Montreal, Canada
'93 Base, Yellow

- ------- Forwarded Message Follows -------
Date: Tue, 08 Apr 1997 08:07:09 -0700
From: Steve Brown
Organization: Magnecor Race Wires

They are very popular for RX7s and I'm confident you'll receive a good response, but feel free to contact me if you have any tech. questions.

I'll send you some information

FYI, one of our information sheets follows, that explains about spark plug wires in general, feel free to pass this information on to other RX7 owners...

- --
810-669-6688 (Michigan)
- -------------------------------------------------
Australia (Thundercords) mailto:neilf@zeta.org.au
or http://www.zeta.org.au/~neilf/default.htm
UK (Magnecor UK) mailto:magnecor@sst1.demon.co.uk
- -------------------------------------------------


Carbon conductors are used in original equipment ignition wires by most vehicle manufacturers who sell their vehicles in the USA, and in the majority of stock replacement wires. This style of ignition wire is cheap to manufacture and generally provides good suppression for both RFI and EMI. Conductor usually consists of a substrate of fiberglass and/or Kevlar over which high-resistance conductive latex or silicone is coated, and functions by reducing spark current (by resistance) to provide suppression; a job it does well while the conductor lasts. Vehicle manufacturers treat ignition wires as service items to be replaced regularly, and limited life is not an issue. This type of conductor quickly fails (burns out) if a high-powered aftermarket ignition system is used.


Solid metal (copper, tin-plated copper and/or stainless steel) conductor wires are still used in racing on carbureted engines, but can cause all sorts of running problems if used on vehicles with electronic ignition, fuel injection and engine management systems, particularly if vehicle is driven on the street. Damage to some original equipment and modern aftermarket ignition and engine management systems can occur if solid core conductor wires are used.


By far the most popular conductor used in ignition wires destined for race and performance street engines are spiral conductors (a.k.a. mag, pro, super, spiral, monel, heli, energy, ferro, twin core etc.). Spiral conductors are constructed by winding fine wire around a core. Almost all manufacturers use constructions which reduce production costs in an endeavor to offer promoters and mass-merchandisers cheaper prices than those of their competitors.

In the USA, most promoters of performance parts selling their products through mass-merchandizers include a variety of high output ignition systems together with a branded ignition wire line using a spiral conductor. Most perpetually try to out-do their competitors by offering spiral conductor ignition wires with the lowest electrical resistance - some publish results that show their wires are superior to a competitor's wires which use identical cable (on which another name is printed). The published "low" resistance (per foot) is measured with a test ohmmeter's 1 volt direct current (DC) passing through the entire length of the fine wire used for the spiral conductor.

Low-resistance conductors are an easy sell, as most people associate all ignition wire conductors with original equipment and replacement ignition wire suppressed carbon conductors (which fail as a result of microscopic carbon granules burning away and thus reducing the spark energy's path to the spark plugs) and with solid wire zero-resistance conductors that were used by racers with no need for suppression. Consumers are easily led into believing that if a spiral conductor's resistance is almost zero, its performance must be similar to that of a solid metal conductor. However, nothing is further from the truth!

What is not generally understood (or is ignored) is that as a result of the laws of electricity the potential 45,000 volt or more alternating current (AC) from the ignition coil (a transformer) does not flow through the entire the length of fine wire used for a spiral conductor like the 1 volt DC voltage from a test ohmmeter, but flows in a magnetic field across the outermost surface of the spiral windings (skin effect). The same skin effect applies equally to the same flow of AC current through carbon and solid metal conductors.

A spiral conductor with a low electrical resistance measured by an ohmmeter indicates, in reality, nothing other than less of the expensive fine wire is used for the conductor windings - a construction which cannot achieve a clean and efficient current flow across the windings, resulting in poor suppression for RFI and EMI.

Of course, ignition wire manufacturers save a considerable amount in manufacturing costs by using less fine wire, less exotic winding machinery and less expertise to make low-resistance spiral conductors. As an incentive, they find a lucrative market amongst performance parts promoters who advertise their branded ignition wires as having "low-resistance" conductors, despite the fact that such "low-resistance" contributes nothing to make spiral ignition wires perform better, and RFI and EMI suppression is compromised.

In recent years, most ignition wire manufacturers, to temporarily improve their spiral conductor's suppression, have resorted to coating excessively spaced spiral windings, most of which are crudely wound around strands of fiberglass or Kevlar, with a heavy layer of high-resistance carbon impregnated conductive latex. This type of construction hides the conductive coating's high resistance when the overall conductor is measured with a test ohmmeter, which only measures the lower resistance of the sparse spirally wound wire (the path of least resistance) under the conductive coating and ignores the high resistance of the outermost conductive coating in which the spark energy actually travels. The conductive coating is rarely shown in advertisement illustrations.

The suppression achieved by this practice of coating the windings is only temporary, as the spark current is forced to travel through the outermost high- resistance conductive coating in the same manner the spark current travels through the outermost high-resistance conductive coating of a carbon conductor used in most original equipment and stock replacement wires.

In effect, (when new) a coated low-resistance spiral conductor's true performance is identical to that of a high-resistance carbon conductor.

Unfortunately, and particularly with the use of high-output ignitions, the outermost high-resistance conductive coating over spiral windings acting as the conductor will fail from burn out in the same manner as carbon conductors, and although in most cases, the spiral conductor will not cease to conduct like a high-resistance carbon conductor, any RFI or EMI suppression will be lost as a consequence of the coating burning out.

Some European and Japanese original equipment and replacement ignition wires including Bougicord and NGK do have spiral conductors that provide good suppression - usually none of these wires are promoted as having low- resistance conductors. However, none are suitable for competition use, as their conductors and pin-type terminations are fragile and are known to rarely last as long as good carbon conductor ignition wires.

To be effective in carrying the full output from the ignition system and suppressing RFI and EMI in particular, spiral conductors need windings that are microscopically close to one another and precisely spaced and free from conductive coatings. To be more effective, the windings need to be wound over a core of magnetic material.


Every brand of spiral conductor ignition wires will perform the function of conducting coil output to the spark plugs, but NONE, despite the claims made in advertisements and other promotional literature, will increase horsepower. Independent tests, including a recent test performed by Circle Track Magazine (see May, 1996 issue), show that NO ignition wires for which a horsepower increase is claimed do in fact increase horsepower - the test also included comparisons with solid metal and carbon conductor ignition wires.


The most notable of exaggerated claims for ignition wires are made by Nology, a manufacturer of ignition wires with grounded metal braiding fitted over the cable jackets promoted as "built-in capacitors." Nology's "HotWires" consist of unsuppressed solid metal or spiral conductor ignition wires over which braided metal sleeves are partially fitted. The braided metal sleeves are grounded via straps formed from part of the braiding. Insulating covers are fitted over the braided metal sleeves. For whatever reason, Nology specifies that non-resistor spark plugs need to be used with their "HotWires."

Ignition wires with grounded braided metal sleeves over the cable have come and gone all over the world in the last 30 years, and similar wires were used over 20 years ago by a few car makers to solve cross-firing problems on early fuel injected engines - only to find other problems were created. The recent Circle Track Magazine test (May, 1996 issue) showed Nology "HotWires" produced no additional horsepower (the test actually showed a 10 horsepower decrease when compared to stock carbon conductor wires).

The perceived visual effect of a brighter spark, conducted by an ignition wire, encased or partially encased in a grounded metal sleeve (braiding), jumping across a huge free-air gap (which bears no relationship to the spark needed to fire the variable air/fuel mixture under pressure in a combustion chamber) is continually being rediscovered by promoters who always imagine there's monetary value in such a bright spark, and all sorts of wild, completely unprovable claims are made for this phenomena.

Like many in the past, Nology demonstrates a brighter free-air spark containing useless flash-over created by the crude "capacitor" (effect) of this style of wire. In reality, the bright spark has no more useful energy to fire a variable compressed air/fuel mixture than the clean spark you would see in a similar demonstration using any good carbon conductor wire. What is happening in such a demonstration is the coil output is being unnecessarily boosted to additionally supply spark energy that is induced (and wasted) into the grounded braiding around the ignition wire's jacket. To confirm this statement, ask the demonstrator to disconnect the ground strap and observe just how much energy is sparking to ground.

Claims by Nology of their "HotWires" creating sparks that are "300 times more powerful," reaching temperatures of "100,000 to 150,000 degrees F" (more than enough to melt spark plug electrodes), spark durations of "4 billionths of a second" (spark duration is controlled by the ignition system itself) and currents of "1,000 amperes" magically evolving in a "capacitor" inside the ignition wires are as ridiculous as the data and the depiction of sparks in photographs used in advertising material and the price asked for these wires! Most stock ignition primaries are regulated to 6 amperes and the most powerful race ignition to no more than 40 amperes at 12,000 RPM.

It is common knowledge amongst automotive engineers that it's unwise to use ignition wires fitted with grounded braided metal sleeves over ignition cable jackets on an automobile engine. This type of ignition wire forces the cable jacket to become an unsuitable dielectric for a crude capacitor (effect) between the conductor and the grounded braiding. While the wires function normally when first fitted, the cable jacket soon breaks down as a dielectric, and progressively more spark energy is induced from the conductor (though the cable jacket) into the grounded braiding, causing the ignition coil to unnecessarily output more energy to fire both the spark plug gaps and the additional energy lost in the grounded braiding. Often this situation leads to ignition coil overload failures. It should be noted that it is dangerous to use these wires if not grounded to the engine, as the grounding straps will be alive with thousands of volts wanting to ground-out to anything (or body) nearby.

Unless you are prepared to accept unsuppressed ignition wires that fail sooner than any other type of ignition wires and stretch your ignition system to the limit, and have an engine with no electronic management system and/or exhaust emission controls, it's best not to be influenced by the exaggerated claims, and some vested-interest journalists', resellers' and installers' perception an engine has more power after Nology wires are fitted. Often, after replacing deteriorated wires, any new ignition wires make an engine run better.


Electrical devices, including spark plugs, use only the electrical energy necessary to perform the function for which such devices are designed. Ignition systems, both stock and aftermarket, are designed to have a capacity in excess of what is needed to fire the spark plug gap under normal operating conditions and control spark durations. Inductive ignition amplifiers and direct (e.g. Electromotive) ignitions used by racers are designed to make up the extra spark energy needed by engines designed and built for racing that obtain higher RPM than stock engines and use fuels more difficult to fire. CDI (capacitor discharge ignition) ignitions create sparks that are compressed (and intensified) into shorter durations - some incorporate multi-spark circuits to enable the engine to run smoother under 3,000 RPM.

Ignition wires are nothing other than conductors, and whereas an ignition wire's inefficient or failing conductor or jacket (particularly a jacket inside grounded braiding) can interfere with the flow of electricity to the spark plug, an ignition wire that allegedly "increases" the flow of the electricity will have no effect on the spark jumping across the spark plug gap, as the energy consumed at the spark plug gap won't be any more than what is needed to jump the gap (e.g. a 25 watt light bulb won't use any more energy or produce any more light if it's screwed into a socket wired to supply current to a 100,000 watt light bulb).

Although most new ignition wires will perform the function of conducting coil output to the spark plug, what is important to racers and owners of street vehicles with exhaust emission controls is EMI suppression. All electronic devices can be effected by EMI emitted from ignition wires, and the problem is often exacerbated by installing a high output ignition system. As the vehicle ages, sensors and wiring deteriorate and become more susceptible to EMI from ignition wires. To be truly effective, ignition wires need to be EMI suppressed (for a reasonable time) while having the ability to maintain good conductance without subjecting other parts in the ignition system to risk.

Tuners should also take into account that most stock engines and some hi-tech aftermarket engine management systems use resistance in ignition wires to sense additional information needed by the computer.


Since 1987, Magnecor has recognized that ignition wires capable of conducting the extreme energy output from ignitions available from Accel, Crane, Electromotive, Jacobs, Mallory, MSD etc., all of which are used on engines controlled by electronic engine management systems, need effective and permanent EMI suppression to avoid interference to vehicle electronics.

Magnecor Race Wires completely eliminate the need to resort to short-lived carbon conductor wires to overcome the effect of EMI from improperly suppressed ignition wires on race and performance vehicle electronics. Magnecor Race Wires are extensively used on both stock and modified street vehicles that must maintain exhaust emissions within the legal limit.

Unlike its competitors, some of whom have chosen to market low-resistance imitations of Magnecor Race Wires, Magnecor does not make any claim that their current KV85 Competition (8.5mm) and R-100 Racing (10mm) Race Wires have "low-resistance" conductors, nor do they need to have so for any practical reason. Magnecor does not claim its race wires increase horsepower, and any horsepower gained by the use of Magnecor Race Wires results entirely from the ability of the wires to maintain full conductance and suppress EMI that previously robbed the engine of horsepower.

Magnecor's 2.5mm Metallic Inductive Suppressed Conductors are designed to carry the full output from all race ignitions and are exclusively manufactured in Magnecor's specialized facilities with precision machinery and equipment, and include microscopically close spiral windings wound over ferrimagnetic cores. No conductive coatings are used over the spiral windings. Magnecor conductors are jacketed entirely with the highest temperature silicone rubber to resist the extreme temperatures generated by race engines.

Since first introduced, progressive versions of Magnecor Race Wires have been consistently used by leading contenders all over the world, including those competing in SCCA, NASCAR, IMSA , NHRA and club events in the USA. To date, Magnecor has not sponsored any particular racer to promote the use of its ignition wires in competition events. All racers using Magnecor Race Wires do so to ensure their engines perform efficiently and without the risk of EMI from ignition wires ruining the enormous effort and expense necessary to prepare and tune engines for competition.

This information sheet has been prepared by Magnecor to answer questions asked every day by both resellers and consumers. The information contained is also based, in part, on what has been conveyed to Magnecor's staff by racing and street engine tuners and vehicle owners in respect of their experiences with the majority of brand name ignition wires before and after they used Magnecor Race Wires.

2550 Oakley Park Road 200, Walled Lake,  MI  48390  
Telephone: (810) 669-6688  
Fax: (810) 669-2994 
E-mail: magnecor@teleweb.net

Or contact our overseas distributors:

Telephone: (02) 9749-9600
Fax: (02) 9749-9431
E-mail: neilf@zeta.org.au
Magnecor UK
Telephone: (01869) 32-0753
Fax: (01869) 32-0915
E-mail: magnecor@sst1.demon.co.uk


Date: Wed, 19 May 1999 10:23:13 PDT
From: "Firas Arabo" (firas_arabo@hotmail.com)

I live about 10 minutes from Magnecore's North.American head quarters here in Walled Lake, Michigan. I'm not sure why everyone buys them from other places like PFS, but if you want, and your relatively local, you may just want to order direct 248-669-6688. They ship regularly. I've been to there shop, and it's pretty neat. Huge spools of wires, gigantic ones. Red, blue, black, all for the different thickness. They make them all from scratch right there. Pull out the specified length, cut, tag them with the correct style boot (among which they have dozens), and voila. 10 minutes of work for some of the best wires around.


Most people have had very good things to say about the Magnecors, but here is a counterpoint. --Steve

Date: Mon, 2 Mar 1998 07:44:00 -0600
From: "Westbrook, Chuck"

I have Magnecors on my 93R1 and will never buy them again. Even though the basic cables are of very good quality, the brass connectors on the ends are just crimped on and the caps are just slid over the ends. The ends are not molded like Racing Beats or Taylors. After installing my new Mags, I decided to remove one from the rear ignition coil inorder to place some nylon spiral wrap on it where it was rubbing part of the engine. I carefully pulled it by the cap and the wire just pulled out of the crimped connector which staid in the coil. Had to use needle nose pliars to remove the connector, then had to recrimp the connector back on the wire.



Date: Thu, 18 Dec 97 13:40:37 -0500
From: "Kyle Krutilek"

...Thanks also go out to the guys at Motorsport Technologies in Houston, they turned me on to a most excellent set of Taylor spk wires (about 200 ohms per foot). These wires at a cost of about $40 are simply the best that I have seen for an RX7.


Date: Tue, 22 Jun 1999 09:53:18 -0400
From: "Schlagheck, Ryan W." (ryan.schlagheck@unisys.com)

Who says _all_ FD aftermarket parts need to be expensive? Red or blue (same specs, different color) Taylor spark plug wires are $32.94 shipped via UPS standard ground to Windsor, CT from Summit Racing Equipment in Tallmadge, OH. Base price is $26.00. Summit Racing's number is (330) 630-0250.


Date: Mon, 02 Mar 1998 01:25:46 -0800
From: Tim Stiles

Taylor Plug Wires

The top banner has an 800 number to call for the dealer nearest you. It is:



Date: Wed, 08 Apr 1998 15:32:48 -0700
From: Tim Stiles

Someone care to educate me on spark plug wires. I'm not an electrical engineer so when I see or hear statistics I want to know what that means to me.

Taylor Vertex makes spark plug wires. Good ones at that. Their best wire, the "409" series has an ohm rating of 24 ohms/per foot, the next wire down, the "Spiro Pro", has a rating of 350 ohms / per foot. Available in resistor or solid copper core.

Racing Beat's "Red Hot Race Wires" at $108.00 have a rating around 1000 / ohms per foot. That's what they just told me over the phone but I doubt their claim cause that would mean their wires are no better than the cheapest ones Pep Boys sells.

While I'm fairly certain less ohms are better in this scenario would I realize any benefit paying double the price for "409" type wires. Though not offered in their catalog they are willing to make a set for me. The Spiro Pros are readily available in red or blue. The part number is 77224 for the red ones and you can order them from Summitt.

In summation, it appears that I can get a much higher quality wire from Taylor Vertex at less than one third the price of the ones Racing Beat sells. What gives?


Date: Tue, 05 May 1998 11:40:03 -0700
From: Tim Stiles

Here's what I learned from talking to Taylor directly. They DO NOT make a set of 409 wires for the RX7. They are willing to take a set of their Spiro Pro wires and copy them in order to make a set of 409 RX7 wires for a customer's car. You would have to pay extra--we never got to discuss how much----and give them extra time like a month or so to make them special order. I'd do that before I tried to make them from the universal kit. I've been running the Spiro Pro's on my 7 and I've been really happy with them!


Racing Beat

Date: Wed, 08 Apr 1998 15:32:48 -0700
From: Tim Stiles

Racing Beat's "Red Hot Race Wires" at $108.00 have a rating around 1000 / ohms per foot. That's what they just told me over the phone but I doubt their claim cause that would mean their wires are no better than the cheapest ones Pep Boys sells.



From: richardt@lava.net (Richard H Thomason)
Date: Wed, 09 Apr 1997 10:54:46 -1000

On several occasions various people in this group have posited that Nology wires are, shall we say- not all their cracked up to be. I just had the opportunity to see the results of back to back dyno testing of a set of Nology vs Magnacor wires installed on a friends '95 240SX. AND THE RESULTS ARE:

Nology hp peak:  138.8
Magnacor hp: 141.00

Pretty impressive huh? $180 for 2.2 LESS hp.

But wait, there's more......

Nology torque peak:  149.00
Magnacor:            169.8

WHAT A DEAL!!! For you guys who have ever given thought to "moving up" to the Nology, think again. For those of you, if any, who have already invested, you might want to reconsider.

Ignition Coils

Date: Wed, 11 Apr 2001 12:47:25 -0400
From: Gordon Monsen (gmonsen@fast.net)
Subject: (rx7)[3] aftermarket ignitions systems comments

There have been a lot of posts on this over the past week or so and I know I chimed in a few times. I want to revisit it one more time after thinking about it. First, on the list there are people with cars in various states of tune or modification and each level of modification will respond differently to aftermarket ignitions. Also, there are substantial differences between the aftermarket ignitions themselves.

Very lightly modded twin turbo cars are going to get very little to no benefit from aftermarket ignitions. In fact they may be hurt by most of them. the crane, jacobs and msd 6 (non-digital) are all multiple spark systems from 0-~3500 rpm. this means that it will run the cars very lean down lower in the rpm range and may put the motors in jeopardy of detonation when the cars have warmed up and/or the outside temperatures are hot. They do put out more spark (joules) energy up high as well, but it's not multiple sparking. In these applications i can think of no reason not to stick with the stock ignition.

As cars get more extremely modified as twin turbos to some degree and certainly with all single turbos, I believe there are real benefits from going with the MSD digital ignitions. (Crane and Jacobs are analog.) The reasons are that the rotary ignition trigger is an internal reluctor that fires off the falling signal from the ignition amp. If the analog sine wave signal is not crisp (for whatever reason and this happens), then the ignition may fire slightly before or after it should. This directly changes the timing and that will change the way the car runs, the horsepower it makes, and it may detonate, if it fires enough times before it should. The MSD digital ignition generates a square wave at all times that is identical in shape. Therefore, it will fire at precisely the same time every time and at all RPM levels. Analog signals are going to have a much harder time at high rpm generating a clean wave form than a digital signal. related to this is the issue of precision of timing. At high RPM, the analog signals are not going to fire precisely and axactly at the moment they are supposed to, whereas the digital signal is more capable of doing so. Finally, the MSD digital ignition has electromagnetic interference and radio freqency interference suppression built into it. These unwanted signals are one of the sources of interference that could cause an agnition to fire at the wrong time or with a wave form that is not accurate.

In summary, most lightly modded cars will not benefit at all from non-digital aftermarket ignitions and may be leaned out too much at lower rpm (a bad thing...). They may run a bit cleaner with a digital aftermarket ignition, but should not increase power significantly if tuned for proper air fuel ratio to begin with. (I am still interested in learning more about the atlanta club's testing of the HKS.) The benefits of going with an aftermarket ignition in general seem better with more modified cars, though there is little hard evidence of this. I believe, however, that the benefits of going with a digital aftermarket ignition, like the MSD digital 6 plus and dis-2, are substantial for the reasons I outline above. this is especially true in highly modded or single turbo cars.


Date: Wed, 11 Apr 2001 10:49:11 -0700
From: Aarroneous (aarroneous@pobox.com)

I agree with some of what Gordon wrote, but wanted to clarify that both crane and jacobs make both inductive AS WELL AS capacitive discharge ignition boxes (analog and digital). It depends on what model you buy. In the Jacob's case, the earlier "RotaryProPaks" (whatever they were called) were rebadged MileageMasters, but the newest crop are rebadged ProStreets. The mileagemasters are inductive (and won't fry your stock coils), and the prostreets are capacitive discharge (which did fry my stock leading coils).

One more thing - the car comes stock running pig rich. An ignition box helps clean that up.

Oh, and another thing, running lean is caused by an improper AIR/FUEL ratio. What does spark have to do with running lean? I think Jim LaBreck had a nice rant about this topic once. Should be on Steve's website?


Date: Tue, 23 Mar 1999 16:00:19 -0500
From: ryan.schlagheck@unisys.com

For future reference, MazdaComp prices for coils are as follows (retail prices are allegedly higher):

N3A1-18-100    Trailing Coil front                       $95.00
N3A2-18-100    Trailing Coil rear                        $95.00
N3A3-18-100    Leading Coil        Brace yourselves!    $395.00

That's not a typo...


Jim responds to people who think that the Crane HI-6 is causing detonation, lean conditions, etc. I think he makes some very good points on why it shouldn't be. --Steve

Date: Fri, 25 Sep 1998 10:56:00 -0700
From: "Jim LaBreck (ECA)" (a-jimlab@microsoft.com)

Call me stupid, (OK, I know a few of you will jump at the chance... :) but what does burning an air/fuel mixture more efficiently have to do with a lean or rich condition? The lean condition would be caused by too much air and not enough fuel, neither of which the Crane HI-6 is responsible for.

If the exhaust and intake are opened without adding fuel, then a lean condition will result. If the ECU is reprogrammed to add additional fuel, assuming that the fuel system (pump, lines, and injectors) can provide that additional fuel, then no lean condition will result from the improved breathing of the engine. If the boost level is raised, and even more air is added, then additional fuel will be required to prevent a lean condition. The main problem seems to be that the factory injectors are unable to provide enough fuel for reliable operation over roughly 13.5 psi of boost.

The Crane HI-6 has been proven to control tartar build-up as well as the nasty hi-end miss associated with additional fuel trying to be burned by the stock ignition system. By providing multiple sparks at low rpm, a hotter spark at high rpm, and a rev-limiting system (correct me if I'm wrong about the function of the HI-6...) the HI-6 is helping the ignition system to burn the air/fuel more effectively and efficiently, while also safeguarding the engine from over revving. Anyone have a problem with this?

I fail to see how a lean condition could result from the use of the Crane alone... the lean condition above 6,800 rpm is more than likely the result of the limitations of the factory fuel system when combined with the additional flow of intake and exhaust and increased boost levels.

Instead of blaming the Crane HI-6, blame the fuel system. More tuners should be warning those who are upgrading to spend as much time, effort, and money on their fuel system as they do on their other modifications. For the price of an ASP intercooler, you could keep the factory intercooler and upgrade your fuel pump, fuel filter, lines, and injectors and add a fuel pressure regulator. With the proper fuel management system, you could then be assured of providing enough fuel at ALL boost levels the factory turbos are capable of without worrying about running lean and detonating.


Date: Tue, 16 Sep 1997 17:24:46 -0400
From: "Carlos A. Iglesias" (rotary@highway1.com)

>Does anyone know of a source and price on the
>Crane Hi6 DI2 Model? This is not the base model.
>This one has the rev limited and timing retard as
>well? The Jeg and Summit catalog don't list this

I looked into the HI-2 DI2 model, but at a Summit quoted price of $330, I'd rather buy two HI-6's at $149 each. Besides, the DI2 isn't compatible with the upgrade ignition coils (Crane PS or LX Series) because of its lower output than the HI-6.

_________________ P>Date: Thu, 20 Jul 2000 13:40:44 -0400
From: "Wade Lanham" (walanham@mountaineergas.com)

You might consider the HI-6S. It is only about 3.5" x 5", (about a third of the size of the standard one). I think they are also epoxy filled like the HI-6R. The only difference I can find on Crane's site is the multi spark stuff ends at 2000rpm instead of 3000rpm.

And the price of this unit is only about $130 (about $30 less than the standard HI-6).

The only reason I didn't use that one is because I didn't find out the differences until a half an hour after I ordered, and when I called back it was "already shipped."

Finding a place to mount that one should be an easy task. You could probably mount it on the back side of the driver's shock tower. You'd have much shorter lengths of wire that way.


Date: Tue, 4 Apr 2000 08:46:24 -0400 From: Scot Kight (skight@reliacom.com) Subject: RE: (rx7) (3) Crane HI-6 and coils

>Is anyone using or know if it's possible to use the Crane Fireball 
>PS91, PS92 or Crane LX91 Ignition Coil without the Crane HI-6?
>What is the best Crane coil to use with the Crane HI-6, PS91, PS92, 
>LX91, or LX92?  The LX91&92 are lower profile.

You do need the HI-6 with those coils. Mostly because the coils are going to have a vastly different resistance then the stock coil. You have to wire the coils in series or parallel, and the resistance is just way different, the stock setup is only optimized at the stock coil resistance.

I am running a hi6 with 2 LX91's. They work great.


Date: Tue, 04 Apr 100 12:24:55 -0700
From: "Andrew R. Ghali" (andrewg@netcom.com)

This has been bugging me for a long time. Based on my engineering experience and this page: www.cranecams.com/ignition1/igntech1.htm you can see that you really need to replace your stock coils if you go with an aftermarket CDI system. Most stock ignition systems, like ours, use the ignition coil as an energy storage device (think of it as a magnetic flux capacitor). The igniter module is basicly a switch that puts current into the coil, creating a stores magnetic field, then abruptly shuts off the current, causing the field to collapse, generating huge voltage across the secondary winding (for the engineers out there: V = L * di/dt). This requires a heavy steel-cored coil and large air gap to store the field - hopefully without saturating (saturation is where the magnetic field becomes too intense for a material to hold, so any further energy is disappated as heat). Saturation concerns are the reason for the big air gap- air is nearly impossible to saturate (outside of a nuclear blast). Energy storage coils are generally low frequency, hence performing well at low RPM's with performace dropping of as RPM goes up.

All the aftermarket ignitions seem to be a capacitive discharge system. In a CDI, you take your 12V, run it through a DC/DC converter to something between 300V and 500V, and charge a photo flash capacitor (this is your energy storage device). At the right moment, the CDI abrubtly switches the cap across the ignition coil, causing a high current spike in the primary winding, which gets coupled to the secondary winding as a much higher voltage spike. The ignition coil becomes a pulse transformer in this case. This requires a tightly coupled magnetic circuit between the primary and seconday windings (meaning an almost nonexistant air gap), and a light, probably ferrite core, and saturation is not a concern. You need the ferrite because of the high freqency of the input pulse- you don't want a conductive core that will disappate power as eddy currents.

Now here's my problem: the optimum design of a pulse transformer is radically different from an energy storage coil. In other words, each device makes a lousy substitute for the other. I haven't seen anything that quantifies these differences between the two systems. And then I see things like the MSD "Super Crazy Ninja Blaster Coil" that looks like an old GM tower ignition coil spray-painted red and I've just got to wonder: what are these guys really selling and how much of all of this is just hype?

At least Crane seems to realize that different transformers are necessary. This explains Scot's observation about resistance. I wish they would spec them out better, so you can know what you are getting. Useful information would include turns ratio, mutual inductance, coupling factor, insulation breakdown voltage, DC resistance, frequency response, saturation field strength, etc. Then you could pick the ponies out of the marketting hype.

My question is this: has anyone tried the Crane Hi Dis-4/6/8 (I forget exact name, but it was reviewed in the latest Turbo magazine)? It is designed for a distributorless system with multiple coils (like ours). My thought was could this thing be adapted to a rotary using 3 or 4 coils and replace both the leading and trailing ignition with a single box?


Date: Wed, 05 Apr 2000 09:40:14 -0400
From: Wael El-Dasher (wael.el-dasher@efini.net)

Space is an issue, and I would suggest you make a small cardboard about the size of the coils and try to fit 2. I know Gordon uses the MSD blasters and I have seen them mounted in stock location in Japanese magazines but they machine a 1" thick aluminum spacer that fits between the upper manifold runners and lower manifold with longer bolts (it still clears the hood). So effectively they raise the intake manifold about one inch. I am using the Crane dual post coils (I can't remember the part number but they are discontinued but from their harley coils part numbers use 4 as the last digit, I think it was 5004) But it has been done, that is you split the trigger signal and send it to 2 coils. It works great if you have the room.

I would call Crane and ask them what the difference is between the HI-6 and Fireball, but I suspect its just marketing.

Back to the data I wanted to get you before responding. I order the HKS DLI, which I suggest you consider instead of the Crane, it plugs into the factory harness (no splicing, butt connectors...) just clean "click" and you are done. I sends amplifies the signal to all 3 coils and will not overcharge the factory coils the way Crane does. I was going to wait until the HKS arrives and spend some time on the dyno toggling between the 2 setups, then respond with some numbers. As far as getting a replacement coil, Mazda Comp sold me a new coil for about $100.


Date: Wed, 05 Apr 2000 11:16:37 -0500
From: Gordon Monsen (gmonsen@fast.net)

I suggest you read a bit more on the MSD system. it seems, as always that there are many opinions on what to do re ignition. I'm not an engineer and can't respond knowledgeably to most of your comments technically.

I use an MSD Digital 6 Plus with two "Ninja" Blaster coils on the leading plugs and an MSD DIS-2 (2 channel ignition) on the trailing with the same coils. I have used MSD ignitions on my cars for many years and although I tried the Crane, I think the MSD set-up I have is far better.

The reason Demetri and I are also running a stronger ignition system on the trailing is that, while the trailing plugs do "clean-up" duty on stock and lightly modded cars, on highly modified single turbos putting out over 425 rwhp, the spark to the trailing plugs makes a bigger difference at high RPM.

The MSD coils have a 100:1 turns ratio, btw, on a segmented bobbin, though I don't know what core they use. you could call them at 915-857-5200. also, I would suggest you speak with Paul Yaw of "Yawpower" who I believe is one of the most knowledgeable experts in ignition for rotoaries. You might also want to talk with David Lane, who has been using Paul Yaw's type of MSD set-up for some time with great results. -gordon


Date: Tue, 28 Mar 2000 00:43:49 -0800
From: Aarroneous (aarroneous@pobox.com)

First off, thanks to all who helped out with my installation questions, Max, the Crane link you sent me helped me understand the basics of the mod, and cleared up my questions, thanks!!

Here's what I learned:

The Jacobs unit, like all other ignition amplifiers only controls the leading plugs. The trailing plugs are only there to clean up the combustion process, and 98% of your power is from the leading plugs anyway.

Spool up with my non-sequential turbos is noticeably improved. Wow! I was very suprised. Here are a list of mods:

Knightsports intake with cool air induction kit made by me. I may decide to sell this on the list for all you guys who have already bought "hot air intakes." If y'all are interested, I'll get some pics up somewhere.

HKS EVC IV set to 1.00 bar (about 14.7 psi).

Greddy Intercooler with associated piping and elbow. Hacksaw-ed and ground Pettit intercooler duct made to fit with Greddy intercooler. This makes a HUGE difference everyone. I have an intercooler temperature gauge with sensors before and after the intercooler. Here are temps I got tonight: pre intercooler: 180F post: 82F This was after a number of 3rd gear runs to 7600 rpm (about 100 mph).

Tri-Point high flow pre-cat, and cat (with tube that connects to air pump)

Apex'i N1 Dual exhaust.

The power comes on much more smoothly after installation of the Jacobs unit. I used to get a huge KICK from the turbos when they FINALLY reached max boost at around 4600-4800 RPM. Ahn can attest to how terrifying this can be =) With the new set up, I get 1 bar by 4200 RPM in 3rd gear. I couldn't be happier.

Oh, before I get flamed with, "you're gonna blow the engine, etc etc," I also have an HKS F-CON and FCD. FCD is set to 7, F-CON is set to 4. According to the air/fuel ratio meter, I'm running rich at WOT. Running pretty rich everywhere else too. Oh well.


Date: Thu, 18 Dec 97 13:40:37 -0500
From: "Kyle Krutilek"(kekr@lubrizol.com)

I recently had a Hi-6 installed in my 94 R2 and I love it. I strongly considered the Jacobs given the sales pitch from both Jacobs and Rotary Performance, however, I am now so glad that I went Hi-6. I have sent some private e-mails to others on this subject but have not posted to the list yet. I think its time. What I have attached to this note is relevant copy of several messages ...

************************ First Excerpt **************************

Get this!

Jacobs sucks. I called Jacobs and ordered my stuff over a week ago. Since the first spoken word by Jacobs I have experienced the following:

  1. Called Jacobs and was told that system is plug-in, no wire stripping etc required except maybe power and ground.
  2. Placed order on Friday, should arrive by following Fri/Sat, had to be drop shipped from RP in Garland
  3. following Friday nothing had arrived, I called Jacobs and learned that the order bounced, no reason given except that might have been a computer problem due to power outage. Noone called me to inform me of the bounce,but, Jacobs claimed that someone should have called me. Kyle very upset.
  4. re-ordered, attempted to next day but everyone at RP was at SEMA show. Jacobs was to process order first thing monday
  5. Monday, called Jacobs, Jacobs claimed that everything was in progress, they would pay xtra ship charges to get part to me by Tuesday.
  6. Monday, called RP, RP had heard nothing but Arie would personnaly see to order and make sure it was shipped for next day, Tuesday delivery
  7. Tuesday nothing arrived, Kyle very upset, again
  8. Wednesday, called Jacobs in am. Jacobs called back in two hours and we talked. They never called back again.
  9. Wed, called RP and was told that part was shipped ground, get to me in couple of days. Kyle very upset.
  10. Same day in pm, Arie called, apologized repeatedely for the mix up with Jacobs as he informed me that nothing was shipped yet but it was ready to ship. We talked. The system is not plug-in yet, Maybe soon. Kyle died suddenly, then spoke. Arie said that plug-in may be ready in week or so(who knows?) but offered to give me the new experimental Jacobs unit when I decide to place order.
  11. Kyle cancelled order until plug-in is available. Kyle curses Jacobs and is now just very upset, but still alive.
  12. Anyone want to install a Crane Hi-6? The line starts at the rear.

I may wait for the plug-in. Arie says the new unit has a special feature such that the ignition energy is increased when full throttle is applied, but even he doesn't know that much about it. Jacobs has completed their tests and RP is now running their own.

*************************** Second Excerpt *****************************

get this. Just talked with Jacobs technician and got another explaination of the Rotary Master.

  1. Its a Jacobs Mileage Master model and Rotary Performance makes the Mazda plug-in connectors. This unit is inductive. It can restrike or multi spark up to 3500 rpm. After 3500 rpm, it goes full intensity with single spark, no restrike capability.
  2. The new technology unit as described by RP, is the Pro Street Jacobs unit. It is higher energy unit due to a capacitive discharge design. The unit has same multi-spark design up to 3500 rpm. Only change is a sensor that you install which senses full throttle condition and changes the unit's output to full intensity.
  3. Crane HI-6 is multi spark up to about 3000 rpm, it multi sparks thru a fixed crank angle. After 3000 rpm or so, it goes full intensity single spark.

*************************** Third Excerpt ***************************

Fellow seekers of higher energy,

I have decided to go with the Crane HI-6 and new spk wires to fix the high end. I have had it with Jacobs and Rotary Performance.


From: Wael El-Dasher [mailto:wael.el-dasher@yale.edu]
Sent: Sunday, April 25, 1999 11:21 PM

Having installed a Hi-6 in my car and helped Ryan install the Jacobs which he bought from RP-Online, I would say that the Jacobs is a better choice. The quality of the unit is better, especially the connectors. The Hi-6 is a good unit, except that I couldn't help but dislike their tech. support staff who really did not want to offer any support for an install in a rotory or help troubleshoot. The Jacobs only disadvantage is size. Although it occupies approx. the same footprint as the Hi-6, however it stands taller, about 1.5 or 2 times taller. Still if I were to do it all over, I would choose the Jacobs from Trey.


Date: Mon, 26 Apr 1999 14:20:59 -0700
From: Zak Speakman

The Jacobs "RotaryMaster" is merely a Jacobs "MileageMaster" re-labeled with a custom harness for 7's. You can save $150 by wiring-up a "MileageMaster" yourself. Summit sells the "MileageMaster" for about $200.00


From: Schlagheck, Ryan W. [mailto:ryan.schlagheck@unisys.com]
Sent: Monday, April 26, 1999 5:46 PM

Would you be able to tell us what the Rotary _ProPack_ is in it's original packaging? Is there a buffed up version of the MileageMaster that pulls double duty as the Rotary ProPack? On a related note...the Crane dual post coil for the leading plugs is the same identical unit as the Jacobs Rotary Ultra Coil. Wael has the Crane, I have the Jacobs...identical.


Date: Mon, 26 Apr 1999 18:10:39 -0700
From: Zak Speakman (zspeakman@whisper.com)

Jacobs makes 2 "MileageMasters" one I believe is the "MileageMaster Pro" (Thus the "PRO" in "Rotary_ProPack"????) and a plain "MileageMaster". It's been a couple of months since I talked to Jacobs about this stuff, but they were totally up-front about it. With the coils you mentioned, you are probably once again experiencing a vendor re-labeling already available and less expensive merchandise. This happens with all kinds of parts that are "specifically" for our 7s...


Date: Thu, 29 Jan 1998 22:03:59 -0500
From: Tuck

> What is this Jacobs all about? I saw it at Rotary Performance
> online ( http://www.rx-7.com ) . Is it worth it? On the HKS
> upgrade chart, an ignition is on there, so I guess it would
> help. Can someone tell me about these? I guess it is about
> a 5-8hp gain?

I've made my opinion on this very clear before, but I absolutely refuse to believe that there is any need to "upgrade" the ignition system on anything other than the most aggressively driven and highly modified RX-7's. From the ground up they have always had excellent ignition systems, with more than adequate coils for the job at hand. While it is true that some of the higher-boost forced induction engines get some breakup at higher rpms, this is simply not true of a properly functioning stock 86-91 NA ignition system.

The third gens may have a problem at the top end with breaup once they've been modified, but since the coils on those cars are roughly a third of the size of the coils on the second generation cars, that's not too surprising.

And as for personal experience, I can say two things about where to spend your money. First, my normally aspirated 87 can beat an 89+ Turbo II in a rolling street race through third and fourth gear - where the only contest is power and quick shifts. Second, it does so with the stock ignition.

As for the HKS ignition box, I acquired an HKS twin power ignition unit for the hell of it and aside from the fact that it completely hosed my stock leading coil without me even starting the car, it is a ridiculous thing to spend money on. I have the thing sitting on a shelf as I ponder whether I should risk trashing another coil just to try it out (and yes, I checked the wiring about a billion times, and no, I never even got a chacne to adjust the thingy so the LED was brightest). For the cost of one HKS ignition box you can buy a light flywheel and a competition clutch, it's not worth it.


Date: Tue, 10 Mar 1998 01:35:11 -0500
From: Tuck (sldbrass@darksideresearch.com)

Since I have long been preaching that I'm not a big fan of spending money on ignition boxes as a performance modification (especially on the normally aspirated first and second generation cars), I thought I would comment on my experiences with the HKS Twin Power ignition box I recently installed in my car (namely, last friday).

I acquired the unit several months ago for 75 bucks, but for a variety of reasons, hadn't really used it since acquiring it. Friday afternoon I got bored and decided that I would give it a shot.

A few months ago, during one of the brief interludes during which I had my car from the body shop, I tried to install it and had a profound lack of success. My leading coil was totally fried, and I had to drive out to Rotary Performance on only the trailing ignition (which is really unpleasant, trust me) to get another leading coil. Needless to say, that left me with something of a bitter taste when it came to this ignition box, but I decided that I would give it another shot, and I called HKS to get another copy of the installation instructions faxed to me. I also made absolutely sure that the model I had was the correct one (they have different models depending on which impedance range your stock coils fall in). The guy from HKS point-blank told me on the phone that putting these things on the trailing coils was a waste of time, and that it was exceptionally difficult to fit three of those boxes under the hood. Didn't bother me, I had no intentions of doing so, but figured I would throw it out there.

So that having been done, I said what the hell, no guts, no glory, and gave it another whirl. I was painfully careful doing the very simple wiring (5 whole wires, big deal), but I wanted to be absatively sure that I hadn't screwed the pooch myself if the leading coil got cooked again. I took my time installing the wiring with the harness unhooked from the twin-power box while I was doing it. Then I turned the ignition on and slowly pushed the plugs together. As soon as I did, the HKS box started making a weird high pitched noise, which didn't seeem normal, so I unplugged it, checked the wires again, and decided that maybe it was normal. So I plugged it in again and decided to try starting it. The car started right up, and I walked around to the front of the car and turned the little adjust screw until the light was blinking nicely.

At this point, I was pretty happy with the whole thing (not cooking my ignition again), and was deciding where to install the ignition box. I ended up screwing it to the plastic fan shroud where the inlet ducts used to be, and that allowed the harness to run unobtrusively behind the driver's side headlight mounts. The only downside is that I have this garish thing that says twin power just blatantly displayed when the hood gets popped, but I guess the all-show-and-no-brass crowd gets off on that sort of thing.

I didn't expect to notice anything when I drove it afterwards, but that turned out not be the case. It wasn't any dramatic improvment at all, and there is no way in hell that I would shell out what HKS normally charges for one of these things, but I did notice a difference. Throttle response is slightly crisper, and both hard and very light (part throttle) acceleration through the rev range seems a bit smoother. My idle is also a little better, perhaps because the ignition is covering up for somewhat worn plugs. ;-)

Anyway, the final verdict is that it makes a slight difference on my car, which is in all likelihood more heavily modified than almost any other street NA second gen on the list, but I doubt it is worth it at all on a near-stock engine. With the stock ignition on a stock car, I'd say that the difference would be almost unnoticable. Basically, in the long list of things to upgrade, save the ignition for last. Dead last. Do the open exhaust, the intake, the struts, the springs, the sway bars, the ported motor, the paint job, the brakes, the tires, the gear shift knob, and the steering wheel FIRST. Then consider spending money on the ignition. I think HKS charges nearly 600 bucks for one of these things, and the benefit isn't even CLOSE to worth it. In all fairness, I do like it, I just wouldn't spend more than the 75 bucks I spent on it!


Date: Tue, 25 Apr 2000 23:40:07 -0400
From: Wael El-Dasher (wael.el-dasher@efini.net)
Subject: Re: (rx7) (3) HKS Twin Power Rotary ign....

Just like a turbo timer, it comes with a cut and splice type harness, but HKS sells a specific FD harness using OEM connectors, just like turbo timers. I highly recommend you get that harness. The HKS is a simple and nice clean unit, with the harness all you do it connect it between the ignitor plug and coil harness plug, just click click and ground at ignitor bolt (they even clamped the ground for you).

I doubt its as powerful as the Crane or MSD, but it works on all three coils. It also does not overcharge the coils, because it monitors the charge level, or so it says in the 6 page information package HKS faxed me. Unfortunelty their info package has no numbers to know how much of an increase it adds to the system, my guess is not much. I have one though and I wouldn't go back to the cut and splice variety. It has been dynoed on a 2nd gen. by a very reputable Mazda racing shop and it showed a genuine 2hp gain after several days of testing, but the main benefit has been part throttle response in their opinion. I am waiting to hear their testing results on a 3rd gen. Hope this helps.


Date: Sat, 11 Mar 2000 10:50:28 -0500
From: Anthony Wilson (wilsona@nswccd.navy.mil)

Jacob Electronics has dual-post coils that suitable for the leading ignition coil. This coil is a direct replacement for the Crane Cam coil part # 8-3004. The Jacob part # is 3800070. This coil has identical dimension to Crane's dual-post, which I understand Crane not longer sells.

The primary resistance is 0.73 ohms and supplies a spark energy of 36 millijouls. Jacob also provide higher performance dual-post coils. Part #380060 knowns as a premium performance coil. It has the mounting holes (2-hole mounting) but the coil itself is much longer and the coil is heatsinked. The primary resistance of this coil is 2.2 ohms and supplies a spark energy of 72 millijouls.

Another dual-post coil is part # 380065 and is known as the Ultra Coil Hight Output. Again it has the mounting holes (2-hole mounting) but the coil itself is much longer than first coil mentioned. The primary resistance of this coil is 0.63 ohms and supplies a spark energy of 89 millijouls.

FYI, the Crane dual-post coil as well as the Jacob coils are originally for Harley Davidson motorcycles. I could not locate these coils on Jacob Electronic web-site but this is their web address: http://www.jacobselectronics.com/. Their phone number is (800)627-8800.


Date: Wed, 29 Mar 2000 13:49:30 -0500
From: Scot Kight (skight@reliacom.com)
Subject: RE: (rx7) rx7[3] Sound of leading coil failing...

> Does anyone have symptoms for a leading coil going bad?  
> I've noticed in my two previous

Lead coil failure is a hollow sound in my exhaust note, it's almost like a sticking whoosh sound. I've been told that this is a miss in the combustion cycle. I've been hearing it again lately since getting my car back with a new motor. If I burn another coil I wouldn't be surprised. Many other owners have switched over to upgraded coils and had the problems go away.

Mine got very loud, with an idle that would drop to 600 or 500 before returning to 750rpm. Eventually it would stall out when going to a stop.

Also, power is way down, no increase past a certain amount of boost.

Ignition Wiring Harness Improvement

Date: Wed, 19 Jan 2000 12:06:51 -0600
From: "Westbrook, Chuck E." (CWestbrook@tmh.tmc.edu)

The ECU on passenger side sends the firing trigger pulses to the igniter on the drivers side. This can't be changed and doesn't need changing.

The problem is with the wiring from the igniter to the coils. The coils are only about 2 feet from the igniter. But, the wiring goes from the igniter back inside the car to the main engine harness by the ECU, out the right firewall, to the engine where the solenoids are, across the front of the engine, then back on the left side of the engine to the coils. The 2 feet distance is now about 8 feet of wire carrying pulsating DC which can emit EMF if not properly shielded. This excess length also increases the possibility of the wiring being damage and/or misfiring.

While reinstalling my engine, I decided to go for the direct 2 foot route. The short ignition coil harness was removed from the main harness and the three coil connectors were cut off. These were then rewired with shielded wire to go directly to the igniter. The igniter output wires were cut and connected to the new harness. While doing this, the primary igniter wires were also connected to an extra male/female connector that allows them to run normally or be connected to my Crain HI6R.

Currently while breaking in the new engine, the Crane is disconnected and all are working fine. I did all of this to insure that the coils received the best possible signals and to increase reliability.


Date: Mon, 02 Apr 2001 11:31:27 -0400
From: "Alan Cross" (CrossA@mail.vetmed.ufl.edu)
Subject: Re: (rx7) [3] Ignition Wiring Harness

>Dealer says it is available for about $50 (from prior experince),
>but could not find the part number.

From a previous post, this is reported to be it. If you find a cheaper source please let me know (other than mazdacomp)



Date: Thu, 25 Oct 2001 15:05:17 -0700 (PDT)
From: Chuck Westbrook (cewrx7r1@yahoo.com)
Subject: Re: (rx7) (3) How much for complete engine wiring harness?

From my local dealer because MazdaTrix does not sell them:

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