Sato Tatsuya

Hi Ian,

Just a little heads up for you, although I had read that your RX-8 R3 already has a 13B-REW engine swap, so I do not think that this will affect you at all; however, I did want to bring to your attention that I had been working together with Heath from Sakebomb Garage, and the existing ignition coil kit bracket only fit well on a Series 1 RX-8. There are a lot of changes to the engine bay area that forced me to make some major modifications on the existing bracket ( I had originally installed this kit on my 2004 RX-8 ) in order for it to fit properly.

Like I said before, though, I do not think that this will affect you, because if your R3 already has a 13B-REW engine swap, then most likely you will not experience any fitment problems.

9krpmrx8

iTrader: (46)

Please explain what you mean by this exactly? IIRC the D585's draw like 7amps at most. I'm not sure on the wires but from memory I would say the wires are least a 12AWG which should handle that just fine. I'm just curious since my 13 year old wiring harness has been running my D585's (not LS coils) for coming up on 8 years.

SBGarage

The wires are 12 gauge? Or 20 gauge? That's an important distinction. 1000% they're not 12 gauge wires . We use a 12 gauge to supply ALL of the coils on our standalone wiring harness kit which is rated for 40 amps. But you know, no one knows better than Mazda right... I'm sure you've kept your car stock for a reason.

[IMG]http://cdn1.bigcommerce.com/server5200/mjpwat6/products/255/images/1051/IMG_7675__12827.1432065086.1280.1280.jpg?c=2[/IMG[

RX8 IGN-1A Smart Coil Plug & Play Mil-Spec Harness Adapter

9krpmrx8

iTrader: (46)

I guess those of us running D585's have just been lucky all these years.

boricua13

If I remember correctly, in order to handle 40amp and up you WILL have to go up to 8 gauge or greater, 12AWG is usually rated for 20 or below, obviously based on mats and strands. Now, if you are using a single strand 12awg, then 40 amps is possible, stupid but possible.

SBGarage

So would anyone like to guess the ACTUAL GAUGE of the stock wiring that everyone is so happy to plug right into?

SBGarage

dannobre

iTrader: (3)

LOL. It I recall it's 18ga. might be 16....

18ga is good for 16Amps for chassis wiring
16ga is good for 22Amps

dannobre

iTrader: (3)

Cause it isn't as big a problem for the D585 coils.

They draw less current. And without any need for the increased output on 99% of the cars .....it's like the old "if a tree falls in the forrest" 😎

dannobre

iTrader: (3)

Personally I would run a new power and ground sup ply to them if I was running anything over stock power where a missfire can be fatal.

I think as time goes on there will likely be more issues as the harnesses get older and more brittle. It's like the FD's and older RX-7's have tons of electrical issues.

Might be a good upgrade harness design to add to the offerings in the future

pallas

I would just like to add some numbers for consideration, based on my calculations. I know that theory and practice may differ in important details, but certainly the practice cannot violate the laws of physics (only I can screw up the calculations). I do run my car using BHR ignition and a dwell table based on those calculations, and cannot really complain.

I designed my tables based on the fact that the D585 coils self-trigger at approx 8.4 Amps. I use dwell times so as to limit the maximum current to 7.5 Amps to have a safe margin and remain in control of the ignition. So if you only take peak currents, I'm looking at 30 Amps peak, but only for a rather short amount of time.

The current flows through the coil only during the dwell time and increases exponentially with a time constant determined on the coils resistance and inductance. The necessary dwell time depends also on voltage you can supply.
The point is, at 14 Volts, I can reach the 7.5 Amps in 4.15 ms of dwell time. At 9000 rpms, 4.15 ms corresponds to 62% duty cycle (at 1000 rpms, it would be 7%), so even if the peak current of 7.5 Amps was flowing through the coil for the whole dwell time, it would still be only 4.67 Amps on average.

If you actually take into account that the current increases from zero to the peak along the exponential (http://hyperphysics.phy-astr.gsu.edu...mgele/indt.gif), the average current at 14V and 9000 rpms with a dwell of 4.15 ms is 1.4 Amps (and 0.15 Amps at 1000 rpms). I have limited my dwell times to 2 Amps maximum average current, which is only seen at lower voltages (below 12 Volts) and towards lower rpms. The highest I have for normal voltages (such as 12.75 Volts) is 1.79 Amps with 4.79ms dwell at 9000 rpms.

That's for one coil of course. For 4 coils, the average current they draw at 14 Volts and 9000 rpms is about 5.2 Amps, even though for a very short time before firing, they peak at 30 Amps.

BTW, that only holds if you use custom, more aggressive dwell tables. TeamRX8's tables had a max average current of 1.9 Amps at 14 Volts with 4.71ms dwell at 9000 rpms (peak 8.15 Amps), and Oltmann's had 0.73 Amps with 3.20ms dwell at 9000 rpms (peak 6.25 Amps, but 7.51 Amps at 1000 rpms). MazdaManiac's dwell tables were at 0.31 Amps with 2.32ms dwell at 9000 rpms (peak 4.87 Amps, but 9.80! Amps at 1000 rpms which would mean the coils self-trigger).

I don't have all the info for stock coils (apart from there being a dwell time of 1.54 ms at 14 Volts and 9000 rpms), because I don't have a model of the coil (resistance and inductance). For the D585, I approximated the model (the time constant) based on some oscilloscope snapshots I found on the web.

In the end, even if you size the wires for maximum current, I think that the average current reflects the kind of load the wires are subjected to from the thermal perspective. Could this be the explanation why the stock wires apparently work fine over the years?