Coil Relocation Project

As some people who have gone non-seq know, once you start in on the project it tends to quickly change from a simple vacuum line plugging job to an all-out assault on the engine bay.

Once of the changes I made was finding a way to relocate the coils to the corner firewall location (Mazda used this location in the FC series, but most likely stopped due to needing a place for cruise control). The advantages revolving around moving the coils away from the primary source of heat and ease of maintenance - with a minimal impact on weight effects. It required a good amount of time test-fitting and taking measurements in order to figure out the best way to have everything mounted in a stable fashion and still allow room for the ancillary ignition equipment like the igniter and, in my case, HKS twin-power - without hitting the hood.

The parts I used were:

1. 24 x 2 x 1/8" thick aluminum plates.
2. 24 x 1 x 1/8" thick aluminum 90 degree channel.
3. Taylor 8 mm custom-length plug-wire kit.
4. 6 mm x 1.00 pitch x 25 mm length allen-head bolts.
5. A bunch of 6 mm Mazda nuts recycled from parts I removed from the car.

Every single one of these parts is available at Home Depot. I am not going to provide templates because the templates are already there if you're resourceful enough (hint: use the coils to mark a hole pattern, then duplicate that pattern three times). In addition I cannot really provide measurements because simply changing the alunimum stock and/or design will change all of the measurements used. I might go back and grab general length and width however.

I started by trying to just fit the coils in the space by hand, placing them near the bottom of the brake booster.


[click on image to enlarge]


I ended up figuring out that it was pretty much impossible to mount them on the firewall "shelf" as the coils are not low-profile enough to fit under the brake booster. When moved towards the fender side they would hit the clutch cylinder. Basically that route wasn't going to happen cleanly.

An interesting side-note is that Mazda applies some of their unused bolt hole covering tape before painting the chassis. Seemed kind of lame to me to do it that way.


[click on image to enlarge]


Using the test-fitting and measurements I had taken with a good amount of guessing and refining afterwards I went from this:


[click on image to enlarge]


to this:


[click on image to enlarge]


This is essentially what I used for the bracket itself. Not every hole is used (the one in the very corner of the main plate will be used for an additional support to the firewall if I find it to be needed).

After more test-fitting, I ended up with a bracket that worked pretty damn well, if I say so myself. It's solid and mounts flat up against the side of the engine bay (I shaved down the bolts I used on the hanging bracket pieces flush to the bracket to prevent them from sticking out and hitting the wall). It also allows any coil pattern you want (I switched back to T/L/T when I mounted it to offer more room for the plug wire boots).


[click on image to enlarge]


This is what the bracket looks like in the car, without the coils present:


[click on image to enlarge]


If you look closely you can see the little shelf Mazda has placed under the brake lines. This is what I will use with the extra corner hole I drilled (add a dowel pin or something) if I need another securing point (I'm really not a fan of anything "hanging").

So after getting this all squared away in there, I tried finding a way to stuff the igniter and fuel-pump resistor underneath. The FP resistor had many options, but the igniter had funky fitting issues with curved walls and it's large heat-sink. I ended up modifying the original bracket by adding a little sub-bracket just to hang the igniter off of:


[click on image to enlarge]


You'll notice the new plug wires in there as well. I picked these up for 80$ at local domestic car shop. Considering that for 80$ you get EIGHT good quality plug-wires, it's a bargain. The plug end is already crimped by Taylor, you just need cut to length, if desired, and crimp the coil end onto the wire (totally easy). These wires are solid and used by a lot of the knowledgable guys on here (Chuck Westbrook, for example). Do not bother with the 10 mm versions, they are the same as the 8 mm wires and just have 2 mm more of silicone wrapping (it's already thick enough, trust me) at an increased cost.


[click on image to enlarge]


I flipped around the Mazda coil sub-harness and mounted the coils in a T2 / L / T1 pattern (if viewing from passenger side, same order as rotor housings). Also affixed the ground plug to the bottom of my bracket.


[click on image to enlarge]


The OEM coil sub-harness uses the following plug colors:

T1: White.
L1/L2: Black.
T2: Blue.


[click on image to enlarge]


You may notice the 3rd holes in the coils not being used. This is because I did not have wide enough 1/8" thick aluminum to work with from the start - but I don't feel it to be really necessary anyways.

That's about it. I've still got to re-secure the MAP/fluid level/boost/water-temp wires I have just sitting there. HKS twin-power was mounted using one of the 10 mm holes mounted on the curved portion of the shelf (you can see it in one of the above pictures). I just enlarged the HKS mounting hole with a drill bit and used a Mazda bolt I had laying around.

 

Some more pictures:


[click on image to enlarge]


[click on image to enlarge]

 

Nice pics!

 

thats cool... but somebody has too much time on their hands

 

Yea it did take a bit of time. But it ends up resulting in less time in the end as plugs are joke easy to change already, and any little thing to increase reliabilty and heat radiating away from the engine is a good thing as far as I think.

 

Good job ,Garfinkle put his Harley D ,crane coil on the finder wall below the brake booster and the stock trailing coils just below the brake cylinder on the finder wall , some time ago . The new AEM 4 channel box is in the space below the cruise control .Phil or Rotorbrain may have pictures . Good modification and good skill for you .You coils should last longer .

 

Nice. I think we have the same scroll saw.

 

Very beautiful setup! I ended up doing this on my 7 about 6 months after buying it. With the JDM FD, I had to get rid of my ABS(since ABS is located on the Passenger side of the JDM FDs) and mounted it almost in the exact same spot. If you can get ahold of a set of cosmo 13B coils, they're a direct plug into the stock wiring harness and look a little "cooler".

 

Job well done, very creative, I like that.
Just the other day I was thinking of removing the cruise control (I probly used it 2-3 times in 9 years) It's just there for no reason, make that space for something like you did.

 

Awesome. Very well done!

 

While I think your workmanship and your idea is good. I think there is nothing wrong with the location of the factory coils! I think if anything you just complicated things by moving them.

Now If you moved the rats nest! That would be genius!

 

The coils in the stock location get heat soaked and will not last as long as a coil that is in a cool location .

 

Yep. In addition, I prefer to see it as simplification rather than complexification due to moving an auxillary portion of the engine to an auxillary location.

Would I put the alternator in the back hatch if there were a way? Sure.

 

Really nice execution, write up, and pics. And dude, that was your 1000th post! Congrats. I'm printing this for my future projects file.

Thanks.

 

QUOTE: As some people who have gone non-seq know, once you start in on the project it tends to quickly change from a simple vacuum line plugging job to an all-out assault on the engine bay.


Word.


Nice job though. Are those new Mazda coils or just clean originals? And have you checked for how/if your bracket can fit aftermarket coils?

 

Wow, thorough as usual.

How much do you suppose the wires are flexing & stressing when the engine rocks? Not that our wires last that long to begin with...

 

Mine is a Dremel 16", picked it up from Home Depot.

 

I did move the rat's nest. It's on my garage floor now.

 

I doubt it would work with aftermarket coils without having to drill new holes. Something like that is pretty easy to do, however.

They are the original coils - just cleaned off. They're plastic and it's really only oil and grime present before you clean them.

 

Definitely not even a miniscule amount to be worried about. Good thing is that this mod moves the ingition components away from the heat source, leaving only the spark plugs to take the heat (they're ceramic anyways).

 

Another advantage is you can now change your plug wires in 30 sec instead of 30 min .If any ones engine moves enough to stress the wires then the motor mounts must be on the street 100 miles back . This is a mod with probably no drawbacks .Garfinkle can still get to the oil dip stick and set the throttle body air screw with ease . Your paint look brand new and the install is clean and neat , good skill .

 

Much better then my coil relocation!

 

Awsome job!

I relocated mine about a year ago. I was thinking of putting them up there but I actually use my cruise control. I ended up making a braket that goes between the master cyl and fuse box and the coils are mounted to it. Worked out ok since I could retain my factory plug wires but I'd still rather it be in a nicer location like yours is.

Maybe its time for me to ditch the cruise control? Hmmm

STEPHEN

 

I like it! Tools and metals rule!

 

wow I am VERY impressed

clayne that is one of the nicest projects ive ever seen someone do on the forum
im not sure how much it will help with the coils lasting longer it turned out excellent and looks factory.

im sure the car runs beautiful by looking at the engine bay