I'm slowly perusing most of Option 2 on my other project (sans racepack) and I believe you are about right on that one.

PCMs are baller but cost big $$$... If you do it right, you can use a standard blade fuse box with resettable blade circuit breakers, or even those breaker panels they use for RVs. Mount your fuse box or breaker panel in the dash so it is accessible and your circuits can be reset from the drivers seat.

Well wehre I used to work, MoTeC, we would charge around 5-6 grand for an engine harness.

Figure 3 grand in parts to do it yourself (Deutsch Autosport connectors, Mil-spec wire, DR-25 heatshrink, etc) plus a month of planning/work to get it all done.

So just use the stock harness is what I am saying unless you love wiring like I do haha.

$3k in parts for an engine harness wtf?

We don't work for MoTeC, so we can charge about half that price. :) In the world of used Miatas, this is big money. Hell, it's a spare car! In the world of professional racing, this is a weekend tire budget, or Ricky Bobby's bbq bill. If you're setting up one of Emilio's Race Pack systems it will cost even more. And that would make it even better. And will give you more options and accessories.

That said, most guys can get away with taping up their extra plugs...

Pm sent cordycord... Thx man

A lot of that is the cost of the motec power management system. But some of those detsch connectors are over $100 a piece. Honestly if I was going to rewire a real racecar these days it would have some sort of PMS, not sure it would be motec but it would have one unless it was a ridiculously simple car that required 8 fuses and 2 relays or less.

Ok that makes more sense. I was thinking just engine harness.

It looks like we'll be doing one with a RacePak SmartWire system soon. It makes this wire layout even simpler.

Yeah...simpler is the idea for sure.

I did a firewall connector on my car awhile back, excuse the wad of spaghetti that it turns into as I hadn't finished everything on the build at this point the picture was taken but I just wanted to protect the wires from chaffing as I moved things around.

https://www.miataturbo.net/attachmen...ine=1412831236

My best advice I can give is plan out everything you want to run in your car, and buy the right connectors the first time. Nothing hurts more than having to buy a $90+ connector twice...

Yep. Also think about future expansions that you even MIGHT want. Mostly things like data which can consume lots of ports. Or even move that off to a separate harness, and where to route that.
Even for a simple harness from scratch it's easy to break a grand in parts alone just when talking OE level stuff not even mil-spec that's standard on professional race cars. . I'm redoing some of the wiring in my car to make it more weather proof. $250 to delcity later I've got some of what I need, but not a single sensor connector yet.

1. This is a solid option but will take a lot of time, research and care. As the insulation ages, it tends to embrittle with time and the copper can corrode, sometimes invisibly (beneath insulation). Some connectors may require replacement, especially going back far enough. The older the car is, the less functional this option is.

2. This will cost you a TON of time, effort, planning & cursing. Figure over 100 hours for a typical inexperienced person to do everything. You will need to spend more time than you thought mastering crimping and more money than you thought in tools, connectors, sleeving, heatshrink, etc.

In trade parlance, the Smartwire system is a PDM (Power distribution module). They are fantastic where the Motec one is a benchmark able to control # of retries, amperage limiting, failure notifications. It has limp-home functionality to bring a car back to the pit/paddock during the race instead of outright failure. As a general rule, they exceed the scope of a low cost vehicle or street car.

Ballenger Motorsports could build a harness but this is a difficult issue. We could do a proper, made in USA harness and sell it for something like $1,200. We could do a little more volume and get an off-shored one made with some knock-off components for about half that. If we got 20-50 people together who were willing to make this choice and sign up for an identical harness, we could release a product. The Miata community is small, doesn't like spending money (except for a few select racers), and often wants a lot of custom variation. So I'm not sure on this point. Maybe a poll thread and checking with people. I suppose the Spec Miata people would want the product too.

At present we track Miata's and love them, so we offer product to make it easier for people. It isn't a profitable endeavor but Miata's are a lot of fun and some of the parts are also used on higher volume applications.

Yeah. In the pro world, often a tiny short harness for something like an ignition/injection subharness can run $5k using specialty products and methods.

The problem with getting a harness from you thats made for everyone is that we all have different setups and need different wires of different lengths and other varying requirements. Its not like jim bob's carb'ed camaro where there's thousands of cars out there with essentially the exact same wiring requirements.

+1

Even wiring from the same model year will be different based on the options list. 100 hours for a complete job seems a bit low, actually.

I know. Hence my word choice "and often wants a lot of custom variation."

It may be possible to subharness the sections that tend to have variation as a workaround. This and the year to year variation is the big problem to get around.

Yep. Also why I said "Figure over 100 hours" rather than figure 100 hours. It is a hugely larger task than the average enthusiast realizes in time, cost, labor, research, etc. I've seen skilled go,go,go type mechanics thwarted by this sort of project due to the planning & paperwork necessary. It requires several new skills and validation to get acceptable results.

There is sort of an open question of is there someone who has a product and then the issue of whether an individual should make their own harness from scratch. I think we at least covered the issues for the purpose of answering the thread.

Sounds like the Miata crowd should get in touch with one of the companies that does custom Honda harnesses. What you're all asking for is readily available for most popular Hondas, with tons of customization available.

Call up Rywire. they already make custom harnesses for the 13B:
Mil-spec Tucked 13B Harness (FD3S/Rx7)

Basically what I'd be happy with right now is an engine harness that went to a bulk head fitting on the firewall and a harness from there to go to my ecu of choice. Single point of disconnect from all the low current connections on the motor. An Anderson style connector for the alternator/starter/battery line as well. There's 3 options of wiring harnesses for just the engine side.

It's worth a look. Anyone have a complete engine harness they can mail to us for evaluation to make a product?

errr well, stock there isnt an engine harness its kind of bastardized into the rest of the harness. If you were on a couple months ago I could have hacked one off of an early 95 model right at the fire wall, just cut straight through. Without cutting wires someone would end up sending you like more than half the car's harness.