Progress Report and Future Musings

Updates from across the pond.

My kit was completed this week and transported to the firm that handles the packaging and shipping

Folks at R West building the shipping crate around the kit (below). I have heard these are very sturdy crates - another US builder turned his crate into a ramp he can drive his car up onto for easy access to the underside.

The port of entry will be Minneapolis. So I'm either paying someone to transport it here, or flying to Minneapolis, renting a truck, and driving it back myself.

With some help from a fellow Central Indiana Miata Owners group member much progress has been made stripping the donor car. Just a few odds and ends left and it will be ready to lift the body shell off of the power train.

Some of the remaining odds and ends are potentially high hassle factor. I need to remove the pedal assembly which involves a lot of heavily rusted and nearly inaccessible nuts and bolts. Also need to remove the wiring harness (wiring loom over in the UK). 

I estimate that over half of that wiring isn't necessary for my car because there's so much stuff it will not have: air conditioning, windshield wipers, air bags, power windows, cruise control, radio.... So most builders either a) stuff all the excess wiring behind the dash, b) carefully engage in the massive project of paring down the wiring harness, step by step, lest one accidentally remove something essential c) combination of a) and b), or d) completely rewire the car from scratch.

Among the rewire from scratch crowd, standalone ECU units are a popular move. These are basically aftermarket computers that replace the original Mazda engine control computer. The most attractive of these, to me at least, is Speediuno: an open source ECU designed for the DIY crowd. It's the most affordable aftermarket ECU and there are a lot of freeware resources for it - including shared tuning settings.

So if, hypothetically, you were wanting to do something crazy - like replace the Rube Goldbergesque Miata air intake and fuel injection system with individual throttle bodies from a Suzuki motorcycle, there is a community of people who have already done that and shared their engine tuning algorithms online.

This requires a manifold that fits the Miata head on one side and mates with the Suzuki throttle bodies on the other. This is available as a product for purchase, but can also be fabricated/welded using a cut-up Miata manifold. Or, it can be 3D printed... which I believe would be a fairly manageable SolidWorks project.

ITBs are not exactly "period correct" for a 1958 racing car - but it does look a lot more like something that belongs in a race car than the crazy Mazda collection of tubes and airboxes and flow meters that is almost as large as the engine itself, and meanders its way over to the hot (exhaust) side of the engine before sucking in air.

There are theoretical advantages to an ITB setup and possibly a bit of extra horsepower (probably not enough to notice). It does make the engine sound a lot more like a performance car - maybe a touch louder but mostly a different sound quality - however this effect is probably mostly eliminated when you put air filters over the trumpets. If I wind up going this route, I'll be doing it mostly for simplicity and appearance.

Doing all this with bespoke aftermarket parts could easily run over $1500-2000. However, the motorcycle throttle bodies can be had under $100 and Speediuino runs $250ish (add in maybe another $75 for the different sensors required by Speeduino). 

There are ways to simplify the Miata air intake, but those aren't free either and generally require some additional engineering/fabricating - because the Replicar kit doesn't come with handy mounting points to attach all those weird Mazda air intake parts. Designing a manifold on Solidworks and 3D printing it seems like a much more satisfying project than making a bunch of brackets and improvising a bunch of air plumbing to make the original Miata setup work. 

Also, re-wiring from scratch sounds like a more attractive project than a long involved dissection of the Miata harness, trying to remove unnecessary wiring bulk without disabling circuits I still need.

None of this has to be decided now... but this will be one of the thoughts percolating as I go forward.