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At the risk of getting flamed, I wonder about a mechanical alternative to all of the established IRTB (Jenvey, Mahruna, et al) units in the marketplace. Specifically, the SPICA that came with the U.S. market Alfa Romeo 1750 and 2000 motors. Especially the later, as the power bands are pretty close to the 1.8 cars.

Setting aside the ignition, plus making a bracket for the fuel pump, how viable an option is this? I should think that the SPICA injectors should be adaptable to the DCOE manifolds. I'm not ruling out the "conventional" IRTB, just considering possible options.
 

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To be different? No, I was actually approaching it from the standpoint of the ECU programming. Or avoiding it. Corky Bell once said that the value of a piggy back box to the main computer was that off boost, the Mazda engineers had already done extensive mapping: http://www.bellengineering.net/article_info.php?articles_id=50 . In a similar vein, I'd think a programing issue comes up again with a computer to drive the "contemporary" IRTBs. You end up having to play with base maps. I'm not being critical of the manufacturers and vendors who support our Miatas, just being realistic of my own tuning/programming skills. And no, forced induction, while a cheaper route in the hp/$, isn't an option for me.
 

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My signature quote is very well.... poignant in this case.

There's been so many people who have run a standalone on IRTBs on Miatas.

... none that i know of that have used a piggyback like what you're suggesting. Due to this, your idea will be MUCH harder than going down the well-paved path.
 

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My signature quote is very well.... poignant in this case.

There's been so many people who have run a standalone on IRTBs on Miatas.

... none that i know of that have used a piggyback like what you're suggesting. Due to this, your idea will be MUCH harder than going down the well-paved path.
The essential point that I was trying make was that programming an ecu takes time and patience. Not about a piggyback computer. My sense regarding a SPICA f/is that the fuel pump's cam has already been tuned to run at 3-5.8k rpm. Essentially the same upper mid-range that I tend to drive at. A mechanical PNP, maybe? To my understanding, a MS or a Freedom computer has base maps already programmed in. A starting point. There are many variables (temperature, altitude) that one may not encounter while programming their box of magic rocks. (The point, I believe, Corky was inferring when mentioning the Excede add-on vs. a Hydra, et. al.) To be sure, many folks have gone with off- or near off the shelf set ups and have had great success with cars. I'm just trying to consider other possibilities, not just limit myself to what's currently on the shelf.
 

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The essential point that I was trying make was that programming an ecu takes time and patience. Not about a piggyback computer. My sense regarding a SPICA f/is that the fuel pump's cam has already been tuned to run at 3-5.8k rpm. Essentially the same upper mid-range that I tend to drive at. A mechanical PNP, maybe? To my understanding, a MS or a Freedom computer has base maps already programmed in. A starting point. There are many variables (temperature, altitude) that one may not encounter while programming their box of magic rocks. (The point, I believe, Corky was inferring when mentioning the Excede add-on vs. a Hydra, et. al.) To be sure, many folks have gone with off- or near off the shelf set ups and have had great success with cars. I'm just trying to consider other possibilities, not just limit myself to what's currently on the shelf.
A SPICA setup as it sits is going to be nothing more than a starting point, in itself.

It's great to consider other possibilities, but this one is going to be an utter nightmare to make work, and it will never work as well as a well-tuned EFI setup. Basically, for fear of complication, you're making something more complicated. :lol:

I just don't get it. I don't see how a Megasquirt takes time and patience, but doing something that quite literally NOBODY has ever done before (so.. you're on your own) doesn't take time and patience.

How do you plan on even getting the stock ECU to work in conjunction with this? If you're considering this, you must have already figured this out, right?

What does Miata.net think of this idea?
 

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It would seem to me that the appeal would be from a strict mechanical fetish sort of thing to have something like this. I totally understand it because that makes up a large part of what I enjoy about meticulously working on the details of a build to get everything to work well. The thing is I don't really see the Miata from that point of view. For example, having an old British car with a Cosworth BDA and a mechanical fuel pump.



Now that would be cool. But the essence and feel of that classic package isn't something you get outside of the genuine thing. And yeah I know the Miata strongly follows that "style" but it's just not the same thing. And putting a mechanical fuel pump on it wont bring it any closer.

As has already been mentioned, it will be ALLOT more complicated than any other single modification you could possibly do to a Miata and it definitely wont perform like EFI.
 
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