However, stm32f407vEt won't do for our purposes. so replacing that with a VGT version, we get this:
megaEFI:

it's the same size as Mega2560 Arduino, but with an stm32f407vgt on it which lets us run rusEFI

That fits onto this board:

it goes on the back:

and fits into an ECU kinda like this:

This board runs rusEFI, Today i started my car on it without any drama. it ran just like other rusEFI boxes i have prepared. It has to run in waste spark/batch fuel mode, which rusEFI handled just fine. The base speeduino board is 4ign 4inj, this ecu with speeduino board runs the same car in wastespark/batch fuel using the native mega2560 board with intended software on it just as well.
So why is this cool, or useful at all ? Well, for one, it gives people with an existing Speeduino board installation a potential upgrade path as they progress in their DIY EFI journey. Speeduino is a fantastic project, with incredibly low barrier of entry, economical and frankly quite a bit less intimidating than rusEFI, but the feature set and functionality are limited if the user starts demanding more.
As this is just a logic board without any power components, it could be used on lower budget and more DIY-oriented projects, in the spirit of Speeduino but different firmware.
There are also quite a few different form factor ECUs out there that could benefit from this at very attractive prices, products that have been proven by trial. Namely the 2 channel compact boards
no2c:
which shares the footprint with Arduino Mega
as well as
openlogicefi x2:
At the same time, This board was designed to run Speeduino's STM32 version, which runs just fine on this board.
it should also work in:
ua4c:
preignition x4:
and of course, the basic 0.4 and 0.3 speeduino boards:
this is just a trial run to see if it was possible and do a proof of concept for something like this, but who knows, perhaps this can become more real for those interested.