Regarding a swap kit for the Multiair. (Not speaking for Tony but having observed this modification and thought a fair amount about it.)
As Tony intimated there is a lot to this swap, much more in real terms than the K series due in large measure to the lack of a standalone electronic control system.
The structural changes are notable but not any worse or more extensive than the K swap (Tony has made some parts to make it more factory appearing in places because he is who he is
) this is not to suggest the body changes and mechanical work needed are easy or a walk in the park.
This swap‘s painful work is primarily around the electronics and managing the wiring of all the subsystems a modern CanBus control system expects, the fact there is no outside support, beyond the hard work done by Tony and whatever elves he knows, is where the real problem lies. The other issue is this is a turbo motor in a mid engine car what has very little extra room and getting rid of heat in the intake air in particular is a major divergence from the K swap problem which so far Tony has solved in two ways, one air to air and the other air to water to air.
There is an unusual tension in this swap in that there are a fair number of these motors and transmissions available around the country as these engines sit on shelves as cars are totaled by insurance companies and there is little market for the engines for Fiat 500 replacements. This is the opposite of what is going on with the K swaps there the donor cars are disappearing and the engines are wearing out in the cars as they went out of production and the easy flow of donors from Japan is drying up.
Where the K swap is a fairly simple engine to control, the Fiat engine is an electro hydraulic mechanical nightmare due to the way the valve system is actuated you can’t just use something other than what Fiat created to make it run. The unfortunate part is Fiat has not seen fit to make a standalone engine controller which allows you to jettison the rest of the CanBus system which also runs the many subsystems embedded in a Fiat 500 or Abarth. Those systems don’t exist in an X (ABS, traction control, climate control and a myriad of others) and then added to that a CanBus system is constantly verifying the wiring in the system as it looks for specific resistance in the wiring, connectors, sensors and so on.
Midwest-Bayless looked at this and found the technical part of the problem to be more than they felt a customer could handle (I am told). At the time they were building customer K swap cars and not only the kits (they stopped producing cars though Matt’s son, a member here, has since built a number of others). As people are already whining about the cost of the K swap kit to adapt just the mechanicals, combining the mechanical part changes and an electronic package is likely not economic.
There has been an interesting alternative posed to make the engine possibly more swapable with a simpler controller which substitutes a valve actuation system which is a much simpler electro mechanical variable valve actuation akin to VANOS, VTEC etc. which is much easier to control ie a solenoid actuator. This has been done on MultiAir engines with parts imported from the EU, there is an interesting thread you can dredge up with videos of Fiat 124 (the Miata based one) where they converted one.
Anyway, a kit is not a simple thing to come up with despite the availability of these engines.
