Fuel Injection Options
Turbo Mini Forums

HI,
I have just bought a mini-based kit car (GTM Rossa). It has an MG Metro 1275 engine. It will only ever be a road car not any sort of competition tool.
I am interested in making it as reliable and tractable to drive as possible. Ultimately it nees to be able to drive from Aberdeen to Birmingham reliably (if my spine can stand it!)
So I am looking at replacing the distributor with an EDIS system and the carb with an injection system (Not necessarily at the same time unless it makes sense)
Ive read all the posts I can find on here and a few on other sites and what I understand is summarised below.

To get best performance requires port injection and use of software for the controller specifically designed to cope with the Siamesed ports. This software is available for the Megasquirt 3.
There are no commercially available manifold/injector/throttle body set ups and people who have done this have done their own using a variety of parts

If I do not want to go to this length, the other option is to use a “wet manifold” that effectively creates an electronic carb
A full kit is available to do this from Specialist Components but it is expensive and there are comments about the software being poor
Other options
Buy the SC injector side alone and use a different controller (The Megasquirt, Microsquirt, Megajolt or Emerald?)
Buy a carburettor replacement from Jenvey that will bolt to a manifold designed for a Weber DCOE and use with one of the controllers mention above
Use Injection setup from an MPi Mini with one of the above controllers
Build a one-off using an existing manifold and some bike injector(s) and throttle body or bodies

Am I right with what I have picked up?
My background is electronics/software rather than mechanics so I am much more comfortable dealing with that than I am trying to cobble together the mechanical side (although I could get access to a machine shop/fabricator if I had the designs). I am quite keen on the Megasquirt as controller as there is an Android version of the software and I intend fitting an Android tablet a a nav/additional dash display and maybe even replace the main dash display at some point
The Rossa is a wee bit limited in space as can be seen on this picture and although it could be possible to cut away the fibreglass into the boot area, I‘d prefer not to. The proximity of the engine cover may preclude the Rover MPI option for the same reason

Any other ideas and what do you recommend for my situation?

Edit: I now understand the Rover Mpi is a port injection of sorts

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Edited by Gustywinds on 28th Dec, 2021.

"To get best performance requires port injection and use of software for the controller specifically designed to cope with the Siamesed ports. This software is available for the Megasquirt 3."

No.
Although the MS3, and any other injection system that allows variable injection timings, can be made to work, it's only the MS2 that has specific code for the siamese ports.
This is not an easy task to setup to work correctly, as a minimum you need seperate widebands on the inner and outer exhausts to see what is happening and set it up accordingly.

The rover Mpi is port injection, it's just that the ECU/firmware/software isn't user programmable. The manifold, injectors, fuel pump however is easily controlled by another ECU.

Unless you want to go through a big learning curve on siamese port injection, you would be best doing a "wet manifold" setup.

Not with the SC software as IMHO it is awful but their manifold/throttle body is good and once you have a decent manifold and throttle body (there are others than just the SC version) you can use pretty much any ECU to run a wet manifold (batch injection) type setup.

Schrödinger's cat - so which one am I ???

I thought polestar ecus also provided MPi fuelling too? They have it as an option in their fuelling menu.

There may be a few that "do it" but how ?

If it's just a standard Mpi mini just stick with MEMS.

If it's tuned and especially if it's turbo'd you need to be using something you are confident that deals with the charge robbing of the siamese ports and you need to have seperate inner and outer widebands (and ideally a third after the exhausts common up) to know what is going on.

Schrödinger's cat - so which one am I ???