Author Topic: The Classic Mini DIY fuel injection throttle body  (Read 39 times)

Online 94touring

The Classic Mini DIY fuel injection throttle body
« on: August 01, 2022, 12:46:14 AM »
I will start this thread to discuss a future down the road project where I ditch my hif44 and try going fuel injection.  The plan is to start off naturally aspirated and eventually put a small turbo onto it.  Here's links showing what it is.

https://store.classicminidiy.com/products/efi-throttle-body-hif44-replacement

https://youtu.be/2ffDDLZ7eBs


I was researching about fuel injector sizes that would work as a good starting point.  I decided to see what size MPI injectors were and to my surprise they spec out at 480cc's, which is pretty large considering the MPI made something like 63hp.  Specialist components use a 440cc injector on their kits which can give enough for 1400cc built up motors according to them and smaller boost turbo applications.  So I think I will start with 440cc as to not be too large in naturally aspirated form for smoother running and tuning experience.   My goal isn't to make 170hp whenever I do put a turbo on anyways.  100-120 to the wheels I'm thinking will suffice.

The fuel pump which I already have in the tank is an MPI pump.  It's rated for 73psi which is perfect for whenever I do put a turbo on.  I will have the pressure regulator keep me around the stock 44psi for non boost then 1:1 for each pound of boost. The turbo I have has a wastegate set for 13psi. 

Next up is deciding on an ECU.  Since I already have a bunch of ignition timing gadgetry in my shop for tuning turbo applications, I really only need an ECU for controlling fuel.  Otherwise it's buying crank angle sensors and wheels and having to wire all that up which for now I'd like to avoid. Perhaps later down the road I'll streamline it differently.  The ECU I keep coming back to in my research, at least for the moment, is a microsquirt.  It's able to be in fuel only mode, seems pretty basic and relatively simple to wire up, and doesn't cost upwards of $1500 for some of the more advanced ECU's.

More to come...

 

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