Fuel injection

[Hans Efde]

As reported earlier I acquired an Emerald K6 ECU and throttle bodies from a Honda Firestorm motorbike. The Midas is being run in with a SU carburettor and standard Lucas distributor, but I want to have the ECU conversion ready before the winter. I expect plenty of problems and want to make sure the car is ready for Stoneleigh 2014 (where we hope to be going with 2 to 4 Dutch Midasses).
The whole Honda assembly looks like this:

It's high tech but cheaper than a SU carb!

I disassembled everything and started building a single throttle body. At the moment my idea is to have all electronics away from the exhaust. So the MAP (manifold air pressure) sensor and TPS (throttle position sensor) go on top. Therefore the throttle cable and spring will be at the bottom. But the cable connects from the RH side, so it should be a very short cable. The injectors will be horizontal.
These Honda parts are just like Lego, so I had it done within 5 minutes. The fuel pressure line is mounted on the left injector, the right hand injector has the fuel pressure regulator and fuel return. It is controlled via the inlet pressure. The setup will be something like this:


I think it's easiest to grind away the protruding edge on the flange and make a flange with a 55mm pipe that bolts onto it. On this pipe I can install the air hose that is connected to the KN cone filter in the nose of the car (nice cool air). Perhaps it can become a sort of ram air system.


This is the front of the throttle body. Via another flange and rubber adaptor it mounts to a standard MG inlet manifold. You can see the nozzle of the left injector.


This is the top of the throttle body. MAP and TPS visible. On the right hand side the fuel pressure regulator. The fuel lines go to the left side of the engine bay (where my present fuel pressure regulator and return is located).


Here is a small problem. The linkage connection (that connects the other throttle assy on the Honda) on the throttle assembly hits the fuel rail. Since I use only one throttle body it will be cut away. The Honda bracket for the throttle cable will be replaced by a homemade bracket where the standard throttle cable fits in. I'll have to go to a bike shop to see what they have that screws on the cable and will click into the throttle assembly. Shouldn't be too difficult.

[cubera]

I admire your optimism ("shouldn't be too difficult"), but hope it all works out well. A couple of questions/observations, though. Firstly, is there a good reason for not using both throttle bodies? The Firestorm is only a litre, after all, and though Honda ccs are probably worth a lot more than British Leyland ones, I wonder if the gas flow capabilities of a single body might be a little low. Secondly, I would be disinclined to "grind" the throttle body flange - better to mount it in a lathe (tricky?) or milling machine, and cut the excess off that way.

[Hans Efde]

You need only one throttle body for the A-series engine since it revs only half that of the Honda. This throttle body is about the same size as the HIF44. Doubling that will half the air flow which is bad for the air fuel mixture. 2x 45mm is too much for a 1300cc engine. If people use double carbs or throttle bodies on a 1300cc, they are usually 38mm's.

[Rich]

I'm looking forward to seeing this come together Hans, I've got a real blindspot for injection systems.

[cubera]

Fair enough, Hans, I just thought I would ask. I have always regarded Firestorms as weary old plodders, revs-wise, but then that is comparing them with R6 and Fireblades. Compared with the venerable A series, it's a different matter. Good luck, anyway.