|The MGA With An Attitude
FUEL INJECTION For The MGA - FU-301
On Aug 2, 2015, Ian Cowen in Gold Coast, Queensland, Australia wrote:
"Last week we started the 5 bearing engine, fitted with an "O" Head, for the first time in our `59 model American import MG A Coupe. It's now fitted up with Fuel Injection.
The task has been most involved technically, also a huge challenge, but not very expensive. The Carburetors, Coil, Lucas distributor and choke cable are all now dispensed with. The system is timed through an ex-American Ford 4 cylinder system called an EDIS4. This was readily obtained second hand. It features a control computer for ignition which receives a signal from a 36 toothed cog wheel mounted on the engines front pulley. Its mounting position is crucial to the timing of the engine. The Main Computer, ECU system, is American designed and sold by MegaSquirt. There are other brands to consider. This ECU on a printed circuit board is available either built up, or in kit form to be soldered up. (I chose the latter, I used to build wireless sets as a hobby).
As with all of the gear in a project of this kind, lots of thought and planning are required. For example, there are a number of ways of going about fabricating the induction system. I used inch and a half motor cycle throttle bodies, mounted on spacers and secured to the original MG induction manifold. 263cc injectors fit these, which will run the engine well. The throttle bodies are set up A-la` SU carburetor fashion. It has taken me 23 months to complete the project.
Was the effort worthwhile? Well to hear it start up for the first time was most gratifying. Yes, Yes plenty of frustration goes with the challenge. From fuel lines to an unsuitable petrol tank requiring modifying-- limited space to build it all up in--making an extra harness with the necessary wires to length to do the job. And much more. Out side assistance relieves a lot of tension. One cannot be an expert on all matters.
Performance? It is designed to use pump fuel. Performance is greatly improved since the mixtures are all correct. Torque is now higher at 2M. In traffic, I find that I am using the brakes a lot more!! When it all settles down, water injection might interest me further. There is a snippet in Piers Hubbard`s new MG A Book, on our car`s additions, Elect. windows, Air Cond, 5 speed G.Box, 3.9/1 diff. gears, modified radiator air intake etc. The Coupe` is now a great long legged economical touring car".
Follow-up a year later:
On 16 July 2016, I.W. Cowen in Queensland, Australia, wrote:
"Now there have been 2 major alterations to the system - MK 3 version is fine.
5 port cylinder heads were never intended to be fitted with EFI's. Balancing the fuel to each cylinder is a huge challenge. I used an American Ford Electronic Distributor Ignition System, a 36 tooth cog wheel fitted to the front crank pulley, a Cam Sensor fitted into an old distributer body, 2 Suzuki motor cycle throttle bodies, a specially made fuel tank, and a well known American ECU that more or less suits this engine. The ECU is available either built up, ready for mapping or as a DIY kit to solder up onto a printed circuit board. There is fitting and machining, reading electronic circuits, soldering up electronic components, fabricating moving linkages to fit and work properly, and programming/mapping the completed system, involved. It runs better, because it is set up correctly. Its performance is strong, but limited to fuel in use, Cylinder Head design and other 50's limitations. Tossed the Choke Cable!!
On 17 July 2016, I.W. Cowen wrote:
"The Injectors and the breathing of a 5 port head, have been the issue. In the development process, it was considered to place an injector in the cylinder head in the induction chamber and above each of the inlet valves. It is possible to machine this, however properly sealing the water jacket under pressure, and conversely the manifold vacuum combined could cause reliability issues. So, this time it uses "Timed Injection" rather than "Dumped Fuel". The ECU had to be altered to provide 2 timed injector shots from each injector rather than one dump from each injector per cycle. In the original "one dump" arrangement, the first inlet valve that opened grabbed the available fuel charged waiting in the induction. When the other valve in that port opened, it received the remainder, only, of the fuel charge. Due to the engine's firing order, the 2 inner cylinders had first go at the fuel charge, and the 2 outer cylinders tended to run lean, since they received only what charge remained. For tuning purposes, mapping, the exhaust manifold has plugs fitted in each of the 3 outlets to take a wide band Lambda analyser. This accurately reads the cylinder's output. The ECU normally runs with a narrow band lambda fitted in the beginning of the exhaust pipe.