MembersPage/KeithU

I started playing with VEMS back in about 2005 when I bought a V3,2 bare board s/n 195 to fit to my 1974 Porsche 911 Carrera.

The car itself was much modified before I bought it, representing a Carrera 3.0 RS, and was prepared for racing back in the 1980ís. When I acquired the car I fitted a later Motronic powered 3.2l engine, but was never happy with the later looking engine bay arrangement of single throttle body and wrong manifolding.

I started by keeping the Motronic ecu and standard intake and injection system. I used my VEMS board and a simple trigger to first just run the injection, and then just the ignition, in each case the other function being handled by the Motronic. This gave me confidence in the systemís integrity and mapping techniques before allowing the VEMS to take control of the full engine management with a 36-1 trigger wheel attached to the front pulley, and retaining the standard distributor.

The next step was to fabricate my own throttle bodies to fuel each bank of cylinders. To make the engine bay represent an early 1970ís look, I used triple carburettors, manifolds and air cleaner system. By cutting the bottom 25 mm from each bank of the one piece Motronic manifold which held the injectors, and sandwiching the two banks between the carburettor manifolds and the heads I could also utilise the standard fuel supply system as well. The pair of triple choke Zenith carburettors were gutted of all internal parts apart from the butterflies, internal drillings filled, and fabricated cones slid into the now empty bodies to give a clean airflow.

There are tappings from each manifold to a common reservoir to provide a reference for the fuel regulator, but the fueling strategy is Alpha-N because of the lack of working vacuum once the throttles are opened significantly.

The engine bay look is now more representative of the true age of the car, and the injection system is usually only noticed when pointed out to the casual observer.

I live in the UK, but because I take the car over to Europe every summer, I initially did not have confidence in using a totally home built management and hardware system for several thousand miles at a time so far from home. I used to put the Motronic system back on, then replace it again once back in the UK. Although I have now run a lot of miles with my VEMS setup, I still feel vulnerable should my VEMS fail in some way, so two years ago I decided to permanently leave the TBís and VEMS in place even during my continental jaunts, and I purchased a new factory unit, s/n 3954, which I now carry in the car as a spare. To date apart from trial runs to confirm configurations, this unit has never had to be substituted for my original home built board.

Along the way there have been various trials and tribulations with the VEMS, and as time allows I may update my page to detail some of the problems which I have overcome, and some which I still cannot bottom out.