Advertising literature at the time stated:



"The exciting news from Maserati, however, is their new twin turbo, double overhead camshaft, six-valve per cylinder V6 engine.



This engine, designated the '6.36' (6 cylinders, 36 valves) with a 1996 cc displacement (121.75 in³) developes 261 bhp at 7200 rpm, and is ready to be placed in a new Maserati two-seater to be announced later in 1986.



This represents almost 130 bhp per litre, which is no mean feat for a standard production power unit."



WHY SIX VALVES? Throughout the history of the internal combustion engine, the search for the maximum performance has followed a number of different routes. To increase engine performance, the air/petrol mixture entering the combustion chamber has to be transformed into mechanical energy. The air/petrol mixture is always a suspension made up of micro-drops of fuel and air.



Experience has shown that if there are changes of direction in a moving column (as there are in the cylindrical window typical of engines with only one inlet valve), the proportions of air and fuel will tend to be uneven, and they will tend to separate. This lack of uniformity between the two phases leads to imperfect flame propagation at the combustion stage, reducing engine performance, wasting energy, and last, but not least, causing the emission of highly polluting non-combusted particles from the exhaust. Twin-valve engines are also subject to some problems, caused by the slow passage of gases in the inlet and exhaust phases which restrict filling and emptying respectively.



These and other considerations have, over the years, led to an increase in the number of valves in order to increase cylinder filling, thereby increasing the air circulation area and loss of pressure around the valves. If the number of valves is increased, the mixture flow will collide, ensuring that the air and petrol will always be homogeneous.



Next, it is essential to ensure that non-combusted gases are not trapped in the combustion chamber at the exhaust stage. In addition to increasing the proportion of pollutants emitted in the exhaust gases, these "intruders" also reduce the space available for the mixture, thus causing a further decline in engine performance. And the flow of gas around the exhaust valves aids cleansing of the combustion chamber. The advantages of an engine with more than two valves can, therefore, be summed up as less waste of energy (with obvious environmental and financial advantages) and higher thermal and volumetric efficiency.



As we have seen, an increase in the number of valves brings many advantages. However, experience and history show that the limit of four valves per cylinder has hardly ever been surpassed. The reason is technical problems, avoidance of excessively complex timing systems and higher costs, which have slowed down progress in this field.





A fantastic six-valves per cylinder! After years of research, Maserati has now perfected a sports car engine with six valves per cylinder: three inlet and three exhaust valves. The designers avoided all possible complications and intricate parts which would inevitably make the engine more delicate, unacceptable on today's automobile market, and focused on simplicity.



Maserati has patented a valve control (driven by a double overhead camshaft) called a "finger control", in which the loads are evenly spread (each control drives three valves), thus guaranteeing that the part will last. Valve adjustment is simple; it is the type with a screw and lock nut, which requires no particular care except the normal maintenance carried out by the dealer, with no need for the car to remain in the workshop for lengthy maintenance work.



And as the moving parts are extremely light, the metal is not subjected to any particular stress; each part of the exclusive 'Maserati Sei Valvole' timing system is made to last, and to give the maximum performance obtainable from a modern 2-litre car.





The fantastic 36-valve engine The central valves (inlet and exhaust valves) are fitted at a different angle to the two outside valves. While the side valves are inclined at 11.25º and 10.50º respectively for the exhaust phase, the two central valves are inclined at 3º (inlet) and 2.5º (exhaust) from the head plane. This difference in angles produces an obvious 'swirl' effect inside the combustion chamber at the point where the mixture flows arriving from the various inlet valves cross.



This gives a high crossflow effect which produces a perfectly even air/petrol mixture. The engine can thus run with an optimum stoichiometric (stoichiometric combustion is the ideal combustion process during which a fuel is burned completely) air/petrol ratio and consumption which does not exceed the exceptional ceiling of 200 gms/hp/hr. The final and most evident result is shown by the maximum power achievable, which is really exceptional for a 2-litre engine: 261 hp! And it should be remembered that Maserati engineers have achieved this power at only 7200 rpm, although the simple, logical finger valve control system would enable even higher performance to be attained without any wobble. The 'Sei Valvole', like all Maserati sports cars, features a twin turbo, in which each unit supercharges one bank of three cylinders. Here again, we have not attempted to go right to the limit, but preferred a boost restricted to only 0.8 bars. Finally, the turbines have a logical water-cooling circuit, guaranteeing total reliability and unprecedented durability."



Unfortunately, we are still waiting!



It appears that Maserati decided on the more conventional four valves per cylinder option and whilst this was probably the most sensible, now proven to be the correct, decision, it would have been nice to see this revolutionary engine in production.



