G`day fellas new old bloke here from Oz For decades flat heads have sucked me in, their simplicity fascinates me to no end. Sure they have their shortcomings for certain applications but in some ways they work similar to Diesel, good torque down low and reliable but way less efficiency. As my Avatar name suggests, my point of focus has been combining a pre-chamber and combustion chamber together as one not just using a separate pre-chamber. Im old so sorry for the pixelated pics done on paint with the help of arthritis! The bias is on one side of the valves shrouding the other where to my surprise Toyotas latest eco engines employ to great effect. https://imgur.com/j4Mdj5k The exit although not visible in my pics is shaped like a small banana or quarter of a circle wedge as an exit passage. This is my thinking to arrive at a tumbling charge that goes deep down to the bottom of the downstroke on a very under-square design that creates a strong clean pull effect. https://i.imgur.com/yEmQILb.jpg (valves like most of it is not drawn up to scale - they would be larger but didnt want to interfere with the general shape funnel shape) This design would allow the use of short inlet manifold runners and the usual exhaust design. Spark plugs would a small industrial units with the pre chamber already on the end which are common for industrial and Formula 1 but not the street. These would have 2 - 3 holes biased towards the gas flow path to help the flame front exits along the tunnel shaped elephants horn etc. Essentially this is like 2 pre chambers as a combustion chamber. Another version of this design is to swap the inlet and exhaust sides to keep the chamber cooler via inlet charge flowing over exhaust valve yet reshape the elephant trunk port to curve and swirl rather than tumble and create perhaps even more torque than the tumbling design. Can anyone put me on to a fluids dynamic dude that is able to help me further my dream of making a flat-head more efficient? Also your constructive views are welcome as Im not trying to outdo an OHV design but to raise the efficiency of the flat head so it can use fuel more efficiently.