Moderator: Series8217
The core MS2 processor for the microsquirt is a little more powerful than the Arduino unit, but the collective brain trust of the Arduino environment closes the gap much more.
From Car and Driver June 1985.The head has larger, freer-flowing ports, better cooling, and provision for stouter valvetrain components. A forged-steel crankshaft with full counterweighting spins inside the crankcase, and it can be machined to provide a variety of strokes from 2.60 to 4.125 inches. This crank design profited from the lubrication-and-stress analysis expertise of General Motors R&D. According to Callies, it is bulletproof to 10,000 rpm with a 3.25-inch stroke, even with only two-bolt main-bearing caps. The crank is spun by JE forged pis~ons via connecting rods from a Chevrolet small-block.
Keeping the valvetrain together at elevated engine speeds has been more of a problem. The heads are fitted with 2.02-inch-diameter intake valves and 1.60-inch exhaust valves for good breathing, but these components are not light, even though they're made of titanium. They are
actuated by roller rocker arms, special pushrods, and roller lifters-a lot of hardware to be jiggling around at 8000 rpm. Initially, very stiff valve springs were fitted to control these parts, but the results were broken rocker arms and excessive valve wear. These problems have been remedied
by placing springs from a Ford flat-head engine between the roller lifters and the top of the block. These springs keep the lifters and pan of the pushrod mass under control, allowing lighter valve springs. According to Callies, this solution is good to 9600 rpm. Another knotty problem cropped up in the cam-driven gears. The crankshaft of this large four-cylinder engine may not break, but it does bend at high rpm. This phenomenon caused the early, helically cut cam-drive gears to break, even when the cam-gear material was upgraded from aluminum to cast iron to nodular iron. A change to straight-cut teeth eliminated the thrust forces and solved the problem.
