[asphaltgambler]

My opinion. What ever engine you build you will make it more efficient by substantially reducing the deck clearance.

If you set this at the minimum for each particular engine design, the engine will be less likely to detonate, the fuel mixture burn will be more complete by generating more combustion turbulance. The engine in general will be more responsive and generate more HP and TQ. This is especially true when using cams with aggressive duration and centerline.

Short stroke engines with steel con rods and relatively mild RPM like the Porsche that run tight piston to cyl clearance can go "way close" How close?? .010-.012" on street motor. This is assuming that the pistons are new with proper side clearance.

Remember that the case, cylinders, heads are aluminum and 'grow' slightly with heat as the engine runs.