scrubnick said:
From what the SR20 people have said, piston makers don't like to go less than 26mm on compression height. Bad for the rings.
Well, that's a step in the right direction. 26mm is still 6mm we could use for something else, like extra rod length or extra stroke.
For instance if we use my earlier example with new numbers:
223.49mm (8.799") Deck Height (still verifying)
146mm (5.748") Rod Length
88.9mm (3.500") Stroke
26mm (1.023") Piston Compression Height
223.49 - 146 - 44.45 - 26 = 7.04mm of clearance
146/88.9 = 1.64 r/s ratio
Now we have a few more mm left to play with. Let's say we increase the rod length to 151 (5.945") and the stroke to 92mm (3.622").
223.49 - 151 - 46 - 26 = .49mm clearance
151/92 = 1.64 r/s ratio
Again, this is not including the headgasket clearance or the squish volume. This is just clearance to the top of the deck, if the deck is as high as I posted above.
FYI, 4" bore + 92mm Stroke = 5.96L...
Ninja Edit...I wonder how hard it is to make a deck spacer...I would just need 15mm...165mm Rod = 1.8 r/s ratio = 8000rpm 6.0L...mmmm...