Big Tea wrote: ↑
Tue Apr 30, 2019 3:12 pm
godlameroso wrote: ↑
Tue Apr 30, 2019 1:30 pm
Big Tea wrote: ↑
Tue Apr 23, 2019 11:45 am
If they did, as the 'v' angle is set would it not make a 'taller' engine and rise the c.o.g? (longer crank throw etc?)
It would not seem a good trade off?
Taller engine is determined by deck height, not stroke. You can just use shorter rods to go with the longer stroke, and/or lower the compression on the pistons or make them flatter. Deck height is really determined by the length of the rods plus crank throw.
Would not a longer stroke mean the crank needs more 'space' throughout its motion? IE, if the stroke is increased by 25mm then 25 mm on top and 25mm on the bottom which is 50 mm that has to be accommodated?
Crank ctr 25mm higher (or sump 25mm lower) and 25 mm clearance between the top of the throw and bottom of cylinder liners? I am assuming it is already cut to the limit and the extra can not be accommodated?
(not disagreeing, asking)
Again you can play with both rod and crank throw as well as piston thickness to keep deck height identical.
Simple example, Honda's F20c became the F22c with shorter rods, a longer throw crank, and lower compression pistons. The block is exactly the same between the F20 and F22 with the only real change being the crank angle sensor.
F20c crank throw = 87mm F22c crank throw = 91mm F20c has 153mm rods, F22c has 149mm rods. This lowers the rod ratio, and increases mean piston speed which lowers max rpm.
You are right, longer crank throws require more block space, usually the bottom of the sleeve is notched to clear the longer throws. However, longer crank throw doesn't necessarily mean a taller engine, there are ways to clearance the lower block without increasing external dimension.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee