VN1700 pistons to raise 1600 comp ratio

[andyvh1959]

Well hmmm. if the crank throw is changed and the same rods are used, the result is no change in stroke length, just piston position at the top and bottom of the stroke. If longer rods are used with the same crank throw, the piston position at the top of stroke will be higher into the combustion chamber. At the bottom of the stroke it'll just be a bit higher in the bore. At least that's how I envision it, and maybe I am wrong. I do understand how a longer rod increases piston dwell time at TDC, which may produce more power.

Looking at any specs on the 1500 Mean Streak shows the same 9:1 compression ratio as the 1600. So how is a Mean Streak piston in the 1600 able to increase compression? All the pistons I've seen for a 1500 are the similar dished style as in the 1600, unless I'm not looking at the right pistons.

I have a pair of 1700 pistons/con-rods I bought from a cycle salvage yard, for $125. In the 1700 the comp-ratio is 9.5:1. Now I realize that is not due alone to the pistons. But the 1700 pistons are clearly crowned (with valve reliefs) and the 1500 or 1600 pistons are dished. Then I found this info about rod lengths and power:

https://www.thirdgen.org/forums/tech...ion-ratio.html

https://www.enginebuildermag.com/201...ng-rod-ratios/