Short stroke 2.6 vs. Short stroke 2.8
 

The question says it all. Besides the displacement difference (173cc), it seems the only difference is the heads:

2.6 (CR 10.3:1)
Valves I46/E40
Ports I36/E35
Combustion chamber 68cc

2.8 (CR ?)
Valves I49/E41.5
Ports I39/E35
Combustion chamber 90cc


I’d like to know which is a more potent engine in terms of power band, torque, responsiveness, and characteristics.

TIA :) ;)

Well the 2.8 that you listed has bigger valves and ports which allows more air flow, so in conjunction with the extra capacity and higher rev's (that the larger valves and ports will allow), the 2.8 example should make more HP. But that assumes that the pistons cams, intake, exhaust and so on are configured correctly.

The reality is that the factory 2.8 RSR engine was a configuration that was specifically developed to fit the FIA's rules. If you built a 2.7 the same way that the factory built their 2.8's (which many people have done), you'll have almost the same HP, if not more due to more modern gas.

What are you trying to get to?

Re: Short stroke 2.6 vs. Short stroke 2.8
 

I wouldn't use those port specs. I'd open them up. 38mm ports at least.