How to maximize Delta V for rocket engines

Ok. Btw check out my thanksgiving challenge entry!
https://www.simplerockets.com/c/XDCzNJ/A-4B-A9-V-2-Manned-Hans-Thanksgiving-Delivery-Vehicle

If it’s in space, lower pressure and smaller throat whilst larger nozzle is best @TopSecret2

@plane918273645 Yeah but when you’re constrained to size Nozzle length and size outright can be limiting, so the other variables count especially if you don’t expect to get more than 2500 m/s like making a replica.

It’s dependent, although not really needed because 15km/s is easy to get with almost all combinations