Same size, same modifier, same ship. Results in more power, which in the same ship results in higher speed and faster fuel consumption but an identical range.
Same size, same power, same ship. Results in drastic fuel efficiency increase, which in the same ship results in an identical speed but a practically doubled range.
Same modifier, same power, same ship size. The more advanced engine actually loses a small amount of range with this configuration, since the larger, more primitive engine gains that in fuel efficiency. The maths in my test case work out that said range is 95% of the larger. The ship with the modern engine did gain all of those hull spaces as potential component space.
Same modifier, same power, same ship components. With the engines and ships in my test case, by saving out on the space of the larger engine the new ship gained a 12% speed boost and a ~7% increase to range.
Also of note is that reduced modifier/reduced size cases saved a handful of crew in the modern engine's favor, and all other cases had crew parity.
In conclusion, this is... very interesting.
Overall speed is so crucial to survival in trans-newtonian combat that I had never considered new engine tech as a means to anything but a speed increase.
But that way lies stagnancy in range with tech, completely ignoring fuel efficiency research.
Matching engine power through size ratios won't always be practical by the nature of our engine size options, but that just means you'll have to check the numbers of what you can actually achieve.
The option to increase component density for a slight reduction of range at the same speed doesn't strike me as very desirable, except perhaps for system defense ships whose range need not be large. I'm sure somebody's situation says differently.
Increasing speed AND range, albeit marginally, while retaining all other functionality of a ship? The size difference makes this ill-suited for refitting a ship, but as an option for a standalone class upgrade it's very interesting.
Now, putzing the power modifiers to get the same power in the same space with drastically increased fuel efficiency? That holds all sorts of potential for survey ships, freighters, and other such applications where speed is less of a concern than in combat.
edit: Just cludged together a spreadsheet for easy comparison.
Using a 2000-ton ship with 500 tons dedicated to engine space, 500 to fuel storage and a base modifier ion drive as base...
Replacing the ion drive with a magneto-plasma drive of the same size and same power modifier results in:
33% speed increase, no change to range or available mission space.
Replacing the ion drive with a magneto-plasma drive of the same size and same total power results in:
105.28% range increase, two less crew, no change to speed or mission space
Replacing the ion drive with a magneto-plasma drive of the same modifier and same power wasn't possible with the available size increments, so the closest sizes above and below the target power were used and resulted in:
One notch lower:
6.67% decrease in speed, 3.23% decrease in range, but requires three less crew and frees up 3 HS for mission space.
One notch higher:
6.67% increase in speed, 2.17% decrease in range, requires two less crew and frees up 2 HS.
Using those same engines, but leaving the extra space unused results in:
One notch Lower:
0.9% speed increase, 4.62% range increase, three less crew.
One notch higher:
12.28% speed increase, 2.97% range increase, two less crew.
Then I toyed with replacing the ion drive with a magneto-plasma drive with the same size but with modifiers between base and the one necessary to match the original drive's power(.75).
.85 power:
13.33% increase in speed, 50.12% increase in range, one less crew.
.9 power:
20% increase in speed, 30.13% increase in range, one less crew.
I'm going to investigate more of those intermediate modifiers
edit: And so I did
These are increases from replacing an ion drive with a magneto-plasma of the same size into the same ship
