Where to place a single KR-1 Engine

[Daelkyr]

So, I'm working on parts for my little Jool DIRECT mod and I wanted to make a new 1.25 m engine. After looking at the LFB KR-1x2, I decided to do what Squad did and cut the single KR-1 engine off the rest of the model, leaving me with this.

The problem I'm having now, is what tweaks to make to it. If I just divide the information from the "Twin Boar", I'm left with an engine that gets 1000 kn of thrust in Vac, 933 kn in Atmosphere, and a slightly worse Isp than the "Vector". The LFB KR-1x2 gives a description that the KR-1 sacrificed thrust and efficiency for the booster design. Would this be a good fit as a upper stage J-2x or RL-10 analog to compliment the KS-25 "Vector" when that is used as a lower stage booster?

[NecroBones]

 

Gosh, yeah that's a tough call. Usually when splitting clusters, I prefer to make the stats make sense, by giving it the correct fractional thrust and mass, and similar ISP. But from a gameplay perspective and balance perspective, sometimes you have to fudge things. If it's stepping on the Vector's toes,making it a J-2 equivalent upper stage engine isn't a bad idea. But then again, the Twin Boar is modeled after some of the earlier SLS concepts, and those LFBs would have used F-1B engines, which are of course high-thrust kerosene engines with a lower ISP.

 

I guess it really depends on how you want the engine to be used, and whether it will completely obsolete the other 1.25m engines.