[Suicide Junkie]

SE4 will RCE when the thrust of a ship hits 256.

You are limited to:

255 Solar Sail 1's
127 Solar Sail 2's
84 ion engines. (or Solar Sail 3's)
63 CT engines (or G-Spike 1's)
51 JP engines (or G-Spike 2's)
42 quantum engines. (or G-spike 3's)
36 G-spike 4's

I didn't want to restrict engines to 36, since that would then place dreadful restrictions on the lower tech propulsion systems.

If you get an RCE, just remove one of the engines to get you back under the limit, and it'll work fine.