Battletech Theory - Fusion Engine Discussion

Hey all, I just wanted to talk about a hotly contested and debated topic in Battletech....engines.  There are three main types of fusion engines used to power 'Mechs: standards, light and extralight (XL).  Most players have very strong preferences related to each type of engine.  I fall into the "I like them all" catagory, so I feel like I have somewhat of an impartial view.

Pre 3050, the engine debate is pretty unimportant.  Pretty much everything is standard fusion, with Star League relics might have an XL.  However, at 3050, with the Clan invasion, the TRO's went pretty crazy with XLs, especially after 3055.  It seems logical that the Inner Sphere, would want to put XLs on everything so they could pack more weapons, armor, and speed on these new 'Mechs.  However, fluff and mechanics diverge, like they always do and the debate rages on.

Mechanically, the main trade-off between the various types of engines is reduced weight, which free up more tonnage, and durability. Standard engines are heavy, but take up less crit spaces, meaning it makes the 'Mech more durable, since 3 engine crits cripples a 'Mech.  XL engines are light, but take up more crit spaces (6 more, 3 per side torso), making the 'Mech much more fragile to the 3 engine hit death.

Personally, the trade-offs and advantages and disadvantages of each type of engine is dependent on the role in which the 'Mech is designed to fulfill. 

Standard Fusions - This engine type is very vital in the modern battlefield.  By only taking up crit slots in the CT, it means that the 'Mech can survive side torso destruction.  'Mechs equipped with standard fusions are best served as soldier/brawler types.  Because they are typically slower and less heavily armed, they excel at making meat shields or "tanks".  You lure your opponent into attacking these 'Mechs by making sure they are easier to hit in comparison to other 'Mechs. 

XL Fusions - This engine frees up a lot tonnage.  This tonnage can be reinvested into a 'Mech in two main categories:  Weapons and Speed (bigger engine). There are two ways that XLs can be utilized.  The first, is to increase speed, significantly, in order to increase it's survivability.  Allowing the 'Mech to have a higher move mod, it increases the durability by damage mitigation (ie. missed shots).  The second, and more popular, is to pack more weaponry into a fire support platform.  Ideally, you don't want your fire support 'Mechs engaged in close combat, so the fragile nature of the XL engine is mitigated.

Where I think the XL gets a bad name is the liberal use by the canon 'Mech designers (freelancers) employed by the various entities that license the Battletech brand.  There are too many instances of XLs being dropped into slow and heavy brawler or light 'Mechs.  Either type die too quickly to side torso lose.  Only in certain circumstances, such as the Falconer, are great uses of XL to get speed and long ranged fire support, which keeps the 'Mech durable.  I'm not going to discuss specifics Mechs which illustrate bad ways to use XL engines, but I'm sure everyone knows a handful or two. 

The Light Fusion, is sadly a night widely used engine, mostly due to it's relative newest to the Battletech universe, I believe coming into the fold around 3062.  The lovely thing about this engine is that it has only 4 extra crits, not 6 like the XL.  Meaning, that side torso lose does not immediately cripple the 'Mech.  While this matters little for one-off battles, it is extremely important for campaign play, where a crippled 'Mech might have to left for dead, while one with a light fusion can still manage itself off the board.  The downside to the light fusion is that it's typically not enough saved weight to both increase speed and firepower like the XL.  You really have to pick one aspect to enhance.  It's easy to fall into the though process that you can improve both speed and firepower, but typically that's when light fusions end up looking bad. 

To summarize, all types of fusion engines are good, when used properly.  Fusions are great for enhanced durability.  XLs are great for 'Mechs reliant on speed (scouts and flankers) or are niched in the fire support role.  The light fusion is useful to add a little more zest to a 'Mech while still keeping it survivable.  That said, I'm interested to hear what everyone thinks about the various versions of the fusion engine.