Someone in chat remarked that it takes a whole match for a Steam Engine to overtake a Lava Golem. So I thought I'd see. Here's what I've found.
It takes 5|7 turns for a Steam Engine to outrace a Lava Destroyer. Any longer than that, and it becomes better.
I said that, and I was talking about Destroyer, and your calculations are incomplete.
At turn 8, after both are placed, provided you have enough quanta to supply them, Steam will have attack of 22, while Destroyer will have attack of 21.
Including that turn, Steam will make overall damage of 91, while Destroyer will make overall damage of 114.
I was going to comment, but since you ninja'd me I'll just put it up anyways.
I added a little something to the chart, to make it more accurate, because it now shows what has done more
total damage, since if one has already killed the opponent, the other's attack is irrelevant.
Steam Engine:
1|0/8- 0 damage 5
2|3/8- 4 damage 5
2
3|6/8- 11 damage 5
4
4|9/8- 21 damage 5
6
5|12/8- 34 damage 5
8
6|15/8- 50 damage 5
10
7|18/8- 69 damage 5
12
8|21/8- 91 damage 5
14
9|24/8- 116 damage 5
16
And then you win, unless your Machine is dead, stalled, blocked, or your opponent is using any type of healing.
Lava Golem:
1|5/1- 5 damage 5
2|7/3- 12 damage 5
1
3|9/5- 21 damage (Incidentally, exactly 1 turn ahead of SE in damage and attack) 5
2
4|11/7- 33 damage 5
3
5|13/9- 46 damage 5
4
6|15/11- 61 damage 5
5
7|17/13- 78 damage 5
6
8|19/15- 97 damage 5
7
9|21/17- 118 damage 5
8
So, either Zanz already planned they could kill at the same rate, or this has all come together nicely. Of course, the Lava Golem in this chart is unupgraded, and has the risk of easily being killed before it can even deal 6 damage, but the Steam Machine has the disadvantage of costing a bucketload of quanta.
And, since someone is sure to ask, the Destroyer should make the kill-shot at the 8-turn mark, unless of course my math is completely screwed up (Which I have a sinking feeling it will turn out to be...)
Lava Destroyer:
1|7/1- 7 damage 5
2|9/3- 16 damage 5
1
3|11/5- 27 damage 5
2
4|13/7- 40 damage 5
3
5|15/9- 55 damage 5
4
6|17/11- 72 damage 5
5
7|19/13- 91 damage 5
6
8|21/15- 112 damage 5
7
So, to those who said Golems are faster, be amazed!