tengo ese problema con el simulador de humo, el renderizado sale muy pequeño 
I have that problem with the smoke simulator, rendering leaves very little (sorry I do not speak English )
thanks
On the Domain object, check the colour ramp on the material you set up to control emission. Make the transparent section at the left side smaller.
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I have had this problem before. I believe it occurs because your domain was scaled in edit mode. You have to scale the domain in object mode to maintain the smokes size. What I assume happens is that the smoke simulation is based off the objects scale and when you scale in edit mode all you do is change its dimensions.
Tienes que quitar de domain y crear un nuevo cubo para domain. Solo no utilises “edit mode” y estiras el cubo con “S” en “object mode”.
Disculpe me para mi espanol pero soy ruso =)
Gracias, si funciono