There is, in fact no suggestion whatsoever in Norse mythology that Nidhogg (Niohggr / Nidhug) actually died! It could be assumed that since Nidhogg's only purpose was to kill the world tree, Yggdrasill (by gnawing through its roots), that Nidhogg died at the same time as the tree. There is also the possibility that Nidhogg was one and the same as Iormungandr, the "world snake". If this is to be believed then Nidhogg was killed by a stroke from Thor's hammer, Miolnir, during the battle of Ragnarok. For all other intents and purposes, Nidhogg did not die. As a personification of the gnawing presence of a malevolent evil, it could be said that Nidhogg was the only truly immortal being of Norse mythology, and can simply never die.
The size of the Norse dragon Nidhogg is never specified. He is a simply mentioned as a large dragon who gnaws on one of Yggdrasil roots in Niflheim.
Nidhogg, see: http://www.thorshof.org/znidhogg.htm
How much horsepower is 439
how much hp is 140cc
About 6.5 hp.
how much cc's is a 6.5 hp engine
1000 hp
110 HP
About 27 hp
17 hp
160 hp