Whp vs. Engine hp?

Pelican170

Ok, just curious about if there is any real conversion to tell what the engine hp is when knowing the whp? Here is my logic but im sure its not accurate. For example, when comparing the sport vs nismo, we see there is a 19 engine hp difference. From what ive read, there is approx a 5 whp difference (19 bhp) between the two cars (this is not a nismo vs sport thread or anything of the sort, so please dont bring it to that level. If my info is wrong, i appologize). So my logic tells me the whp to engine hp is 3.8 =(19/5). So for add on parts that get dyno'd, can you simply take the dyno whp and multiply it by 3.8 to get the bhp? Make sense? Lol, im sure thats not accurate but very curious...