Yah, holy cow, no kidding... Maybe you've got something wrong there in the specs?
I just looked at my 25CFM Delta BFB1012HH blower and it says it draws 0.69A at 12VDC, so that would be a little over 8 Watts power to push 25CFM of air....
...and you said your blower is drawing 4A at 12VDC? That's 48 Watts, 6 times the power draw of the 25CFM blower I have here. Six times 25CFM would be 150CFM if all things were equal in efficiency, which would be equivalent to about a 25MPH wind! What is the CFM rating on that blower? Is this a flying smoker? LOL
Why don't you give a little more information about the smoker and the setup in general so we can offer you better advice. From what I see you plan on using enough power to create a whole LOT of air flow there and I am not sure why you would possibly need that much?