Ok, So I am building my second oil tank roaster, smoker, grill. Need to figure out how large and or how many stacks to put on for ventilation. This is going to be a simple build with a coal rack across the bottom and a cooking rack across the top........slow or fast cook will be entirely dependant upon where the coals are placed......but needs to vent right whether I have coals out to the sides, or all across the bottom. I went thru alot of goofs building my first one.....I want this one to be as simple as possible.