tlowe see previous post.
I think the low ports are for more hood clearance, how would it influence burn rate, if you decrease air flow to make more power something is wrong with your combination or tuneup, if you want to increase burn rate give it more advance, who cares about emissions on a race car.
Well, for starters, a low port entry angle can induce "charge tumble", a common method on 4-valve engines to increase the rate at which the fuel in the chamber is consumed, and thus, the rate of pressure rise against the piston. If you can increase the rate of pressure rise against the piston after ignition commences then you can reduce the ignition timing. If you reduce the optimum ignition timing then you will do less "negative work", i.e., the pressure that is building as the piston is approaching TDC actually is working against the crank and reducing power. So your premise ..."if you want to increase burn rate give it more advance"... is fundamentally flawed and a common misconception of how ignition timing affects performance. Ideally one should strive for an engine that needs as little timing advance as possible to reduce the negative work.
Don't think for a minute that Detroit wouldn't lay the engine over like a slant six if it meant picking up a bunch of power by raising the ports.
As fas as ..."who cares about emissions on a race car"... I care about emissions on every engine I own, from my DD to my lawnmower to my race car. My grandchildren are going to inherit this earth as are their grandchildren. I don't want the entire earth to have the air quality of a Beijing.
