I have been thinking about a way to reap some of the benefits of siamesing the stock intake without the extreme loss of low end that occurs when this is done. This intrigues me despite the fact that nearly everytime I see results on this the car actually slowed down. But people seem to love the top end rush it creates. I feel this is because the motor now sees the manifold as the entire runner length. To it the runners are now non existent and function as a plenum. The size of the runners is now effectively doubled which is way more than is needed. What I am thinking of doing is cross drilling holes in on an angle between the ports. One angled in each direction from one port to the other. This way each cylinder would perhaps see only a small % of the other runner. You could really get cool with it and epoxy a reed valve on each one to keep it from feeding back thru the hole coming the wrong direction. Make the total area seen by the port perhaps 10% to 25% larger (rather than the 100% larger that siamesing accomplishes) and you could raise the powerband by a similar percentage without experiencing the extreme loss of low end that siamesing accomplishes. So I guess I am looking for opinions on the size of holes to try. Could it be as simplistic as saying Ok if I want to raise the maximum point I make power from 5000 to 5500 I need to make 10% more port area available? opinions?

 

I hear about people siamesing the manifold here and there, but I think that for the most part, people don't do it.

...would you idea cause turbulance?

What about siamesing the manifold only 1/2 and inch?