I was looking at intake manifolds on ebay and I saw some old 4x2 intakes where each runner pair was opened up into one larger runner. Seems to me that the mixture is just gonna slam into the port divider in the head which is no good.
Then I thought, what if you knife edged the divider between the intake runners in the head? Or you could go further and cut it back in the head an inch or so.

What effect would this have on flow? I'm thinking low speed torque would suffer, but total flow at high rpm would increase. I also imagine mixture "stealing" between cyclinders would become more of an issue.

I've never seen this done before which suggests its not a good idea, but I'm curious all the same

 

With any port fuel injection system, this would probably not work out too well because of the factors you described.

I'd also suspect that #7 would be lean/starved because of the lack of available mixture after #5 sucks it all away.

 

"I've never seen this done before which suggests its not a good idea, but I'm curious all the same"

your gut feeling is correct, it would HURT performance noticably, in fact it would be a total disaster as far as effective inertial ram effect goes

what youll wind up with is a port that has an effective runner length that has a natural tuned ram frequency far higher in the rpm range than any chevy could spin, youll have an effective runner length less than 3" long


http://www.rbracing-rsr.com/runnertorquecalc.html

http://www.bgsoflex.com/intakeln.html


you might want to run some data thru these calculators and youll see why the TPI intake has the long runners its designed with


but you also need to keep in mind the rpm the exhaust scavaging that the headers primairys are tuned for also has an effect as does the cam timing and the intake runners tuned frequency

get them ALL tuned for the same RPM range and youll get exceptionally effective results, get one or more tuned for differant rpm ranges and youll hurt the potential result you might and SHOULD have gotten if they were correctly matched the differance is VERY noticable in both peak hp and TORQUE CURVE,,THE further you spread the rpm ranges of the three the worse things become......Im not saying it can,t be done or make power, but I am saying it will be far less effective that a correctly tuned combo would be


heres some examples on the same engine combo, notice that the longer runners on the HOLLEY STEALTH RAM moves the power up noticably over the siamesed TPI runners, the MAIN REASON is the LONGER RUNNERS MORE EFFECTIVELY USE THE INERTIAL RAM EFFECT IN THE INTAKE RUNNERS TO FILL THE CYLINDERS


http://www.eecis.udel.edu/~davis/z28...age021105.html