actually the primary ports would go lean w/ a tb off the middle of the plenum. that's why guys like bullish and aebs use 2 tb's for better air distribution. but w/ the traditional placement on the end of the plenum, the rear rotor has a tendency to get leaner. that reverse header does sound good though, like the one on the quad turbo camaro.

 

I read a post by rotarygod and he said he had done some flow testing and found that the primary ports didn't run lean (like he expected them to) and that distribution of air was very uniform.

The 20B intake manifold always made me wonder how uniform the air distribution could be. hmmm

 

that is the old setup KNONFS, it was only high heat painted. at that time the only reasont th alternator was on the car was so that i could turn the water pump! now i am using an electric pump and there is no longer an alternator or t-stat housing.

i try a smaller pic later

MWW

 

oops i meant to say that if anything would be leaner it's the primaries not the secondaries.

 

Thanks for the info

 

Hey man I hope you don't mind, but I was showing this pic to my father and he raise a good question (in my opinion). Why are you using copper tubes for the waste gate lines? Wouldn't they break eventually with all the vibrations in there?

 

That is his old setup. I can stick my fat head in his new plenum!

When I ran the tests on my manifold I used vacuum not pressure. Vacuum indicated even flow from all ports regardless of location. Pressure may be different since the air entering the 3" pipe from the throttlebody fires directly at the center runners. However the area of the center runners is smaller than the outers limiting their potential airflow compared to the outers. Furthermore, the sheer volume of air entering into the plenum is such that only so much can even be crammed into the smaller ports forcing the rest to go to the outer runners. The plenum is large enough (but not Marcus large!) that the air doesn't have to make a very hard turn to the outer runners which is easy on airflow. If there is any disadvantage to my setup over optimal I consider it minimal. The plenum isn't wide enough to really hinder airflow to any particular port. I can see problems with plenums like the Mustang 5.0's where the plenum is skinny depthwise but long front to back. You bet that would run lean on the outers. Also since 2 ports connect to the same chamber there will be a tendency to have much more even airflow distribution since one port can't suck in airflow at a much different rate than the other unless runner size is a factor. Marcus' plenum is so cavernous that there shouldn't be an airflow problem to any part of the engine. He could put a throttlebody anywhere in there and not see a change. He only has 1 middle runner anyways so there will always be good airflow into at least one port (OK all of them!) at all times. You guys should see it in person. It is impressive. Hope you keep it waxed man. It'll make it easier to clean all the jiz off of!

 

why would copper break? copper by nature is VERY soft and maleable. i have since changed because over the last few months i have changed the system 4 times and nothing ever fits the same!!

 

I thought it would break (eventually) with the all of the vibrations, I guess not.

Thanks for the info!!