SPArKy_Dave 8,863 Posted June 22, 2017 From memory, AU went back to smaller valves, but had a better head casting. Share this post Link to post Share on other sites
Red 3 Posted March 22 Hi team, this is great insight. Can anyone recommend someone to do a decent port job for me in WA? I had a guy lined up but his wife recently passed away so I might just give him some space… I’m also running experiments on the lower section of the bb manifold as the short runner butterfly’s in the barra manifold are 4mm bigger than my AU one. 4mm is a massive amount of cross sectional area. My plan is to have them both put through a bandsaw along a casting line and check the ID. If there is no difference in ID then it doesn’t really matter. I’ll lightly port both the AU flange end and the barra other section before getting my mate to weld them back together. Interesting thought though, if the ID between both manifolds is no different why are the butterflies bigger? The runners OD is nearly the same (less than 1mm) before it transitions into the barra port shape. Unless the casting is thinner it might be the same ID. It seems as if you may just be able to remove the throttle shaft from an AU manifold , grind/port it out to barra butterfly size and go from there… I just want to be on par or better than as many of these barras as possible. Big rant I know but I like how people in this thread actually share their findings. Cheers! Share this post Link to post Share on other sites
