We are building a new flow bench that is capeable of pulling 400 cfm @ 40" of vacuum. I have known for quite some time the importance of flowing at higher depressions, but COST is reason most of us don't. More inches = more blower motor which = more $. I will be able to pull "normal" SB heads that flow in the under 300 range to easy 50+ inches, and exhaust ports well over 60". Dwyer 120" vertical manometer should allow room to grow in future if I ever saw need for more airspeed. I just want to be able to test a W8 style head at over 28 inches and figured 40 would be good place to stop $ wise on the blower motors and complexity of the bench.

Biggest thing is just being able to generate enough airspeed for BIG ports to see what the short turn REALLY does. What may be stable at 10 or 20" may not be at 28 or 35"+ Or sometimes it's other way around, port can be unstable at 10" but crank airspeed up and air can actually hang onto the ST better.

Some of the Formula 1 type guys are testing now over 100 inches because they have measured presure spikes in oprating engines of similar outputs. Jim McFarland who used to design intakes for Edelbrock used sensors in between intake and head to measure airspeed in running engines. If have never heard his auido interview on SpeedTalk I'd highly recommend it. It's 98% about inatke manifold science not heads, but is best interview I have ever heard. That is one sharp dude, I learned more about intakes in hour and half than I had in my whole life.