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## RE: large runner 1500 (single ZS) manifold needed (longish)

 To: "'Randall'" RE: large runner 1500 (single ZS) manifold needed (longish) Bill Babcock Mon, 6 Dec 2004 07:47:47 -0800
 ```Why would you want to maintain laminar flow on a flowbench? So you could avoid seeing what the problems are? In practical terms, most flowbenches don't flow enough with heads that have reasonably large ports--the pumps aren't big enough. The only reason you wouldn't use 28 inches is because you can't get that high with the valve open to any degree. It's only a pound of differential pressure but it takes a lot of flow to reach that when you're sucking through a big straw. But your premise was that this is a lot compared to the real flow (or differential pressure) of the engine (at least I think it was) and that's not so. At anywhere near the torque peak your engine will be flowing about ten times that much air. Even at idle it flows more. So there's two reasons for 28 inches (which is the standard everywhere). It's reasonably close to the maximum that a practical bench can reach, and you have to convert differential pressure to flow--unless your flow bench has a handy computer built in. The math is easier if you can reach (or convert to) 28 inches. Of course I remember Jerry Branch had a home built flowbench that used a GMC Blower connected to a humongous electric motor. As I recall, for some heads he was using 15 inches of _mercury_ -----Original Message----- From: owner-fot@Autox.Team.Net [mailto:owner-fot@Autox.Team.Net] On Behalf Of Randall Sent: Monday, December 06, 2004 6:54 AM Cc: fot@Autox.Team.Net Subject: RE: large runner 1500 (single ZS) manifold needed (longish) > For fully developed tubulent flow, the flow is proportional to the > square root of the pressure drop, But isn't the whole idea to develop laminar flow, not turbulent? At the point where it changes, there should be a fairly big discontinuity in flow rate, no? Avoiding turbulence is the whole reason we try to keep passages straight, smooth changes in cross-section, etc. Randall ```
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