Most engines have this already, a mass air flow (MAF) meter.Conceptual wrote:Would it be better to simply purchase a $20 flow gague and hook it to the motor?
The first number sounds about right.Conceptual wrote:I actually found another site where they were doing the same thing, and the numbers they were getting out of a 2.4L 4 cylindar was 253CFM@6000RPM, so the 400 number would probably be pretty close.
It amazes me how high these numbers are. My first thought was that it would be around 50CFM, but WOW, do these engines consume ALOT of air!!!
To know VE precisely all you need is displacement and a P-v (specific volume "v" not "V") diagram for the effective cicle at a given load and speed. A modern dyno can get you this graphic. No need to know valve, port and intake/exhaust system geometries or the air volume flow.SZ wrote: Engine bore, stroke and cylinder count can give you a good guide to efficiency characteristics (VE particularly, though to be accurate you need valve, port and intake/exhaust system geometries), but they don't tell you how much fuel you're combusting. This (which requires the air volume flow you're trying to calculate) is independent of the engine configuration.
No:SZ wrote: How much energy you're releasing in combustion from a fuel mass flow perspective - once you consider efficiency - therefore determines your air demand.
Watch your criticisms, they may come back to bite you.
Particularly that bit about a good operator... 120% VE for a NA street engine at 7kRPM? You're beyond a bit optimistic - I'd revise your understanding of VE.1D analysis is as precise as you'll get for simulating gas dynamics in an engine, and in that, in capturing factors particular to VE. It's a common tool in modern engine development - used properly a good operator an achieve accuracy in VE within 1-2%. This is what it takes to simulate VE accurately (the approach being discussed), to which all intake and exhaust path geometries play a part.
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