Build Your Own Flow Bench
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- Опубліковано 28 вер 2024
- Showing some of the theory and the important details needed to build an uncalibrated flow bench.
Flow benches can be used to measure the air flow through various items in your engine, such as cylinder heads or filters.
This flow bench is uncalibrated and is only useful for comparing your own test pieces.
been reading about this in David Vizard book, and he talked about pro's and con's about a standard used 28" pressure drop.
He said that his very earliest simple flowbench worked with floating pressure drop. And came with very good results.
I am building a simple device to start with, using my 2KW vacume cleaner, see what it does. and go from there.
Very good diy flowbench
Very good video for understanding how such a flow bench works. I built a similar in 2019 and still use it today.
Can this simple flowbench read flow rate (CFM)??
Are you sure you have 28" and not 14? I don't think you count the opposing column. I could be wrong
It's a COMPARATIVE flow bench only. It can't / shouldn't be used to compare with results from other benches. The numbers don't actually matter. As the 28" is a bigger reading, any differential will be easier to see.
@@pingu393 I understand. Mine does measure actual flow using an anemometer. I use the column to standardize the pressure. That's why I bring it up. Plus, you need to know you are in the right neighborhood if you want to do something like determine the effect of a bigger cam.
@@ericthered9655 see (ua-cam.com/video/5G-cnCadl5c/v-deo.html) for a "proper" flowbench that I built. (porterbility.co.uk/flowbench_calculator.html) is a calculator that you can use to standardise the data.
I've done some investigations on this topic, and my biggest concern is that all flowbenches work on the principle of steady flow. As you know, an IC engine is a pulse flow engine, and the "air" is pulsing through the cylinder head.
A comparative flowbench can be used to equalise the flowrate in the cylinders. Any work/machining on one cylinder should be equal to the work on the others, otherwise your losses due to imbalance may be greater than your gains due to machining.
It's my conclusion that flow benches can only really be used where the flow is mostly steady. This would be up to the throttle tubes and after the exhaust headers (and the exhaust is mainly tuned for pulse, not steady flow, so even this is probably the wrong model)
Any work between the entry to the throttle tubes and the exit of the headers is using the wrong model. You should be using a pressure tool that can measure pressure differences per millisecond.
Think of a valve closing - you can measure the flowrate at each millimetre of lift, but you don't see the effect of the movement of the valve in the flow. It's the difference between measuring the flow around your hand in a stream, and measuring the flow around your hand as you move it through the stream. The steady hand is only turbulent at the edges, the moving hand can create a lot of turbulence. It's the turbulence that we want to minimise in order to maximise the volume of air passing the valve.
This design is invalid. The whole point of a flow bench is to measure flow through an engine head and an engine head only, meaning you cannot pull atmospheric flow from "A" on your diagram to regulate your plenum to 28" H2O.
The objective of THIS flow bench is to compare one thing with another. It doesn't matter what those things are.
The lower the reading on the inclined manometer, the higher the flow rate.
A flow bench can measure the reading of air flow, it doesn't give one fucks if there's a cylinder head sitting on it or your granny's ass!!