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DIY Flow Bench Web Interface

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Version Information

General Version V2.0-RC.X

Download the latest official release

NOTE: This project is still in active development and is currently at Release Candidate stage. We are working towards a stable software and hardware release.

If you are interested in contributing with testing please head over to our discussion forums or Discord channel.

What is a Flow Bench?

A Flow Bench is a basic system to measure and display volumetric air flow.

It is used as a tool for measuring and quantifying modifications and improvements made to items suxh as automotive cylinder heads and carburettors by measuring the volume of air that they can flow within a set time period. By measuring the volume of air that can be passed through the item the user can determine if modifications made to the item help improve air flow characteristics.

Traditional flow benches utilise a manometer and regulate the reference pressure using calibrated flow orifices. Volumetric flow is then calculated using mathematical methods to convert the pressure drop across the testpiece into flow.

Modern flow benches use sensors to measure flow and reference pressures and then calculate flow in real time by microprocessor.

What is the DIY Flow Bench Project?

The DIY Flow Bench project (DIYFB) is a professional quality flow bench controller that produces results comparable with, and in some cases exceeding commercial grade systems.

The project comprises of two distinct aspects.


The software code is developed in C++ and runs on an ESP32 microprocessor. The ESP processes sensor data and uses the results to calculate volumetric flow data, which is then displayed via web browser on any web enabled device.


The hardware aspect of the project comprises of a PCB (commonly known as a 'shield') which connects to the ESP processor, The PCB includes environmental sensors to measure temperature, humidity and barometric pressure along with pressure sensors to measure the reference depression from the vacuum source. It also interfaces to a MAF sensor or additional differential pressure sensors. This sensor data allows the software to accurately measure and calculate volumetric flow.

The project aims to bring professional grade results to the DIYer without the price tag associated with owning a professional bench.

This repository contains the hardware schematics and software code needed to build a volumetric flow bench based on an ESP32 controller and commonly available automotive MAF sensors.

Support is included for the following systems architectures.

  • MAF based benches
  • Orifice based benches (In Development for V3 release)
  • Pitot style benches (In Development for V3 release)
  • Venturi style benches (In Development for V3 release)

The DIYFB system can be used on any flow bench and makes an ideal retrofit for older manometer based benches as well as being the perfect choice for new builds. We include DIY hardware plans so you can build a basic MAF based flow bench that uses a shop vac for the vacuum source. This is a great entry level bench and perfect for most shops and hobbyists. We also provide support for larger and more complex bench designs.

Project Goals

  • Validated software and hardware design.
  • Affordable & easy to source components.
  • Can be built & operated by a layman.
  • Generates results comparable with commercial flow bench.
  • Open source software and hardware design.
  • DIY Shield kits available to purchase.

Development Info

This branch contains the current release candidate and is based on the ESP32 port of the original project.

After unit and peer testing is concluded and all bugs are resolved, this version will become the official DIYFB V2 release.

If you use this code and have found issues or have comments relating to the release, please raise an issue in the bugtracker, comment in the support thread for the current version or hit us up at our Discord channel.

Please note that support is only provided for the current release so make sure that you are up to date and running the most current version.


Documentation is provided for installation, configuration and use in the WIKI.

If you get stuck, feel free to create a discussion in the support forum, or see if anyone is available over on the Discord channel.

If you find a bug, or have a feature request, please raise an issue


This software is released under the GPLV3 license. For details on usage please refer to the license file included with this project


You can view an online demo of the Web UI at the followng link

Further Information