2 Stroke exhaust calculator

2Stroke Tech

About this app

A simple 3 stage two stroke exhaust calculator based on formulas of G.P. Blair from the book: The Design & Simulation of Two Strokes.
You can also save and load the data by using the provided functions.

Note:
This coefficient Kh is called the horn coefficient, with typical values between one and two. Small values of Kh are best suited to Grand Prix engines with narrow power bands, larger values are for wider more flexible engines.

Ratings and reviews

This app is simply brilliant, and brilliantly simple. I have used this app with tremendous success to design and fabricate over a dozen exhausts for both reed and piston port induction motors. I overcome the issue of not being able to work transfer timing into the design by working backwards; choose an exhaust duration that suits the rpm/target hp, then select transfer timing to suit from one of A Graham Bells graphs, adjust the ports and build the pipe. Trust me, it works!

been a while since i made a pipe but results look about as expected. no transfer timing? guess i can only try and see. any pipe is better than no pipe. have to soup the chainsaw up a bit!

Hi, i am having trouble using the calculator. No matter what i try, the calculated i.d is wrong (header pipe i.d is larger than the belly i.d, etc). Do i enter my port messurments in Millimeters or inch, etc? Engine is a "66cc" motorised bicycle engine. Cheers.

What's new

1.0 First version
1.1 Added landscape mode and qVGA resolutions
1.2 Added hydroformed calculations as promised