Gordon Bennet !
Gordon Jennings. I wonder what this thing does book.
Read it several times.
So much measuring, guessing and then theorising.
And then gives you a tune length forumla with the guts of it hidden away to produce an imperial value in inches.
Magically jumps from ft/sec sonic velocity to inches of tuned length, where'd the 12 go ?
Try that calc with m/sec to mm tuned length to see the fail.
Gordon Blair
How to make an apparatus (QUB SP ) that doesn't properly simulate 2 stroke exhaust compression / expansion wave timing.
When the expansion wave returns to the port window it does NOT meet a closed end in peak operation, it meets a still open ex port and transfer, and what happens when an expansion wave meets an increase in area, it inverts and reflects a compression wave, where a closed end does not invert sign and reflects another expansion wave, he knows that.
Thus induces a signal in the pressure ratio timing graph that would be the opposite signed secondary reflection.
Not only that it would be dimished in strength (according to his own study), so would it even induce the shock waves he shows, who knows, he didnt try that model.
And then he waxes about effect of gas properties at 15 AFR ratio on wave velocity, when if you ran 15 AFR in a 2 stroke it would seize.
And the typos in diffuser model pointing to the wrong graphs doesn't help.
And why obsess over wave resonance timing at a fixed sonic velocity.
It doesn matter what resonant effect happens at 6000 rpm if you are at 7000 RPM a second later.
Engines accelerate and if they are not accelerating they are not at WOT and if a 2 stroke is not at WOT it is not even 2 stroking.
Investing time into one book or study done by an Irish engineer is fraught with danger of wasting a lot of time, to be sure to be sure, to be not so sure.
I though I knew how they worked after building them for bikes with my Jennings bible under my arm, till I started building them for karts with no gears then I discovered I didnt.
Anyway that's my 2 bobs worth on the books of Gordons.
Ill just end with these.
https://www.youtube.com/watch?v=Yp91Ml5mxg0
https://www.youtube.com/watch?v=dT0hqhVNSH4