The vacuum is formed by the explosive movement of those high pressure exhaust gasses rushing out of the exhaust ports from well before BDC to after it, leaving behind a negative pressure wave behind them in the cylinder.The definition of scavenging.At which point the inlet port is uncovered in overlap.Think of it as a type gas piston making a good simulation of an inlet stroke.Obviously no exhaust gas negative pressure waves at start up.There’s nothing like the sound of a V16 when it catches and suddenly fires up in that regard.
The author might have bought into the myth of the forced induction naturally aspirated two stroke.Like the high engine speed one.
However to be fair diesel induction terminology always references inlet port pressure difference v atmosphere not vacuum.
Come on CF why don’t you just Fox Trot Oscar !
Not before he’s answered my questions. 
Ok Bewick the guvnor has spoken.Let CAV sort it all out.
Does the John Deere tractor company ring any bells
?.
Not known for their over 1 hp per cubic inch potential designs.
As opposed to naturally aspirated termed in inlet port pressure v atmosphere not vacuum.
I’m assuming you’re claiming they designed the Series 60. Got any reference for that, or are you going to sidestep that question, like the one about how many 300hp trucks you’ve driven??
At least he speaks from the right end of his body.
What Bewick even wants to know about two strokes is the square root of zb all.As he would proudly admit himself.
While like Franglais you think scavenging means forced induction and John Deere didn’t invent the 60 series.
Again, where is your proof?
You’re very good at chucking hair brained statements direct from your imagination, but not so good at cementing the gobbledygook. Admittedly, it’s hard to prove an untruth is factual.
Are you really suggesting that you can’t find any confirmation of the 60 series’ John Deere origins.
When you’ve found that check out the timeline of the 60 series’ introduction and the last two stroke truck engines.
The 60 series didn’t replace the GM Detroit Diesel two stroke or even really enter the market under GMC’s custodianship of Detroit Diesel , or at least close enough in time to make any difference.
The circumstances which stopped two stroke production operations, considerably later than introduction of the 60 series, weren’t even foreseen when the 60 series was introduced let alone designed.
Now back to the definition of natural aspiration, scavenging and forced induction ?.IE three totally different terms, meaning three totally different processes, in the operation of two stroke diesel engines.Scavenging by definition means a negative pressure wave in the cylinder left behind the exitting exhaust gasses.Thereby creating the required pressure differential v atmosphere to create natural aspiration.
But which has to be replaced/assisted by a fan/blower in situations of insufficient or no exhaust gas flow creating scavenging, like at start up.
Forced induction being added to that process is something else entirely.
The difference actually defined as N and T in Detroit two stroke designation at least.
But would like to hear CAVs interpretation of the Foden set up if thinks maybe different to the Detroit ?.
No I’m waiting for you to post a reference stating that JD designed the Series 60.
As for the rest of you waffle, I told you that the Series 60 was introduced after Penski was a partner, but you’re very good at taking stated facts and making a grand revelation as if you were the only person who knew and introduced them.
Nail on the head. No wonder TN members have voted with their feet.
Some days Carryfast is the only reason I come here. This thread is more fun than the political thread.
I’m with you there. Far too much sneering and hysterical mud-slinging instead of measured political debate on that thread! 
I can deal with not so bright people and will help them if I can, but I can’t tolerate fools. That is why I keep asking a certain poster for proof, he makes foolish statements and expects me to accept them. The name’s Billy, not Silly.
Voted with their feet because someone dared to disagree with myth , stated by them, as being fact.
Like the workers destroyed their own industry and jobs and AEC’s bus based engine designs were a credible rival to Rolls Royce diesels as gross weight and speed expectations increased…
Now the myth that the naturally aspirated two stroke is ‘supercharged’ among others.
So SDU agrees that the 60 series was designed well before the Detroit two stroke was even ever envisaged to need replacing by it.
He just doesn’t agree that John Deere actually designed the thing, not Detroit Diesel as a GM engine manufacture division.
While compare my input on this topic with Bewick’s.Maybe there’s your reason why no one with any sense wants to get involved.
Unfortunately CF you have infected TN with your BS for many years with all of your "expertise " and “nuggets” of wisdom gleaned from Truck Comics and promotional pamphlets you blagged from the likes of the Commercial Motor Show at Earls Court and latterly at the NEC ! Not to put too finer point on it CF I can claim to have bought sold and operated many types of motors over the 30 years I built up and ran my own Haulage group. I doubt whether you ever got beyond running Dinky or Tonka toys ! Well certainly by the garbage you spout I reckon I am not so far from the truth ! Bewick.
A pretty accurate description, Bewick, but you forgot to mention the gold star he got.
Fancy getting a gold star for stretching the job out.
You won’t find anything which I’ve said which isn’t actually backed up by history.Yes the Gardner 8 LXB put up more than a good fight v it’s NA rivals.
But even you eventually ran off to buy the turbocharged imports of choice like all the rest.
How long did the TL12 last in the T45 before having to put Rollers in the thing to find a customers for it.
That was the truth that finally sent gingerfold crying foul.
It was the maths as to what made the Rolls the better motor that inexplicably set anorak off in a huff.( You’ll need more force applied on the piston and rod and ends and head anchorages and gasket ) to compensate for having less leverage of a shorter stroke.
So now just busting the myths of the ‘high engine speed’, supercharged, but naturally aspirated, two stroke.
Strange how someone with no enthusiasm for Fodens or two stroke diesels would have any interest in this topic just to have a moan at me.