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Hi Jerry,
Looks like you have copped the same treatment that
I copped, and still continue to cop. HIM (His Imperious
Majesty) never misses an opportunity to put someone down if they are right and
he is wrong. He's been bad-mouthing me for the past three
years.
Unfortunately, the majority on the ACRE
mailing list believe whatever HIM says is true, including all
the the libel and slander. And there is no right of reply or redress of
grievances.
As John Slade rightly says, those of us who
know what it's all about might start taking notice of him when he
actually gets a plane in the air, or even an engine running.
But, what about all the poor people who are being willingly
misled??? In the meantime I suppose, it's a case of
"Them's wot can ... DO, them's wot carn't
... prognosticate!"
As for the size of any PP runner, the ONLY
way ANYONE will know is to DO it, build the engine, and dyno the
sucker. From my perspective of a car racer, it's not only
size, but actual port timing and shape that makes a difference. This
is all RPM dependent. The higher the RPM, the more overlap and
the bigger the ports and runners that can be accomodated.
As a racer (as opposed to an aviator), we are
always trying to get MAXIMUM power, which means BIG runners, and
LOTS of ARE PEE EMMS. Current PP thoughts are 52mm ports being fed by
60 mm throttle bodies with a tapered runner. Great for 10,000 -11,000
RPM, But this just wouldn't work in an aircraft. The engine
wouldn't even get on the pipe until around 5,500. A two piece,
centre bearing crank is mandatory.
Obviously, the corollary is true. While
not being a fan of PPs for aircraft use, I can only agree with
you. At the RPM we are using in aircraft, the overlap
needs to be reduced (port size, shape, and placement on the
trochoid), and the runner sizes and lengths need to be commensurate with
the gas speed required, as well as any back pressure caused by
mufflers. In the end, this can only be a matter of applying a
bit of intelligent theory and doing some educated surmising, guided by
whatever people have done in the past, and then followed by trial
and error and dyno time.
For instance. I'm developing a four runner
manifold for the race car. The current one in the pix is steel (for ease
of fabrication), and will be replaced by an all alloy manifold once the
development is finished. So far, we have picked up an extra 25 BHP
throughout the RPM range, and something like 35-40 BHP at the top
end.
I eventually want to have computer controlled
adjustable length runners. Easily done with a stepper motor and a worm
shaft. Now I already have a ROUGH idea about lengths, based on
past expereince, but until I actually put the car on the dyno, I
really didn't know EXACTLY what length would work at what
RPM with the current style of bridgeporting I'm using, and the actual
mufflers and exhaust system on the vehicle.
So, I've made the trumpets manually
adjustable (crude by effective), and have done some dyno tuning and track
time to see what lengths work at what RPM. I am now at that point in
time where I can get my machinist to make an adjustable trumpet mechanism of the
correct stroke. I know HIM has been talking about it, but I'm
actually doing something practical about it!! Just do likewise
Jerry. Don't let the nay sayers get you down. In the end, you
will know who's right, because the dyno is the final arbiter.
Cheers,
Leon
I have come to realize that
what Paul has to say may not only not be true but in fact can be intentionally
false. I have also experienced a pile of profane, invective laden e-mail
attacking me and those who supported me concerning the p ports. Most of these
were sent privately. I have also had my comments suppressed so that in no way
could I present my side in a friendly debate about a technical matter.
Why so much strong emotion about whether a p-port should be a little
larger or smaller is a question that I cannot answer. At a certain point Paul
seemed to cross a line where fairness was no longer required. For sure, not
accepting his reasoning, mathematical or otherwise, can trigger rage.
Canceling my subscription to ACRE was not a decision easily reached,
but in the end, there was no choice at all. That was the way it had to be. I
do miss much of the theoretical discussion on ACRE. I found it educational and
challenging. Jerry
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