17 inch is right from port to dynamic chamber for both 3000 and 6000.
At 3000 RPM the pulse travels 34 inches from one
port over to the other while at 6000 RPM it looks like two simple
17 inch runners and a somewhat restricted plenum chamber.
This is about the stock 3rd gen configuration.
As I said low RPM torque is their biggest problem
If yours is 17 inches from side housing port to side housing port it
is
primarily tuned broad band for about 6,000 and 12,000 as simple
pipes.
Here are a couple of shots of the third gen dynamic chambers.
Mazda claims they are a large improvement over the 2nd gen versions.
The main improvement is putting the air feed pipe/throttle body in
the
same
plain as the runners more or less. The 2nd gen feed the air
in at 90 degrees. They could not quite pull it off on the
inner loop as you can see here. It goes in at about a 45 degree
angle. I noticed that Able Ibarra with his 800 HP turbo third
gen 13B engine uses this stock manifold that has been extensively
extrude honed.
This is a fascinating subject to me and I am sure Mazda spent
millions
researching this stuff.
Paul Lamar
I agree, fascinating indeed - Ok, looks like my 21" from port to
dynamiic
chamber vice 17" is a bit long for 6000 rpm which probably explains
why my
peak torque appears closer to 5700 rpm than 6000. I will shorten
this one
from the current 21" to around 18" just to see the effect. Can always
shorten it another inch or so {:>).
Too bad we don' t have the resources to research/experiment/test to
determine optimum for aircraft use, but considering what we get its
fairly
close with the Renneses even closer to the perfect power plant.
Got a copy of Flying Magazine, Peter's article on the rotary engine
referes
to you as the "Spider at the center of the web" {:>).
Ed
Yes I know :(
Can you shorten it to 8.5 inches? That would be optimum for
the manifold to actually work as a dynamic chamber. At 17 inches
and 6000 RPM it is working as four tuned pipes (two at one length
and two at another length) feeding off two piss poor plenums :)
At 17 inches it is working as an actual dynamic chamber only at 3000
RPM.
As far as the slightly different lengths are concerned an electronic
analogy would be two series resonant circuits tuned
at slightly different frequencies in parallel. The impedance would
be lower if they were both tuned at the same frequencies
and the bandwidth narrower.
Hopefully Jerry Hey will have a p-port engine running soon
and it is easy to vary the runner length so we may have some dyno
data on this soon. The dyno is close to being done. All I need now
are some engines to run on it.
Paul (Spider) Lamar
Spider,
I just bought a little horse ranch near Fort Wayne, Indiana, about ten
minutes from Smith Field and will be moving the operation there as soon
as I sell the California place. Showed it three times today and each
person said they wanted to buy it. Firm offers are hoped for on
Tuesday. Maybe I will get the PPort done before the big move. I am
sure going to try. If not, then it will be a while.
I think the content on this site for the last month has been exciting
and relevant. It was fun to just lurk.
Jerry
We are going to miss you here in CA Jerry. You'll freeze your pippy
off back there in the winter. Are you sure you want to do that?
Paul Lamar
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