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Boy, Bill, what an intake manifold project. If it should not turn out to work as you desire - it will sure make a nice piece of artwork! Sorry, couldn't resist it - I know nice artwork is not what you are looking for. Looks like a lot of work has gone into it already. Will eagerly await its production and test results.
I am still curious as to how you plan to get the engine close to 9000 with the prop load. One of the problems that typically happens is that a manifold may be designed and may give great performance at say 9000 rpm in a car engine. Because they can shift gears and regulate the engine load, which of course we can not do ..... unless....Aha! you plan on using a constant speed/variable pitch prop - don't you.
At least my experience with a fix pitch prop is that due to the prop load the engine simply won't get up into the rpm promise land that the intake design would seem to promise. My very first intake manifold was being used by the rotary racers at the time and producing 280+ HP at untold rpms - I tried it and the engine could simply not get past a 5500-6000 rpm range. I replaced it with an intake of longer, much smaller diameter intakes and have now hit as high as 6800 rpm.
In any case, hopefully your results will everything you aim for. In any case, it should provide us with an expert on carbon fiber intakes - that in itself would be great 3lbs vs my 11lb intake would be great.
Ed A
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message ----- From: "Bill Dube" <william.p.dube@noaa.gov>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, February 07, 2006 8:49 PM
Subject: [FlyRotary] Six port bolt-on manfold progress (was: RX-8)
The six port will supposedly make 248 HP 100% stock. This is at about
9000 RPM, however. The four port does not make as much HP stock.
I am working on a carbon fiber composite manifold for the 6 port that
(hopefully) will emulate the stock manifold with all the valves open.
CNC machining of the molds will commence the beginning of March. We CNC
machined a foam test mold a few months ago. We did a test layup of the
carbon fiber about a month ago.
Attached is a picture of the CAD rendition of the six-port manifold. As
you can see, it will use the stock throttle body, stock injectors, stock
injector rails, and will be 100% bolt-on. Should weigh about 3 pounds.
(Stock manifold weighs 22 pounds.) High temperature epoxy will easily
withstand 300 F. Back-of-the envelope calculation says the burst presure
on the carbon fiber tubes should be well over 10,000 psi.
The goal is to make a lightweight manifold that will hug the top of
the engine and will simply bolt on.
It is going slower than I would like, but I am working on it in my
spare time and trying to keep the costs down.
Bill Dube'
randy echtinaw wrote:
Gentlemen,
I have the opportunity to purchase a 4 port or a 6 port RX-8
engine. I thought I wanted a 4 port because I thought it would be
easier to muffel. I just heard a "rumor" that the 4 port is junk and
go with the 6 port. I need 220-230 hp using the 2.85 PSRU, no turbo.
I would consider P-porting if absolutely necessary to get the HP.
Obviously, I know very little about engines and want to start with
the best I can get so, considering my needs which one do I want?
Thank you,
Randy
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