Thanks for your thoughts.
I think Tracy just spoke the other day about feeding 4 runners from
2 mains. So, I thought that using 4 TB's and reducing from 48mm
(1.65in) to 1-1/4 would avoid what you described.
Another plus with setup, is that the fuel rail is on the cold side
of the engine. Which brings up another question. Which
is better; injectors near or far from the port?
From:
Ed Anderson <eanderson@carolina.rr.com>
Subject: [FlyRotary]
Re: renesis intake possibility
To: "Rotary motors in aircraft"
<flyrotary@lancaironline.net>
Date: Saturday, February 7,
2009, 10:33 AM
Welcome.
Here is my experience using a TWM throttle body (a different model
than you are looking at). Back in 1992 there was no one around
that I was aware that could provide any answers to what made a good
induction configuration for a flying rotary. So I turned to the
only “rotary aware” crowd around and that was those racing with rotary
engines.
So after
discussing my needs, I purchase a TWM throttle body with 4 injector
positions. It was a two throat (Webber style) design with each
throat 2” in diameter. Two injectors per port (I used MSD 32
lb/hr injectors that fit the injector holes) for a total of 4
injectors on the TB. The TWM throttle body was then bolted to a
cast aluminum “Webber” style rotary intake manifold which then
took the two TB channels and divided them into 4 (two primary and two
secondary) distribution runners.
I estimate
that the best HP I ever made with that set up was around
130-140HP. My static rpm was 4800 swinging a 68x72 two bladed
wooden prop using the 2.17:1 gear ratio.
I later
replaced that arrangement with 4 tubes of smaller diameter (1 ¼” for
primary and 1 ½” for secondary), made the runners longer in length and
install the stock Mazda 3 port TB which had considerably smaller
openings than the TWM arrangement.
I immediately
picked up over 300 fpm increase in my ROC and top speed moved from 186
MPH TAS to 195 MPH TAS.
As I learned
over the years, it became apparent that what works great for the
racers turning 9000 + rpm may well suck (but may not suck very well –
pun intended) at 5000-6000 and was therefore of questionable use
for aircraft. As best I could figure out the problem, it appears
that with the large runner openings and runners that the mixture
velocity in the runners was very much lower than optimum. That
meant the air mass had little momentum and did a poor job of filling
the combustion chambers during the short time they were open. By
going to smaller runners, the mixture velocity increased considerably
and resulted in more mixture in the combustion chamber and more
power. Now if I could of somehow (using a shifting gear
box?) have gotten my rpm range up into the 8000 + range, then that
intake system might have been the cat’s meow – but, of course, I could
never get above 4800 rpm static (and about 5400 once
airborne)
Now the TWM
Throttle body in the photo based on your description may not have the
same problems as it does have a considerably smaller throat than the
one I used. I personally do not believe the use of the four
throats would give you what you are looking for – however, the use of
two of the throats (one module) might work. You could always
place your second injectors else where on the secondary part of the
intake.
Just my
opinion, of course, if the price is really good, you have little to
lose if it doesn’t work out.
I now use a
$25 65 mm dia Mustang throttle body which is much lighter (and much,
much cheaper) than the TWM model I purchased back over 15 years
ago.
Good luck on
your project
Ed
Ed
Anderson
Rv-6A N494BW
Rotary Powered
Matthews,
NC
eanderson@carolina.rr.com
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Bryan
Winberry
Sent:
Saturday, February 07, 2009 8:57 AM
To: Rotary motors in
aircraft
Subject:
[FlyRotary] renesis intake possibility
I have a chance to purchase a TWM
throttle body(see attch pic) at a very low
price. I have a couple questions for the
group.
The inlets are 42mm (appx 1.65
in.). Is this too big to the point that they would be
incompatible with the injectors? I plan on using 1-1/8
and1-1/4 in runners.
Also, the bosses are sized for
Bosch, Rochestor, or Lucas injectors. Does this
necessarily eliminate my using the stock Renesis
injectors?
This setup also would allow the use of a
lightweight airbox thus simplifying the intake system
from a manufacturing standpoint.
RV7, Renesis,RD-1C,EC3,EM3 (in the
pipeline I hear)
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