Here is the information on my 88 engine (turbo 13b), original

intake

manifold.  Notice that the equivalent area is over three inches

dia.

Rino

Good work Rino. Thanks for working this out. Next time this

subject

comes up we will hit them with this.

Perfectly CLEAR! Thanks guys. So what you are saying is short

of making one, everything out there is going to be small?

...Chrissi

Chrissi,
You do it deliberately. I know you do.
Good luck getting a big enough throttle body. I hate to admit it now,

but I

need one too. Let me know what you decide on.
John Slade

Just for the record,  I do use just two barrels of the stock Mazda  (3
barrel) throttle body.  Nothing wrong with having a bigger one except that
throttle response just off idle is sudden and difficult to modulate if it is
too big.  This will mainly affect taxi operations but still worth
considering.

  For power levels around 180 HP I find the two barrels about right.
Remember that Mazda used basically the same throttle body on engines up to
285 HP (latest Jap-spec RX7 numbers).   I note that on takeoff and climb
speed I get no increase in power with the last 35 - 40% of throttle opening.
At speed, when the engine is able to rev up more, the amount of 'dead space'
in throttle shrinks to *almost*  zero at top speed.  This indicates to me
that the throttle body is almost perfectly matched.    If you intend on
making more power via higher rpm or turbo charging, a slightly larger one
may be in order.  It may be instructive to look at the throttle plate size
on Aircraft engines of the same HP as you intend to make. I made my decision
based on the MA4 (or MA5, its been awhile) carb used on the O - 360  180HP
Lyc.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

I can think of several reasons why your systems is acting the way it is.
Perhaps your intake air scoop on top of the cowl is not working as well
as it might given it's area and that it has no boundary layer air bleed.
Perhaps your intake runners are too small.
As I recall there is no radius for the air going into your throttle
body at a right angle. That could be 5% or 10% more power right there alone.


Without making pressure measurements on your intake system relative to
to dynamic pressure it is hard for me to say what is going on.
I really wish you would take the time to make some pressure measurements
here and there on your intake system. It would also help a lot if we had
some pressure measurements on your cooling system. The same low cost tool
will work for both. Namely the water manometer. I'll be down
in Florida about the 15th of Feb for the helio expo in Orlando
so I will bring some of the manometer makings and all you have 
to do is go up and fly around a bit with me
in the back seat photographing the water manometer with my digital
camera :-)> In the mean time figure out how we can tap into your
airspeed indicator pressure source and static air pressure source 
so we can use those as reference pressures.

Also if you don't mind please contact Dave Garber and ask him
if I can stop by and take some pictures of his rotary huff and puff.
 
BTW Carbs need high velocity through the venturi to suck fuel out of
the float bowl at the lower power levels.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org