Al Gietzen wrote:

I can't help but think how very much lighter and stronger the part

would

be if you made a male mold and did it with glass cloth layups.

You

could even incorporate machined al fittings for injectors if you

wanted,

epoxy bonds nicely to al.  It would, of course, also do away with

the

exothermic heating problem.
Al

Ok, Al

    Them are fighting words! {:>).  I must admit that I am impressed

with

your manifold for a 20B at 2 1/2lbs.  So I went back out to the shop

and

weighed everything.

Lower Manifold Casting (Paul's)         = 3 lbs (after trimming)
Flange and tubes                                 = 2 lbs 6 oz
Plenum/injector boss (Resin casting)     =   1 lb 6 oz
Throttle body                                      =         9 1/2 oz
four injectors                                        =       14 oz.

Total                                =  8 lbs 3 1/2 oz for total

intake

system

The only thing I can think of I did not measure was the fuel rail - a

10"

length of thick wall aluminum tubing, the AN fittings for the fuel

line and

the bolts to hold the manifold to the block and such.

Now 8 lbs 3 1/2 oz for the total intake system might not seem too hot,

but

my current one (same components weighed) comes in at 21 lbs.  The boat
anchor lower stock manifold, the almost 5 lb 13B throttle body and

tubes

inside tubes came to that.  So I am quite pleased with the weight.

The fiberglass strands should hold the thing together and keep it from
falling apart.  If it does start to craze and leak, I am confident I

will

notice it (unexplained higher idle, whistling plenum, {:>), etc.)

I agree, you could certainly make a similar thing out of fiberglass

and

resin and probably come in a bit lighter than 1 lb 6 oz for the
plenum/injector bosses.  But, with the 4 injectors along weighing 14

oz, I

feel it is reasonably light.
Ed Anderson

Ed;

I take it back, you're right - it is quite a lightweight system.  I had
guessed the lower manifold casting, and your resin casting to be
considerably heavier; like by a number of lbs.  Adding the glass fiber
will definitely add to the strength.

My total induction system, including the 'weigh heavy' TWM TB, both fuel
rails and air box is very close to 11 lbs.  So, on a roughly equivalent
2-rotor, that's only a lb less than yours.

Anyway; it got you to weigh everything :).

Al

Yes, I agree,  both units come in fairly light, I think.  I used a two
throat 4 injector TWM TB when I first started flying, but came to the
conclusion that the two 2" dia holes just did not create enough velocity of
the mixture to stuff the chambers fully at 5000-6000 rpm.  Apparently worked
fine for the guys turning 8000 and above in race cars.  It is certainly a
nice, well made unit and for your 3 rotor will probably be just the thing.

Onward to more (less weight that is) progress.

Ed Anderson

I am not going to go there Ed. However if what you and Paul Yaw say is true
the Lemans engine should fall flat on its face at 6000 RPM but it does not.
It generates 120 HP per rotor at 6000 RPM. For the math challenged 
that is 240 HP for a two rotor. Please repeat that over and over again
so it is burned into your cerebral cortex for future use :)

Paul Yaw has yet to build an engine that puts out as much HP per rotor 
as the Lemans engine at any RPM. What is fooling Paul Yaw is he is pumping
air through a carb and carbs need velocity or they don't work.

Paul Lamar
 
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