From: Lehanover@aol.com
Message-ID: <1a2.1861c1a6.2c5d088c@aol.com>
Date: Sat, 2 Aug 2003 08:29:00 EDT
Subject: Re: [FlyRotary] Re: Low pressure fuel pump flow
To: flyrotary@lancaironline.net
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In a message dated 8/2/2003 12:20:03 AM Eastern Daylight Time, 
rotary.coot@verizon.net writes:

>   Yes I tried low psi pumps at first and it just didn't cut it and 
>  when I got the flow and pressure up the power went up also.
>    What kind of carb do you have ?
>  
>    Ken
>  
>  
>  
>  >Found your comments interesting Ken because my Duce with carbed 
>  >engine needs both pumps on for climb out or engine will sag. I 
>  >thought this was a problem unique to mine that I'd have to track 
>  >down sometime but maybe not. I will eventually get around to 
>  >measuring flow from each pump.
>  >Peter
>  
> What are you calling "low" pressure pumps?

  When we first started out with a rotary engine, we were at Sebring Florida 
and the engine was not running well at all. In the lower gears it seemed OK 
but on a long pull in top gear it would just not have that much power. I asked 
one of the Rotary powered competitors for help. He had a clear plastic stand 
pipe with a banjo fitting that replaced the drain plug on the side of the Webber 
float bowl. Whatever the fuel level is inside the bowl, it is the same in the 
stand pipe. He revved the engine to 6,000 RPM. The fuel level was cut in 
half. He revved it to 9,000 RPM and the float bowl was empty. The needle and seat 
became the main jet for both throats. 

That was quite an education.

The engine will run just fine, way lean of peak EGT. It will sound crisp and 
sharp, but it won't have much power. Best power is well rich of peak EGT. 
There are some reasons for running lean of peak EGT. There is less fuel to burn. 
There is less waste heat to dispose of. There is less oil dilution. So, if you 
need more range some dark and stormy night. Or, you develop a cooling problem, 
it is an option. If you mix oil and fuel, there will be slightly less oil for 
the apex seals. Generally only a problem with long runs with the throttle 
fully closed. We have big (rich) idle jets for that reason.

For our problem, I installed a 3.5 Gross jet Needle and seat assembly. I 
increased the main fuel line diameter to 5/16 ID. I took off the two street fuel 
pumps and put on the Sliding vane racing pumps. We still could not hold 6 PSI 
at the end of a long pull. I replaced the fuel filter with a really big fuel 
filter with a replaceable element. 

All is well now. I can jet it rich enough to shoot out big fire balls, and 
lean enough to run cool on a very hot day. In between those extremes is what I 
am shooting for best power. Or 1575 to 1600 EGT. Some racers look for 1650 to 
1700. But with steel apex seals, they are knocking on the door to disaster and 
hoping nobody answers.
The carbon seals are more forgiving, and the ceramic seals don't seem to mind 
anything.  
>  
But as usual, I run on.

Lynn E. Hanover