Tracy,

 

I have no filters on the inlet side of the pumps. Early on I had one filter at the outlet of each tank but they were removed after a few flight hours. They were the same GM style filters that may use on the high pressure side of our fuel systems. Never any indication of fuel flow problems but no pressure drop data was available from the manufacture. I was experiencing fuel pressure not tracking manifold pressure on a one to one basis. It would go higher under boost but sometimes not come down as expected. I removed the filters at the suggestion of Aeromotive tech support. I still have the condition and need to try a different regulator. I have one large filter at the firewall and it always looks clean.  I’m confident my power failure was not fuel “filter” related and I don’t think it was vapor lock.   But I’m also not 100% sure it was the Hushpower muffler. I moved throttle several time through its entire range with no improvements. Sitting on the taxiway after landing the engine would not make power. A few minutes later when restarted it made full power. I did call Ed Klepis the day after the FAA inspected the plane and suggested they check the muffler. No feedback so far.

 

Just for fun play the attached file in Google Earth. My poor piloting skill are evident as I let a stiff wind blow me off center line just after rotation. However tracking the centerline on landing was not an issue even with the tail wind. As Ed says “emergency’s have a way of focusing your mind.”

 

Bobby

 

 

<if there is not a method to bleed down the rail the risk of vapor lock exists

 

So you are saying every car built since 1990 has this "vapor lock" problem? We would see thousands of cars unable to start at every desert truck stop. This concern for fuel rail is a myth.

 

Vapor lock is not a myth. It occurs at the fuel pump inlet. Very important to minimize pressure drop there. You can actually measure how far your design is from vapor lock. You don't have to guess.

 

The bleed helps if you totally blew the plumbing from tank to fuel pump. But much better to fix that plumbing error.  

 

 

-al wick

----- Original Message -----

From: Dave

To: Rotary motors in aircraft

Sent: Tuesday, August 30, 2011 9:14 PM

Subject: [FlyRotary] Re: CG Products Intake Manifold

 

HOWEVER..... if there is not a method to bleed down the rail the risk of vapor lock exists, as the rail heats, the fuel boils, and the vapor gets trapped in the line.

If you DO put the regulator upstream of the rail, its imperative to be able to be able to flow fuel past the injectors and to a return line to avoid any possibility of vapor lock. The easiest way is simply to put the regulator downstream of the rail and injectors, but again.. this arrangement is more about preventing vapor lock, not ensuring adequate pressure.

Chris and I were forced into the upstream approach by the Mistral fuel rail configuration, and I didn't want to mess with drilling out the pinhole and then running a regulator downstream - Mistral was hard enough to get the intake from, and we didn't expect getting a replacement part if we had an OOOPS would have been easy. As others have now found out, Mistral isn't selling parts.

So... anyways.. just wanted to clarify previous post.  1) can regulate pressure anywhere in the fuel circuit between pumps and injectors. 2) Must provide for mechanism to flow fuel past injectors to prevent vapor lock.

Dave

On 8/30/2011 11:06 PM, Dave wrote:

No... at the flows and pressures we are using (and barring any major obstructions between the regulator and the injectors), the regulator can be anywhere in the circuit and adequately regulate the pressure.

On Chris Barber's install, I purchased the Mistral intake for use on his engine. The fuel rail was a dead end tube with a pinhole on the end. Presumably the pinhole was to prevent vapor lock in the fuel rail. The regulator HAD to be upstream of the injectors when using the intake. We had stable fuel pressures and no problems getting fuel to the engine.

We had return lines from the pinhole end of the rail, as well as from the pressure regulator, that fed back to the sump tank. Since there were not check valves running from the wings to the sump, there was no chance of pressurizing the sump.

Dave

On 8/30/2011 10:30 PM, CozyGirrrl@aol.com wrote:

Ed, I must have mispoke to give this impression, I thought the pressure reg HAD TO be last in line to maintain pressure in the fuel rail?

 

 

Chrissi & Randi
www.CozyGirrrl.com
CG Products, Custom Aircraft Hardware
Chairwomen, Sun-N-Fun Engine Workshop

 

In a message dated 8/30/2011 10:13:53 P.M. Central Daylight Time, eanderson@carolina.rr.com writes:

  If the pressure regulator is place before the injectors then there is less fresh fuel flowing through the rails.