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