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Ed,
Assuming that most turbo users are limiting boost to 8-10 lbs maximum,
that would be a pretty high fuel pressure.
Assuming 8 lbs of boost @ 12 psi fuel pressure increase per lb of boost,
that would be an increase of 96 lbs (8*12), on top of a static (0) fuel pressure
of 38 lbs, that would be a whopping 134 lbs of fuel pressure if I
understand your message correctly. That seems pretty high, and I
don't know that the injector seal would hold up to that.
I'm
using the Aeromotive regulator, since I had trouble with the Mallory. It,
as you stated is a 1:1 ratio of adjustment. I don't have a panel mounted
fuel pressure gauge, but I do have a sender installed which I can attach an
analog gauge to for testing, and also for the day I put in an EM-2. With a
38 lb static fuel pressure, the fuel pressure at an idle was down to about 20
lbs. It did go up with boost, but being on the ground, it was hard to get
an exact reading on the gauge. It responds kind of slow, and I was also
watching where I was going, more so than watching the gauge. It did look
like about 40 something lbs at a 5 lb boost setting.
I'm
still running rich at low RPM's, but in flight, the mixtures are
good.
Steve
Brooks
Here is some food for thought for you turbo
folks. Most of the pressure referenced fuel regulators regulate the fuel
rail pressure on a 1:1 ratio with the manifold pressure change. In other
words if the manifold pressure changes 1psi (2" HG) the fuel pressure changes
1 psi. This increase does of course increase the rate at which the fuel
will flow through the injector. However, the flow rate changes on the
order of the square root of the pressure increase (as best I
recall). This means if you double your fuel pressure you Do NOT double
your fuel flow.
With higher boost pressures the preferred
regulation ratio is like 12:1 or 12 psi for each psi of manifold
pressure. Not certain that for the lower boost levels being used in
aircraft whether this is really significant - but, just though I
would pass this on in case anyone wants to investigate it further or
comment.
BLOX FMUs
The
Blox fuel management unit is designed to increase the fuel pressure as the
pressure in the intake manifold increases. The Blox FMU is a universally
design product with a 12:1 fixed ratio. The FMU is used on fuel injected
vehicles, either supercharged or turbocharged, using the factory electronic
engine management system. Blox FMU's are available in blue, red, gold and gun
metal
Ed
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