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Tracy,
I must be missing a point somewhere, or we have
crossed wires, as I haven't mentioned the combustion chamber. My only concern is
high pressure fuel leak in flight. Don't get me wrong I like fuel injection
because of the control over injection volume and performance. I only wish there
was high pressure at the point of injection - only.
I have fuel injection on my Suzuki 1800 Motorbike
and it's great, but I would hate to have to work on it, like I did on the old
carbied bike.
I've noticed the Jabiru are running a very simple
system. Their using a Honda ignition module with an altitude compensating
carby - not that the system is perfect either.
George ( down under)
I think you are missing Ernest's point George. Note the
location of the injectors in the 16X. They are NOT in the combustion
chamber. Tracy
On Sat, Sep 6, 2008 at 2:16 AM, George Lendich <lendich@optusnet.com.au>
wrote:
Ernest,
Very
true mate, to me high pressure in a cowl is my concern - paint me
paranoid. If we could have low pressure injection I would be most
appreciative, but sadly the carby is 'old hat' now. The Bendix type systems
are about 30 psi - not too bad!
Are they really going to have ceramic
coatings on the side housings?
George ( down under)
George
Lendich wrote:
Jim,
The
biggest volume is at BDC- anything past this is compression, it's not
getting high until it goes past the inlet area; but it certainly is
quite high at the 12:00 O'clock position where the direct injection is
taking place.
Direct Injection has to be high to atomize the fuel
particles finely enough to get complete combustion. Of course it has to
be high to also counter the compression pressure at this
stage.
George ( down under)
But, George, "high" is a
relative term. We run our fuel system on the road anywhere from 30
to 60 psi. That 60 seems awfully high; but the natural gas in
the portable tank that I buy from the grocery store to fire by BBQ grill
comes with 300psi. That's what it takes to make natural gas a liquid
at room temperatures. And that crazy guy, T. Boon Pickens, is trying
to convince us Americans to run our cars on that same natural gas
(actually, many are doing it already). At a 10:1 compression ratio,
ambient pressure is driven to 147 psi. You still only need 60 above
that to get the good atomization. Yet, you can buy tanks from the
GROCERY STORE compressed to 300.
Granted, the BBQ grill doesn't get
the same sort of vibrations as a car (unless I've got the burgers REALLY
flying), but that is just a matter of engineering the connectors to handle
the stress. Simple engineering that has been done a gazillion times
before (see diesel engine). I'm not saying they don't have some
engineering and testing to do. I'm just saying that they're not
having to blaze new trails into unknown territory. This seems to me to be
very much a small evolutionary step, and not a major revolutionary
one.
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