Why is that the case? the optimax injects directly into the cylinder ?
And why does it make it more reliable?

P.S.

one of my theories about ETec vs 4stroke vs optimax is that the Etec
seems to be using slightly (5-15%) gas. Which may be because of its
"nosed" piston which helps efficiency at low rpm but not at high rpm.

Lets not even go into the BRP claims it is more efficient .. which are
measured at idle speed and true... But also at that rpm and fuel use
even 50% more would be irrelelvant.



Matt

Sorry Matt I missed this one.

The Optimaxes are not true DFI (as in, Direct into the combustion
chamber Fuel Injection);

(i) they have a second inlet manifold between the air pump & a large
electronic fuel/air mixture injector (inlet valve).

(ii) The "fuel" is actually injected into this second inlet manifold.
with "normal" fuel injectors from a pretty much normal fuel rail
(slightly higher fuel rail pressure).

(iii) The fuel is therefore better atomised not much different from
normal 4 strokes fuel fuel injection & the same as a 4 stroke's
injection the fuel can get further atomised in a mostly hot (compressed
air) manifold before

(iv) an inlet valve opens & allows the fuel air mixture to flow into the
combustion chamber.

The reasons Optimaxes were better but still unsuccessful as OB engines,
were;

(v) the fuel was better atomised & a better mixture was allowed into the
chamber (though still way too lean), also

(vi) the injectors themselves were not subjected to the rigors of the
combustion chamber although the electronic inlet valve (air fuel mixture
injector) was & just as with Ficht they contributed to the reliability
or lack thereof making them failures from a commercial sense.

If any confirmation were needed after OMC, that low pressure DFI using
lean mixtures up into the mid power range doesn't work, take a look at
the Optimaxes & Ficht type systems. They could not be more different in
their execution of basically the same idea, extremely lean mixtures at
low revs fired directly around the spark plug even just to get ignition
(in ficht like systems they even have to just leave the plug
firing!!:-)) Yet they both suffered way too high failure rates for
consumer usage, gee they'd be too unreliable even as specialty race engines.

K