Can anyone give an informed opinion about injector diffusers? I'm talking about the little plastic inserts that go in the injector holes- the injectors spray fuel on and through them. Are they necessary for our application? Why does Mazda(and presumably other manufactures) have them? Is it for better fuel atomization at low  airflow rates? It seems that they  add a bit of restriction to the airflow in the manifold, and might be unnecessary in our application, if, as Paul says " all the fuel eventually ends up in the combustion chamber".

Anyone?
Brian Trubee

Well atomization as they call it is very important. Recent automotive industry
test indicates that improved BSFC can be had by increasing the EFI fuel
pressure. The drawback is the injectors wear out faster as I recall.

If the injectors are right near the rotor housing there is precious
little time for this atomization to happen. The inserts cannot hurt
if used on the other end of the intake tube and I don't think they
hurt where they are now. I suspect they help the BSFC or Mazda would
not use them. They were mentioned and briefly discussed in SAE paper
841017 Recent Tech.... which should be on Todd Carricos site for
downloading.

www.thecarricos.com/ACRE/

The effect may be less pronounced on the RX8 as raw fuel is recycled.
Paul Lamar

Could you clarify that statement Paul?
Royce

Sure. The RX8 uses side exhaust ports so the raw fuel is not swept
out the exhaust port by the apex seal but is trapped along the rotor
housings. This is the main reason the fuel consumption is better.

This is a bit fuzzy but it is from SAE 950454 which should be on
Todd's download site. Todd, if this paper is not there let me know
and I will send the pdf.

Paul Lamar
 
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