SNIP
The key of course (more better we call it "detail
devil") is coming up with a way to bias fuel injected through each the two
injectors while maintaining the sum of the quantities injected at that needed
for proper combustion. That's one hell of a devil, but not nearly as
difficult as the original devising of a system that that figures out how much
fuel to inject and then delivers it. I would guess at this point that it
would be easier to adjust intake Temperature than intake Length. Tracy,
you listening??
Different folks desiring different flight regimes
would need runner lengths that bracketed the temps and rpm's they expected to
be operating at.
Just a theory ... Jim S.
Pretty cool theory, Jim. The stock
Mazda injectors for turbo engines have enough flow so either set could handle
max power for a NA engine. And the turbo guys don’t need DIE
anyway. Modeling an override to modulate pulse width to allocate fuel
shouldn’t be that tough if you know what the curve looks
like.
Al
Interesting problem
for sure. Since the EDDIE effect is mostly desired at higher
rpms (not much point having it at idle), the fuel flow will already be
relatively high. Latent heat of vaporization of that much fuel will
probably already have the temperature of the air near a low point -
maybe??. Pumping more fuel in might not necessarily result in lowering
temperatures if the air stream is already saturate with fuel vapor. I
don't know enough about how gasoline acts in such a situation, so that is just
a guess.
The basic bottom
line is that the engine will need a specific Air/Fuel ration to produce the
desired power. Anything that distrubs that ratio is likely to disturb
the power produced. Now, certainly the engine does not know or care how
that fuel quantity is delivered so long as it gets what it needs.
I can sort of see a
program that calculates the amount of fuel needed to lower the air mass flow X
degrees. I would think you would either need to know the ratio of fuel
needed to cool X CFM of air flow Y degrees or would need to have a
temperature sensor and then adjust the fuel flow to get the temp
desired. Then so long as that amount of fuel injected by the upstream
"Temp Control Injectors" does not exceed what the engine needs overall for the
desired Air/Fuel ratio, then the down stream injectors could be modulated to
make up any difference.
However, if the
amount of upstream fuel needed to get the desired air temperature exceeds that
required for the desired air/fuel ratio for engine power, then I see a
problem. It looks like someone is going to have to put some number to
the problem to see what it really looks like.
I found the latent
heat of vaporization for gasoline and while there are some variations
(probably dependining on the exact formulation of the gasoline), it looks like
117 Btu/lb or 900 Btu/Gallon are a rough average.
I know 6.5
lbs/gallon * 117 BTU/LB only = 760 Btu/gallon so
there is some inconsistency.
But in any case,
here are some preliminary numbers. Assuming 5500 rpm and A/F of 13
producing 161 HP with an inlet temperature of 90F, it appears that if all the
fuel injected and evaporated before reaching the combustion chamber, it
would lower the inlet temperature by 36F down to 54F.
It would seem that regardless of
where the fuel is injected, if it all vaporizes (which you
want it to in order for it to burn in the combustion chamber), then the
air temp is lowered by 36F (in this example - assuming my calcuations are
correct). So, I am not certain how much we could materially affect the
cooling and still maintain the desired Air/Fuel ratio. It seems that if
the net total of fuel is that needed for the desired air/fuel ratio, then it
must all vaporize (in order to burn) and if it does that then regardless of
where it does it, it would seem to lower the accompanying air by 36F.
Now, since the
velocity of the pulse is dependent on the average air temp in the manifold,
there might be something said for using fuel to get the desired temp drop
early on (immediately after the air enters the throttle body) and then delay
injection of the fuel need to achieve the desired air/fuel ratio until
the last instance (say the primary block injection ports), then the
average velocity of the pulse would likely to be more impacted by the
long average lower air temperature for most of the runner length before that
last bit of fuel is injected. Clearly lots of things to
consider.
So some other folks
need to run some numbers and see what they get.
At 5500 rpm
assuming WOT the airflow for the two rotor would be around 255CFM which works
out to around 19.51 Lbs of air/minute. For a air/fuel ratio of 13, that
give 1.50 lbs of fuel/minute. I used the
Te = Ti
+Q/W*cp where Q is the latent heat of vaporation BTU removed (per pound
of fuel)from the air flow (W air in lbs/second), Cp = 0.25 for air.
I used 90F for Ti and calculated 54F for Te. So some of you who
understand this much better than I, jump in with your
calculations
I think I will
leave this approach to others, while really elegant (if the theory holds to
gether), I am going to try the more direct but simple, brute force approach
and vary the lenght of the runners.
Ed
Anderson