fuel evaporation & injectors

[Robert Harris]

One very simple thing to make life very easy.  If you can the piss dribble 
injector stream directly onto the intake valve, such as by locating the nozzle 
in the valve pocket, then you have magic.  It seems like the back side of the 
valve averages about 600 F or more depending on load.   This should totally 
vaporize and keep vaporized the fuel.

BTW, on a properly cammed engine, there is very little or no exhaust 
"reversion".  It's a Mass velocity not wanting to change direction thing.  Plus 
properly tuned exhaust's create a vacuum at intake opening and can actually 
over-scavenge the engine, drawing fresh fuel/air mix into the exhaust.

Honda, and Cosworth on turbo racing engines place injectors into INLET of 
supercharger to maximize mechanical carboration of the fuel and take maximum 
advantage of the latent heat of evaporation.  (Yes - even with an aftercooler)

See Bruce Hamiltons Exhaustive Gasoline FAQ for discussion of Honda's fuel and 
air heating scheme.

If the first ingredient ain't Habanero, then the rest don't matter.
Other Obsessions: Ferro-Equinary , 1972 "Killer Whale" Mustang
Currently Interred in the Peoples Democratic Republic of California - Stalag 
Montclair
Puck da guns - ban Politicians!!!!!
Robert Harris <bob at bobthecomputerguy.com>


-----Original Message-----
From:	Chris Conlon [SMTP:synchris at ricochet.net]
Sent:	Thursday, January 08, 1998 8:56 PM
To:	diy_efi at efi332.eng.ohio-state.edu
Subject:	fuel evaporation & injectors

Gary wrote:

> With non sequential port fuel injection, fuel puddles behind the intake
> valve.  When the valve opens, residual exhaust blows it upstream causing
> good vaporization.  Other things to try are heating the intake air and
> heating the fuel.  I believe Honda's last turbocharged Formula 1 engine
> heated the fuel to 70 degrees C.  Gasoline has an end point around 300
> degrees.  If you heat it to 150 or so, much of it will vaporize as it comes
> out of the injectors.  Heat it to 300 and you can be injecting vapor.  Under
> pressure in the fuel rail it would be liquid.  As it flowed past the
> injectors, it would flash into vapor.

Apart from the danger, & probably fried injectors, it sounds like fun!  ;)
If I get my own cone shaped hat, can I try it???  **j/k!!**

This reminds me, what's the deal with Mitsubishi's GDI (gasoline direct
injection?) engines?  Is this a diesel type setup? I can't get anything but
Mitsu's hype about more power, less emissions, more mileage.

I did talk to RC Engineering, thanks all for the suggestion. They did agree
that fuel evaporation is often incomplete, but didn't seem to see this as a
problem. (Obviously FI *does* work.)  I plan to satisfy my tweak compulsion by
putting my additional injectors either in the throttle body or just after
the supercharger, and picking very fine spray units. Good enuff I guess.

Plus I may put a temperature sensor on the fuel rail; perhaps part of the 
design
is that the rail itself will get pretty warm. If so, that's kinda elegant.

   Chris C.