injector resistance

[Robert Harris]

If it ain't vapour it ain't agonna burn.  Period.  See laws of physics - 
combustion section.

Ideally, for maximum power, fuel "droplets" will enter the cylinder under their 
boiling temp, having absorbed the maximum heat from the mixture possible 
(thereby making it as dense as possible), and will then completely vaporize 
after the intake valve closes and prior to ignition.  The rising cylinder 
temperature aids this process - but the rising pressure raises the boiling 
point and hinders it.

Now, if you are not at full power, Wide open throttle - V E Schmee Eeee.  For 
maximum power, fuel/air mix is like teenage sex - quantity matters more than 
quality.   At less than WOT, the loss in VE incurred by external partial 
vaporization (boiling) of fuel is more than made up for by the increase in the 
quality of the mixture.  Two basic ways to increase the quality of the mixture. 
 Add heat to the mixture such as in exhaust crossovers or pre-heating the fuel, 
and add turbulence (carboration) such as swirl ports etc.  The trick is to 
greatly improve the part throttle without hosing the full throttle ( this has 
been left to the class as an exercise for the last 100 years ).

BTW the reason Honda chose 70 degrees C is not particularly magic.  It's 
because that's the temp that results from pre-heating the fuel with the engine 
coolant.  This, coupled with raising the intake air temp gave them bettor 
mileage and response.  Vee Eee Scmee Eeee - with you have a turbo to shove the 
air in, the small difference in VE this results in was swamped by the turbo, 
and the mileage increase gave them a competitive advantage (pit stops yu know).

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:	Michael Baxter [SMTP:MBaxter at compuserve.com]
Sent:	Sunday, January 11, 1998 11:57 PM
To:	Blind.Copy.Receiver at compuserve.com
Subject:	Re: injector resistance

"Gary Derian" <gderian at cybergate.net> writes:

>> 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.
<<

Hmmm..I wouldn't think you would want the fuel to vaporize if it can
be helped? Vapor takes up many, many more times more volume than fuel
in micro-droplet form and will reduce the VE.

There's a local injector guru here doing extensive research on injector
spray patterns and droplet sizes on a dyno and in a lab using lasers to
measure the the droplet size. When ever I drop-in for a visit, it's all I
hear. "Droplet size...droplet size...droplet size."


 -- Michael Baxter, MBaxter at Compuserve.com
 http://ourworld.compuserve.com/homepages/MBaxter
 From Reno, NV USA on 11-Jan-1998