Direct Injection

Robert Harris bob at bobthecomputerguy.com
Wed Apr 28 10:58:55 GMT 1999


Detrimental to power output - tell that to the Spitfire pilots that ate it big
time when they met the Direct Fuel Injected Me109's etc.  Tell that to the
drivers of other makes who ran up against Mercedes Direct Injected 300's in
the early fifties.  Bosch and Mercedes routinely used Direct Injection thru
the mid fifties.  Tis an old old idea laddies - and was making POWER long
before Orbital was a stain on daddies leg. Try like operational on German
aircraft engines in 1934.

Some day, when you have nothing to do, you might enlighten yourself about
mixtures.  Like try inverting fuel air mixtures i.e. holding fuel constant and
changing air and plotting air to fuel vs power.  You will find that the power
varies far more with the amount of fuel than with the amount of air.  Then you
will realize that max power is made with the fuel held equal in all cylinders
- the first major benefit.

Then - re-read about the Bosch System - which Horror of Horrors was a direct
adaption of Bosch Diesel systems and shared most parts.  Since they injected
the fuel after the intake valve was closed - well into the compression stroke
and these old krauts knew all about "atomization" and vaporization etc ad
nauseum, they did not screw around with puffs of air or whatever - but passed
go, collected their 200 dollars and went to aiming the fuel spray right onto
the face of the exhaust valve - instantaneous fuel evaporation in a CLOSED
cylinder and heavens to murgitoid, actually cooling the exhaust valve.

Silly stupid german engineers didn't read the DIY_EFI archives on how to get
optimum fuel atomization or care about it.  They got instant vaporization -
screw atomization, they cooled the exhaust valve so they could get even higher
power outputs and by cooling the HOTTEST spot in the cylinder, they were able
to raise the compression ratio at least 2 whole ratios on the same octane
fuel.  With total vaporization, they were able to get incredible throttle
response, power and performance. 

But silly us didn't realize that all they wanted to do was stratify the
charge, get milage by sacrificing performance, and have poorer mixture's than
port injection.  Great Nazi propaganda apparatus must have covered this up
along with those stupid engineers at Bosch who forget to put the port injector
on the Messerschmits and Mercedes for high power usage.

Further for the record, Bosch developed the timed port fuel injection as a
CHEAP almost as good replacement for the Direct Mechanical Injection and then
went on to develop the K "CIS" system as a more efficient implementation of
Fuel injection than the timed port injection and was only forced backwards
because of air pollution constraints - not power not economy - just smog
nazies.

If you want Direct Injection without waiting for someone to get around to
re-inventing the wheel, you can directly adapt an automotive/light truck
diesel unit by running a little 100 to 1 synthetic 2 cycle oil with your
gasoline.

Of course, then you would have to come over to the dark side and use air
control instead of fuel control because the high pressure ~1800 PSI side
doesn't let you do much.  But then why bother - we all know that fuel shot
thru a diffuser nozzle at 1800 psi is not going to be well atomized without a
puff of air or be as good as piss dribbles into the intake runner timed to
whizz into the cylinder when the valve is open.

1963 Ford C-600 Prison Bus Conversion "Home"
1971 Lincoln Continental 460 "Christine"
1972 "Whale" Mustang awaiting transplant
1978 Dodge Long Bed Peeek Up "Bundymobile"

Habaneros - not just for breakfast anymore



More information about the Diy_efi mailing list