DeTomaso Mailing List: June 99, Message #171

when pepole talks aboth EFI they seems to talk aboth any system that
do not use a floater to regulate the gas...

there are several diffrent types of injetion systems and tequnices
used, here is a simple list that i know of... (may not be 100% ac. )

mechanical injection:
TBI
using a "regular" carb setup (TB = trottlebody) and else using the
same tecniq as regular carbs, using a simple neadle controled by
vackume and the trottle level.
Used in a lot of older cars (70-80's) as "injection" and in some newer
also, even works with a cat.conv and is cheaper then a regular carb to
make...


DTBI
Found on older streetrods (was in demand in the 50's? 60's?)
a v8 would have 8 trottlebodys and 8 injectors using NO intakemanifold
as it is not needed,
this has been claimed as a bad solution and dont work by many that
have used it...
as it is relly impossible to setup unless you have all the right tools
and know how.
As this system to my knowlige has the lowest flow restriction i have
ever seen it should work like magik on big brethers like M426hemi, it
do not work with turbos or compressors (that i have seen)
there is NO delay when you hit the pedal ! it's a neck breaker for
reel... 100% mecanical !
but it uses a lot of hegt on the engine as it is tuned! (looks like
the formel 1 cars but bigger)
This out peforms any carb i have seen, and is also unaffected by any G
forces !!!
And it looks so CoooL !

Electrical injection:
TBI
using a "regular" carb setup (trottlebody) and else using the same
tecniq as regular carbs, using a simple neadle controled by vackume
and the trottle level (secundarys).
and electrical injectors on the primary (mostly)
Used in a lot of older (80's) cars as "injection" and in some newer
also, even works with a cat.conv and is cheaper then a regular carb to
make...
This is the typ pepole often say "gives no power on full trottle".
why? often the injectors are to small ! especially if some one puts
3,5" headers on it... also the kickdown is so "untrimmed" on these
that there is nearly no more fuel, it usally takes many seconds before
the secondarys kick in at all AND you will need good rpm's as it is
untrimmed (needs lots of vacume before anything hapends (yes the car
gets more air not air/fuel....)
that is also why they tends to feel sluggish, also the nice Cat.conv
helps....
Often also need a mechanical choke ! as the injectors cant handle the
extra fuel needed...
Old carbs works far better ! unless it is tweeked....

EFI
uses the setup found on most the cars with fuelinjection, pop the hood
in the corvette... there it is, no more carb + manifold setup, all in
one pice and a lot smaller to... right ?
even tho it looks diffrent the common type is EFI type in newer cars
as it is lower (no air filter on top of engine...)
How to trim the car? well check the size of the injectors, and the
size of the channels as the engines are often trimmed down to help the
exhust... there shuld be less restiction compared to a regular carb
and the blending is 100% so it aght to be faster right ?
also check the programming of the controller chip as it often also
controls the ignition point !

Clamed to be DEFI
Found on some of our beloved panteras :) one injector a cyl. often has
one or two TB
this is "The rail injection system" also common on race cars and other
high power engines
like cars with NOS, turbos and superchargers.
There are two types, preset ( like a carb, may have a simple sensor :)
and self setting with sensor.
first is mostly used in race engines...

This is the system i am using on my racer... that i have blown up the
engine once more on... the vacume retard was blowns by the turbo and
to early ignition as result and boom she went...  :( I even got dents
on the hood :)  I have melted the insides of it once... lucky for me
it is a small engine and simple to fix if i find the parts once
more...

REAL DEFI
Found on some cars, slightly uncommon yet. often used by diasel
engines
may have a single TB or multiple.
The system shuld also be able to set the individual gas/air for every
cylinder during running for to be what i call "true" DFI (also needs a
sensor for every cyl then....)

I know of a racing boy that used to be using it... he whent back to
rail.... :)
shuld work ok for fuel economy and low emissions perhaps.... else ?

I belive mutsubishi claming to be using this "GDI" (havent looked at
it yet so cant tell how true it is... or if it is some type of rail
system also)


/Gunnar
my views only so... injoy!