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Re: [T3] Injector interchangability?

Well let's see if Understand this , the PS only cares about 
vacume or what we call absolute manifold pressure ,
in Idle the vacume may be at 15 for example then at acceleration 
it is at 4 lets say , well this vacume energy
sucks into the Pressure sensor which moves the bellows and 
electrical accordingly inside . at constant velocity the engine may have a 
vacume of 14 on flat ground and 9 on hills or load, the lower 
the vacume the closer to resting position the P.S. 
guts are when engine turned off , the more load, the less 
vacume going to the P.S. the more voltage (?) sent to the brain to 
tell it more fuel  by lenghtening  injection time (tiney 
fractions of seconds more .  When engine is hard accellerating the 
vacume drops and sensor goes more towards resting position 
and this P.S. position tells the brain keep the fuel comming 
some more ,by even longer injection times. , to me that is 
basically what the pressure sensor does and does not 
care about anything else except for vacume. 

If the manifold throat is the same a s the 1600 and you increased 
the engine gigataically like 2500 then more 
aire will flow throught the same throat and the the vacume will 
always be higher at all velocities because now
more air is going through the same size hole engine varied but the 
hole did not  , that is why differsnt 
vacume sensor type for different cars exist , volvo may have different 
vacume charchteristics in their manifold where the 
hose is located as well as porshe , Mercedes,Jaguar , Saab etc... That 
is why you must mess with the P.S. adjustment for this , the 
objective is to make it stiffer for the bigger engine that sucks stronger 
through the same whole , you do not want the 
engine to be always a super high vacume at all times then your engine will 
always be leaner and will not work properly ,
this system has it's limitations , the injector points at high speeds will 
float and limit the fuel switching at the injectors,

 the points are the injector's on off switches , everything else is 
the injection time lengthening circuit,  for big engines bigger 
injectors may be used to compensate for the limitations of the amout of 
injection time that can be maxed out by the sensor that is properly setup .
Increase in fuel pressure can compensate for some of this also but 
will place more load on pump, hoses,injectors, resovoirs etc... 

What can be varied if the same manifold is used is the p.s. characteristics ,
injectors, pressure and size of manifold intake .

This is what I think :

1700 to 1900 P.S. external adjustment to make it richer .
1900 to 2200 in addition to above , bigger injectors , blue/green base
2200 and above , in addition to above , bigger runners, custom made manifolds.

Jim you are right , a really big engine may leave the P.S. maxed out and if it is a giant one 
with a stock EFI , the P.S. may be maxed out , even at moderate speeds.

More mods need to be made at every engine scale size. It will take patience and 
and determination and an air analyzer to do this right.

Well I know Djet is old but it is fun to work on , to keep it in , the engine will 
look stock and no real hacking will be needed. Other Efi system install will 
also need lots of external engine modifications and fabrication but if done right will 
outperform the djet system easily because they do not have efi points and have an
oxygen sensor . Reliablity of the system may be in question though with all 
fabricated systems , many heart aches can be created also when fabricated parts do not 
work as planned.


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