BUNDERA/LJ70 (2LT) maximum boost + pump tips

[Monox]

Hello I'm new on this good forum, I have a LJ70/Bundera since 2 months and I have liftet and fixed it thanks to this board informations too. Ilive in the far Italy.

Now I run about @ 0,8 bar OR 12 PSI
If i increase pressure, I am sure the fuel pump cuts fuel on 0,9/1 bar or 13/14 PSI.
I read somewhere the Denso pump is made to cut fuel over a certaijn pressure.
Example : @ 12 PSI i can run up to 4.000 rpm but on 14 PSI i cannot go over 3.200 rpm because of fuel cut (on full throttle). In 1st gear the sudden rpm increase lets me go to 3.800 for a second (this means - I think - the pump sensor is not fast enough to act and cut) but in 2nd gear and over... engine sleeps.
I have no ECU or electronic as the car is 1986 model.


QUESTION :
doES anyone know how to trick the pump ? I want to run @ 18 PSI (not continuosly ! I have installed a boost regulator)
and
does anyone know the maximum pressure for the CT20 turbocharger of 2LT engine ??

[hdj105]

I take it you have a rotary injection pump fitted with a boost compensator (BC) or aneroid?

You need to take the BC lid off, remove the diaphram and pin, and either do some careful measuring and add spacer(s) to limit the stroke the pin travels (to prevent it going into overboost), or put more spring preload on the diaphram so at 18 psi it only travels to the full fuel position, and turn up your main fuel screw.

Either way, it may mean removing the pump depending on how much room you have.

[Monox]

Yes I have a BC on it... I was wondering the "problem" is there but now I am sure, thanks 4 reply
Maybe i could "trick" the pressure hose going to BS same way we trick the wastegate using a T and a pressure relief valve.... uhm...i'll work on it and will loose some sleep LOL