Outer Limits 4x4 Board

A friend has just bought a navara d40 and he has fitted a tuning box to increase the fuel rail pressure . He has placed the car on a dyno and the device definately improves performance and you can map the increase in fuel pressure. Unfortunately at just over 3 grand the car experiences boost cut and the fuel increase is far from maxed out .

I know that in some cars it can be a matter of adjusting the wastegate actuator rod , or even fitting mig welding tips into the vacumn line of the wastegate , but as I am totally unfamiliar with this model can anyone offer advice as how to go about upping the boost .

afaik the boost is fully computer controlled. you may need to fit a boost cut defeater and use a seperate boost controller. i'm not sure if anyone has a tuning box for these yet.

i assume they have fitted an EGT gauge and boost gauge as these motors are pushed to the limits.

i would start by fitting a better intercooling setup to help keep the EGT down.

The D40 is pushed pretty hard already - I wouldn't be surprised if the fuel pressure mod has pushed it over...

Ok I think we may have been wrong in thinking the boost was cutting off . After a bit more discussion it appears as if the device fitted is connected to the fuel rail pressure switch and may act as some sort of resistor to doctor the voltage readings being sent back to the ECU . Trouble is that out of settings from 1-10 we can only get this to run on setting 2 , higher settings give better performance but they are triggering the fuel pressure switch earlier at lower revs and cutting the fuel supply .

So is it as simple as adding a resistor to the return from the fuel pressure switch (as I suspect this unit is allready doing) to enable a higher fuel pressure to be run (whilst sending a reduced voltage signal back), and what might be the consequences down low say at idle . I know it may be trial and error but has anyone played with this?? .

Was thinking of getting a Pot so we can adjust the resistance to a desired level and then see what effect it is having through the rev range down to idle?? .

How u going with this?

what EGT gauge are u using and where did u get it from?

Been away for a few days Mick and have not progressed far at all really . Was hoping for some technical feedback from this site before we went in too hard .

PATROLSNIFFER wrote:Been away for a few days Mick and have not progressed far at all really . Was hoping for some technical feedback from this site before we went in too hard .

Well keep us posted i am interested if u can get any more power out of the D40 without blowing it up. FYI the oil pick up is tiny so maybe that should have a mod made to it to keep the juices flowing

Mick

mickrangie wrote: Well keep us posted i am interested if u can get any more power out of the D40 without blowing it up. FYI the oil pick up is tiny so maybe that should have a mod made to it to keep the juices flowing
Mick

If it has a roller bearing turbo then the oil supply size is surprisingly small.
In Zoom magazine a few issues ago the diameter oil feed they needed for their roller bearing turbo ended up between 1.0mm and 1.2mm to get the required flow rate. There are commercially available restrictors to limit oil supply for turbo's both roller bearing and bush bearing types.
An oversupply of oil to the turbo will push oil past the seals into the compressor housing.
Regards Andrew.

awill4x4 wrote:

mickrangie wrote: Well keep us posted i am interested if u can get any more power out of the D40 without blowing it up. FYI the oil pick up is tiny so maybe that should have a mod made to it to keep the juices flowing
Mick

If it has a roller bearing turbo then the oil supply size is surprisingly small.
In Zoom magazine a few issues ago the diameter oil feed they needed for their roller bearing turbo ended up between 1.0mm and 1.2mm to get the required flow rate. There are commercially available restrictors to limit oil supply for turbo's both roller bearing and bush bearing types.
An oversupply of oil to the turbo will push oil past the seals into the compressor housing.
Regards Andrew.

Ok i was talking about lubing the engine parts i.e cranks bearings etc not the turbo... its seriously small!!