increase boost on 12H-T engine?

xorph · Post by **xorph** » Sat May 05, 2007 4:22 pm

I have an old 4l turbo diesel cruiser and I installed a bleed valve on wastegate signal line to adjust boost.
This part works great- from in the cab you can adjust boost from std 8lb to 14lb watching pressure gauge. -cost about $30 from surplustronics and HCD.
Problem is it didnt do anything

because the factory boost compensator doesnt seem to move further than about 8psi...
somewhere there is a full load screw you can wind out but i dont know which one it is.
I wound out the 'full throttle stop screw' and all it did was make the auto shift later :shock:

so i wound it back. anyone have a picture of which screw to muck with? I also dont want to harm engine, anyone have any experience with these engines? Ive heard they are a Hino truck motor and will kill you before you kill it

krazynutta · Post by **krazynutta** » Sun Jul 08, 2007 9:44 pm

Hey you have probely figured this by now but the screw on the front of the pump its under a little screw on cover and is 6mm in screw size thats the fuel screw, wind it up and check the anaroid diafram the on with the vacume line going to it is not got a hole in it, be careful not to run round with to much boost and too little fuel could melt a piston!

xorph · Post by **xorph** » Mon Jul 09, 2007 7:33 am

cool cheers for that.
still havent got round to it, got carried away turbocharging my 1hz cruiser.
I found the fuel screw on that is also a 6mm hex screw.
think i might leave the old girl alone and concentrate on setting up new cruiser properly. goes bloody well, only running 6lbs but smokes the old one with 8lbs.
speaking of smoke.. might have some trouble getting warrant when smoke testing comes in cos it has no aneroid so before the huge turbine spools up it'll chug black soot if you are in fact an idiot and dont understand how to not use full snot off the line.
was going to get feuling set up by a specialist to avoid molten pistons but kind of no point if going to need to unwind screw every warrant.....
might start a new thread on that actually

smurf182 · Post by **smurf182** » Tue Jul 10, 2007 2:49 pm

krazynutta wrote:be careful not to run round with to much boost and too little fuel could melt a piston!

Incorrect. For a diesel:

too lean = cool/no power/no problems,
too rich = hot/lots of power/high EGTs/melted pistons

I recommend you install an EGT gauge if you're playing around with fueling.

xorph · Post by **xorph** » Tue Jul 10, 2007 3:15 pm

ahh, another person who agrees.
Thats what I suspected, so I was planning on running about 11psi but only adding extra fuel for about 7 or 8 psi. (easier said than done with no equipment)
only running 6 at mo, mucking around making an adjustable spring add on for the wastegate arm. Also thinking about legacy water to air intercooler to bring temps down a bit.
ill punt it round to a specialist before i kill it i think