Thread: Low boost from new turbo install

Hi


Am having problemswith boost on a isuzu 4BD1T in my 6x6 pernetie.


Have fitted a MambaTD04 HL 19T with 6cm housing and 9 blade turbine


Exhauxt is 2.5” tomuffler & 2” from muffler back (yet to be upgraded)


At the moment cannotget more than 10 PSI of boost under load/full throttle


Testing to date:


Fitted boost gauge(in compressor outlet next to WG sense port)
Fitted exhaust pyroin manifold adapter prior to turbine.


Wound out max fuelscrew on side of pump, getting 750oC at full load @ 10PSI and blacksmoke when first accelerating.
found that donaldsonfilter service indicator was pulling in and removed airfilter inlethose that runs from under RH guard which stopped the serviceindicator pulling down.


Tried running withno ducting,filter on compressor housing – still only 10 PSI boost


Tried running withonly 2.5” dump pipe fitted – still only 10 PSI boost


Tested boost gaugewith mitey vac and tested up to 15 PSI boost ok


Inspected WG and isseating ok, fitted shop air and WG starts to open at 15 PSI


Removed exhaust pyroand fitted pressure gauge – 15 PSI exhaust pressure at 10 PSI boostpressure under load


Truck drives ok(havent been able to put a load on the back but unloaded going up thetest hill seams to pull ok) but thought I should be getting betterthen 10 PSI out of the turbo???

I've never confirmed for myself, but my understanding is that 15psi opening on a bench test will be opening at a lesser pressure in operation as there will be pressure in the exhaust manifold acting on the wastegate trying to push it open.
As a quick test you could try wiring the wastegate shut and see if it makes any difference. If it does it would suggest that its opening too early.

Vern's "wound the actuator rod in" might be the key....

Steve