According to Garret specs the wastegate is set at 12psi.
From what I've seen with a hand pump & gauge, the wastegate opens half way at 10psi and full way at 20psi.
Perhaps this thing would run at 12psi if I had like a 2.25" exhaust restrictor or something which could be one way to do it?
Looking down the inlet hole the wall by the wastegate tappers inwards thus directing the flow away from the wastegate and towards the turbine.
What I had done was the wastegate hole was overbored by 3mm, making the wastegate hole approx 1.5mm smaller diameter than the door itself. A path was also ground out in that inner tapper so that some flow is directed towards the wastegate. In addition to all this, the bracket that connects the actuator arm to the wastegate itself was modified (welded and redrilled) to bring the arm closer to the pivot point, thus allowing the wastegate door to open closer to 90 degrees instead of just a mere 45 degrees at full opening.
Now on wastegate pressure it seems to hold 0.9 bars, and 1.0 with my boost controller dialed into 1 bar - in all gears which is good.
The downside is I've lost ALOT of low end response, I'm hoping this can be remedied with a better EBC than what I have (HKS EVC 1) otherwise I think I've ruined was already a very perfect T28 housing (when paired to a factory size exhaust).
When I am able to tune this thing, and with that standard T28 housing rapid responsiveness boosting to 20psi on the tip of the pedal, I think I will get a fresh T28 housing to start over with again.
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Other minor updates:
Installed a stock black speedo surround as I was getting sick of the one I painted aluminum colour.
Replaced heater valve with item from 3s-fe Celica, as mine was brittle and chipped from running hot (probably should have bought new but this one seemed to be in good condition and still black and solid)
Run Bar's Radiator flush & rust remover then separately blasted out engine, radiator, turbo coolant lines, heater core and refilled with fresh Toyota LL coolant. (This fixed the heater just in time for winter
)
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Still to fix:
Started having some weird electrical issues since the turbo setup and battery relocation, like headlights getting brighter when throttle applied, sometimes the starter motor when I turn the key does nothing.
Voltage test shows 12.5v when ign off and 13.4v when running at idle (which is what it should be right?)
I think I already know the culprits, I've had these issues on a previous battery relocation and solved it by running a separate ground from battery to engine in addition to grounding in the boot. - That and I had soldered every joint except the main power wire to the fuse box (the smaller wire) which I had used an audio crimp on, so I will solder this joint too.
Need a better EBC to dial my boost in better, one that controls the wastegate opening threshold too
Lots of bodywork repairs needed
Needs an oval muffler for the rear as it's way too loud.
This post has been edited by delusionz: May 27, 2011 - 7:17 AM
