CT12a wastegate actuator on my CT26; installed

flubyux2

Madd Tyte JDM yo ®
Apr 2, 2005
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st. pete, fl
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since the brakes on my car were acting up, its been parked for a while. i decided to get off my ass and pull the turbo off to fix my pre- and post-turbine exhaust leaks as well as port out my WG hole to alleviate my boost creep issues. i wanted to be able to reliably control my boost level so i can run 16 psi or so on my stock CT but that proved to be nearly impossible with the stock 8psi actuator and my bleeder valve; chalk it up to the crappy bleeder, small WB hole, shimmed actuator, exhaust leaks, lots of top end porting, idk...

i figured if i could start out w/ a WG that was intially of a higher spring pressure, i could more easily increase the boost levels. i got to thinking what i had laying around. i found an adjustable gate from my roomies old FP3052. that tested out to require 23psi before it opened! no way thatll work. then i remembered i had an old, working set of 1jz twins; 14psi stock! that will get me right in the range i want... now how do i put it on the `26? a little unbolting and a lot of cutting and grinding!

i started off by unbolting the stock `26 actuator. i used pliers to get the E-clip off the flapper arm. (i tackled the WG port-job here) an hour later, i began to eyeball the `12 and `26 gates. i lined them up and the large tab that they diaphragms are welded to appear to be the same shape and radius. however, the actual WG diaphragms are way diff sizes. the `26 unit is much larger compared to the `12 unit.

in order to separate the `26 actuator from its mounting flange, i had to grind thru the spot welds around the outer diameter of its base. then on the flip-side/bottom of the flange (mating surface to the turbo) i had to drill out about 4 spot welds. once the majority of its metallurgical matery was disabled, i persuaded it from its mounts with a hammer and screwdriver driven between the diaphragm and mounting flange.

the thru-hole of the mounting flange is too small for the base of the `12 diaphragm to fit inside and allow adequate mounting depth. i used my carbide burr and die grinder to enlarge this diaphragm base hole to accept the base of the `12 housing. (NOTE: i didnt bother to remove the `12 diaphragm from its original mounting flange. the shape and contour of the `12 flange is oriented in such a way taht it will nestle right over edge of the `26 flange if the actuator hole has enough clearance.) once the `26 actuator base hole in the flange is clearanced enough to accept the `12 actuator base, it sits perfectly on top of the modified mounting flange. at this point, i placed several factory-style tack welds to join the "scab" flange of the `12 to the recieving `26 flange to make it one unit. like this, the combination will physically bolt to the CT26 compressor housing.

at this point, the WG actuator rod has to be addressed. since i was already past the point of no return by cutting up BOTH actuator assemblies, i didnt worry the least bit by cutting the actuator rod from the dead `26 WG. i mounted the amputated `26 actuator rod on the WG flapper arm and clipped it in. with the hybrid `12-`26 actuator bolted to the turbo and the `12 actuator rod still intact, i simply aligned the amputated rod with the fixed rod, measured appropriately and cut. one thing i had to keep in mind was that it couldnt just be measured and cut to length. i had to account for the pre-load that the WG actuator has to apply to the flapper when in its final mounting position. so from the zero-cut mark, i subtracted about 2mm-3mm of length. then i removed the `26 rod from the flapper and aligned between the end of the `12 rod and the mounting lug of the WG flapper and tacked them together. once the rods were temporarily joined, i double checked its alignment and ensured it was 2mm-3mm short of reaching the WG flapper lug. here, i unbolted the `12-26 actuator and fully welded the rods together.

final mounting of the `12-26 actuator assembly was identical to mounting the stocker, including applying pre-load tension to the WG flapper by pulling the actuator to mount on the turbo. from this point, i can always re-shim the WG actuator flange or bleed off boost pressure... but here is my final product

DSCN1418.JPG


cant wait to get this thing back on and try it out... just need to decide if i want to rifle thru a bunch of left-over gaskets, make my own or order a turbo drain gasket to put this back on.
 

flubyux2

Madd Tyte JDM yo ®
Apr 2, 2005
1,019
0
0
43
st. pete, fl
www.myspace.com
i mash the throttle all the time. my car was set to 17psi on this before i took it apart. the only catch was, it wouldnt hold 17psi; it fell off to 13psi every time at about 4500. between 2500 and 4500 was strong though. also, this turbo is unusually tight; extremely low mileage. unfortunately, my car is only tuned for about 16psi before fuel cut on the stock 440's so thats about all ill be running untill i switch out injectors and retune it... whenever that may be. im not too worried about killing the turbo; im just waiting for it to fail on me so i have a reason to go bigger :)