[Supras] 57 trim CT26 alteration

[Jeff Mohler]

What advantage does this offer..if you dont have boost creep, then
opening up the boost release (wastegate) isnt..adding anything.

Is it?

On Dec 10, 2007 5:11 PM, berniek at technicaldevelop.com
<berniek at technicaldevelop.com> wrote:
>  From what I understand, the customary way to allow more exhaust flow
> through a CT26 is to clip the turbine wheel.  I discussed this with
> Performance Techniques when I had one modified for 57 trim.  To cut to
> the chase, I decided on boring out the wastegate passage instead, as the
> cross sectional area can almost be doubled while still leaving at least
> .080" at the circumference for sealing by the disk.  The area is still
> far less than the area of the diaphragm in the actuator, so cracking
> open early from disk force did not appear as if it would be a problem.
>
>
> Waste gate passage boring is one aspect of the modifications I forgot to
> mention in previous postings about mods.  The 15-17 PSI boost comes on
> explosively at 3000 RPM and it pulls strongly to redline with stock cams
> and a cleaned up head (valve bowls and intake passages cleaned up with a
> die grinder and carbine burr) with the other mods.  Caught it once at
> 6500 RPM at the top of second gear, it was so quick.  Maybe the former
> owner installed an earlier ECU (from before full crankshaft
> counterweighting), also indicated by idle speedup when turning lights on
> (90-up does not have the circuit board parts stuffed for that
> function).  Just curious if anyone else has done waste gate boring.
>
>
>     Bernie
>
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