[Supras] 57 trim CT26 alteration

[Rockey Fox]

There was some but not a huge difference in lag when I upgraded to 57 trim but that may have been offset some by the addition of the aluminum flywheel and one piece steel driveshaft install at the same time. The most noticeable difference to me was the strong pulling power all the way up to redline where I flattened out earlier on the stock trim. I forget how much was clipped on the exhaust side but it was clipped during the upgrade/rebuild.
Honestly even with my stock (3.73?) gear and 10psi boost I'm close to spinning tires launching aggressively in 1st gear and after that I never drop below the power band of the turbo when I'm accelerating hard through the gears. With the manual transmission I can just pick the gear that will place the rpm's in the proper range for the level of acceleration I'm looking for while cruising which seems to be the logical circumstance for lower rpm power from boost.

Rockey 91T
----- Original Message ----
From: Dan Gyoba <dgyoba at abstractconsulting.com>
To: "berniek at technicaldevelop.com" <berniek at technicaldevelop.com>; "Supras at supras.com" <Supras at supras.com>
Sent: Tuesday, December 11, 2007 10:59:24 AM
Subject: Re: [Supras] 57 trim CT26 alteration


On 10 Dec 2007 at 22:11, 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. 

I gotta agree with Jeff, too.

As I understand it, this isn't going to help make more power, but it
 would reduce the possibility of boost 
creep.  A 57 trim upgrade to the CT26 is what I'm considering as well,
 so I've looked into it.

Because of the increase in lag associated with clipping the exhaust
 turbine, I didn't want to go that way 
myself.  I would rather have the boost come on sooner for a broader
 power band at the expense of a bit of 
top end power.

Dan Gyoba
'89 NA 456,600 kms, Turbo swap COMPLETE
http://www.abstractconsulting.com/~dan


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