[Supras] 57 trim blowoff valve recommendation

[berniek at technicaldevelop.com]

Dan:

    The recommendation from Performance Techniques was the Turbonetics 
Raptor.  I do not understand how the Bosch valve ever could have worked, 
looking at the TO4-57 map, closest to the CT26 with 57 trim.  The surge 
line leans way to the right.  The SSQV should work as well from what 
I've looked at.


    To recirculate the discharge to the accordion hose, if you want to 
do it, one way seems to be as follows:


1.  For the Raptor, the discharge is 1-1/2".  A similar size or at least 
the recirculation approach should work for the SSQV if you want to do 
it.  LOWes has reinforced PVC hose and "spa" hose which looks more 
substantial.  I did not even look at Home Despot, with the garbage they 
have.  PVC is not the best for handling fuel vapors (Buna-N would be 
better, but even McMaster-Carr does not have it except in heavy wall stuff).


2.  The only place to introduce the recirculation appears to be at the 
convex curved section behind the AFM.  It appears that two large 
washer-like segments cut from an empty Bernzomatic cylinder will be the 
right size, with a 1-1/2" hole in one and a slightly larger hole in the 
other.  It will be necessary to hammer the segments into a compound 
curve to fit the hose, in which a 1-1/2" hole is also bored.


3.  Braze one end of a 1-1/4 copper coupling into the Bernzomatic washer 
with the smaller hole.  A good size fillet can be used on the coupling 
side.  Install the completed assembly in the accordion hose from the 
inside and put the other "washer" on the outside.  The OD of the 
coupling is 1-1/2", just the right size for the recirculation hose. 


4.  Drill through both washers and the accordion with 8-10 holes for #8 
screws.  Do a trial fit of screws and nuts to seal both washers to the 
accordion with the coupling sticking out.  Touch up washer shape as 
required. 


5.  Take the assembly apart and coat all mating surfaces with contact 
cement, wait 10 minutes and reassemble.  I'd put the screw heads inside 
the accordion with elastic stop nuts outside. 


6.  On the pressure side, it appears as if I'm going to upgrade the 
turbo piping using 1-1/4" steel exhaust tubing, so I'll be making a 
flange to adapt the inlet side of the valve to the segment that comes 
out from under the right fender.  That will be one of next weekend's 
jobs, in addition to "Honey-do" stuff. 


As always, any comments would be appreciated.


       Bernie



Dan Gyoba wrote:
> On 14 Nov 2007 at 22:51, berniek at technicaldevelop.com wrote:
>
>   
>> With the money and effort put into the engine and the turbo ($600+ for
>> the 57 trim modification, rebuilding, wastegate port boring, a new
>> turbine housing for the turbo alone), I'm not about to take any
>> chances.
>>     
>
> Likely wise.
>
> For myself, I'm looking at putting in an HKS SSQV before I get to that mod level.  Certainly not 
> the cheapest, but you can get a recirculation fitting for the valve, so I consider it "upgradable" 
> for if I ever do decide to go with a MAP system and get rid of the AFM.
>
> I'm not necessarily convinced that the SAAB or Porche unit is going to be a lot better, so I'd 
> like to go to a unit that I'm not likely to "outgrow" at all.
>
> Anyway, that's my take on it.
>
> Dan Gyoba
> '89 NA 453,298 kms, Turbo swap COMPLETE
> http://www.abstractconsulting.com/~dan
>
>
>
>