[Supras] 57 trim blowoff valve recommendation

[berniek at technicaldevelop.com]

Dan:

    The PVC I spoke of is not hardline.  It is hose.  I just want to 
keep the blowoff quiet and maximize bogging during shifting.  The only 
copper used was a 1-1/4" coupling (1-1/2" OD for the discharge hose) 
brazed to sheet steel flanges to mount inside and outside of the front 
of the accordion hose, not much work with a torch, soft steel, and a 
hole saw. 


    Venting or recirculating blowoff is a matter of personal 
preference.  Although there are not many Supras on the road, I don't 
want to attract unnecessary attention, especially from cops.


       Bernie


Dan Gyoba wrote:
> On 16 Nov 2007 at 22:34, berniek at technicaldevelop.com wrote:
>
>   
>> 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.
>>     
>
> Well, the SSQV seems to be able to handle the job from stock all the way to power that's beyond what I 
> consider to be the safe working limits of the 7M-GTE.  Since I'm not likely to ever be upgrading engine 
> internals, I figure that's plenty good enough.  Plus it's readily available, and the fittings for the BOV are 
> easy to find.
>
> The recirculation fitting is good, however, I don't think that such an extravagant recirculation installation 
> is warranted.
>
> The accordian hose is not under pressure.  This remains true even when the BOV is operating.  As such, 
> elaborate precautions against leaks aren't needed.  A much simpler fitting will do the job, and do it well.  
> The main issue in my mind is presenting as little bakepressure to the valve as possible so that it works 
> efficiently at venting excess boost pressure.
>
> As such, also, there isn't much need for even a hardline from the BOV back to tha accordian hose.  While a 
> hardline with a nice, gentle bend would still be ideal, A 1.5" hose should be adequate to the job.
>
> Also, fuel vapors aren't an issue.  All of the BOV's function should be in the intake track before even the 
> throttls body.  As such, none of it should ever contain fuel vapors.  (Can you imagine if it did, for people 
> venting to atmosphere?  A gout of flame under the hood every time you shift!)
>
> Therefore the biggest issue with re-routing the BOV is ensuring that the accordian hose does not take in 
> unmetered air.  This means that there needs to be a reasonably tight fitting to the accordian hose of the 
> appropriate diameter.
>
> Though I've seen people venting to atmosphere with a stock ECU/AFM combo.  The largest setback seems to be a 
> puff of black smoke (rich) at shifting.  Not that big a deal, really.
>
> Dan Gyoba
> '89 NA 453,298 kms, Turbo swap COMPLETE
> http://www.abstractconsulting.com/~dan
>
>
>
>