[Supras] 57 trim blowoff valve recommendation

[Dan Gyoba]

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