turbo II blow off valve
 

does the stock 87' turbo II have a blow off valve? is it sufficient when you have the dual racing beat exhaust with the 3" downpipe, i.e, no cats? How do you add a blow off valve and where does it go? Sorry to be so dumb about this, i only know how to add the racing beat FCD and exhaust and the FCD is broken so i need a good working one.

all stock tii's have a factory diverter valve, which is like a blow off valve but it recirculates the air instead of venting to atmosphere. the factory unit is sufficient, all you will gain by replacing the diverter valve with a BOV is noise. you would install the BOV in place of the diverter valve, and cap off the recirculation tube.

thanks for the info, i have little mod experience, my list of Rx-7's though the years are probably twice yours but i have only owned two turbo II's, a 1990 and the 87 i have now. I had two rx-7 race cars, ran in SCCA with a 12a 1978 production car for 10 years ran an 84' for a few years with the 13b and street weber carb set up sold by Mazdatrix, i got a second place at Road America and would have had first but blew up the tranny on the last lap. Stock ported engine, full race car suspension with roll cage, fire system ect ect. I have also only owned two RX-8's loved em, just wish they had more torque. Started with an RX-2 in 1978, raced an RX3 for a few years in the 80's. Built a few 13b's non turbo with success, i been at it for a long long time.

Yeah you've been in the rotary scene longer than I've been alive then! If you still need a FCD PM me.

i bought one from HKS on eBay, have not looked into installing it yet, my son says the old one you could get from Mazdatrix was just a resister in the black box, ever taken one apart?

I've never taken one apart, but a simple circuit with a resistor or diode would make sense as i believe they work by capping the voltage signal of the map sensor just before the value would trigger fuel cut by the factory ecu. As such, its important to understand that the ecu can never read above what fuel cut pressure was at so the ecu doesn't add any extra fuel or pull any extra timing for boost beyond that value. If you're just fighting fuel cut an FCD does the job, however if youre looking to push more boost the FCD really just gives you the opportunity to push more boost than the ecu is designed for and that does end well.