high-RPM

hey, just a quick one

if installed, would a blow off valve vent the air fuel mix into the engine bay?

this thread suggests that you can? but I'd like some reassurance before going ahead and buying one

https://www.rx7club.com/showthread.p...ow+through+13b

thanks

-Ben

Broken09

iTrader: (1)

What car are you looking to purchase a BOV for? FB, FC, or FD?

rdavidsrx7

unless you had injectors position upflow of the throttle plates there shouldn't be any fuel on the side of the butterflies where a bov would go.

high-RPM

custom turbo job on SA (already has a carb 13b)

high-RPM

sorry should have specified that it was for a blow through

DCrosby

Well unless fuel can make it out of the carb, with butterflies shut, I'd doubt it...

high-RPM

this is what prompted me to ask...

http://home.iprimus.com.au/mrtx3/perdollar.htm


"One thing I should ad, is that for those of you who don't know, you cannot fit a blow off valve to a suck through carby fed system. This is because the blow off valve would release air and fuel from the inlet pipe, and as all you firebugs know, this would not be good."

or is that because the turbo would be after the carb rather than before it?

rdavidsrx7

blow through means.....air filter (optional) ---> turbo ---> intercooler ---> blow through carb (where the throttle plates are) ---> engine

the blowoff valve should optimally be placed between the intercooler and throttle plates and since the fuel should be put into the air after the throttle plates there should be no way for it to get out the blowoff valve.

My friend runs a t04b on his 13b in his SA, he is fuel injected now but used to have it carburated. With either of these setups we never saw any fuel coming out the blowoff valve and he has one of the old watercooled intercooler setups that has almost no piping between the turbo and throttle plates.

The blowoff valve should only onpen if there is vaccum on the engine side of the plates thus all air would tend to pulled in that direction.

DCrosby

What rdavidsrx7 is talking about is what I was refering to, with the throttle plates, I can't see how fuel would rush backwards, through the carb, since the whole idea of a carb is to draw fuel through a pressure differential down, that differential still exists or your motor would stall... even when you snap the throttle plates shut, and part of the pressure gets vented, the idle controll still draws air into the combustion chamber and drags what's now minimal fuel with it into the combustion chamber...

high-RPM

thanks for the help, i was thinking the same... wanted to confirm before setting fire to my engine bay
LOL

rdavidsrx7

OK, looked at my friends old carb setup tonight. And yes...if you were to mount the blowoff valve right on top of the carb ( and i mean right threre ) a small amount of fuel could get out...but nothing serious, infact it would be so small you would probably never even smell it. I would just say mount it a half meter from the carb and you will be 99.9% safe (hey nothing is 100% right ). I say swing away merill, the setup is simple and it works...enjoy it.

Bob

bcty

just recirculate the bov and youll be fine