Blow off valve question
05-26-2003, 04:34 AM
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Three Wheelin'
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Blow off valve question
Can you get by running a bov vented atmosphere? I know I can with a speed density setup. But how about on our cars. Plenty of other turbo cars run mass air before the turbo and run themlike the eclipse etc. TIA
05-26-2003, 04:54 AM
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Drifting
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Any special reason why you would want to do that, other than the cool sound you'd get?
If I've understood correctly, not venting to atmosphere is better because you get to preserve some of the boost when you're changing gears. Right?
Probably the worst thing you'll get by dumping the excess boost is flames out of the exhaust. Can't be all that good for the turbo, cat, muffler etc...
If I've understood correctly, not venting to atmosphere is better because you get to preserve some of the boost when you're changing gears. Right?
Probably the worst thing you'll get by dumping the excess boost is flames out of the exhaust. Can't be all that good for the turbo, cat, muffler etc...
05-26-2003, 05:04 AM
#3
Three Wheelin'
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Sami951:
<strong>
Probably the worst thing you'll get by dumping the excess boost is flames out of the exhaust. Can't be all that good for the turbo, cat, muffler etc...</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">What the heck, I have never heard of that before. I am putting a VTA BOV on my Miata. I wonder if it will shoot flames??!!!?!
<strong>
Probably the worst thing you'll get by dumping the excess boost is flames out of the exhaust. Can't be all that good for the turbo, cat, muffler etc...</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">What the heck, I have never heard of that before. I am putting a VTA BOV on my Miata. I wonder if it will shoot flames??!!!?!
05-26-2003, 05:46 AM
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Drifting
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Michael, I think it depends entirely on how the amount of air is measured.
With the stock configuration, a 944 turbo measures the airflow before the turbocharger... and the blow-off (or recirc valve) is naturally after the turbo. So what happens is that at first the turbo is sucking in air like mad. Then you let off the gas and blow-off vents the pressure out of the intake manifold and into the atmosphere... but since all that air that just got out was measured already, the DME thinks you still need a lot of fuel -> goes very rich for a moment. The excess fuel then burns up somewhere in the exhaust, giving the flames.
So basically if you measure the airflow after the blow-off, you should be fine. I don't know how the Miata does this...
With the stock configuration, a 944 turbo measures the airflow before the turbocharger... and the blow-off (or recirc valve) is naturally after the turbo. So what happens is that at first the turbo is sucking in air like mad. Then you let off the gas and blow-off vents the pressure out of the intake manifold and into the atmosphere... but since all that air that just got out was measured already, the DME thinks you still need a lot of fuel -> goes very rich for a moment. The excess fuel then burns up somewhere in the exhaust, giving the flames.
So basically if you measure the airflow after the blow-off, you should be fine. I don't know how the Miata does this...