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Discussion Starter #1
I need advice-I installed a second big red bov on blower to intercooler tube and now i'm not showing any low boost.Prior to adding the second valve I could rev the engine to 2500 and see 3-4 psi now nothing.both valves close when I wack it and open at idle.I tried to disconnect vacuum to one valve but it still opens.Is it possible that I had this much backpressure in the tube before?I do see the fuel pressure go up when I wack it hard also the timing retards a little.The engine sounds normal you can tell it's making huge h.p. like before and the intake pipes to the intercooler are getting hot.Has anybody had the same experience?
 

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Discussion Starter #3 (Edited)
There are no leaks in the intake tract , the guage is working correctly-I blew air into it to check , I also leak checked all the boost lines to the guage,ignition,bov's and fuel pressure regulator no leaks anywhere also the hat is sealed.I think I may have had a huge amount of back pressure from spinning the blower so hard 81-46 pulleys and only one valve before.I also checked both bov's to make sure they hold vacuum and they are fine
 

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I think you may have left a V-band or hose clamp loose, lost an o-ring from the V-band or you inter-cooler is cracked and you didn`t notice it before... You might take the new bov off turn it over and pour solvent into the piston bore, look for leaking piston seal.... Look for damage at the compressor wheel, F.O.D. foreign object damage.. Once we left a rag in the piping and it caused much anguish....
 

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from your picture i dont see an intercooler on your set up maibe a/w inside? how much boost are you running are you testing driving around or just punch the gas on neutral need a little more info also were are you retarding the timing form were is the vac line connected? and you are sure both big reds are closing 100% they are not out off adjustment
 

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Discussion Starter #6
none of the above- both valves completly close when you snap the throttle the blower just came back from a rebuild and is blowing normal massive air at idle at the outlet.The intercooler is a brand new chiseled 3000-I checked for air at the water connections and there is no leaks.the engine is fine- leakdown and compression were just done.The intake system has no leaks
 

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Discussion Starter #7
from your picture i dont see an intercooler on your set up maibe a/w inside? how much boost are you running are you testing driving around or just punch the gas on neutral need a little more info also were are you retarding the timing form were is the vac line connected? and you are sure both big reds are closing 100% they are not out off adjustment
I have a new chiseled 3000 inside the car,the fuel pressure rises and timing retards when I snap the throttle,I am just running in park snapping the throttle, we normally make 23 psi on a run.The bov's hoses are both connected below the carb.
 

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by you adding another blow off valve you did not change what boost the motor should see at any rpm no matter what if you took the new blow off valve off and welded the hole shut and left the original blow off valve on there you will still see no boost, all that i just said is only true if both valves completly close. other than you changing the setup with a aditional blow off valve what else was changed.
 

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Discussion Starter #9
I hear what your saying makes sense but before I used to be able the snap the throttle up to 2500rpm and I would see 3lbs boost on the guage now I'm not seeing anything.I added the second valve,went to 4 inch piping from 3.5 inch and removed the pwr ice box and installed a chiseled 3000 a/w
 

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thats your variable right there you just decresed the volume of air by prob 200cfm at the snap of the throttle before it would move the air into the motor faster with the 3.5in pipe and now you have more volume of pipe to move air into the motor. stop worrying (lol) that is the difference in boost loss by changing to the 4in pipe cant move the air fast enough now
 

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Discussion Starter #12
I think your correct- maybe i'm being concerned over nothing,I just don't want to get to the track in the spring and have to chase my tail around.
 

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thats your variable right there you just decresed the volume of air by prob 200cfm at the snap of the throttle before it would move the air into the motor faster with the 3.5in pipe and now you have more volume of pipe to move air into the motor. stop worrying (lol) that is the difference in boost loss by changing to the 4in pipe cant move the air fast enough now

i agree their it is all volume difference before you had more pressure in the pipe with the one bov open now that you have 2 you have no pressure and the added volume of the pipe gives it a small delay to get the boost number you should still see the same boost number wen you go to the track and it might go faster do to their been more volume going to the motor. "that is if you're boost number does not drop do to the extra volume" good luck take it out and let her eat let us know what happens
 

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Could this have also been contributing to your original belt issues ? Spinning the blower hard and only having one BOV. Now that you have dual BOV it's venting twice as quick plus the addition of the 4" piping would definatly hold more volume
 

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i agree with dart. just less responsive with the larger piping. the good news is your iat`s should drop some. if that is a newer larger cooler maybe you should add a little fuel to the curve.
 

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Discussion Starter #20
Could this have also been contributing to your original belt issues ? Spinning the blower hard and only having one BOV. Now that you have dual BOV it's venting twice as quick plus the addition of the 4" piping would definatly hold more volume
I think you are exactly correct and so does a friend of mine that I spoke to that owns finishline performance.He said that the last time we dynoed the nova he was seeing the boost spike 2-3 psi when I lifted.He said every higher power car they put a second blow-off on had longer belt life and in one case solved a problem with blowing the tube off the blower/blowing the hoses when he lifted.he also said that it's definetly possible to have backpressure in the system if the bov is not letting enough air escape when at mid throttle holding the rpms up.
 
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