Is there any benefit to running a bypass valve without the use of an intercooler on a blower setup? Could this reduce any present compressor surge, even if just a little? I know that they're typically used to vent extra boost in the intercooler piping to stem compressor surge, but could it be used on a non-intercooled setup as well? I don't see why not. I mean, I don't see the necessity, but I know people love the sounds of BOV's so it might be an option for someone working on their intercooler setup. They can run the valve before the intercooler is installed.
marxummers
Bypass Valve Without Intercooler
Yeah, every blower setup will have a bypass valve. It's just that if you have a draw through MAF, the valve will not vent to the atmosphere, it will vent back to the air inlet. You need a blow through MAF to vent to atmosphere or else the MAF will be reading more air than what the motor actually gets.
When guys do intercoolers, the extra required piping allows for more room to use a blow through MAF, which is why you see most IC'd guys vent to atmosphere.
When guys do intercoolers, the extra required piping allows for more room to use a blow through MAF, which is why you see most IC'd guys vent to atmosphere.
+3 to what these guys said.
The blower is always pushing air in proportion to what RPM your engine is running. However, you can be in 3rd gear going highway speeds turning some high rpms, but not being on the throttle much. Without some way to get rid of this air being forced through the supercharger with no where to go (the butterfly valve in your throttle body will be nearly closed), the air bounces back into the supercharger, making it fight against itself. This is caused compressor surge, and, if left untreated, will kill your blower.
This is where the blow off valve (BOV) or bypass valve (BPV) comes into play. Both of them provide an exit path for the supercharged air when the car is under vacuum (which means you are giving it little or no throttle).
Bypass valves must be used on a draw through setup, like most non-intercooled entry level supercharger kits are. This is because the MAF is essentially the first component in the path that the air travels to get to the engine, so you must recirculate the extra air the engine doesn't need because the MAF has already measured it and assigned fuel trims accordingly.
Blow off valves are a similar deal, except they just blow the air out of the system. BOVs must only be used with a blow through system. This is because in this setup the BOV is positioned before the MAF so it can vent all the air it wants and not cause issues. The MAF only knows about the air that passes through it.
Now, with a blow through setup, you can also run a BPV without any issues. Most people choose not to though because BPVs tend to be a little more restrictive, and can increase the chance of compressor surge. A big BPV like a Tial QR would not give any issues though. Unfortunately, it would not give that awesome "whoosh!" sound that I have a feeling you are after.
If you wanted to, there is no reason you couldn't run a blow through non-intercooled setup. There are a few people online doing it. You will need to get custom piping, and figure out a way to orient the MAF and the BOV between the blower and throttle body. The main issue you will run into is the lack of distance between your MAF and your BOV. They need to be a pretty good distance (12"+) apart, or else it can cause turbulence in your MAF which will make your car buck and carry on like no tomorrow. In my non-intercooled setup, there is only 18-20" of piping between the supercharger and the throttle body all together, so I am unsure of how I would fit a BOV in there.
For what it's worth, I am running a draw through setup and really wish I had gone blow through to begin with. It's a lot harder to cram the MAF, air filter, and power pipe down in the fender well. I have also found that this setup is a lot harder to tune, and a lot more finicky. Remember all that air getting recirculated back from the pressurized end of the supercharger? I am having issues with it backwashing into my MAF, and causing turbulence in my MAF counts. It is very mild at this point, but occasionally I will notice it. This winter I will be adding an intercooler to my car along with dropped a few pulley sizes and converting to a blow through system.
The blower is always pushing air in proportion to what RPM your engine is running. However, you can be in 3rd gear going highway speeds turning some high rpms, but not being on the throttle much. Without some way to get rid of this air being forced through the supercharger with no where to go (the butterfly valve in your throttle body will be nearly closed), the air bounces back into the supercharger, making it fight against itself. This is caused compressor surge, and, if left untreated, will kill your blower.
This is where the blow off valve (BOV) or bypass valve (BPV) comes into play. Both of them provide an exit path for the supercharged air when the car is under vacuum (which means you are giving it little or no throttle).
Bypass valves must be used on a draw through setup, like most non-intercooled entry level supercharger kits are. This is because the MAF is essentially the first component in the path that the air travels to get to the engine, so you must recirculate the extra air the engine doesn't need because the MAF has already measured it and assigned fuel trims accordingly.
Blow off valves are a similar deal, except they just blow the air out of the system. BOVs must only be used with a blow through system. This is because in this setup the BOV is positioned before the MAF so it can vent all the air it wants and not cause issues. The MAF only knows about the air that passes through it.
Now, with a blow through setup, you can also run a BPV without any issues. Most people choose not to though because BPVs tend to be a little more restrictive, and can increase the chance of compressor surge. A big BPV like a Tial QR would not give any issues though. Unfortunately, it would not give that awesome "whoosh!" sound that I have a feeling you are after.
If you wanted to, there is no reason you couldn't run a blow through non-intercooled setup. There are a few people online doing it. You will need to get custom piping, and figure out a way to orient the MAF and the BOV between the blower and throttle body. The main issue you will run into is the lack of distance between your MAF and your BOV. They need to be a pretty good distance (12"+) apart, or else it can cause turbulence in your MAF which will make your car buck and carry on like no tomorrow. In my non-intercooled setup, there is only 18-20" of piping between the supercharger and the throttle body all together, so I am unsure of how I would fit a BOV in there.
For what it's worth, I am running a draw through setup and really wish I had gone blow through to begin with. It's a lot harder to cram the MAF, air filter, and power pipe down in the fender well. I have also found that this setup is a lot harder to tune, and a lot more finicky. Remember all that air getting recirculated back from the pressurized end of the supercharger? I am having issues with it backwashing into my MAF, and causing turbulence in my MAF counts. It is very mild at this point, but occasionally I will notice it. This winter I will be adding an intercooler to my car along with dropped a few pulley sizes and converting to a blow through system.
Exactly what I was looking for guys. I see a lot of guys running lower boost without intercoolers and bov's but I figured the bov would be benficial on both applications. Thanks for the input
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I would probably place the bov right after the blower and put the maf after the first turn to the throttle body between both elbows. So blower > bov > elbow > maf > elbow > throttle body
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I would probably place the bov right after the blower and put the maf after the first turn to the throttle body between both elbows. So blower > bov > elbow > maf > elbow > throttle body
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