BOV Risks
Mar 13, 2013, 06:09 AM
#1
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BOV Risks
So I need to reassure the wife that nothing is going to happen if I get an HKS bov bc I still have 2 yrs of warranty and she might actually kill me if I do something to void any of it. I'm 99.9% sure that nothing will happen but I still want to bring the question to all you subject matter experts to get that last 1% assurance. So what are the risks if any involved in changing my stock bov to the HKS SSQ4 atmosphere/recirculated?
Mar 13, 2013, 06:24 AM
#3
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I completely understand where your coming from and thank you for the advice but this is just one of those parts I've invisioned having and hearing for a very long time.
Mar 13, 2013, 06:26 AM
#4
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Nothing will happen nor will it void any warranty you have if you rec. the air. If you dump into atmosphere you will need a few parts and tune. But a rec you'll be just fine. The bov is one of the most swapped out parts in building our cars and by far the easiest for the diy'er/ weekend warrior. Tell the wife to chillax as it will take about 25-30 min to change the sound of your Evo
Mar 13, 2013, 12:48 PM
#5
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As stated, do not waste your money. $250-$300 for a part that gives you zero performance benefit. Look up BOV or BPV threads and see how many people agree that replacing the stock air filter box with a cone-style filter gives you all the sound you will need. I was shocked when I decided to follow that advice - I think you will be pleasantly surprised. Plus you'll get a few extra ponies and mpg's to go along with it. 
Edit: And if you decide to ignore our advice
make absolutely positive you get a recirculating kit.
Edit: And if you decide to ignore our advice
make absolutely positive you get a recirculating kit.
Mar 13, 2013, 01:04 PM
#6
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I keep getting mixed information on atmosphere/recirc. Why is it so vital to have the recirculate kit? When I talked to IKT he said he has the SSQ4 right now vented to atmosphere and has no problems. He is only going to recirc when he gets tired of the chirpping. I'm so confused.
I know there is no performance basis to it but I just love the sound the HKS makes.
I know there is no performance basis to it but I just love the sound the HKS makes.
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Mar 14, 2013, 05:08 AM
#9
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To actually answer your question though, The reason you need to recirculate your BOV is the you are dumping metered air, and as a result, you will go extremely rich between shifts, and possibly have a difficult time idling.
Let's take a trip through your engine. The air goes through the filter and pass the MAS. IT measures the air and tells the computer how much is coming through. The air goes through the turbo, and the intercooler, and towards the intake manifold, and on through the engine. And since the turbo is moving air, the air pressure begins to build. We call it boost. This is fine during Acceleration, but what happens when you need to shift? You let off the throttle. Now you have a turbo that's still spinning and still pushing air. But since the throttle plate is now closed, it needs to go some where. This is where the BOV (Actually called a Bypass valve) comes into play. Due to the magic of springs, vacuum lines and some clever routing, when you let off the throttle, the BOV opens to allow the pressurized air to escape safely back into the preturbo intake tube. The computer is programmed for this. It's calibrated for X amount of air to be released, and therefore X amount of air to be there when you get back into the throttle.
But when you open to atmosphere, You're losing metered air. So when you get back into it, it has to pull MORE air through the MAS. So the ECU will try to send fuel for the air it measured, PLUS the new air. Meaning it will run Extremely RICH. Which will result in bogging, black smoke, and crappy idle.
The other reason you want to keep the bov recirculated is during idle, the Recirc valve may be partially open. IF it's connected, it's pulling metered air. If it's open, it's pulling in unmetered air, and the car can't send the proper amount of fuel.
That's the reason people will wait til they run a GM Maf Blow through set up. (They put the MAF down stream of the BOV so anything released is unmetered air.) Or the can tune the engine specifically for the lift off situation.
I know it's Long, but it's as close as I can come to an explanation.
That explain it well enough?
Let's take a trip through your engine. The air goes through the filter and pass the MAS. IT measures the air and tells the computer how much is coming through. The air goes through the turbo, and the intercooler, and towards the intake manifold, and on through the engine. And since the turbo is moving air, the air pressure begins to build. We call it boost. This is fine during Acceleration, but what happens when you need to shift? You let off the throttle. Now you have a turbo that's still spinning and still pushing air. But since the throttle plate is now closed, it needs to go some where. This is where the BOV (Actually called a Bypass valve) comes into play. Due to the magic of springs, vacuum lines and some clever routing, when you let off the throttle, the BOV opens to allow the pressurized air to escape safely back into the preturbo intake tube. The computer is programmed for this. It's calibrated for X amount of air to be released, and therefore X amount of air to be there when you get back into the throttle.
But when you open to atmosphere, You're losing metered air. So when you get back into it, it has to pull MORE air through the MAS. So the ECU will try to send fuel for the air it measured, PLUS the new air. Meaning it will run Extremely RICH. Which will result in bogging, black smoke, and crappy idle.
The other reason you want to keep the bov recirculated is during idle, the Recirc valve may be partially open. IF it's connected, it's pulling metered air. If it's open, it's pulling in unmetered air, and the car can't send the proper amount of fuel.
That's the reason people will wait til they run a GM Maf Blow through set up. (They put the MAF down stream of the BOV so anything released is unmetered air.) Or the can tune the engine specifically for the lift off situation.
I know it's Long, but it's as close as I can come to an explanation.
That explain it well enough?
Mar 14, 2013, 05:11 AM
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I have an HKS SSQv3 its cool and all but eventually the noise gets annoying lol
Keep the stocker and save some money or get a Tial Q if you really want one
Keep the stocker and save some money or get a Tial Q if you really want one
Mar 14, 2013, 06:47 AM
#12
Evolving Member
I like the sound of it too.
Don't listen to these guy's about getting a cone filter and all that you will hear the bov better.
1 Cone filters give little to no gains over stock box with a free flow panel filter.
Test done on Mighty car mods:
<iframe width="560" height="315" src="
" frameborder="0" allowfullscreen></iframe>
2 you might be able to hear it a little better from in the car but no one else you pass buy or out side the car will hear it. The only way is a full VTA BOV or a 50/50 BOV like Go Fast Bits BOV.
<iframe width="560" height="315" src="
" frameborder="0" allowfullscreen></iframe>
In the end the choise is yours if you go VTA it won't hurt your car you will get stumble on the high way. I went with the Go fast bits bov shown and at 60% vent 40% rec I get no backfire or stumble. Just had to loosen the nut a little so it would open under light boost works perfect and it gives a very big noise any on with in 30 feet could hear.
Lastly updated BOV is needed when running more boost and on stock. A better Bov will let the car hit boost faster and hold it longer then the stock.
Do what you want and not what others think with no proof. It's your car make it your own and not a copy.
Don't listen to these guy's about getting a cone filter and all that you will hear the bov better.
1 Cone filters give little to no gains over stock box with a free flow panel filter.
Test done on Mighty car mods:
<iframe width="560" height="315" src="
2 you might be able to hear it a little better from in the car but no one else you pass buy or out side the car will hear it. The only way is a full VTA BOV or a 50/50 BOV like Go Fast Bits BOV.
<iframe width="560" height="315" src="
In the end the choise is yours if you go VTA it won't hurt your car you will get stumble on the high way. I went with the Go fast bits bov shown and at 60% vent 40% rec I get no backfire or stumble. Just had to loosen the nut a little so it would open under light boost works perfect and it gives a very big noise any on with in 30 feet could hear.
Lastly updated BOV is needed when running more boost and on stock. A better Bov will let the car hit boost faster and hold it longer then the stock.
Do what you want and not what others think with no proof. It's your car make it your own and not a copy.
Mar 14, 2013, 07:24 AM
#13
I am very uncomfortable with the above statement. While I agree to the extent that warranties cannot be "voided" by a modification of this sort, I know that a dealer can refuse to honor the warranty for certain repairs if and when a non-OE diverter valve is found on the car, and the Regional Rep might very well agree with the dealer, and you might very well lose the argument if you took it to arbitration. To suggest that the OP will not have any warranty-related issues if he or she replaces the diverter valve could very easily be giving him or her false assurances. This is not a slam-dunk.
