Maverick87
Member
New to Syclones. Having problems with over-boosting. Curious if anyone uses blow-off valve to help control boost.
Blow-off Valves
- Thread starter Maverick87
- Start date
typhoon1588
New member
that would probably make it worse,installing a BOV on a perfect truck is often the cause of Overboost
I received a blow off valve when I purchased my typhoon(not installed). Can someone please be kind enough to explain the positives and negatives to putting this on. Really don't know much about them besides they are suppose to prolong the use of your turbo. Thanks for your help
Methuselah
New member
Im making some of this up...but it seems logical:
A blow-off valve's goal is to prevent excessive pressure from building up when your engine stops demanding air in a turbocharged vehicle. It vents the boost (compressed air) thats caught in your intercooler when the butterfly valves in your throttle body shut to the atmosphere when the pressure of the boost is great enough to overcome the pressure driving the compressor wheel, and therefore the air pushes its way past it on intake side of the turbo. This causes chatter of the compressor wheel in mild cases, but in extreme cases the compressor blades will get bent the opposite way from the boost escaping.
I dont have any practical experience with blow-off valves thogh, so I cant understand how they can cause any problems.
Let me know if Ive stated anything wrong and I will fix the post for future readers.
<font size=-1>[ This Message was edited by: methuselah on 2002-01-18 16:14 ]</font>
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Ford Vn Platform
A blow-off valve's goal is to prevent excessive pressure from building up when your engine stops demanding air in a turbocharged vehicle. It vents the boost (compressed air) thats caught in your intercooler when the butterfly valves in your throttle body shut to the atmosphere when the pressure of the boost is great enough to overcome the pressure driving the compressor wheel, and therefore the air pushes its way past it on intake side of the turbo. This causes chatter of the compressor wheel in mild cases, but in extreme cases the compressor blades will get bent the opposite way from the boost escaping.
I dont have any practical experience with blow-off valves thogh, so I cant understand how they can cause any problems.
Let me know if Ive stated anything wrong and I will fix the post for future readers.
<font size=-1>[ This Message was edited by: methuselah on 2002-01-18 16:14 ]</font>
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Ford Vn Platform
Last edited:
KGB Pilot125
New member
I think you might be a little confused, you cant use a Blow Off Valve to control boost. it only becomes operational when the throttle blades close and compressed air is forced back toward the turbo.
what you might be thinking of is a POV or Pop Off Valve. They use them on Champ cars to regulate boost. at a predetermined setting, lets say 16 pounds for a stock truck, the compressed air over powers a spring and the excess boost is vented to the atmosphere. To me this sounds like a poor mans fix to a overboosting problem. but if you ever have a problem on a truck and lets say something sticks or breaks it could save a motor.
if your having an overboosting problem post in the mod repair forum and I am sure someone will help you out.
**Disclaimer I am no syty or turbo guru but I did stay at a holiday inn once**
what you might be thinking of is a POV or Pop Off Valve. They use them on Champ cars to regulate boost. at a predetermined setting, lets say 16 pounds for a stock truck, the compressed air over powers a spring and the excess boost is vented to the atmosphere. To me this sounds like a poor mans fix to a overboosting problem. but if you ever have a problem on a truck and lets say something sticks or breaks it could save a motor.
if your having an overboosting problem post in the mod repair forum and I am sure someone will help you out.
**Disclaimer I am no syty or turbo guru but I did stay at a holiday inn once**
KGB Pilot125
New member
no its wouldnt, its actually hlps the turbo survive longer. when you are at full boost and you lift off the throttle suddnely the blades snap closed and you have all this compessed air trying to be forsed in to the throttle body, well it has now where to go so it turns around and starts heading ack towards the turbo stopps the wheel and then exits making a horse sound on the way out. with the BOV when the blades are snapped shut the air turns around and the BOV opens and the air is vented to the atmosphere. thus increasing the life of the tubo
I got a BOV (free) on my truck. Email me if you want to see a pic
Denny
92 ty nyc
Denny1213@yahoo.com
Denny
92 ty nyc
Denny1213@yahoo.com
ghostrider_85
New member
post it here bro?
SyTyJedi
Jedi Council
I'll post some pics of my BOV setup later.
Add this to the FAQ:
BOV's CANNOT control boost in any way, shape or form.
BOV's CANNOT change the way your truck drives.
BOV's are for improvement in turbo life, keeping the turbo spooled if you are trying to get a race going with someone (stabbing the throttle), and a nicer sound than the stock fart echo.
Add this to the FAQ:
BOV's CANNOT control boost in any way, shape or form.
BOV's CANNOT change the way your truck drives.
BOV's are for improvement in turbo life, keeping the turbo spooled if you are trying to get a race going with someone (stabbing the throttle), and a nicer sound than the stock fart echo.
Actually KGB your wrong i have a Turboxs Type Blow off valve and my dial a boost isnt wroking properly so i am venting boost at like 13.5-14 psi. All a blow off is is a device to stop the pressurised air that would be coming out of the engine because of a shift or a quick let off, it has a screw on it or washers in my case that you can adjust to put more tension on the spring, therefore requiring more boost to open it or vice versa. I have been using my successfully for two weeks now no problems. And it still sounds like a supra when i let off the gas. Blow off valves are nothing but good for any turbo charged vehicle it keeps your turbo running longer.
chad
chad
KGB Pilot125
New member
how the hell does that work? I have never heard of a BOV doing that before. do you have any links to the manufacture or anything? it sounds like a POV and a BOV in one.
S
SickLife
Guest
incorrect. the bov does not in any way control the watsegate.
the blowoff valve just lets out the boost when the throttle plates close, so it doesn't go back to the turbo & cause damage.
your bov may be adjustable, mine is dual stage..one for lower boost, one for higher. but that doesn't mean it adjustable how much boost your car is running.
KGB Pilot125
New member
little test Pilsbury, turn up your quasi-boost controlling BOV and tell me if you get more boost. I am willing to bet you dont.
S
SickLife
Guest
see, thats the thing. you turn it up according to how much boost you're running...but turning it up doesn't control how much boost you run. heh.
BOVs have springs in them and some can be set to vent excess boost via the screw on the back. i've seen 7 second turbo cars doing this and some accually used wastegates in place of a BOV by swapping the port used.
stock and near stock trucks don't need a BOV, but its a good idea when using bigger turbos.
stock and near stock trucks don't need a BOV, but its a good idea when using bigger turbos.
turbojimmy
New member
I have a BOV on the Buick (http://www.jimmyz.net/gn_bov.jpg) and a POV on the Ty (lost the pic of that). You'll note that the BOV on the GN has both a vacuum fitting AND an adjustment screw at the top. A POV has just the adjustment screw. Why? Because a POV is simply a spring-loaded plunger that plugs a hole in your turbo-to-intake path. When you hit x pounds of boost, it opens and vents the boost to maintain x pounds of boost. It does little to relieve pressure when you let off the gas. I say little becuase a tremendous amount of pressure builds up when you let off the gas and it does vent some of it. But, it's not as effective as a BOV. The BOV has a vacuum line so that it actually knows when you let off the gas. As soon as the pressure acting on the plunger is greater than the pressure on the vacuum line, the plunger opens and it vents boost. The BOV, unlike the POV, will allow you to continue to build boost until you blow the heads off your truck. As long as there's boost on that vacuum line, the valve will stay shut. The BOV's only purpose is to vent boost when you don't need it. The POV's purpose is to act as a safety valve when your wastegate can't keep up. Then why the adjustment on the BOV? You can control how sensitive you want it to be when there is a difference between the vacuum line and the pressure in the inlet tube. I suppose if you disconnect the vacuum line and mess with the adjustment, it'll act as a POV but that's not the intent.
That is all.
Jim
_________________
1992 GMC Typhoon: Stock, 13.7 @ 96
1987 GN: PT51, PTE 50#, LS1 MAF, T+, Ext., THDP, TT 3" duals, Walboro, Comp Cams 206/206, Level 10 trans/TC
http://www.turbojimmy.com
<font size=-1>[ This Message was edited by: turbojimmy on 2002-01-18 22:18 ]</font>
That is all.
Jim
_________________
1992 GMC Typhoon: Stock, 13.7 @ 96
1987 GN: PT51, PTE 50#, LS1 MAF, T+, Ext., THDP, TT 3" duals, Walboro, Comp Cams 206/206, Level 10 trans/TC
http://www.turbojimmy.com
<font size=-1>[ This Message was edited by: turbojimmy on 2002-01-18 22:18 ]</font>
Hu Ryde
Donating Member
Everything Jim said is true. With my BOV I have a HKS SSQ. (I highly reccomend it) The thing is great! I used to get a horse noise when I let off the gas now I get a awesome fluttering whistle. With the SSQ valve you get 2 valves in one. A large and small valve, both for different boost levels. During low boost I get a rushing air sound when I let off the gass. During high boost the rushing air flutters and I get a loud whistle. It's awesome. Check it out----->
_________________
Jesse Allmyer
13.32 @ 98.63
Bottles are for babies, real men get blown!
Sy1178
<font size=-1>[ This Message was edited by: Hu Ryde on 2002-01-19 01:22 ]</font>
_________________
Jesse Allmyer
13.32 @ 98.63
Bottles are for babies, real men get blown!
Sy1178
<font size=-1>[ This Message was edited by: Hu Ryde on 2002-01-19 01:22 ]</font>