wastegate and bov
- Thread starter sean
- Start date
vortecfiero
New member
Re: wastegate and bov
i found the bov to be a huge benefit for spool up from cruise (2 way OEM style) to max boost and of course maintaining some of the rpm in the turbo between shifts. At cruise a turbo wants to spin from the exhaust velocity and a bit from the pressure. Since the throttle is almost closed the small amout of pressure has nowhere to go so it causes the tubo to not spin as fast as it could at cruise... waiting to make boost. Having the bov open at cruise allows the turbo to spin a little faster, closer to the point where it makes boost. Opening the throttle closes the bov and the turbo now is closer to boost mode.
In my set up from cruise to boost with no bov was about 3 heart beats.
With the bov it was about one... instantainous and lots of adrenalin.
Between shifts the small amout of lag completly dissappeared.
also at the moment the throttle is closed at high boost... the boost has somewhere to go rather than poping off any intake connections
Not all bovs function the same.. most just blow off between shifts (they do not draw air... only blow off air)
Most OEM units work both ways so the benefit at cruise is available. I use a Bosch unit from an Audi. A friend of mine uses 2 of them on a 400 whp turbo 4 cyl
you should try to mount the bov as close to the throttle as possible (or just before the A/W IC on a sy/ty) and run vacum from the intake plenum. Otherwise the intake charge has to repressure and get the velocity up again from the bov to the throttle body.
on systems running high boost and high turbo rpm serious damage to the compressor as the throttle is slammed closed. It could go into surge, spin up way past its safe range and grenade.
this info is what i have seen first hand... no it wasnt mine that granaded lol but i saw and heard it lol OUCH
sean said:
i found the bov to be a huge benefit for spool up from cruise (2 way OEM style) to max boost and of course maintaining some of the rpm in the turbo between shifts. At cruise a turbo wants to spin from the exhaust velocity and a bit from the pressure. Since the throttle is almost closed the small amout of pressure has nowhere to go so it causes the tubo to not spin as fast as it could at cruise... waiting to make boost. Having the bov open at cruise allows the turbo to spin a little faster, closer to the point where it makes boost. Opening the throttle closes the bov and the turbo now is closer to boost mode.
In my set up from cruise to boost with no bov was about 3 heart beats.
With the bov it was about one... instantainous and lots of adrenalin.
Between shifts the small amout of lag completly dissappeared.
also at the moment the throttle is closed at high boost... the boost has somewhere to go rather than poping off any intake connections
Not all bovs function the same.. most just blow off between shifts (they do not draw air... only blow off air)
Most OEM units work both ways so the benefit at cruise is available. I use a Bosch unit from an Audi. A friend of mine uses 2 of them on a 400 whp turbo 4 cyl
you should try to mount the bov as close to the throttle as possible (or just before the A/W IC on a sy/ty) and run vacum from the intake plenum. Otherwise the intake charge has to repressure and get the velocity up again from the bov to the throttle body.
on systems running high boost and high turbo rpm serious damage to the compressor as the throttle is slammed closed. It could go into surge, spin up way past its safe range and grenade.
this info is what i have seen first hand... no it wasnt mine that granaded lol but i saw and heard it lol OUCH
crashing_sux
Blow Me?
Re: wastegate and bov
Hmmm...I'll have to read up on this more, mine doesn't work at all like yours. Hell, it almost never seems to work, I've only heard it a few times, like if I make 15lbs of boost and let off the throttle I'll hear it for a brief second, but if I just make 8-10lbs of boost and let off the throttle the turbo will just flutter, like it's not enough pressure to open the BOV.
Hmmm...I'll have to read up on this more, mine doesn't work at all like yours. Hell, it almost never seems to work, I've only heard it a few times, like if I make 15lbs of boost and let off the throttle I'll hear it for a brief second, but if I just make 8-10lbs of boost and let off the throttle the turbo will just flutter, like it's not enough pressure to open the BOV.
DynaGlide
Ton-Eighty
Re: wastegate and bov
A little bit of luck. Every time your turbo flutters, it could do damage to your compressor wheel, turbine shaft, bearing, etc.
Compressor surge is potentially a very bad thing. At the same time your turbo is creating boost, it's also having pressure directed back over the compressor wheel. A BOV vents that excess boost into the atmosphere, in theory, eliminating compressor surge.
EcSy#2671 said:
A little bit of luck. Every time your turbo flutters, it could do damage to your compressor wheel, turbine shaft, bearing, etc.
Compressor surge is potentially a very bad thing. At the same time your turbo is creating boost, it's also having pressure directed back over the compressor wheel. A BOV vents that excess boost into the atmosphere, in theory, eliminating compressor surge.
SY2932
Administrator
Re: wastegate and bov
Don't worry at full boost, the stock turbo spins at 130,000 to 140,000 RPM's (2,166 to 2,333 times a second). When your throttle body blades close that 14.7 pounds of boost pressure back feeds where it came from, the compressor wheel. There are MANY high mileage trucks out there that have never had a problem and they have never had a BOV. One owner actually had the nut that held the compressor wheel spin off his big adtermarket turbo due the the rapid decceleration that the compressor wheel experienced without a BOV. To run one or not is a personal choice since time has shown that they aren't *really* necessary on our trucks.
EcSy#2671 said:
Don't worry at full boost, the stock turbo spins at 130,000 to 140,000 RPM's (2,166 to 2,333 times a second). When your throttle body blades close that 14.7 pounds of boost pressure back feeds where it came from, the compressor wheel. There are MANY high mileage trucks out there that have never had a problem and they have never had a BOV. One owner actually had the nut that held the compressor wheel spin off his big adtermarket turbo due the the rapid decceleration that the compressor wheel experienced without a BOV. To run one or not is a personal choice since time has shown that they aren't *really* necessary on our trucks.
cloneman315
Active member
Re: wastegate and bov
bov are just another thing to mess up i have learned this and on these automatic trucks thewy are not needed
bov are just another thing to mess up i have learned this and on these automatic trucks thewy are not needed
HotRudyRod
New member
Re: wastegate and bov
Is fluttering, that series of blows you hear after letting off the gas? It sounds kind of kool to me but i thought it was just a better wastegate from the lil bigger 20G, the stocker used to do a single blow not even half as loud instead of the 3 to 5 blows i hear now.
Is fluttering, that series of blows you hear after letting off the gas? It sounds kind of kool to me but i thought it was just a better wastegate from the lil bigger 20G, the stocker used to do a single blow not even half as loud instead of the 3 to 5 blows i hear now.
HotRudyRod
New member
Re: wastegate and bov
So the flapping noise is better than a single weaker blow?
So the flapping noise is better than a single weaker blow?
EcSy#2671
Si vis pacem, para bellum
Re: wastegate and bov
The reason I ask is because the other night I was moving about 110 mph, let off and clam to a stop and had a slight tick. As I sat at the stoplight it got louder, the light turned green and as I drive though the tick became a loud knock/tick. I have had some lifter talk at start up but always went away and from what I understand that is "normal" I had been drive the truck for a good 1/2 hour before this happened is the truck warm and running great. Do you guys have any idea what it could be?
The reason I ask is because the other night I was moving about 110 mph, let off and clam to a stop and had a slight tick. As I sat at the stoplight it got louder, the light turned green and as I drive though the tick became a loud knock/tick. I have had some lifter talk at start up but always went away and from what I understand that is "normal" I had been drive the truck for a good 1/2 hour before this happened is the truck warm and running great. Do you guys have any idea what it could be?
Re: wastegate and bov
hot rudy rod: which bov do you have? there are 2 different things you can hear on a sy/ty.
1. compressor surge. This the Chuf-chuf-chuf sound you hear when you let off the throttle and there is no bov, or its adjusted so tight it never opens. This is air trying to go backwards through the turbo.
2. The "fluttering" you could be hearing that is more of a series of smaller bov sounds is when the bob isn't adjusted quite right, and opens and closes several times in a row. If you're getting this when you let off at WOT, then you want to soften up the preload on the bov's spring just a little bit.
hot rudy rod: which bov do you have? there are 2 different things you can hear on a sy/ty.
1. compressor surge. This the Chuf-chuf-chuf sound you hear when you let off the throttle and there is no bov, or its adjusted so tight it never opens. This is air trying to go backwards through the turbo.
2. The "fluttering" you could be hearing that is more of a series of smaller bov sounds is when the bob isn't adjusted quite right, and opens and closes several times in a row. If you're getting this when you let off at WOT, then you want to soften up the preload on the bov's spring just a little bit.
HotRudyRod
New member
Re: wastegate and bov
Thanks Spinall4, actually i dont have a BOV. It started making those loud chuff noises when i changed the stock turbo for a 20G. It doesnt necesarily do it when im completely at WOT but yeah it does increase the number of chuffs as i get closer to it. Im thinking it could be that the wastegate is just working better than on the old turbo, it had 89k miles when i changed it.
Thanks Spinall4, actually i dont have a BOV. It started making those loud chuff noises when i changed the stock turbo for a 20G. It doesnt necesarily do it when im completely at WOT but yeah it does increase the number of chuffs as i get closer to it. Im thinking it could be that the wastegate is just working better than on the old turbo, it had 89k miles when i changed it.
Don W.
Stab it and steer it
Re: wastegate and bov
Great thread with lots of good info, except… Big over-the-road diesels don’t have throttle butterflies. They draw a full charge of air every time, are direct (into the cylinder) injection and are throttled by the amount of fuel delivered. Consequently there’s not any compressor surge and no need for a BOV. Some small, non-turbo, automotive diesels notably the older Mercedes use a throttle butterfly in the intake to generate some vacuum to operate the power brake unit. (And generate smoke.
)
Just FYI
SY2932 said:
Great thread with lots of good info, except… Big over-the-road diesels don’t have throttle butterflies. They draw a full charge of air every time, are direct (into the cylinder) injection and are throttled by the amount of fuel delivered. Consequently there’s not any compressor surge and no need for a BOV. Some small, non-turbo, automotive diesels notably the older Mercedes use a throttle butterfly in the intake to generate some vacuum to operate the power brake unit. (And generate smoke.
Just FYI
SY2932
Administrator
Re: wastegate and bov
Read "MANY high mileage trucks" to mean high mileage syclones and typhoons...
As far as BOV's go, I have been venting boost to the atmosphere since 2000 :lol:
Don W. said:Great thread with lots of good info, except… Big over-the-road diesels don’t have throttle butterflies. They draw a full charge of air every time, are direct (into the cylinder) injection and are throttled by the amount of fuel delivered. Consequently there’s not any compressor surge and no need for a BOV. Some small, non-turbo, automotive diesels notably the older Mercedes use a throttle butterfly in the intake to generate some vacuum to operate the power brake unit. (And generate smoke.)
Just FYI
Read "MANY high mileage trucks" to mean high mileage syclones and typhoons...
As far as BOV's go, I have been venting boost to the atmosphere since 2000 :lol: