Wastegates, BOVs

5-lO · 08-07-2003, 10:46 PM

BOVs release boost when itis too high I know, but what are the other things it does. Can I get a full over view.

A Wastegate seems to do a job similar to that of a BOV but I am relativley turbo-stupid do im not sure. Also, they are best used for 7lbs of boost and up correct?

Jon

Doug · 08-08-2003, 09:52 AM

Bov doesn't work like that. If just releases that excess pressure when you throttle body closes so you don't get compressor surge and ruin your turbo. Wastegate does what you thought the BOV does except it is on the manifold and vents exahust to by-pass going through the turbo and that controls the boost.

AMRAAM4 · 08-08-2003, 11:43 AM

Too add another version to Doug's (correct me if I am wrong). I tried to keep it really dumbed down:

Wastegate: Controls the amount of boost by bleeding off excess exhaust you do not want to enter into the turbo. So if you have 20lbs. of boost coming out your exhaust, and want to push 10lbs at the turbo, then the wastegate will relieve that other 10lbs by regulating the total exhaust flow. This is why people port their wastegate. If they have a big turbo they may need to release much more air, and quicker. It will help when setting the wastegate to it's parameter.

BOV: When the TB closes there is still air being fed through the piping. You DON'T want that to go backwards into the turbo or get stuck in transit for when you open that TB again. Thus when the TB closes, the BOV is located after the turbo and "cleans out the piping". Hence the PSSSHHHHH you here. Turbo's can run up to 20,000RPMs to create boost, it doesn't feel very well asking that "fan" to all of a sudden go in reverse!

kubiache · 08-08-2003, 07:39 PM

hmm...new info to me, too. Thanks guys.

08-08-2003, 10:43 PM

The primary purpose of a blow off valve is to keep the turbo in a near spooled condition between shifts on a "manual trans equipped" car.

The reversion wave created due to a rapid off throttle is typically not enough to actually reverse a turbine wheel, but it does slow the wheel down substantially, and can present components with excessive stress.

Blow off valves are not used by OEM's on automatic trans. equipped cars, as the throttle plate is open between shifts.

Doug · 08-09-2003, 02:01 PM

automatic supras and rx-7s have them. But GM doesn't use the,.

08-09-2003, 03:34 PM

Yes, and neither do Saab, Mitsubishi, Subaru, and numerous others. The limited "marketing ploys" of a few are irrelevant, the fact is that BOV's are not needed for automatic equipped turbo applications.

AMRAAM4 · 08-09-2003, 03:42 PM

I concur with Doug. And I don't think people include them for "marketing ploys"

The RSM SC has a blow off valve. Aren't all our 3400's auto's? Why did they include it then???

08-09-2003, 04:10 PM

The "bypass valve" on a roots type supercharger is the functional equivalent of the wastegate on a turbo, (i.e. actually controlling boost levels) with an added benefit of reducing cavitation and parasitic loss under certain conditions. Therefore, the type of transmission used on these supercharged applications does not determine the requirement for a bypass valve, it is used for both the automatic and manual trans, just as a wastegate is always required on a turbocharger.
Some roots supercharger systems employ a clutch on the drive, thereby foregoing the need for a bypass valve.

A blow off valve used on a centrifigal supercharger system would offer very little performance benefit on an automatic trans. application. It is also pretty damn hard to slow an impeller driven by a belt down, so a blow off valve on a centrifigally supercharged application would not provide a performance benefit as it does on a manual equipped turbocharged car, although it would help to prevent component stress.
The slight reduction of parasitic loss during cruise and idle conditions, can also provide a bit of an increase in gas mileage.

AMRAAM4 · 08-09-2003, 05:48 PM

Quote:

Originally posted by Mechanic
It is also pretty damn hard to slow an impeller driven by a belt down, so a blow off valve on a centrifigally supercharged application would not provide a performance benefit as it does on a manual equipped turbocharged car, although it would help to prevent component stress.

I don't know of one BOV that does provide a performance benefit. They are all there for the later of your statement.

08-09-2003, 05:51 PM

Then I suggest you do a simple test. Remove the BOV vacuum line from a turbocharged manual trans car and take it for a drive. Then replace the line and compare the difference.

Everything I have stated is considered to be very elementary concepts of forced induction systems. With the vast amount of technical material available on the net, it really does not require that much effort to acquaint yourself with these facts...

AMRAAM4 · 08-09-2003, 07:46 PM

The BOV might allow the turbo system to "perform" better, meaning functionally, but it won't provide a "performance" benefit in output.

If you think so, go to the rx7club message board and ask "What BOV provides the best performance benefit". It's entertaining to see the veterans answer that question that many young newbs post.

08-09-2003, 07:56 PM

A faster spoolup after a shift DOES increase performance, is that really a hard concept to grasp??
Compare the effect on track times of a turbo that needs to respool after a closed throttle shift, to a turbo that is still spooled when you release the clutch..

AMRAAM4 · 08-09-2003, 08:08 PM

OK, clearly someone has a bigger penis than the rest of us so this will be my last post.

...unfortunately that bigger penis must make him shift extremely slow where the BOV makes that much a difference during the milliseconds the TB closes and opens.

For anyone whose interested. Get an average of your 1/4 times, then install a new BOV. I think you'll see your 1/4 times to be the same on average.

08-09-2003, 08:13 PM

Go spew your foul mouthed BS elsewhere you idiot little punk..

5-lO · 08-09-2003, 08:23 PM

Guys come on,... I need information not fighting,...

AMRAAM4 · 08-09-2003, 08:33 PM

Have to jump in again, Sorry Free...someone felt the need to come in and 1 UP everyone else. And yes, I am an "idiot little punk" wtf

wtf

Here are just a couple I found expressing info on BOVs/wastegates. Nothing about performance benefits mentioned AT ALL.
Linky 1

Linky 2

Linky 3

Linky 4

Linky 5

08-09-2003, 08:43 PM

If all you can muster is a few links to an Rx7 board in a pathetic attempt to prove you BS, you are even dumber than I thought. Go buy a clue..

AMRAAM4 · 08-09-2003, 08:57 PM

Quote:

Originally posted by Mechanic
If all you can muster is a few links to an Rx7 board in a pathetic attempt to prove you BS, you are even dumber than I thought. Go buy a clue..

Please stop acting like a 12 year old. Your adding nothing to the thread, and haven't really since you posted your "turbo parts manifesto". Unlike GAs, RX7's happen to actually have a Turbo, so please, stop bantering back like you are Mr. Lingenfelter fresh out of the hospital.

nocutt · 08-09-2003, 09:33 PM

I am with mechanic here...he stated facts and not fiction: 1/4 mile doesn't equate to what he is trying to relate...simple autos "do not necessarily need" a BOV but manual will do better with them...this is like the tranny cooler theory...does it really help? The point is to get the longevity of your precious turbo put a BOV especially if you have an manual...heck put one if you have an auto...performance? subjective? functionality very objective...it does what it was originally inteneded to do...the sound became a marketing tool!!

08-07-2003, 10:46 PM	#1
5-lO Just bought a. . . AKA: Jon Join Date: Apr 2003 Location: Evanston, IL Age: 35 Posts: 2,950 Vehicle: 15 HD 48 XL1200X	Wastegates, BOVs BOVs release boost when itis too high I know, but what are the other things it does. Can I get a full over view. A Wastegate seems to do a job similar to that of a BOV but I am relativley turbo-stupid do im not sure. Also, they are best used for 7lbs of boost and up correct? Jon __________________ CURRENT: WHATEVER I WANT OFF THE DEALER LOT AND 15 HARLEY DAVIDSON SPORTSTER 48: LED HEADLAMP, TURNS AND TAILS, PYTHON BLACK SLIP ONS, SCREAMING EAGLE BLACK EXHAUST SHIELDS. PREVIOUS: 03 GAGT, 04 MAZDASPEED MX-5, 06 TC, 02 SEVILLE STS, 07 HARLEY DAVIDSON NIGHTESTER, 10 MAZDA3 S SPORT MANUAL, 06 SUZUKI KATANA, 11 MAZDA 3 S GRAND TOURING MANUAL TECH, 13 MAZDASPEED3

08-08-2003, 09:52 AM	#2
Doug Hairdryer Power Join Date: Aug 2002 Location: Dublin, OH Age: 36 Posts: 623 Vehicle: 2000 SE-T	Bov doesn't work like that. If just releases that excess pressure when you throttle body closes so you don't get compressor surge and ruin your turbo. Wastegate does what you thought the BOV does except it is on the manifold and vents exahust to by-pass going through the turbo and that controls the boost. __________________ http://www.n-body.net/registry/yeahdoug/ 2000 Grand Am SE1 ex-turbo 1987 Supra Turbo 5 spd Targa 14.2 @100 with only I/E

08-08-2003, 11:43 AM	#3
AMRAAM4 Wiley 'Ol Veteran AKA: Bob (aka Hoss) Join Date: Aug 2002 Location: Azerbaijan Age: 45 Posts: 6,935 Vehicle: See My Signature Block	Too add another version to Doug's (correct me if I am wrong). I tried to keep it really dumbed down: Wastegate: Controls the amount of boost by bleeding off excess exhaust you do not want to enter into the turbo. So if you have 20lbs. of boost coming out your exhaust, and want to push 10lbs at the turbo, then the wastegate will relieve that other 10lbs by regulating the total exhaust flow. This is why people port their wastegate. If they have a big turbo they may need to release much more air, and quicker. It will help when setting the wastegate to it's parameter. BOV: When the TB closes there is still air being fed through the piping. You DON'T want that to go backwards into the turbo or get stuck in transit for when you open that TB again. Thus when the TB closes, the BOV is located after the turbo and "cleans out the piping". Hence the PSSSHHHHH you here. Turbo's can run up to 20,000RPMs to create boost, it doesn't feel very well asking that "fan" to all of a sudden go in reverse! __________________ 2016 GoMango Challenger SRT Hellcat 2014 Redline Pearl Jeep Grand Cherokee SRT 2018 Bruiser Grey Dodge Durango SRT TRADED-2004 Black Grand Am GT,2004 Impulse Blue GTO M6, 2012 Mineral Gray Jeep SRT8, 2010 Bright Silver Jeep SRT8 LEASE TURN-IN-2006 Summit White TrailBlazer SS AWD (Vector CAI & tune) SOLD-2000 Silvermist Grand Am GT Supercharged,1994 Daytona Blue Single Turbo RX7 (427whp/330wtq), 2006 Spice Red GTO A4, 2013 Grabber Blue Shelby GT500 Last edited by AMRAAM4; 08-08-2003 at 08:10 PM.

08-08-2003, 07:39 PM	#4
kubiache Get blown Join Date: Feb 2003 Location: Grand Rapids, MI Age: 42 Posts: 1,858 Vehicle: 1998 GTP	hmm...new info to me, too. Thanks guys. __________________ Dave Woodward '01 GA SE --- 14.864 @ 92.61mph.....NA '98 GTP - NIC cam / P&P heads / 105# springs / Titanium retainers / INTENSE LW pushrods / CC Lifters / INTENSE TCS-300 / ZZP Poly mounts / RT 3" DP / PEMs / ZZP MPS 3.2, 3.0 / Wizair / 103s / DHP / AFC 2.2 .......still tuning

08-09-2003, 02:01 PM	#6
Doug Hairdryer Power Join Date: Aug 2002 Location: Dublin, OH Age: 36 Posts: 623 Vehicle: 2000 SE-T	automatic supras and rx-7s have them. But GM doesn't use the,. __________________ http://www.n-body.net/registry/yeahdoug/ 2000 Grand Am SE1 ex-turbo 1987 Supra Turbo 5 spd Targa 14.2 @100 with only I/E

08-08-2003, 10:43 PM	#5
Mechanic Guest Posts: n/a	The primary purpose of a blow off valve is to keep the turbo in a near spooled condition between shifts on a "manual trans equipped" car. The reversion wave created due to a rapid off throttle is typically not enough to actually reverse a turbine wheel, but it does slow the wheel down substantially, and can present components with excessive stress. Blow off valves are not used by OEM's on automatic trans. equipped cars, as the throttle plate is open between shifts.

08-09-2003, 03:34 PM	#7
Mechanic Guest Posts: n/a	Yes, and neither do Saab, Mitsubishi, Subaru, and numerous others. The limited "marketing ploys" of a few are irrelevant, the fact is that BOV's are not needed for automatic equipped turbo applications. Last edited by Mechanic; 08-09-2003 at 03:40 PM.

08-09-2003, 03:42 PM	#8
AMRAAM4 Wiley 'Ol Veteran AKA: Bob (aka Hoss) Join Date: Aug 2002 Location: Azerbaijan Age: 45 Posts: 6,935 Vehicle: See My Signature Block	I concur with Doug. And I don't think people include them for "marketing ploys" The RSM SC has a blow off valve. Aren't all our 3400's auto's? Why did they include it then??? __________________ 2016 GoMango Challenger SRT Hellcat 2014 Redline Pearl Jeep Grand Cherokee SRT 2018 Bruiser Grey Dodge Durango SRT TRADED-2004 Black Grand Am GT,2004 Impulse Blue GTO M6, 2012 Mineral Gray Jeep SRT8, 2010 Bright Silver Jeep SRT8 LEASE TURN-IN-2006 Summit White TrailBlazer SS AWD (Vector CAI & tune) SOLD-2000 Silvermist Grand Am GT Supercharged,1994 Daytona Blue Single Turbo RX7 (427whp/330wtq), 2006 Spice Red GTO A4, 2013 Grabber Blue Shelby GT500

08-09-2003, 04:10 PM	#9
Mechanic Guest Posts: n/a	The "bypass valve" on a roots type supercharger is the functional equivalent of the wastegate on a turbo, (i.e. actually controlling boost levels) with an added benefit of reducing cavitation and parasitic loss under certain conditions. Therefore, the type of transmission used on these supercharged applications does not determine the requirement for a bypass valve, it is used for both the automatic and manual trans, just as a wastegate is always required on a turbocharger. Some roots supercharger systems employ a clutch on the drive, thereby foregoing the need for a bypass valve. A blow off valve used on a centrifigal supercharger system would offer very little performance benefit on an automatic trans. application. It is also pretty damn hard to slow an impeller driven by a belt down, so a blow off valve on a centrifigally supercharged application would not provide a performance benefit as it does on a manual equipped turbocharged car, although it would help to prevent component stress. The slight reduction of parasitic loss during cruise and idle conditions, can also provide a bit of an increase in gas mileage. Last edited by Mechanic; 08-09-2003 at 05:48 PM.

08-09-2003, 05:51 PM	#11
Mechanic Guest Posts: n/a	Then I suggest you do a simple test. Remove the BOV vacuum line from a turbocharged manual trans car and take it for a drive. Then replace the line and compare the difference. Everything I have stated is considered to be very elementary concepts of forced induction systems. With the vast amount of technical material available on the net, it really does not require that much effort to acquaint yourself with these facts... Last edited by Mechanic; 08-09-2003 at 06:44 PM.

08-09-2003, 07:46 PM	#12
AMRAAM4 Wiley 'Ol Veteran AKA: Bob (aka Hoss) Join Date: Aug 2002 Location: Azerbaijan Age: 45 Posts: 6,935 Vehicle: See My Signature Block	The BOV might allow the turbo system to "perform" better, meaning functionally, but it won't provide a "performance" benefit in output. If you think so, go to the rx7club message board and ask "What BOV provides the best performance benefit". It's entertaining to see the veterans answer that question that many young newbs post. __________________ 2016 GoMango Challenger SRT Hellcat 2014 Redline Pearl Jeep Grand Cherokee SRT 2018 Bruiser Grey Dodge Durango SRT TRADED-2004 Black Grand Am GT,2004 Impulse Blue GTO M6, 2012 Mineral Gray Jeep SRT8, 2010 Bright Silver Jeep SRT8 LEASE TURN-IN-2006 Summit White TrailBlazer SS AWD (Vector CAI & tune) SOLD-2000 Silvermist Grand Am GT Supercharged,1994 Daytona Blue Single Turbo RX7 (427whp/330wtq), 2006 Spice Red GTO A4, 2013 Grabber Blue Shelby GT500

08-09-2003, 07:56 PM	#13
Mechanic Guest Posts: n/a	A faster spoolup after a shift DOES increase performance, is that really a hard concept to grasp?? Compare the effect on track times of a turbo that needs to respool after a closed throttle shift, to a turbo that is still spooled when you release the clutch.. Last edited by Mechanic; 08-09-2003 at 08:06 PM.

08-09-2003, 08:08 PM	#14
AMRAAM4 Wiley 'Ol Veteran AKA: Bob (aka Hoss) Join Date: Aug 2002 Location: Azerbaijan Age: 45 Posts: 6,935 Vehicle: See My Signature Block	OK, clearly someone has a bigger penis than the rest of us so this will be my last post. ...unfortunately that bigger penis must make him shift extremely slow where the BOV makes that much a difference during the milliseconds the TB closes and opens. For anyone whose interested. Get an average of your 1/4 times, then install a new BOV. I think you'll see your 1/4 times to be the same on average. __________________ 2016 GoMango Challenger SRT Hellcat 2014 Redline Pearl Jeep Grand Cherokee SRT 2018 Bruiser Grey Dodge Durango SRT TRADED-2004 Black Grand Am GT,2004 Impulse Blue GTO M6, 2012 Mineral Gray Jeep SRT8, 2010 Bright Silver Jeep SRT8 LEASE TURN-IN-2006 Summit White TrailBlazer SS AWD (Vector CAI & tune) SOLD-2000 Silvermist Grand Am GT Supercharged,1994 Daytona Blue Single Turbo RX7 (427whp/330wtq), 2006 Spice Red GTO A4, 2013 Grabber Blue Shelby GT500

08-09-2003, 08:13 PM	#15
Mechanic Guest Posts: n/a	Go spew your foul mouthed BS elsewhere you idiot little punk.. Last edited by Mechanic; 08-09-2003 at 08:17 PM.

08-09-2003, 08:23 PM	#16
5-lO Just bought a. . . AKA: Jon Join Date: Apr 2003 Location: Evanston, IL Age: 35 Posts: 2,950 Vehicle: 15 HD 48 XL1200X	Guys come on,... I need information not fighting,... __________________ CURRENT: WHATEVER I WANT OFF THE DEALER LOT AND 15 HARLEY DAVIDSON SPORTSTER 48: LED HEADLAMP, TURNS AND TAILS, PYTHON BLACK SLIP ONS, SCREAMING EAGLE BLACK EXHAUST SHIELDS. PREVIOUS: 03 GAGT, 04 MAZDASPEED MX-5, 06 TC, 02 SEVILLE STS, 07 HARLEY DAVIDSON NIGHTESTER, 10 MAZDA3 S SPORT MANUAL, 06 SUZUKI KATANA, 11 MAZDA 3 S GRAND TOURING MANUAL TECH, 13 MAZDASPEED3

08-09-2003, 08:33 PM	#17
AMRAAM4 Wiley 'Ol Veteran AKA: Bob (aka Hoss) Join Date: Aug 2002 Location: Azerbaijan Age: 45 Posts: 6,935 Vehicle: See My Signature Block	Have to jump in again, Sorry Free...someone felt the need to come in and 1 UP everyone else. And yes, I am an "idiot little punk" wtf wtf Here are just a couple I found expressing info on BOVs/wastegates. Nothing about performance benefits mentioned AT ALL. Linky 1 Linky 2 Linky 3 Linky 4 Linky 5 __________________ 2016 GoMango Challenger SRT Hellcat 2014 Redline Pearl Jeep Grand Cherokee SRT 2018 Bruiser Grey Dodge Durango SRT TRADED-2004 Black Grand Am GT,2004 Impulse Blue GTO M6, 2012 Mineral Gray Jeep SRT8, 2010 Bright Silver Jeep SRT8 LEASE TURN-IN-2006 Summit White TrailBlazer SS AWD (Vector CAI & tune) SOLD-2000 Silvermist Grand Am GT Supercharged,1994 Daytona Blue Single Turbo RX7 (427whp/330wtq), 2006 Spice Red GTO A4, 2013 Grabber Blue Shelby GT500 Last edited by AMRAAM4; 08-09-2003 at 08:53 PM.

08-09-2003, 08:43 PM	#18
Mechanic Guest Posts: n/a	If all you can muster is a few links to an Rx7 board in a pathetic attempt to prove you BS, you are even dumber than I thought. Go buy a clue..

08-09-2003, 09:33 PM	#20
nocutt Platinium member Join Date: Aug 2002 Location: Lost Angels Posts: 59 Vehicle: '88 chevrolet Beretta	I am with mechanic here...he stated facts and not fiction: 1/4 mile doesn't equate to what he is trying to relate...simple autos "do not necessarily need" a BOV but manual will do better with them...this is like the tranny cooler theory...does it really help? The point is to get the longevity of your precious turbo put a BOV especially if you have an manual...heck put one if you have an auto...performance? subjective? functionality very objective...it does what it was originally inteneded to do...the sound became a marketing tool!! __________________ v6 turbo

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