Blow Off Valves
07-26-2005, 02:30 PM
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04 E55
Blow Off Valves
I thought Blow Off Valves were for turbos. What the hell are they thinking? Maybe they are for W210's that add turbos?
http://www.horsepowerfreaks.com/pric...low_Off_Valves
http://www.horsepowerfreaks.com/pric...low_Off_Valves
07-26-2005, 02:35 PM
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Blowoff valves are used in just about any forced induction application. My supercharger has one. You're probably thinking of a wastegate. Only turbos have those.
07-26-2005, 04:52 PM
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Originally Posted by Josh K
Blowoff valves are used in just about any forced induction application. My supercharger has one. You're probably thinking of a wastegate. Only turbos have those.
so where can i find a BOV for my 05c230?
i didnt think we could put bovs on... interesting news
07-26-2005, 05:24 PM
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2003 E55 AMG
Blow Off Valves or Bypass valves as they are also called are present on EVERY forced induction application. The E55 has one on each side of the engine (from what I can remember) located near the front. It is a round, brassy-silver coloured metal piece with a black rubber tube coming out of the top.
If a F.I. car didnt have a bypass valve/B.O.V. the pressurized air would slam back into the impellers of the supercharger under vacuum (when you suddenly lift on the accelerator). This would cause impeller stall and could actually damage the supercharger. (this is mostly true for centrifugal superchargers and not so true for lysholm types like ours but it does have a negative effect on ours also).
Typically, a blow off valve will vent to atmosphere (which is what makes the woosh noise you usually hear in between shifts) and bypass valves usually vent back into the intake tract (making them practically silent).
The E55 have BYPASS valves which vent back into the intake tract and that is why you dont really hear them. Also, changing the Blow off valve from venting into the intake tract to atmosphere GREATLY depends on its LOCATION with respect to the MAF.
If the B.O.V is located AFTER the MAF, usually it vents back into the intake tract because the air has already been metered and "seen" by the ECU. If the B.O.V is located BEFORE the MAF you can safely vent to atmosphere becuase it hasnt been seen by the ECU and therefore wont affect air/fuel mixture.
If a F.I. car didnt have a bypass valve/B.O.V. the pressurized air would slam back into the impellers of the supercharger under vacuum (when you suddenly lift on the accelerator). This would cause impeller stall and could actually damage the supercharger. (this is mostly true for centrifugal superchargers and not so true for lysholm types like ours but it does have a negative effect on ours also).
Typically, a blow off valve will vent to atmosphere (which is what makes the woosh noise you usually hear in between shifts) and bypass valves usually vent back into the intake tract (making them practically silent).
The E55 have BYPASS valves which vent back into the intake tract and that is why you dont really hear them. Also, changing the Blow off valve from venting into the intake tract to atmosphere GREATLY depends on its LOCATION with respect to the MAF.
If the B.O.V is located AFTER the MAF, usually it vents back into the intake tract because the air has already been metered and "seen" by the ECU. If the B.O.V is located BEFORE the MAF you can safely vent to atmosphere becuase it hasnt been seen by the ECU and therefore wont affect air/fuel mixture.
07-26-2005, 05:40 PM
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Originally Posted by vrus
Blow Off Valves or Bypass valves as they are also called are present on EVERY forced induction application. The E55 has one on each side of the engine (from what I can remember) located near the front. It is a round, brassy-silver coloured metal piece with a black rubber tube coming out of the top.
If a F.I. car didnt have a bypass valve/B.O.V. the pressurized air would slam back into the impellers of the supercharger under vacuum (when you suddenly lift on the accelerator). This would cause impeller stall and could actually damage the supercharger. (this is mostly true for centrifugal superchargers and not so true for lysholm types like ours but it does have a negative effect on ours also).
Typically, a blow off valve will vent to atmosphere (which is what makes the woosh noise you usually hear in between shifts) and bypass valves usually vent back into the intake tract (making them practically silent).
The E55 have BYPASS valves which vent back into the intake tract and that is why you dont really hear them. Also, changing the Blow off valve from venting into the intake tract to atmosphere GREATLY depends on its LOCATION with respect to the MAF.
If the B.O.V is located AFTER the MAF, usually it vents back into the intake tract because the air has already been metered and "seen" by the ECU. If the B.O.V is located BEFORE the MAF you can safely vent to atmosphere becuase it hasnt been seen by the ECU and therefore wont affect air/fuel mixture.
If a F.I. car didnt have a bypass valve/B.O.V. the pressurized air would slam back into the impellers of the supercharger under vacuum (when you suddenly lift on the accelerator). This would cause impeller stall and could actually damage the supercharger. (this is mostly true for centrifugal superchargers and not so true for lysholm types like ours but it does have a negative effect on ours also).
Typically, a blow off valve will vent to atmosphere (which is what makes the woosh noise you usually hear in between shifts) and bypass valves usually vent back into the intake tract (making them practically silent).
The E55 have BYPASS valves which vent back into the intake tract and that is why you dont really hear them. Also, changing the Blow off valve from venting into the intake tract to atmosphere GREATLY depends on its LOCATION with respect to the MAF.
If the B.O.V is located AFTER the MAF, usually it vents back into the intake tract because the air has already been metered and "seen" by the ECU. If the B.O.V is located BEFORE the MAF you can safely vent to atmosphere becuase it hasnt been seen by the ECU and therefore wont affect air/fuel mixture.
-m
07-26-2005, 07:15 PM
#6
AMG Kompressor engines (C32/SLK32, E/S/SL/G/CL/CLS55) do not have bypass valve. DME uses the clutch to disengage the kompressor instead of bypassing it.
Two brass valves that are on each side of the kompressor are for secondary air injection.
Two brass valves that are on each side of the kompressor are for secondary air injection.
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07-26-2005, 09:41 PM
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2003 E55 AMG
Vadim:
Really? Thanks for the info. I had no idea and just assumed the brass valves were bypass valves. Thanks for clearing that up!! It's odd that they disengage the clutch for the compressor.. Does that mean when you lift off the accelerator and get back on it that the clutch is actually disengaging and then re-engaging?? That can't be too efficient.
Daren_Dallas:
As for not having a MAF, I knew about that since I couldnt spot one anywhere in the engine bay. I only spoke of MAFs to help explain the placement/use of the blow-off valves. Thanks for confirming it though.
Marcus:
Thanks.
Really? Thanks for the info. I had no idea and just assumed the brass valves were bypass valves. Thanks for clearing that up!! It's odd that they disengage the clutch for the compressor.. Does that mean when you lift off the accelerator and get back on it that the clutch is actually disengaging and then re-engaging?? That can't be too efficient.
Daren_Dallas:
As for not having a MAF, I knew about that since I couldnt spot one anywhere in the engine bay. I only spoke of MAFs to help explain the placement/use of the blow-off valves. Thanks for confirming it though.
Marcus:
Thanks.
Originally Posted by Vadim @ evosport
AMG Kompressor engines (C32/SLK32, E/S/SL/G/CL/CLS55) do not have bypass valve. DME uses the clutch to disengage the kompressor instead of bypassing it.
Two brass valves that are on each side of the kompressor are for secondary air injection.
Two brass valves that are on each side of the kompressor are for secondary air injection.
07-27-2005, 12:29 AM
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E55, GLS450, GL63, GLE350
Victor, the clutch is actually engaging and disengaging when you go from WOT to vacuum. Mercedes did this for better gas mileage. However, a Lysholm with a functional BOV/recirculation valve uses very little power at cruising speed under vacuum conditions. I think I remember reading that the blower uses less than 1 hp under a steady cruise at 60 mph because it's basically free spinning but under boost at 6,000 rpm it's using around 120 hp to turn.
The electronic clutch is very neat but IMHO it makes the unit less dependable. The clutch is evential going to fail but the bypas valve is much less prone to failure.
Here is a little more information on the blowers with internal bypass valves.
http://www.magnusonproducts.com/bypass.htm
http://www.magnusonproducts.com/mp112.htm
The electronic clutch is very neat but IMHO it makes the unit less dependable. The clutch is evential going to fail but the bypas valve is much less prone to failure.
Here is a little more information on the blowers with internal bypass valves.
http://www.magnusonproducts.com/bypass.htm
http://www.magnusonproducts.com/mp112.htm
