Is there an advantage either way if I decide to delete my supercharger bypass? My thinking is that it can be one less thing to screw up, but I don't know which way would be the way to go.
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05:57 PM
PFF
System Bot
Dennis LaGrua Member
Posts: 15822 From: Hillsborough, NJ U.S.A. Registered: May 2000
Deleting the BBV is a hotly debated topic. Some guys feel that they are really needed while others like myself don't use one. From what I have read the BBV was put there to decrease supercharger noise and to relieve some of the supercharging loading at low speed operation. I didn't want anything interferring with or delaying the boost coming on so I pinned the BBV lever down, removed the actuator and DTC code from the PCM. Three years later no ill effects but I did lose a tiny bit of gas mileage; maybe 0.7 mpg on the highway. For those that claim damage can result w/o the BBV; I have seen no damage. I actually took the supercharger off last summer, inspected it and everything was clean,tight, the rotor coatings were all there, and it turned smooth with no binding.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
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06:26 PM
Pete Matos Member
Posts: 2291 From: Port St. Lucie, Florida Registered: Jan 2010
I didn't want anything interferring with or delaying the boost coming on so I pinned the BBV lever down, removed the actuator and DTC code from the PCM.
I like the way you think. lol I'm leaning towards deleting it as well, but I wanted some input as to what people were doing with respect to this and if there were side effects. thanks for the input. Troy
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07:23 PM
fieroaddicted Member
Posts: 662 From: aylesford, nova scotia canada Registered: Dec 2012
That's funny - I was watching "My Classic Car" on Velocity the other day. Dennis was visiting the guy that owns the Mad Max Movie car. It was pretty interesting - the blower is a fake monuted above the Carb but it still has the internals so it makes that "whine" we all love! I love those movies - watched the Marathon the other day!
Quoting myself as I feel like it sums up my argument.
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Originally posted by Fierobsessed:
It will never produce boost at an idle, but there will be a pressure differential on either side of the blower, a stronger vacuum on the inlet. This causes load on the blower drive, and the crank. I can't quantify the amount. But that really just effects gas mileage.
The long story short, the Boost Bypass Valve REDUCES or eliminates PRESSURE DIFFERENTIALS across the blowers roots, and this reduces the load on the blower drive and increases gas mileage. It's secondary function is to limit boost. Nothing to do with noise really. The effect is the greatest at low/part throttles on the highway, when the RPM's are higher, and the engine load is low or moderate.
Then there is the argument that the reaction time on the BBV when the throttle is stabbed effecting boost reaction performance. This is an overstated delay. The valve is pretty darn quick. It could be sped up if its vacuum ports were enlarged, but its still probably faster then you can push your throttle, and faster still then the engine reacts to the throttle, so what is it improving?
Honestly, it's just better left alone. That's my personal opinion.
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10:16 PM
Dennis LaGrua Member
Posts: 15822 From: Hillsborough, NJ U.S.A. Registered: May 2000
The long story short, the Boost Bypass Valve REDUCES or eliminates PRESSURE DIFFERENTIALS across the blowers roots
Big deal. What is so terrible about a bit of pressure differential. I inspected the supercharger after two years running w/o a BBV and again nothing looked worn or out of spec. The internals of the supercharger still looked clean and new. Even the coupling was still tight.
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and this reduces the load on the blower drive and increases gas mileage.
Agreed but the decrease in mileage was very minimal. Worth removal as there one less area to possibly malfunction.
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It's secondary function is to limit boost. Nothing to do with noise really.
Call Eaton tech service and ask if the BBV's job is to help reduce noise. Eaton is where I got the info from
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The effect is the greatest at low/part throttles on the highway, when the RPM's are higher, and the engine load is low or moderate.
This means absolutely nothing until you can prove that limiting boost has some benefical effect.
If you like the BBV use it but outside of a bit more noise, and a tiny bit more mileage, I am unable to find any benefit to it
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 01-02-2013).]
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10:57 PM
fieroaddicted Member
Posts: 662 From: aylesford, nova scotia canada Registered: Dec 2012
I was going to keep it, but now I'm thinking of just deleting it.. What's the best way to pin down the valve? I was thinking maybe drill and tap a VERY small hole through the valve stop screw then drill small hole in the valve lever and using a small screw.
Its like deleting cruise control because you dont like lookng at the button on your steering wheel. Yeah the cruise wiring is heavy and decreases performance technically but if its installed and workjng already why remove it for .5lb weight savings ?
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09:43 AM
PFF
System Bot
Dennis LaGrua Member
Posts: 15822 From: Hillsborough, NJ U.S.A. Registered: May 2000
I was going to keep it, but now I'm thinking of just deleting it.. What's the best way to pin down the valve? I was thinking maybe drill and tap a VERY small hole through the valve stop screw then drill small hole in the valve lever and using a small screw.
I measured carefully and then driiled an 1/8" hole through both the BBV lever and the stop screw stub below. Then used a 1/4" long pop rivet to hold it. There are several other methods but this seems easy to do. BTW, in as much as you can get away with removal of the BBV with the leaky rotors of the roots type Easton M90, this is no way implies that you can do this on all superchargers. With a TVS or Whipple the pressure differentials are greater and a good BBV is required.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
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09:49 AM
fieroaddicted Member
Posts: 662 From: aylesford, nova scotia canada Registered: Dec 2012
That's funny - I was watching "My Classic Car" on Velocity the other day. Dennis was visiting the guy that owns the Mad Max Movie car. It was pretty interesting - the blower is a fake monuted above the Carb but it still has the internals so it makes that "whine" we all love! I love those movies - watched the Marathon the other day!
And to add - I have done 2 3800 SC swaps - both had the BBV pinned closed and both ran fine - no issues with either one.
LOL that is a CLASSIC car guy movie, it is just awesome when he pulls that lever and the blower kicks on and the car takes off. I know it would be doable mechanically to make some kinda clutch to drive the blower but getting it to work with the computer at NO boost and then at boost and finding a way to bypass the blower for no boost intake could be a real ***** . Wonder if it has ever been done before on any car in REALITY? Peace
LOL that is a CLASSIC car guy movie, it is just awesome when he pulls that lever and the blower kicks on and the car takes off. I know it would be doable mechanically to make some kinda clutch to drive the blower but getting it to work with the computer at NO boost and then at boost and finding a way to bypass the blower for no boost intake could be a real ***** . Wonder if it has ever been done before on any car in REALITY? Peace
Pete
Mercedes SLK 230 has an electronic supercharger clutch, it is similar to an A/C clutch.
Why anyone wants to limit thier MPG's is strange to me. I would keep the BBV, it's free gas.
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12:10 PM
darkhorizon Member
Posts: 12279 From: Flint Michigan Registered: Jan 2006
LOL that is a CLASSIC car guy movie, it is just awesome when he pulls that lever and the blower kicks on and the car takes off. I know it would be doable mechanically to make some kinda clutch to drive the blower but getting it to work with the computer at NO boost and then at boost and finding a way to bypass the blower for no boost intake could be a real ***** . Wonder if it has ever been done before on any car in REALITY? Peace
Pete
The stock bypass operates like this from the factory. In cobalts they run it as a torque management in first gear to limit boost for traction.
You could wire a simple ground switch to the solenoid to toggle on and off full boost and ~2psi... No tricks required.
Its like deleting cruise control because you dont like lookng at the button on your steering wheel. Yeah the cruise wiring is heavy and decreases performance technically but if its installed and workjng already why remove it for .5lb weight savings ?
Wait..The Fiero doesnt have a CC button on the steering wheel....
I have removed them on ever swap I have done but one. Just how I roll..
