3800SC removal of SC Bypass ? (Page 1/2)
Lou6t4gto NOV 22, 03:07 PM
Is there a Major "Downside" to removing the SC "Bypass valve" ???? Thanks
Darth Fiero NOV 22, 05:40 PM
I wouldn't call it a major downside, but removing the BBV actuator and just blocking the BBV closed full time will make the supercharger work harder at all times which CAN increase wear, reduce fuel economy, and build heat in the blower housing when it isn't necessary (ie: at idle and part throttle).

There is absolutely zero performance to be gained from removing the BBV actuator and blocking the BBV closed at all times.

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More is more. Less is not enough.

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

Lou6t4gto NOV 22, 07:09 PM
Only reason I'm asking is it makes it easier to use the Fiero thermostat housing. Has anyone got a picture of the Fiero thermostat housing on a 3800 With the bypass valve "In place" ? Thanks
djlamp14 NOV 22, 09:22 PM
Use the 3800 t stat housing. Leave that bypass valve alone. No reason to remove it. It's not difficult to bleed the system if you have a jack.

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11.8@115mph 1/4 mile 1999 Regal GSX
11.044@122mph 1/4 mile 87 Fiero GT
11.8 sec pass>>http://www.youtube.com/watch?v=SQT4X2eBlR8
11.044 pass>>https://youtu.be/FsboH9Ba7ZY

Spoon NOV 22, 09:48 PM
Not sure who's pic this is but perhaps it will help. I'm also on the 3800 bandwagon gathering parts.




Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

Lou6t4gto NOV 22, 10:33 PM
That's what I needed. I have to "tilt" the housing a little more where I did the cut/weld it the first time. (but it Will Work) .
I already have a 3800SC using the 3800 housing, and using a 3rd heater hose (capped off) for a filler . I'd rather the Fiero housing.
Dennis LaGrua NOV 22, 10:58 PM

quote
Originally posted by Spoon:

Not sure who's pic this is but perhaps it will help. I'm also on the 3800 bandwagon gathering parts.




Spoon




This looks like a new bracket was made to move the BBV away from the thermostat housing. On a separate note I have been running w/o the BBV solenoid for 6 years with no ill effects. I've run several other cars with Weiand roots blowers and all survived a long time w/o BBV's . I do not doubt that the BBV is helpful in a small way but I read a while back on the Eaton site that it was put there primarily to cut down on noise. I was just wondering how much of a delay the BBV causes when you hit WOT. The BBV is open at idle and cruise and it is directed by the PCM to close when the throttle opens wide. So the process is that sensor signals are sent to the PCM that the throttle blade has been made wide open by the driver slamming the gas pedal. The PCM receives those signals and then sends a signal to the BBV to close. The BBV solenoid is activated and must react. Solenoids do not close instantaneously . I would guess that you would lose a .5 to 1 second in the process.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
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djlamp14 NOV 23, 09:13 PM
the little electronic sensor is for traction control. That is fine to remove. We are talking about the vacuum actuated valve that controls when the engine creates boost. The PCM has absolutely nothing to do with the bypass valve. That is 100% taken care of by throttle response. Past vacuum is boost. That is when the BV closes. Anytime in vacuum the BV has suction therefor the BV is open.

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11.8@115mph 1/4 mile 1999 Regal GSX
11.044@122mph 1/4 mile 87 Fiero GT
11.8 sec pass>>http://www.youtube.com/watch?v=SQT4X2eBlR8
11.044 pass>>https://youtu.be/FsboH9Ba7ZY

phonedawgz NOV 23, 09:20 PM
Same type of argument was used to dismiss vacuum secondarys. If it was anything near a second, GM wound have never used it. Did you drive the 3800 before you pulled it? Did you notice any lag?
Darth Fiero NOV 23, 09:24 PM

quote
Originally posted by Dennis LaGrua:


I do not doubt that the BBV is helpful in a small way but I read a while back on the Eaton site that it was put there primarily to cut down on noise. I was just wondering how much of a delay the BBV causes when you hit WOT. The BBV is open at idle and cruise and it is directed by the PCM to close when the throttle opens wide. So the process is that sensor signals are sent to the PCM that the throttle blade has been made wide open by the driver slamming the gas pedal. The PCM receives those signals and then sends a signal to the BBV to close. The BBV solenoid is activated and must react. Solenoids do not close instantaneously . I would guess that you would lose a .5 to 1 second in the process.




The boost solenoid has nothing to do with normal supercharger and BBV actuator operation. The boost solenoid is PCM controlled and is only activated when the PCM wants to prevent any boost pressure from building - such as when you are in reverse gear, nearing the top speed limiter (and perhaps during an abuse condition), or perhaps during deceleration. Aside from that, the boost solenoid is energized all the time to permit normal BBV "boost enabled" operation. In all the swaps I do, the boost solenoid is removed from the engine since it does not perform any essential operation. I leave the BBV actuator installed and working unless the customer directs me to remove it.

The BBV actuator is 100% vacuum controlled unless the boost solenoid is de-energized which permits boost pressure to act upon it, which forces the BBV open. The actuator closes the BBV once the throttle is opened enough to prevent a certain level of manifold vacuum to build in the blower housing between the "roots" of the blower and the throttle body.

The BBV actuator is very fast acting. Suffice it to say it will permit boost pressure to build as fast as you are physically able to open the throttle to full. So it induces NO perceivable lag whatsoever, if we are talking about throttle response time in terms of how quickly boost can build. In other words, you are never going to notice a "usable" performance increase by removing the BBV actuator and blocking the BBV closed to force the blower to produce boost at all times.

Removing the BBV actuator and blocking the BBV closed to permit boost pressure to build at all times could possibly help the engine produce more power at moderate throttle positions. Installing a throttle with a progressive linkage would have the same effect. However, this small benefit does NOT outweigh the extra wear and tear and temperature increase you'll likely see put on the blower by removing the BBV actuator. And since nobody races down the dragstrip at half throttle, I see no benefit whatsoever to removing the BBV actuator.