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| 3800SC -- Info needed (Page 1/2) |
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Spoon
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OCT 28, 10:23 PM
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I completed my 3800sc swap a few months ago and I believe I may have a problem with the supercharger. (2000 GTP donor). I'm just starting to put my foot into it and I'm not getting that "screaming for mercy sound" like the conversions I've heard on Youtube.
All the vac lines are correct for this year engine. When I start the engine the Bypass Arm goes from the 3 o'clock position and rises to the 12 position viewed when standing at rear of car. As I goose the throttle that bypass arm will modulate in direct proportion as expected.
So I isolated the 2 vac lines upper & lower from the BBV and attached a vac hose to the upper port and drew a vacuum using a separate source, engine off of course. When the bypass arm would rise to 12 o'clock I would cap off the vacuum expecting it to hold it's position. It would slowly go back to the 3 o'clock position within 3 to 4 seconds. Again there is nothing attached to the lower vac port on the BBV.
Experience with unrelated equipment tells me there is a ruptured diaphragm in the BBV or is this the way it's suppose to work or bleed-down?
I'm also not interested in clamping the BBV into boost position due to the increase heat being generated.
Spoon
86 SE 4 spd.
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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
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ericjon262
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OCT 28, 10:29 PM
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use a mighty vac or similar to pull your vacuum, it's way more accurate.
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Spoon
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OCT 29, 07:44 AM
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| quote | Originally posted by ericjon262:
use a mighty vac or similar to pull your vacuum, it's way more accurate. |
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I know, my MIghty-Vac bit the dust some time ago. Used it so little it stopped pulling a vacuum. Appeared to be a sealed unit as I remember.
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
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BadNewsBrendan
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OCT 29, 09:29 AM
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Have you tried using an ODB2 scanner to see what the map sensor is reading under acceleration? I'm usually seeing 3 psi at idle and around 12 psi at WOT and 4500 rpm. I think thats a little higher than it actually is and I am sure these map sensors aren't super accurate. Are the videos you've seen using smaller pulleys than stock? Believe that would make more noise. The supercharger whine on my car with the stock pulley doesn't seem as loud as some of the videos ive seen and only can be heard at probably 75% plus throttle but that might also have to do with how loud my exhaust is. [This message has been edited by BadNewsBrendan (edited 10-29-2019).]
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Dennis LaGrua
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OCT 29, 10:01 AM
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May I suggest adding a vacuum/boost gauge so that you can see the actual boost that the supercharger is making. ------------------
" 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, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, 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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BadNewsBrendan
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OCT 29, 10:27 AM
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^ definitely the more accurate and probably easier way to go than i suggested 
I already run most of my gauges off a tablet and ODB2 so thats what was in my head.
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OntarioKev
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OCT 29, 09:44 PM
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Checking the actual boost being made is a good start to diagnosing any issues the SC may be experiencing.
On another note a SC on factory pully with an airbox intake (without the silencer holes plugged) is not really loud.
Most of the SC Whine you hear in videos are from a combination of smaller pulley, open intake, and silencer holes plugged.
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Spoon
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OCT 29, 10:01 PM
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| quote | Originally posted by BadNewsBrendan:
Have you tried using an ODB2 scanner to see what the map sensor is reading under acceleration? I'm usually seeing 3 psi at idle and around 12 psi at WOT and 4500 rpm. I think thats a little higher than it actually is and I am sure these map sensors aren't super accurate. Are the videos you've seen using smaller pulleys than stock? Believe that would make more noise. The supercharger whine on my car with the stock pulley doesn't seem as loud as some of the videos ive seen and only can be heard at probably 75% plus throttle but that might also have to do with how loud my exhaust is.
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Scanner is on it's way, Actron CP9680. I'll figure out whats going on soon.
I don't know what size pulleys were used in the videos I saw.
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
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Spoon
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OCT 29, 10:12 PM
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| quote | Originally posted by Dennis LaGrua:
May I suggest adding a vacuum/boost gauge so that you can see the actual boost that the supercharger is making.
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Dennis, I have my eye on a Auto Meter 4301 Vac-Boost gauge. I currently have a pillar pod installed with 2 gauges in it. AirFuel-Ratio and Fuel Pressure. One of them will have to go. Think I'll remove the AirFuel Ratio gauge and put the Vac-Boost in its place. I've seen pillar pods for 3 but they look too busy for me.
Spoon------------------
"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
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Spoon
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OCT 29, 10:18 PM
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| quote | Originally posted by OntarioKev:
Checking the actual boost being made is a good start to diagnosing any issues the SC may be experiencing.
On another note a SC on factory pully with an airbox intake (without the silencer holes plugged) is not really loud.
Most of the SC Whine you hear in videos are from a combination of smaller pulley, open intake, and silencer holes plugged. |
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Tell me more about these silencer holes and what airbox? Fiero or aftermarket.?
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
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