Supercharging the Vin C - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

Reply
 
 
 
Thread Tools Search this Thread
Old 07-16-2006, 03:44 PM   #21
Senior Member
Certified Car Nut
 
Join Date: Mar 2003
Posts: 12,432
Thanks: 0
Thanked 0 Times in 0 Posts
J Wikoff is on a distinguished road
Default

The only thing the PCM does to our bypass is open it when boost isn't wanted... engine problems, during shifting, in park, throttle lift off... With the bypass plumbed to the LIM, there is a possiblity that you will have full boost all the time. Routing it to the normal spot will best simulate intended operation. I am positive on this point.
J Wikoff is offline   Reply With Quote
Old 07-16-2006, 03:53 PM   #22
Senior Member
Certified Car Nut
 
Join Date: Mar 2003
Posts: 12,432
Thanks: 0
Thanked 0 Times in 0 Posts
J Wikoff is on a distinguished road
Default

L67'* that unhook the BCS get normal bypass operation as far as creating boost is concerned. The BCS introduces boost pressure to the lower half of the BCA to close the valve.

The way you have it is an unknown, as far as I'm concerned.
J Wikoff is offline   Reply With Quote
Old 07-16-2006, 07:23 PM   #23
Junior Member
 
Join Date: May 2006
Location: BonnevilleHell
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
clm2112 is on a distinguished road
Default

Quote:
Originally Posted by J Wikoff
L67'* that unhook the BCS get normal bypass operation as far as creating boost is concerned. The BCS introduces boost pressure to the lower half of the BCA to close the valve.

The way you have it is an unknown, as far as I'm concerned.
Ok, did some playing with a vac pump and the valve. Here'* what I'm seeing:

Vac applied to the top chamber opens the valve, released the springs close it.
Vac applied to the lower chamber locks the valve closed.
Vac applied to both also leaves the valve closed.
Positive pressure applied to the lower chamber Opens the valve.

When the boost control solenoid is off, it is connecting the lower chamber to the lower intake manifold.
When the boost control solenoid is on, it is connecting the lower chamber to outside air through the foam filter on the end of it.

So, based on that, the only thing the ECM can command the valve to do is open (by turning it off electrically), provided it the lower intake manifold has a positive pressure. In other words, it can only dump the excess boost pressure from the lower intake manifold back into the plenum to recycle it back through the blower. Correct?

That said, connecting the upper chamber to the upper intake manifold is in effect trying the valve to the throttle plate. (Valve stays open in all states except WOT when the plenum vac goes away?)
clm2112 is offline   Reply With Quote
Old 07-17-2006, 12:25 AM   #24
Senior Member
Certified Car Nut
 
Join Date: Mar 2003
Posts: 12,432
Thanks: 0
Thanked 0 Times in 0 Posts
J Wikoff is on a distinguished road
Default

The BCA is designed is such a way that it opens (or closes) the wastegate valve proportionally to the throttle valve by using the pressure differential between atmospheric pressure and pressure/vacuum behind the throttle plate. The BCS normally supplies atmosperic pressure to the lower half. When the top pressure equals the bottom pressure (WOT, as the throttle plate isn't restricting airflow), it closes the valve fully. That is why the valve sits closed when the engine isn't running. When the PCM sees fit, it supplies LIM pressure (positive) that would make WOT (0 psi) look like no throttle (-10ish psi) to the BCA and it will open the wastegate.
J Wikoff is offline   Reply With Quote
Old 07-17-2006, 12:52 AM   #25
Senior Member
Certified Car Nut
 
Join Date: Mar 2003
Posts: 12,432
Thanks: 0
Thanked 0 Times in 0 Posts
J Wikoff is on a distinguished road
Default

After rereading your last post, it seems like you got it (I'm tired). Except that it'* not just open or closed. It can be anywhere in between. Although, I don't know when the BCS is on.
J Wikoff is offline   Reply With Quote
Old 07-17-2006, 12:57 PM   #26
Junior Member
 
Join Date: May 2006
Location: BonnevilleHell
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
clm2112 is on a distinguished road
Default

Quote:
Originally Posted by J Wikoff
After rereading your last post, it seems like you got it (I'm tired). Except that it'* not just open or closed. It can be anywhere in between. Although, I don't know when the BCS is on.
Thanks. I was thinking of it like the secondaries of a carb that open based on load, not like an overflow valve to dump the excess boost. So back to plumbing it to the plenum port and leaving the lower chamber vented to outside air.

Another thing mentioned was the Fuel Pressure Regulator. It'* plumbed to the LIM'* ports. Does it work like other Rochester FPR'* in that it dumps excess fuel back to the tank when it sees vac? (In other words, excess rail pressure will force the FPR open to lower the rail pressure, or high manifold vac will open the FPR to lower the rail pressure)

Just curious what sort of rail pressures I should be seeing when testing the FPR out.

Last, anyone know the injector specs on the SC'd motors. They look like regular pintle type injectors, but I'm not comming up with a flow specification on them based on their Rochester PN from my usual sources.
clm2112 is offline   Reply With Quote
Old 07-17-2006, 01:03 PM   #27
Junior Member
Posts like a Ricer Type-R
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

You have the description correct for FPR operation. You need a 3.0bar regulator to support the SC.

The Series 1 L67 injectors from 92-95 are 29lb injectors. They can effectively and safely be raised to a higher effective flow with better atomization of the fuel by increasing your fuel pressure at the rail, but you must scan and use your fuel trims to dial it in.
willwren is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
whats the difference between a vin#l or vin #n 3800? terry69 1992-1999 11 04-11-2005 11:10 PM
Will 99 Vin K Grand Prix fit in a 96 Vin K Bonneville? parallelcircuits 1992-1999 3 03-08-2004 02:31 AM
VIN number reader/history on VIN number ne 1 hav this progrm SSEimatt93 General GM Chat 1 07-04-2003 01:42 AM
Will a Vin 1 lower end work in VIN L car??? OLBlueEyesBonne 1992-1999 1 07-03-2003 12:59 AM
supercharging a series 1 90_bonnie 1987-1991 7 07-22-2002 10:06 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 09:20 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.