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View Full Version : GM Turbo 3.1 V6 vacuum block help (very long)



TurboSedan
10-31-2006, 06:01 PM
i'm posting this here because the Turbo Mopar guys seem to be alot more familiar with manifold distribution blocks then the other forums i go to.:thumb:

for starters, i own a '91 Oldsmobile Cutlass Supreme sedan with a 3.1L V6 that i turbocharged using parts from a '90 ASC/McLaren Turbo Grand Prix.

i would really like to add a manifold distribution block to the plenum (like i did with my T2 '89 GTS). my 3.1's original vacuum harness is made up of hard plastic lines that are prone to cracking/deteriorating etc. the MAP/FPR and cruise conrtrol/HVAC lines run under the plenum, so they are impossible to access without removing the plenum. like a Turbo Mopar, the original vacuum lines are sourced from the top of the throttle body.

here is a pic of the top of my 3.1 throttle body to give you an idea of what i'm talking about:

http://www.turbosedan.com/cutlass/engine/gauges7.jpg

the vacuum lines are coming from the factory 'vacuum block' that is on top of the TB. this factory vacuum block is used to source the canister purge solenoid, vacuum EGR, cruise control/HVAC (shared) and MAP/FPR (shared). as you can see from the pic, i had to remove the vacuum line for the cruise control/HVAC so i could rig up a boost gauge to work. just recently i deleted the vacuum EGR completely by drilling out and & tapping the EGR hole in the plenum for 1/2" NPT and then JB Welding allen head set screws into the EGR mounting holes as you can see here:

http://www.turbosedan.com/cutlass/engine/DSC02928.JPG

as you can see i capped off the line that previously went to the vacuum EGR (the yellow cap). i temporarily installed a 1/2" NPT plug until i can find a manifold distribution block that will work for my application.

deleting EGR also meant turning off the EGR function in the chip (so no check engine light) and cutting the EGR bung off the turbo crossover pipe and welding it shut:

http://www.turbosedan.com/cutlass/engine/DSC02929.JPG

now, i want to keep the factory vacuum block on top of the plenum but ONLY for the canister purge solenoid source. this is because of the way the passages inside the TB/vacuum block are designed (the CP solenoid only gets a vacuum signal depending on throttle blade angle.)

however, i want to mount a manifold distribution block to source:

- MAP sensor
- FPR
- cruise control/HVAC (will be sharing the same vacuum line again)
- vacuum/boost gauge
- possibly a hobbs switch for alcohol injection later on

i already have a perfect place on the other side of the plenum to source my TurboXS RFL BOV :thumb: so i'm good to go there. btw, that fitting just happened to be the ONLY extra fitting the plenum had, so the whole reason i deleted EGR was so i could mount a distribution block to source all of the extra things i listed above (not to mention no longer having crappy hard plastic lines that are inaccessible under the plenum). fwiw i have my M&M Racing MBC sourced from the fitting on the compressor cover and i want to keep it that way.

now looking back at this pic:

http://www.turbosedan.com/cutlass/engine/DSC02928.JPG

i measured the area around it and what i need is a manifold distribution block that is NO LONGER than 4" in length (preferably more like 3.5"). if it is 4" long the block cannot stick out further from the EGR flange surface more than 1" or the thottle arm will interfere with it when at WOT. if it is 3.5" long or shorter than it can stick out as much as i need it to without throttle arm interferance (although i don't want it to stick out any more than needed)

i could only find ONE feasible option at McMaster-Carr: PN# 5085K26

- because of the mounting scheme i need, the inlets would actually need to serve as the outlets and vice-versa. this is because the distribution block i need must have an inlet (the source) that is not on the outer ends of the block like the ones McMaster-Carr sells. the inlet cannot be on the outer end because i want to mount it parallel to the plenum neck & as close as possible (so it looks nice). i don't want to mount the block sticking straight out because that would be downright fugly and i don't want it spaced out from the plenum neck too far since that would be ugly too IMO.

- since the source (inlet) can't be on the outer end of the block, it would also need to be a 3 port block for two reasons. first - a 4 port block would be too long to fit. and 2nd - it couldn't be mounted on center with the 1/2" NPT hole in my plenum since it dosen't have an odd # of inlets.

McMaster-Carr PN# 5085K26 measures 3.25" long x 1.25" x 1.25" so it would fit my application great with no clearance issues. the block has 3/8" outlets and 1/4" inlets (remember, the inlets & outlets are going to be used opposite in my application). since PN# 5085K26 is double sided it has 3 inlets on each side, however the other two (outer) inlets (on the plenum/source side) would have to be plugged since there would obviously be no room to access them with the plenum/EGR flange surface right there behind it. ALSO, the outlets on the end might need to be plugged since the plenum is in the way on one side and the throttle body is in the way on the other side of the block. i say "might" becuase if the block is short enough i could probably get away with using 90* fittings if i have enough room (that would be really nice if it worked out).

so that leaves me with 3 outlets i could use at a minimum, and possibly 5 outlets i could use max if the outlets on the outer end can be used.

if you can't tell already, this McMaster-Carr block might not be the best solution for me :o

what i REALLY want, is something like this in a shorter 3 port version:

center inlet source :)
http://www.turbosedan.com/cutlass/engine/DSC02960.JPG

only meausures 3/4" x 3/4" so it would be an easier fit :)
http://www.turbosedan.com/cutlass/engine/DSC02961.JPG

with a 3 port version, i could remove those plugs in the end and tap them for 5 outlets total :)
http://www.turbosedan.com/cutlass/engine/DSC02963.JPG

if anyone knows where i can find this brand of distribution block, or one very similar, or even someone that has one in GOOD shape for sale, please let me know!!!! otherwise i'm going to go ahead and try that McMaster-Carr block.

thank you very much for taking the time to read my book :D

any suggestions, help, advice etc is certainly welcome.

--------------------------------------------
Joshua Mitchell
'89 Lebaron GTS Turbo - T2/A555 - 1 of 268
'91 Cutlass Supreme sedan - 3.1 Intercooled Turbo/Getrag HM-282 5-speed - 227whp/325wtq

mcsvt
11-01-2006, 11:25 AM
TU has just added a vaccuum block to there website recently. I wonder if it is more the size you are looking for.
Here is the link (http://turbosunleashed.com/shop/product_info.php?products_id=269&osCsid=823f4d84cde8880d8d5d71616f98c974)

I will see if I can find something else as well.

turbovanmanČ
11-01-2006, 01:58 PM
I didn't go thru all the pics but on the back of the upper plenum, you have the brake booster elbow, I would remove that then you can remove mount your vacuum block anywhere you want, then use rubber hose from the intake to your vacuum block.

TurboSedan
11-01-2006, 03:41 PM
TU has just added a vaccuum block to there website recently. I wonder if it is more the size you are looking for.
Here is the link (http://turbosunleashed.com/shop/product_info.php?products_id=269&osCsid=823f4d84cde8880d8d5d71616f98c974)

I will see if I can find something else as well.

YES! that is exactly the style vacuum block i'm looking for. i wonder if TU can get those in a 3 port (on the side) version? i'll have to call Chris and ask him about that. actually, that one pictured might work since it's so short, but i'd be limited to 4 ports and i really want 5 ports.

thanks for the help!
--------------------------------------------
Joshua Mitchell
'89 Lebaron GTS Turbo - T2/A555 - 1 of 268
'91 Cutlass Supreme sedan - 3.1 Intercooled Turbo/Getrag HM-282 5-speed - 227whp/325wtq

TurboSedan
11-01-2006, 03:50 PM
I didn't go thru all the pics but on the back of the upper plenum, you have the brake booster elbow, I would remove that then you can remove mount your vacuum block anywhere you want, then use rubber hose from the intake to your vacuum block.

i've considered doing just that, but i'd have to have a fitting that spaced the distribution block out pretty far since the bracket for my MAP sensor and cansiter purge solenoid surround the hole for the vacuum brake booster line. i'm worried the block would stick so far out it might hit the firewall during hard launches etc.

i'd also have to relocate the vacuum source for the brakes, which i really don't want to do. fwiw, i've even considered mounting the distribution block in the location of the IAT sensor (aka charge air sensor in Turbo Mopar terms) BUT i was worried the different location of the IAT sensor might throw off temp signal for the ECM.

thanks for the suggestion though, they are always welcome :thumb:
--------------------------------------------
Joshua Mitchell
'89 Lebaron GTS Turbo - T2/A555 - 1 of 268
'91 Cutlass Supreme sedan - 3.1 Intercooled Turbo/Getrag HM-282 5-speed - 227whp/325wtq

TurboSedan
11-23-2006, 10:07 AM
got it all taken care of using the TU distribution block. pics here:

http://www.turbo-mopar.com/forums/showthread.php?t=9297

--------------------------------------------
Joshua Mitchell
'89 Lebaron GTS Turbo - T2/A555 - 1 of 268
'91 Cutlass Supreme sedan - 3.1 Intercooled Turbo/Getrag HM-282 5-speed - 254whp/360wtq

GLHSKEN
11-23-2006, 10:14 AM
Good for you... nice car