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#1 |
Senior Member
![]() Join Date: Apr 2016
Location: Cypress, TX
Posts: 3,698
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One or two ducts to center vent?
In the LMC catalog there is an option for buying plugs to replace one of the hoses to the A/C center vent (plugs are item 16). And in the Brothers catalog they have a special adapter for the center vent that only has a fitting for one hose, and they are claiming on their website and in a video that output of the center vent is increased by 40% by using their one-hose adapter because when using 2 hoses there is a canceling effect. They are saying "A similar modification was illustrated by GM back in 1972 to fix the problem of poor center vent volume." Does anybody have any experience with this one-hose-to-the-center-vent idea vs. the factory design?
Last edited by dmjlambert; 11-27-2016 at 03:54 PM. |
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#2 | |
Old member
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 19,936
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1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 ![]() Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. |
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#3 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: One or two ducts to center vent?
I disagree that going from two hoses to one would increase the flow. They still, in theory, should carry more air than a single pipe, even though limited and constricted at the end by the same outlet.
But two might be largely redundant. GM likely went to 1 because they found it did almost as good a job and saved money and simplified routing.
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#4 |
Registered User
Join Date: Jul 2015
Location: North East PA
Posts: 682
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Re: One or two ducts to center vent?
the static presure or the air would increase by going with a single duct, but you will loose CFM ,(Cubic ft per min ) because you are transitioning the air flow in to a smaller area.
What i am trying to say is ....its like turning your water hose on and then puting your finger over half the outlet of the hose.......... |
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#5 |
Registered User
Join Date: Jul 2015
Location: North East PA
Posts: 682
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Re: One or two ducts to center vent?
The only real way to upgrade your HVAC system would be to increase the size of your entire HVAC system .. including hot water coil, evap coil and compressor and also fan size and all ductiong and outlets.
Although I only have a heating system in my truck that I use every single day ,I have not had any issue as far as the ability of the stock system to heat or defrost the cab at all , |
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#6 | |
Senior Member
![]() Join Date: Apr 2016
Location: Cypress, TX
Posts: 3,698
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Re: One or two ducts to center vent?
Quote:
The ultimate for my Texas truck would be to run one duct to the center vent, and run the other duct on top of the hump (or through a console) to under the seat, then up into the bench seat and into a network of permeable material just under cloth upholstery in the driver's seat and seat back. A seat cooler. |
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#7 |
Florida Edition
![]() ![]() Join Date: Oct 2010
Location: Fruitland Park, FL
Posts: 4,025
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Re: One or two ducts to center vent?
The system was designed to blow from both sides so it came out of the duct evenly in a cross pattern. I blocked the driverside so it blows at me in the driver's seat.
__________________
70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394 |
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#8 |
Registered User
Join Date: Jun 2008
Location: Moss Point,Ms.
Posts: 1,439
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Re: One or two ducts to center vent?
I also blocked the drivers side of the center vent.
I'm greedy and wanted all the air on me! Mike. ![]() |
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a/c, center vent, ducts |
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