Results 1 to 10 of 10

Thread: 4" Downpipe & Exhaust, any such animal 4 the 6.5td?

  1. #1
    Join Date
    Apr 2004
    Location
    Palm Beach, Florida
    Posts
    1,816

    Default 4" Downpipe & Exhaust, any such animal 4 the 6.5td?

    See some statements that people are running 4" turbo/back systems on 6.5td's. I can't find anything other than 3" downpipe w/transition to 4" back, any full 4" systems out there, or?
    99 GMC SUB, 2500, 4x4, 6.5 TD (F) #H32 enhanced blk, Phaser timing set, B&D IC, 3" ATS exh, K&N w/prefilter, 4WD NVG 246, 4L80E kevlar Transgo off road/tow mods/B&M supercooler, 14 FF MagTec w/locker 3.42:1, 9.25" IFS frt/diff 3.42:1 w/ARB locker, AutoMeter Boost & pre-turbo pyro meter, 12,000 lb hydro winch, Warn classic bumper w/brushguard & diesel scoop, Max E-torq Stage 3, hi pop inj, oil bypass sys, on board air comp for front ARB locker & tire inflation, DynaView driving/auto-cornering lts, DZ nerfs, A/T 285/75/16 SilentArmor 3750 lb rated on 3750 lb rated Alcoa, 3 IP drivers 2 r spares.

  2. #2
    Join Date
    Nov 2003
    Location
    COLORADO
    Posts
    723

    Default

    I don't think that anyone manufactures bigger than 3" for the down pipe then 4" the rest of the way. I built my own out of 3.5" mandrel bends, I personally don't see 4" fitting without major rubbing. My 3.5" is bad enough.
    white '93 K2500 started it all..
    red '94 K3500 old faithful
    black '93 K3500 daily driver
    '83 G20 conversion van
    '74 C65 truck diesel conversion...

  3. #3
    Join Date
    Jul 2003
    Location
    Allentown, PA
    Posts
    1,355

    Default

    Ditto what DD said above - actually I'm surprised he even got a 3.5" downpipe to fit! 3" downpipe is pretty much the standard. I wonder if a bigger downpipe would even show any legitimate gains? The biggest factor is probably having the pipes mandrel bent.
    1998 K2500 Suburban 6.5L TD 3.73 rear, Ron Schoolcraft 18:1, Kennedy ECM & IC, Timing gears, Splayed main caps, 3.5" Kennedy Exhuast/No Cat, K&N Filter, Boost/Tranny Temp/EGT(Pre Turbo), Ceramic-coated Manifolds, 195 Stat's, 265/75's (VSSB Adjusted) 7,000lbs (on a scale) Remote Mount Oil Filter, Remote Oil Pressure Sensor

  4. #4
    Join Date
    Apr 2004
    Location
    Palm Beach, Florida
    Posts
    1,816

    Default 4" Downpipe

    I'm diggin deep into this and going to somehow fab an oval 4" downpipe to clear chassis and motor. I already have a 3" inside diameter turbine housing connector for a downpipe and thinking a 3" round to 4" oval transition will work using oval pipe for downpipe then back to a 4" round outlet for rest of exhaust.

    What I'm seeing is restriction at turbine housing going to outlet, porting and a larger 4" diameter downpipe would work wonders for the 6.5td.

    The following link will give ya an idea of parts that can be used.
    http://www.spintechmufflers.com/spin...ntechindex.asp
    99 GMC SUB, 2500, 4x4, 6.5 TD (F) #H32 enhanced blk, Phaser timing set, B&D IC, 3" ATS exh, K&N w/prefilter, 4WD NVG 246, 4L80E kevlar Transgo off road/tow mods/B&M supercooler, 14 FF MagTec w/locker 3.42:1, 9.25" IFS frt/diff 3.42:1 w/ARB locker, AutoMeter Boost & pre-turbo pyro meter, 12,000 lb hydro winch, Warn classic bumper w/brushguard & diesel scoop, Max E-torq Stage 3, hi pop inj, oil bypass sys, on board air comp for front ARB locker & tire inflation, DynaView driving/auto-cornering lts, DZ nerfs, A/T 285/75/16 SilentArmor 3750 lb rated on 3750 lb rated Alcoa, 3 IP drivers 2 r spares.

  5. #5
    Join Date
    Oct 2003
    Location
    Huntington In
    Posts
    1,367

    Default That would be Cool,4" ovel down pipe

    Getting the bends in it for a down pipe would be interesting
    Can they be bent? Maybe by getting the pipe cherry red where the bend needs to be?
    95C3500.Ext.Cab 97 Cooling mods. DSG Gear-1.95 TDCO. Bilstein Shocks. Firestone Air Bags. FSD Cooler. Banks EX System. Egt,Boost & IAT Gauges. JK High Flow/pop Injectors. Turbo-Master. Max-E 2.0. Water/Alky Injection. Amsoil Dual Bypass. Baldwin filter. aFe Air filter, Air box & Turbo Mods. Power Service Product. Large Duels 235/85-16. Tool Box\'s & truck, 8200 lbs.

  6. #6
    Join Date
    Nov 2003
    Location
    COLORADO
    Posts
    723

    Default

    IMO, 3" is plenty big enough with the GM turbo. No matter what it is still the biggest restriction in the system. Bigger can't hurt though. Another thing to consider is how well does oval tubing flow?
    white '93 K2500 started it all..
    red '94 K3500 old faithful
    black '93 K3500 daily driver
    '83 G20 conversion van
    '74 C65 truck diesel conversion...

  7. #7
    Join Date
    Oct 2003
    Location
    Huntington In
    Posts
    1,367

    Lightbulb

    I say use the oval pipes for running boards and EX. into them. Now that's COOL! Slash cut the ends. NASCAR style
    95C3500.Ext.Cab 97 Cooling mods. DSG Gear-1.95 TDCO. Bilstein Shocks. Firestone Air Bags. FSD Cooler. Banks EX System. Egt,Boost & IAT Gauges. JK High Flow/pop Injectors. Turbo-Master. Max-E 2.0. Water/Alky Injection. Amsoil Dual Bypass. Baldwin filter. aFe Air filter, Air box & Turbo Mods. Power Service Product. Large Duels 235/85-16. Tool Box\'s & truck, 8200 lbs.

  8. #8
    Join Date
    Apr 2004
    Location
    Palm Beach, Florida
    Posts
    1,816

    Default Oval Flow?

    Quote Originally Posted by dieseldummy
    IMO, 3" is plenty big enough with the GM turbo. No matter what it is still the biggest restriction in the system. Bigger can't hurt though. Another thing to consider is how well does oval tubing flow?
    Been thinking about the oval tube flow and thinking it's a non issue on a turbo motor that likes rapid expansion of gasses after turbine a 3" 14ga pipe has 6.33 sq inches, a 4" 16ga pipe has 11.76 sq inches.

    The cost of the oval & bent tubes is excessive so thinking of splitting a downpipe and welding in flat panels to make it oval.
    Last edited by DA BIG ONE; 04-11-2006 at 04:12.
    99 GMC SUB, 2500, 4x4, 6.5 TD (F) #H32 enhanced blk, Phaser timing set, B&D IC, 3" ATS exh, K&N w/prefilter, 4WD NVG 246, 4L80E kevlar Transgo off road/tow mods/B&M supercooler, 14 FF MagTec w/locker 3.42:1, 9.25" IFS frt/diff 3.42:1 w/ARB locker, AutoMeter Boost & pre-turbo pyro meter, 12,000 lb hydro winch, Warn classic bumper w/brushguard & diesel scoop, Max E-torq Stage 3, hi pop inj, oil bypass sys, on board air comp for front ARB locker & tire inflation, DynaView driving/auto-cornering lts, DZ nerfs, A/T 285/75/16 SilentArmor 3750 lb rated on 3750 lb rated Alcoa, 3 IP drivers 2 r spares.

  9. #9
    Join Date
    Oct 2005
    Location
    wisconsin
    Posts
    134

    Talking D.B.O. Sounds like a project

    Quote Originally Posted by DA BIG ONE
    I already have a 3" inside diameter turbine housing connector for a downpipe and thinking a 3" round to 4" oval transition will work using oval pipe for downpipe then back to a 4" round outlet for rest of exhaust.
    Building an Oval Downpipe that is. Does that mean you will be using the new downpipe you just got? Thats ok - Ill just stop anguishing for the UPS man to stop at my door with it! Rick
    95K3500.Ext.Cab 4L80E 200,000 + miles; 3 gauge pillar pod pre turbo temp- boost- trans temp. 97 Cooling mods Fan / fan clutch, dual Tstat and water pump, Hi Pop Injectors, fast heat glow plugs, DSG gears, intake snorkel removed, air box mods, hi idle mod, dMax pipes for exhaust, FSD mounted on intake, Monroe Shocks. Homemade cooler lines, H7B coolers replace stock trans and oil devices, remote mount with 2 quart Wix filter aux micron filter, OPS relay and headlight boosters, glow plug extender, and an FPPF cocktail in every tank.

  10. #10
    Join Date
    Apr 2004
    Location
    Palm Beach, Florida
    Posts
    1,816

    Default Whoops!

    Quote Originally Posted by stingthieves
    Building an Oval Downpipe that is. Does that mean you will be using the new downpipe you just got? Thats ok - Ill just stop anguishing for the UPS man to stop at my door with it! Rick
    NOPE, That pipe is different and yours, however, after checking it's sitting all packed up for shipping in the back of my son's truck when it is supposed to be on it's way to you, SORRY!
    99 GMC SUB, 2500, 4x4, 6.5 TD (F) #H32 enhanced blk, Phaser timing set, B&D IC, 3" ATS exh, K&N w/prefilter, 4WD NVG 246, 4L80E kevlar Transgo off road/tow mods/B&M supercooler, 14 FF MagTec w/locker 3.42:1, 9.25" IFS frt/diff 3.42:1 w/ARB locker, AutoMeter Boost & pre-turbo pyro meter, 12,000 lb hydro winch, Warn classic bumper w/brushguard & diesel scoop, Max E-torq Stage 3, hi pop inj, oil bypass sys, on board air comp for front ARB locker & tire inflation, DynaView driving/auto-cornering lts, DZ nerfs, A/T 285/75/16 SilentArmor 3750 lb rated on 3750 lb rated Alcoa, 3 IP drivers 2 r spares.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •