Jump to content

Exhaust pipe sizes for 6.0L

willscary

Recommended Posts

willscary Enthusiast

willscary

Posted
Posted

My 8600 gvw 2003 2500 has a 2-1/2" tail pipe. The 2500HD has a 3" tailpipe. IS this why the GM page lists the HD 6000 as 300hp and 360 ft. lbs. torque, while the light duty is listed at 320hp and 365 ft. lbs. torque in 2003? Why the different size pipe?

redvett Senior Enthusiast

redvett

Posted
Posted
My 8600 gvw 2003 2500 has a 2-1/2" tail pipe.  The 2500HD has a 3" tailpipe.  IS this why the GM page lists the HD 6000 as 300hp and 360 ft. lbs. torque, while the light duty is listed at 320hp and 365 ft. lbs. torque in 2003?  Why the different size pipe?

 

 

 

 

The two engines are in two different familys HD & LD 6L. They are certified different & the internals are different. Most likely the cam exhaust, heads, :cool: PCM calibrations and more.

willscary Enthusiast

willscary

Posted
  • Author
Posted

They make 2 different motors and call them both an LQ4? I understand the high output LQ9 is a different 6.0L motor, but why would they call 2 motors with different internals the same (LQ4)?

redvett Senior Enthusiast

redvett

Posted
Posted
They make 2 different motors and call them both an LQ4?  I understand the high output LQ9 is a different 6.0L motor, but why would they call 2 motors with different internals the same (LQ4)?

 

 

 

 

I hope you are still talking the difference between the 03 & 04 MY. They are 2 different models and HP is different. Just like the 04 5.3 is 295 HP and the 05 is 310HP. Here are the 04 LQ4 engines and there are 3 total.

 

325 hp (243 kw) @ 5200 rpm (Sierra Denali/Yukon/Yukon XL, Suburban) (revised 12/17/03)

315 hp (235 kw) @ 5200 rpm (H2) (revised 12/17/03)

300 hp (224 kw) @ 4400 rpm (Savana/Express, 2500 HD and 3500 Sierra and Silverado equal to or greater than 8600 pounds GVW) (revised 9/18/03)

Here is the site to look at all the GM engines.

http://media.gm.com:8221/division/powertra...ruck_specs.html :cool:

willscary Enthusiast

willscary

Posted
  • Author
Posted

Exactly! In 2003 there were 4 different outputs listed for the LQ4. See this listing. Why is there a different tailpipe size? If I replace my 2-1/2" tailpipe with a 3" like on the factory HDs, will I get more low end torque and HP? Why does the factory do it?

redvett Senior Enthusiast

redvett

Posted
Posted
Exactly!  In 2003 there were 4 different outputs listed for the LQ4.  See this listing.  Why is there a different tailpipe size?  If I replace my 2-1/2" tailpipe with a 3" like on the factory HDs, will I get more low end torque and HP?  Why does the factory do it?

 

 

 

 

Generally larger exhaust pipes reduce bottom end torque and raise mid range TQ. But i am sure GM changed cams from 03-04 & maybe heads, and torque converters too. These all including engine calibrations make up the whole package.

The reason they have different HP in a family is GVW & vehicle weight.

BTW i couldnt open the site you referred to. :cool:

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • asilverblazer
      Slate Electric Truck

      By asilverblazer · Posted

      I like the idea.  I would pick diesel if I had a choice. I need pictures though.
    • newdude
      Help purchasing a touch screen digitizer

      By newdude · Posted

      I've installed cheap eBay new aftermarket digitizers before.  They work.  Did a bunch of Cadillac CUE (aka Cadillac's MyLink) for someone years ago.  They all worked fine after the repair.    That number 22740886, that is a component part # for GM.  You can use it to search, but its not something that's obtainable at the dealer level.     So pretty much any of these will work - 2015 Colorado Digitizer for sale | eBay
    • asilverblazer
      give me some tips to make my truck look better

      By asilverblazer · Posted

      Black bumper and the later years Z-71 style color matched grille.
    • fondupot
      Exhaust heat while towing!

      By fondupot · Posted

      You can install tailpipes that direct the exhaust sideways vs the OEM one that goes straight back. There are several on the market, do you own research. HOWEVER, you need to make sure the Venturi vents are still intact, otherwise it will throw a engine code. There is a sensor somewhere that detects back pressure on the exhaust. And if it doesn't collect the correct metrics, it will throw the truck into limp mode. 
    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      "Teardown" is complete. Head surfaces are clean and ready, new intake is prepped and ready. Coolant drained and water pump is removed, radiator is removed, new hoses and pump are ready.   The replacement intake is also from a '95 (with I think 260k, the odometer said). Noticeably less pitting where it covers the rear coolant passages. I'm not sure if that's a tribute to more frequent use, more frequent coolant changes/upkeep, or if the intake was machined at some point. But it appears I found a good one.   My coolant hoses were original, and the lower hose still retained the factory spring inside. It's not really rusty, but it's got deposits all over it. Unsure if I should re-install it (will thoroughly clean it first). Someone said hose technology has gotten better since 1995 (has it?) and I don't need the spring. I think modern EPDM is what made those hoses last from 1995-2026, so it's a question of how much suction can the water pump really pull, and will it collapse the hose without a spring?   I'm stopped and waiting for parts, however.   When I first brought the truck home, the fan was intermittently hitting the radiator shroud. I could see someone had monkeyed with the shroud (put a bunch of cardboard as a spacer between the upper/lower shroud halves. Someone said the motor mounts have likely failed and the engine has sagged. I wasn't sure I believed that. The engine is really solid in its mounts: To remove the old intake I *just* nearly permanently welded to the heads with freshly cured RTV and gasket snot two weeks ago, I literally had to use the arms on my lift and a chain with a bolt attached to the intake to pull it loose. It almost picked the front of the truck off the ground before ....scuuuuuuuuuuup.... I could actually hear the gaskets tearing and it broke loose and the whole truck settled back down. Motor barely moved.   SO, those parts I'm waiting on... The lower radiator mounts/bushings had completely failed. The radiator needs to be insulated from the rad support, and the bushings help the rad stand at the correct height. The plastic "baffle" was also destroyed at some point. Someone had attached the shroud to it incorrectly, overlapping a joint that should have been underlapped, creating another suspect issue potentially causing things to hit the fan. Broken tabs, side is busted off, and it's perma-formed/bent where it was jimmied incorrectly.   The baffle? Unobtainum. Long since discontinued from GM, of course. Aftermarket/capa/chinese? Also unobtanium. In GM's infinite wisdom, it appears there are at least two different variations whether the Blazer is 2 or 4 door, and I can't yet tell if they shared the same part with the S-pickups. Plan B, if I can't find a viable used one, will be to create a bracket to re-assemble the critical joint I need to seal a gap with the shroud. But that will bug me, it won't be...perfect.   The water pump bolts appear to have been installed with...plumber's putty. I guess, sure, if it works...? I've found a few "backyard fixes" like that. Someone's been here before....   If I can't find someone to jam bamboo under my fingernails to fill my free time this week I think I'll install the driver's power window motor and replace the rear door speaker that's inop. I've got a genuine GM "9.5" ohm working replacement. Why GM used a non-standard resistance....nevermind. Of course they did, you can get more sound from a cheap factory amp that way.   And the saga goes on...

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...