Jump to content

No muffler. Problem?

uh6077

Recommended Posts

uh6077 Enthusiast

uh6077

Posted
Posted

I just picked up a 99 Chevy 1500, 5.3, 4x4 last week. I am noticing little things here and there so I will be asking lots of questions in the coming weeks. The truck does not have a muffler. It does have a cat though. Not near as loud as I thought it would be. Will this cause any problems? Will it affect gas mileage either way? Thanks

lerbud Enthusiast

lerbud

Posted
Posted

i have had straights on all my trucks with no problems. some others here will say you shouldnt do it. After reading all the posts about an x-pipe I finally put one on my 06. its not near as loud as straights but i know i have plenty of back pressure just in case. :crackup:

thecraft Senior Enthusiast

thecraft

Posted
Posted

Nothing wrong with it unless you have inspections... or bitchy neighbors.

 

BTW, there are rumors floating around that say you will lose low-end torque by removing too much backpressure. That is completely FALSE, power loss will only occur when you use pipe so large that the exhaust slows down and cools.

pwall Senior Enthusiast

pwall

Posted
Posted

Yes please....I'm interested to hear what it sounds like too.

uh6077 Enthusiast

uh6077

Posted
  • Author
Posted

I didn't forget about this. It has been raining here for the last few days. I am not in a hurry to take my laptop out in the rain. Maybe tomorrow will be nice.

Mark_in_Tulsa Senior Enthusiast

Mark_in_Tulsa

Posted
Posted
Nothing wrong with it unless you have inspections... or bitchy neighbors.

 

BTW, there are rumors floating around that say you will lose low-end torque by removing too much backpressure. That is completely FALSE, power loss will only occur when you use pipe so large that the exhaust slows down and cools.

 

 

 

 

FALSE.

If you remove the muffler you will reduce back pressure. Which will lower your low end TQ. Which is where you spend all day driving and also what you need a lot of to launch these 5000lbs shaped bricks.

 

During the combustion process, when the exhaust valve is open, all of the compressed (and depeleted) air-fuel mixture spills out from the cylinders as fast as it can, through your exhaust manifold, into your catalytic converter(s), the muffler, and finally out the tail pipe. The problem with this is, just before your exhaust valve is about to close again, your intake valve opens up, allowing the fresh air-fuel mixture to rush into the cylinders. This is called overlap, and one of the things you take into consideration when choosing a cam, because it can be used to your advantage.

 

If there was no valve overlap, it would be 100% impossible to completely irradicate all of the spent gases from the cylinder. This has a two-fold effect on power output, depending on what RPM the motor is running at. At low RPM, this effect actually increases torque, because the least amount of compression is lost during the intake stroke, and the ratio of intake to exhaust gases is high. Unfortunately, as the RPMs increase, there is increasingly less time to evacuate the exhaust gases during the exhaust stroke, and more and more depleted air-fuel remains in the cylinders when the exhaust valve closes. The motor becomes incredibly inefficient near its readline. A motor designed for high-torque applications, such as towing, tends to exhibit less valve overlap then normal. The type of cam used in this application is often called an "RV" cam, because a recreational vehicle doesn't need horsepower as much as it needs low-end torque to get it moving.

 

Your truck would also run terribly if there was too much valve overlap as well. When exhaust gases rush out of the cylinder to fast, they create a low pressure area in the cylinder and the exhaust system, sucking the intake charge right into the cylinder, and right back out into the exhaust system. This is called scavenging. When that air spills out, so does the fuel it was carrying, so the O2 sensor reports a rich condition to the computer, often causing further decreases in the amount of fuel the computer injects. At low RPMs, this effect is most pronounced as there is sufficient time to suck out a significant portion of the intake charge, reducing torque. As the RPMs increase, however, the extra velocity imparted to the intake charge increases the amount that squeezes into the cylinder after the exhaust valve closes, as the valve closes so quickly at high RPMs that barely any intake charge escapes through the exhaust system.

uh6077 Enthusiast

uh6077

Posted
  • Author
Posted

Got clip recorded. I recorded it inside the cab to get a better idea of how it sounds while driving. It is not as loud when driving since it is under a load. I recorded it just siting in the driveway. Drop me a PM with your email and I will send it to you. It is only like 30 seconds or so.

  • 2 weeks later...

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...