Exhaust question

[B2Mann]

1990 B2 2.9, Has a single cat, and magnaflow on it as of now, not sure wich one though(I can see straight through it). Anyone know of any mufflers that are QUIETER but that will still allow as much as a performance gain? Its pretty loud when going through the gears and as well as on the highway, which is the most annoying of all. Alot of drone and resonating inside the vehicle. Just wanted to get something quieter without a loss in performance. Any ideas would be appreciated.

 

[creepinjeepster]

Does it have a tailpipe on it? If so, where does the tail pipe end? The cat would be the one closest to the motor and the muffler to the rear of the vehicle. Flow master has a good selection of mufflers if that is still the route you go.

 

[B2Mann]

No tail pipe on it anymore. About 6 months back 1 of the 2 cats got clogged up so I cut it out, welded the muffler back on and was good to go. Didnt weld the tail pipe back on either. It dumps underneath the truck, and im sure thats where im getting the resonation and drone from. Still loud even when it dumped out behind the passenger rear. Just wanted to get a quit muffer again. I understand that having only one cat will make it louder as well.

 

[UrbanRedneckKid]

Flowmaster Delta Flow 40 series. And put a tailpipe back on it. Not only does not having a tailpipe get really annoying inside the truck, It also doesn't properly vent the CO2 and CO gasses away from the vehicle. Which could be very detrimental to your health. There is a reason that most states require the exhaust to exit from outside the body, and behind the cab or last opening window.


-from Flowmaster's website
"Features and Benefits

This two chamber design incorporates Flowmaster's patented Delta Flow technology. The "Delta" deflectors generate increased scavenging for better performance and reduced interior sound. Milder exterior tone and reduced interior resonance over original 40 Series. Constructed of 16-gauge aluminized steel and fully MIG-welded for maximum durability."

 

[creepinjeepster]

Definately needs the tailpipe. Besides the resonance, it also helps with giving the vehicle proper back pressure, again for the CO2 on the health side also.

 

[BlackBII]

There's that 'back pressure' term again....


I'm going to e-slap the next person to use it on TRS.

 

[creepinjeepster]

Let me guess, you don't believe there's such a thing as BACK PRESSURE? Probably can't tell as much by yourself driving it, but take your tailpipe off and test it on a dino after you test it on a dino with the tailpipe on. I've done it with a car before and guess what? YEP that's right, there is a difference i.e. loss of power with tailpipe removed.

 

[BlackBII]

Let me guess, you don't believe there's such a thing as BACK PRESSURE? Probably can't tell as much by yourself driving it, but take your tailpipe off and test it on a dino after you test it on a dino with the tailpipe on. I've done it with a car before and guess what? YEP that's right, there is a difference i.e. loss of power with tailpipe removed.

Getting the motor to create power in all ranges is about flow velocity of the exhaust, not back pressure.

The loss of power is from a loss in ehaust flow velocity. Not a loss in 'back pressure'.

Back pressure is NOT helpful in any situation, no matter what. Get that through your head.

Here is an excellent post by another member.

What is backpressure?
Backpressure is exhaust gasses backing up in the combustion chambers/primary piping due to poor flow caused by some type of restriction in the system. This can be due to poor design, bent pipes, system too small, junk in the system.

Do I need/want backpressure?
No. The less the better. However, you can't get rid of all backpressure. You will have some, but you want to be able to manage what you have.

Will my valves burn without backpressure?
It depends on your fuel mixture. In earlier days with carburetors, changes in the exhaust system would change total system flow(as it does in all systems) from intake to exhaust. A jetting combination that works for one system, could become lean if the exhaust was changed allowing for greater flow thru the system. The leaning out of the system caused combustion chamber temps to rise, and the material makeup of the valves at the time could not handle the increased temps.

Modern engines with EFI, and better valve material adapt much better to these changes. If the flow is increased, and the system leans out, the O2 sensors will note this change and adjust fuel flow accordingly preventing high combustion chamber temps and no damage will occur. Modern engines are "lean burn" engines anyway, and the fuel mixture is more closely monitored.

Will no backpressure kill my bottom end power?
Backpressure takes away power in all ranges. When the exhaust system is changed, and some low end power loss is noted, it is not due to backpressure, but the loss of exhaust system velocity(the speed of the gasses flowing thru the system). This happens when larger piping is installed in the system. It really doesn't cause a "loss" of power, it just moves the power up higher in the rpm band. Reverting to a smaller pipe would then lower the power band.

The exhaust system is very complex, and all physics involved cannot be discussed on a forum such as this. I just tried to cover some of the points more often discussed.shady

 

[creepinjeepster]

Curious where shadetree got that info. I've even talked to people at flowmaster before and have been told you need a certain amount of tailpipe after the muffler, depending on the muffler, to have proper back pressure for proper performance of the vehicle. Example of one they gave me was a flowmaster 40 needs at least 36" of tailpipe behind it. Not sayin Shady's wrong. I can see where a lot of that info would be correct.

 

[Original_Ranger84]

No the muffler need 36" of pipe behind it to sound decent, well in my opinion of what they were probably saying. I swear back pressure has nothing to do with it, I actually heard of it from a buncha people that were talking backpressure in auto shop and i know they just read it on the internet. (no offence to you creepin jeepin)

A tailpipe exiting out the back passanger side of the truck will get you the quiet you want, because the sound is now leaving from the end of the pipe which is now atleast 5 ft from you and not under the truck to vibrate the rest of the frame and body. going straight out the back will probably be the easiest and will net you the quietest ride (for you) possible.

 

[ajmiller]

i would say a 50 series flowmaster

 

[legoms013]

go with a delta flow 40 series flowmaster....sounds like a regular 40 series but much quieter....and less resonation. and put a tail pipe back on....you cant go wrong with that.

 

[MUDDING B-3000]

alright so i have a magnaflow on my 94 mazda b3000 it was just dumped under the truck right off the muffler it was loud an sounded nice, but turns out e test places wont test it with the muffler an no tail pipe like that so i had to run a tail pipe out before the back wheels an now i cant believe how quiet my truck is you cant hear it a idle, an usually on the highway if i punched it in 4th you could really hear it but now nothing, so if you want it quiet put a tail pipe on it like everyone else said. i now from experience that it will really quiet it.