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No muffler? - EDIT, Muffler Ordered

dhcomp

dhcomp

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Hey guys,
In the middle of a good caffeine high this evening, i finally hacked the stock muffler off the burb. Had been debating it, and hating how quiet it was, just didn't want to buy a flowmaster yet cause of $$$.

As ppl said, its really not that loud with the stock cat and all the exhaust pipe on the burb. Plan is to put some exhaust pipe where the muffler was to connect the cat and tailpipe and keep the exhaust from accumulating under the truck.

After a test drive, it definitely feels like i lost some low end torque by decreasing the back pressure too much. Rather than putting a muffler back on just yet, what do you guys think about putting a reducer in, with some smaller tube where the muffler was? Stock is 3", so maybe 2.5 or 2" for a foot or so, then back up to the 3" tailpipe. Reducers are cheap, and i think i may gain some back pressure back, and hopefully my low end torque along with it.

Comments? Suggestions? Size reducer recommendations?

Thanks guys!
 
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I would just look on craigslist for a muffler should be able to find a 40 series pretty easily. Not sure about reducing it but I feel like it would work
 
IMO there is no way you lost any low end torque by going to a less restrictive exhaust.

The only reason you would ever want smaller pipe is if you have headers that all have the same length primaries and can hence "scavenge" the exhaust out of the pipes (bigger pipes lose the scavenging "pulse" and can actually hurt performance if the motor has headers with equal length primaries).
 
I know less restrictive is better, but i hear the factory 3" single flows pretty well.

I thought for sure i had heard around here that too little back pressure helps in the higher RPM's, but hurts you down low.
 
Backpressure is NEVER a good thing. That's a complete hoax and myth.

You don't want too large, but that doesn't mean you want backpressure.

As 383 said, you only want exhaust small enough to keep the exhaust flowing efficiently.

Read this article: http://www.popularhotrodding.com/enginemasters/articles/hardcore/0505em_exh/index.html

He states specifically "...minimizing backpressure by selecting mufflers of suitable flow capacity for the application."

Oh and "Knowing that 2.2 cfm per open-pipe hp means zero loss from backpressure..."
 
ok, thats why i post here! Thanks for the direction guys.

I'll get some 3" pipe and reconnect the tailpipe tmr.

Really glad i didn't get a 50 series or something quieter, its really not that loud w/o muffler. When i run across a deal, ill slap a 40 series under there to fix the tone....but for now, straight piped sounds better than stock.
 
Yep, my friends dad '88 C-truck had a 350 with a cat and no muffler, I thought it sounded great. Deeper tone, but not super loud.
 
I'm really surprised its not louder. Maybe it will seem so when i drive it tmr.

I just feel like i've heard louder suburbans.....but i guess w/o headers, or other mods, cat back isn't going to get any louder.
 
dyeager535 said:
Backpressure is NEVER a good thing. That's a complete hoax and myth.

You don't want too large, but that doesn't mean you want backpressure.

As 383 said, you only want exhaust small enough to keep the exhaust flowing efficiently.

Read this article: http://www.popularhotrodding.com/enginemasters/articles/hardcore/0505em_exh/index.html

He states specifically "...minimizing backpressure by selecting mufflers of suitable flow capacity for the application."

Oh and "Knowing that 2.2 cfm per open-pipe hp means zero loss from backpressure..."
Click to expand...


Better stated than me and with an article :thumb:
 
i like the cherry bomb glasspack for trucks. More of a raw sound, got one on my k5. I also heard too little backpressure is bad for performance, but that was in reference to my little 4 banger, not anything bigger like a v8.
 
Back pressure boiles down to this.
It is where you have no or the least backpressure for your driving style is what you want.
Large exhaust pipe has more surface area that causes resistance to air flow. Also it has a larger opening thus more atmospheric pressure to over come (22lbs PSI at sea level.) Because of this, larger pipe has more back pressure at low rpm. It does not scavege as well and your engine has to work harder to get the gasses out the pipe. At high RPM because of larger diamater it flows the best So you loose a little power on the bottom to gain at the top.

Small pipe has less surface area restriction and a smaller opening. So there is less of an area of atmospheric pressure to over come. That is why it It flows better at low RPM. It builds power sooner in the RPM band because there is less back pressure at low rpm and the engine does not have to work to get the gasses out.
But at high RPM back pressure increases because of lack of flow in the smaller diamater pipe. So you gain at the bottom and loose at the top.
 
dyeager535 said:
Backpressure is NEVER a good thing. That's a complete hoax and myth.

You don't want too large, but that doesn't mean you want backpressure.

As 383 said, you only want exhaust small enough to keep the exhaust flowing efficiently.

Read this article: http://www.popularhotrodding.com/enginemasters/articles/hardcore/0505em_exh/index.html

He states specifically "...minimizing backpressure by selecting mufflers of suitable flow capacity for the application."

Oh and "Knowing that 2.2 cfm per open-pipe hp means zero loss from backpressure..."
Click to expand...

I completely agree and was going to post the exact same thing...but somebody already did.

I always like telling people "if you stick a tennis ball in the tailpipe it surely increases backpressure...but you won't get additional lowend torque!"
 
If you want the flowmaster sound without paying that high price look at thrush chambered mufflers. at work we have a book with a cut out view and they are identicle to flowmasters. the part numbers even crossreference to each other so I can get the part numbers if you want them and they are about half the price of a real flowmaster.
 
I'm not sure why yours isn't loud. I'm running dual 2.25" straight pipes [no cats] and it's unbelievably loud..it's really obnoxious. I can't bring myself to buy mufflers though. My truck sounds like a top fuel dragster and i love it lol. :p:



If you like the flowmaster sound look into any chambered muffler. Summit has chambered "race" mufflers for about $30 a piece on their website.
 
Ben B. said:
I'm not sure why yours isn't loud. I'm running dual 2.25" straight pipes [no cats] and it's unbelievably loud..it's really obnoxious. I can't bring myself to buy mufflers though. My truck sounds like a top fuel dragster and i love it lol. :p:



If you like the flowmaster sound look into any chambered muffler. Summit has chambered "race" mufflers for about $30 a piece on their website.
Click to expand...


:D:D This^ is an awesome post. I love it.

And on a more relevant note, if you are going to get a Flowmaster knock-off, I'd steer away from this brand- Force Automotive. I had this muffler here, and it sounded great, but one of the baffles collapsed about 20 months after I put it on. I had a LOT of backpressure- and it sucked.:D
 
I have the single 3" that goes into a Flowmaster and then splits back into 2 pipes on each side of the hitch.

I play to put a cutout right between the cat and Flowmaster muffler to make it really scream.
 
the thing i didnt see anyone else bring up is the legal matter. i know in oregon you have to have a muffler and im pretty sure california is the same way since you guys have DEQ testing.
 
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