I have a straight piped exhaust and I do get some resonating around 2200-2400 RPM, especially while towing. Dont want to pay for a new exhaust and really dont want a muffler of any sort. So I was thinking, the guy who did the work for me was going to install a small 4" section around where the muffler was but I declined. I can still get that 4" peice installed and was wondering if it might change the sound of the exhaust and possibly eliminate the resonating. It would act like an expansion chamber? Wonder what that would do for flow. Probably nothing. Does anyone have an open 4" section in their straight piped exhaust?

 

When I put a turndown on my truck, it pretty much killed what little drone I had off. I've got alot of 4" straight section in my exhaust.

 

As do I....from the turbo back. I don't get what you're trying to do.

 

He's basically trying to make a resonator like my 01 had on it. Except the resonator on my 01 was like 5-6".

 

Some guys have been able to cut down on the hamonics by welding a 2-3 foot section of angle iron to the pipe. Wouldn't be too hard to find if it works for you by hose clamping it to the pipe just to see if it works.

 

i think you have an exhaust leak or a pipe touching the cab comewhere. the only time i ever heard of people having alot of resonation is when there stacks don't go past the top of the cab or they dump the exhaust out before the rear tire.

 

straight pipe will resonate too... when I first installed my 5" system, it resonated so bad, it'd split your friggin' ear drums.

but I cured all that

Forrest

 

New ear drums??

 

WHAT??????

 

Exactly what I was going to suggest. Use several different lengths and find which ones work. THe theory behind it is that when you change the mass of the object you change its harmonic frequency.

 

it's sound theory too. I've got all kinds of crap welded to my exhaust pipe! LOL!

one thing that I did on top of welding angle and strap to long lengths of the exhaust was weld a lot of weight in one spot. I had some sch 40 3" elbows laying around... they weigh about 5lbs a piece. I cut one up (so it would clear) and welded it under the downpipe, and welded another one to the front part of the pipe under the bed.

I noticed that the resonant frequency changed a LOT when I welded that piece on... rapping the pipe with a wrench or my knuckle, you could really hear the difference... didn't have nearly the same "ring" to it.

cutting interior resonance is one of those things where every little bit helps. I've done lots of work on my truck in this area, and I LOVE it now!!! I can cruise down the highway at any speed with any amount of weight out back, and it's totally comfortable in the cab.

the ONE thing I haven't done is put a turndown on the exhaust tip... I know that would reduce the resonance even furthur, but I'm totally happy with how it sounds inside the truck now, and I like having the exhaust exit 90* to the truck to bounce the sound off of walls and hondas

Forrest

 

Yes thats right, but you didnt mention if it worked. And was that 5-6 in. or did you mean 5-6 ft. I checked with the muffler shop and he wants to much money in my opinion. He suggested a 3" glass pack and I said NO. Plus I dont want a muffler of any type or I wouldnt have removed the stock resonator. I just dont want to hear the hum of the exhaust in the cab while towing.

 

i have no muffler and two 5inch pipes coming out behind the cab and i don't get any resonating at all no matter how many rpm i turn. i also had a 4in straight pipe on my last truck and i couldn't even hear it

 

and as I've always said, resonance is also totally subjective... one main's throbbing headache is another man's lullaby...

I've had two different stack setups... trust me, you're getting resonance. it may not BOTHER you, but...