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-   -   Increase MPG but added Drone between 1800 and 2000 RPM (http://www.ramforumz.com/showthread.php?t=105411)

feelit2 02-22-2012 05:46 PM

Increase MPG but added Drone between 1800 and 2000 RPM
 
3 Attachment(s)
Just installed the Vararam CAI, Magnaflow 10789 Y pipe and Magnaflow 16869 Cat back exhaust; Initially we routed the driver side exhaust pipe over the cross member and across the back of the transmission instead of across the pan in front of the cross member.
This configuration gave me a terrible drone between 1800 and 2000 RPM.
I went back to the muffler shop and had them route the pipe from the driver side the way it was original. Still have the drone but itís not as loud and no longer vibrates under my feet. I made an appointment to have under coat and sound proofing tomorrow. Iím hoping to bring the noise level down just a little more at cruising speeds.
I can say without a doubt that adding the Vararam CAI, magnaflow 16869 cat back, 10778 y connection increased my MPG. Before 12/17 Ė After 15/21. Also, the throttle response is noticeably improved.
Any ideas on eliminating the drone without losing performance?

seltzer 02-22-2012 08:03 PM

I had to put the stock resonator back on my old Dakota when I went with dual exhaust. Mine had an upstream resonator, a HUGE muffler, and another resonator at the tail...stock.

The drone was terrible once it reached 50-58 mph in 5th gear...put the first resonator back on and it was still there, just not quite as bad.

Resonance is all about giving the exhaust gases somewhere to expand...perhaps put a glass pack or similar expansion chamber before the muffler?

Super12pack 02-22-2012 08:37 PM

That is a big MPG improvement!

feelit2 02-23-2012 06:32 PM

Had the undercoat and sound protection installed today, it is still too loud and the drone would be too much for highway driving. Talked to the dealership and they believe installing the original resonators will help but they are restrictive. Magnaflow customer service recommended I install a magnaflow glass packed muffler 18129 before the 22Ē muffler that came with the cat back system. If this doesnít work, Iíll remove the 18129 and install the factory resonators.

SS4Luck 02-23-2012 11:00 PM

http://www.secondskinaudio.com/index.php

Look into luxury liner or luxury liner pro. Its covering my truck from the front of the footwells to the rear under seat storage and that along with the other sound deadener i have for the audio I hear 0, like absolutely 0, road noise

seltzer 02-24-2012 08:25 AM

Quote:

Originally Posted by feelit2 (Post 731662)
installing the original resonators will help but they are restrictive.

Have you looked through them? The ones on my old 05 Dakota were completely open inside...I could see all the way through...it was really just an oblong muffler looking thing with some packing around the outside...just a place for the gases to expand. I did not notice any loss of performance putting the resonator back on...just a little (and I mean little) quieter. It actually sounded better, more defined...and lost the annoying cackle when decelerating.

Hope it helps, good luck!

mikeb33 02-25-2012 02:36 PM

Quote:

Originally Posted by feelit2 (Post 731662)
Had the undercoat and sound protection installed today, it is still too loud and the drone would be too much for highway driving. Talked to the dealership and they believe installing the original resonators will help but they are restrictive. Magnaflow customer service recommended I install a magnaflow glass packed muffler 18129 before the 22Ē muffler that came with the cat back system. If this doesnít work, Iíll remove the 18129 and install the factory resonators.

That muffler is 2.5", you need 3" like this one:
http://www.magnaflow.com/02product/s...e=main&id=9531

feelit2 02-26-2012 09:17 PM

Mikeb33,
Thanks for pointing out the difference in the core size.

mikeski 02-27-2012 07:33 PM

I believe the resonators are hollow and they are designed to tune out the drone from our standard muffler system.

Mikeski...

TNC 03-01-2012 12:38 PM

Quote:

Originally Posted by mikeski (Post 735226)
I believe the resonators are hollow and they are designed to tune out the drone from our standard muffler system.

Mikeski...

I think this is correct. Our stock resonators don't have any restrictor or baffle in the flow path, do they? I thought I recalled someone posting a Ram resonator cut open to show what they looked like. In fact I think most resonators are not restrictive to flow, but have vents, bulges, and bends inside them to attract and modify sound waves, not exhaust pressure. There are computer programs that are supposed to show an exhaust engineer what length, diameter, and internal design of a given set of resonators work with a given engine. I think there's supposed to be some actual science as to how they tone down unfavorable exhaust sounds without restricting flow.

However, on the drone of our hemis with a higher flowing and slightly louder exhaust, I think it's going to exist with MDS engaged to some degree. The resonators do seem to reduce it as noted by many forum members. I have a Borla straight-through muffler with OEM tailpipes and resonators. I only notice the MDS when driving slowly and just cruising at a steady pacea around town. At highway speed it's practically nonexistent. People are very different in their sensitivity to this sound.


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