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#21
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If adding resonators affects the "tone" of the exhaust, then you have a flow issue as I mentioned before whereby you changed the flow characteristics and therefore the sound. Otherwise, if adding weights or rubber isolators etc. changed it, then that is a different problem.
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#22
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quiet powerful exhaust
Dutch Injun can you post a pic of your exhaust system? I have a full 3 inch
system on my 69 GTO & would like to quiet it down without losing any power.. |
#23
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#24
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That is a 2,5" bullet, I expanded it and blended it into the 3" pipe. I am thinking of switching to a 3" bullet.... I'll have to see first if it is too restrictive. The 'thunderous boom boom" sound is gone however which I like. It may not be for everyone.
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#25
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Ditto...
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#26
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I have a slight drone in my car at around 45 mph. I'm going to add some sound deadener under the carpet, and maybe in the trunk. Don't buy Dynamat, etc. You can get the same stuff from an industrial supplier like Granger for a lot less.
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#27
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I have recently performed a series of exhaust testing using high tech NVH equipment. The resonance is on a lot of vehicles in that rpm range. We fixed the problem on one group of vehicles by installing a Bullet type muffler (like a Walker) in front of the typical muffler. Immediate success and no loss in performance.
I plan on doing the same deal to my street car if the VOE mufflers have any drone in that rpm range. If works, guys. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#28
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The great thing Tom is when closed they will not but open they might . Many seem to love that roar. But, I think Tom's think alike and would rather have sound without roar/resonance.
Tom
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Tom Hand |
#29
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I don't know the sources for the various "resonators", but noticed under a late-model Lincoln Avatar today, a very compact resonator- maybe 3" diameter by about 10" long? I don't know the pipe size, maybe 2 1/4" or 2 1/2"?
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#30
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Not to re-hash an old topic...
...but I did get rid of quite a bit of resonance by using a small catalytic converter on each side, way up front. Keeps it somewhat legal, too, and, as far as I can tell, no sacrifice in performance(provided you don't use a $29.95 converter)
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#31
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I have cured the dreaded Flowmaster resonance on several cars here locally by installing new rubber isolators and making sure the pipes hang freely and are not in a bind where they go through the hangers...FYI...Robert
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#32
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The straight-through resonators are a "tried and true" solution. Sometimes you can eliminate the objectionable resonance by replacing the isolators, but a physical change to the system is usually required.
Based on my experience, Tom Vaught is absolutely correct; resonators eliminate the problem without sacrificing performance. They are the silver bullet. |
#33
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WHAT!
Just kidding, couldn't resist a little hearing loss humor.
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____________________________________ "I work in high speed aluminum tubing." |
#34
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flowmaster, deltaflows no interior resonance at all , all noise goes out back.
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#35
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I noticed on some newer cars that the resonators are upstream, ahead of the muffs and slightly ahead of the driver. This makes sense, as you are canceling (smoothing) the negative pulses/frequencies closer to you. My car, w/o resonators is pretty loud in the garage, not sure it is going to get much quieter on the open road. Might have to do something. I like those ultraflo bullets
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1967 GTO Tyrol Blue/Blk Cordova 400, TKO-600, 8.2 Posi w/3.55 400 + .020, decked to .005 SD Performance 240+CFM 670 heads RARE HO/RA manifolds RARE 2.5" Exhaust (18" Magnaflows) SD "Stump Puller" HR cam (230/236, 112LSA, 107.5 ICL) PRW stainless 1.52 roller rockers Forged TRW slugs SCAT H-Beam forged rods |
#36
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Anyone here have the Welded Dynomax Ultraflos #17560 20" case 2.5 in an out. I was wondering about resonance. I went with the largest case with good flow numbers to tone it down.
Dougs are installed with exhaust system but can't upload any pics. Anyone know why?
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69 400 Block, .030 over, KRE eagle stroker kt, KRE,CNC ported e-heads 310 cfm, port match RPM , comp roller 236/245@.05 586/600 lift 110 LS. 1.5 HS roller rockers, 350 Transmission, Red Neck tight 3500 stall converter, Ford 9” with 3.75’s, Strange center section, Moser 31spline axels, 29”Mt slicks, HRPARTSNSTUff anti roll system, Doug’s Headers 3.5” collectors, 22”Dynomax mufflers w/ H-pipe, Cliffs Q-jet, Fuel cell with sumps, Mallory 140 fuel pump and filter. Denny’s 3.5” drive shaft. |
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