Quad 4 LO
I have 2.25 mandrel bent pipe down from the high output exhaust manifold. A 24" resonator (don't know which brand) to a Dynomax SuperTurbo. I get annoying drone on the highway where I sit at 3000rpm for long periods of time.
What can I do?
If your not too worried about flow a car chemisrty insert will eliminate most of the drone and sounds neat. It will hinder high rpm flow though.
No cat.
I'll look into that insert.
IIRC I have an 18" resonator. Would a longer one reduce the drone or have no effect?
longer will definitely help with the drone, had a 32" glass pack with a magnaflow muffler on a 3" exhaust... flowed great and sounded good with no drone
ʇı ɹǝʍo7 | ǝcoMonstǝrs
You probably have the 18" version super turbo, get the 25" version. This happened to me and the next time I had to redo the exhaust I went with the longer and it helped.
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- Sold my beloved J in April 2010 -
I had the 38" resinator and it sounded perfect
38"? Jesus! No cat I take it?
lol yeah cat, was removed years ago, no emission in Florida, originally I had stock tubing to a 38" resinator straight to a magnaflow performance exhaust. Now i will be running 2.5 to a 22" resinator with antoher magnaflow exhaust. I loved the 38" though, the sound was perfect and the feel was amazing.
Search engine isn't bringing anything up. Who made your 38?
I bought mine from Summit Racing. They have lots of sales on ebaymotors. Search for a 38" glasspack
Dont cut off the inlets and outlet to make it bigger, just take it to an exhaust shop and have them expand the bushing, 10 bucks tops.
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Leafy wrote:Dont cut off the inlets and outlet to make it bigger, just take it to an exhaust shop and have them expand the bushing, 10 bucks tops.
This is what I did with my original set up.
now I am running 2.5 all the way back
MadJack wrote:The core on those Glasspacks are 2 1/2", though the inlet and outlets are 2 1/4". I was thinking about cutting the inlet off and welding a 2 1/2" tube from the header (with a 2 1/2" merge collector) on the inlet. I would still have the 2 1/4" out let going into another Dynomax UltraFlo Welded muffler. The purpose of the larger inlet, is the exhaust gases are still hot up front, but will have cooled enough by the end to no longer need the larger diameter exhaust.
Sounds like what you're making will be like a flared collector-extension. Only problem is, from what I've read & what I can figure, it'll look to the exhaust's pressure-waves like a motorcycle muffler that's been gutted but still has a cap on it's end... making it counter-active to improving exhaust flow.
Perhaps one of us... who has the money to spare... should look into one of those Dynomax-VT mufflers, just to see how well they work dynamically.
Go beyond the "bolt-on".
MadJack wrote:Leafy wrote:Dont cut off the inlets and outlet to make it bigger, just take it to an exhaust shop and have them expand the bushing, 10 bucks tops.
I thought of that, but I need the whole inlet to be a constant diameter. Expanding the bushing is fine, if the core is 21/4". You can't expand the weld that holds the bushing to the body.
Michael, it won't be a flared collector. I'm looking to replace the 4" long by 21/4"diameter ball and socket collector with a longer merge collector with a 21/2" outlet, followed by a constant diameter 21/2" intermediate pipe going into the glasspack. This should keep the velocity up of the exhaust gas flow, till it cools and no longer needs the larger cross section to maintain the velocity.
If there is going to be a problem with this set up, it will be that the step down at the end of the glasspack is too far and the gases may have cooled too much by the end that it would then impede the flow. Thrush can make a special order 21/2" in/21/4" out, 28" long glasspack, which if the inlet is located as far forward as the 35" glasspack's will move the step down slightly forward. Then again, I just may end up doing the shorter glasspack to begin with.
Damnit must you have an awesomely cool set up? lol
yeah i seen it at tje jshow a few years back, loved it.
MadJack wrote:Leafy wrote:Dont cut off the inlets and outlet to make it bigger, just take it to an exhaust shop and have them expand the bushing, 10 bucks tops.
I thought of that, but I need the whole inlet to be a constant diameter. Expanding the bushing is fine, if the core is 21/4". You can't expand the weld that holds the bushing to the body.
Michael, it won't be a flared collector. I'm looking to replace the 4" long by 21/4"diameter ball and socket collector with a longer merge collector with a 21/2" outlet, followed by a constant diameter 21/2" intermediate pipe going into the glasspack. This should keep the velocity up of the exhaust gas flow, till it cools and no longer needs the larger cross section to maintain the velocity.
If there is going to be a problem with this set up, it will be that the step down at the end of the glasspack is too far and the gases may have cooled too much by the end that it would then impede the flow. Thrush can make a special order 21/2" in/21/4" out, 28" long glasspack, which if the inlet is located as far forward as the 35" glasspack's will move the step down slightly forward. Then again, I just may end up doing the shorter glasspack to begin with.
No... What I meant was it'll be in-effect like a flared collector to the pressure-wave. And that glass-pack mufflers look the "wave" like flared collector-ends with a reducer-cap stuck on the end. This is all taken from the various articles I've seen--that latter-part from one written by David Vizard--on exhaust design, and from what I can visualize here. I do wish you luck with it & it all works-out well.
To the OP: Is this drone coming from the engine compartment? I just read in an old issue of Motor Magazine that the 1999-2002 J-cars had a droning issue, usually at higher ambient temperatures & the A/C on, that was result of the accessory-drive setting-up a natural resonance in the larger spans of the belt between pulleys... Namely between the alternator & A/C-compressor's. A change to a new P/N belt of a different rubber compound was the solution.
Go beyond the "bolt-on".
Nickelin Dimer wrote:MadJack wrote:Leafy wrote:Dont cut off the inlets and outlet to make it bigger, just take it to an exhaust shop and have them expand the bushing, 10 bucks tops.
I thought of that, but I need the whole inlet to be a constant diameter. Expanding the bushing is fine, if the core is 21/4". You can't expand the weld that holds the bushing to the body.
Michael, it won't be a flared collector. I'm looking to replace the 4" long by 21/4"diameter ball and socket collector with a longer merge collector with a 21/2" outlet, followed by a constant diameter 21/2" intermediate pipe going into the glasspack. This should keep the velocity up of the exhaust gas flow, till it cools and no longer needs the larger cross section to maintain the velocity.
If there is going to be a problem with this set up, it will be that the step down at the end of the glasspack is too far and the gases may have cooled too much by the end that it would then impede the flow. Thrush can make a special order 21/2" in/21/4" out, 28" long glasspack, which if the inlet is located as far forward as the 35" glasspack's will move the step down slightly forward. Then again, I just may end up doing the shorter glasspack to begin with.
No... What I meant was it'll be in-effect like a flared collector to the pressure-wave. And that glass-pack mufflers look the "wave" like flared collector-ends with a reducer-cap stuck on the end. This is all taken from the various articles I've seen--that latter-part from one written by David Vizard--on exhaust design, and from what I can visualize here. I do wish you luck with it & it all works-out well.
To the OP: Is this drone coming from the engine compartment? I just read in an old issue of Motor Magazine that the 1999-2002 J-cars had a droning issue, usually at higher ambient temperatures & the A/C on, that was result of the accessory-drive setting-up a natural resonance in the larger spans of the belt between pulleys... Namely between the alternator & A/C-compressor's. A change to a new P/N belt of a different rubber compound was the solution.
I know resonances can be tricky, but it "sounds" like its coming from near the rear, by the muffler.
I'll see if I can get my hands on a Dynomax VT and I'll post the result.
ive heard mixed reviews on Dynomax, i stick with Magnaflows.
Alright, I've had the dynomax VT for a couple days now and it is freaking stellar. At least for what I was looking to accomplish.
The drone is gone! I found it hard to believe any other posts because I figured it was the extra 1/2 sq-in of air moving down the length of my car but sheesh, this thing fixed all of the noise.
It 'feels' like I've gained torque back in the low end as well. It might be a mind-trick, because my engine doesn't sound like it's givin' er as hard during regular city driving. But watching my revs I'm finding that to get the acceleration I like I'm consistently revving 300-400RPM lower than with my SuperTurbo on.
On the highway there is very little drone. Little enough for my liking.
When I hit the gas it opens right up. It was a little raspy the first couple of times, but I since then it's been more or less rasp-free.
I'm a fan.
