Time to upgrade exhaust

mhjo

Founding Member

Nov 9, 2000

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Oslo, Norway

Aug 12, 2011

#21

• Aug 12, 2011

• #21

tx65coupe said:

I don't think its from the different diameter mid pipes or the H pipe. I can't believe that your having noise issue with Dynomax turbo mufflers and resonators. I know alot of people that have them with out resonators and they are pretty quiet. Are you sure they are turbo mufflers and not one of thier other lines?

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It has an unpleasant drone at 30 mph (3d) and 50 mph (Od). Sound like pulling up the 120hz lever on your HiFi equalizer.... (boooooooooooh)

 

tx65coupe

Active Member

Nov 29, 1999

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37

Aug 13, 2011

#22

• Aug 13, 2011

• #22

Thats weird. I had a similar issue with the Flowmasters I had, but have never seen anything like that with any type of turbo style muffler. Those VT mufflers are probably louder than the Super Turbos.

 

mhjo

Founding Member

Nov 9, 2000

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Oslo, Norway

Aug 14, 2011

#23

• Aug 14, 2011

• #23

How to get rid of the drone?

 

JonK

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Jun 6, 2007

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Nashville (Smyrna), TN

Aug 14, 2011

#24

• Aug 14, 2011

• #24

Have you installed the VT's? I'm curious to see how you like them. I plan to get these for my car once it's running and would like to know how others who have them like them. I like the idea of a 'quiet' exh. with the ability to open them up with RPM.
Jon

 

mhjo

Founding Member

Nov 9, 2000

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Oslo, Norway

Aug 17, 2011

#25

• Aug 17, 2011

• #25

The VT's are last resort. Today we will open H-pipe, and open the holes in the two main tubes (they are very small) in order to increase crossover flow.

I will report how that works.


Another tip we got i n order to reduce drone was to move one of the mufflers a couple of inches forward so that they no longer align.

 

mhjo

Founding Member

Nov 9, 2000

490

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Oslo, Norway

Aug 18, 2011

#26

• Aug 18, 2011

• #26

Report fro mincreasing holes in H-pipe.

We cut off the H-pip (transverse pipe) and inspectes the holes in the main pipe. On the left tube the hole was 1 " diameter, on the other only 1/2 ".
We opened noth holes to match the diameter og the h-tube, and welded back in place. However, it did nothing to the drone, meybe even increased it.
So, I'm back to replacing super-turbos with "drone free" VT's..

 

mhjo

Founding Member

Nov 9, 2000

490

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Oslo, Norway

Aug 26, 2011

#27

• Aug 26, 2011

• #27

I can't help feeleing that the car became slower after replacing the shorty headers with HiPo manifold - am I dreaming?

Latest:

The Dynomax VT's have arrived at the post office, so they will be installed soon. I will report results then.

 

PoppyMod

Member

Jun 27, 2010

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Severna Park, MD

Aug 26, 2011

#28

• Aug 26, 2011

• #28

mhjo said:

I can't help feeleing that the car became slower after replacing the shorty headers with HiPo manifold - am I dreaming?

Latest:

The Dynomax VT's have arrived at the post office, so they will be installed soon. I will report results then.

Click to expand...

Must be a nightmare! Unless your butt's has the sensitivity of a chassis Dyno LOL!

 

G

GTA6t7

New Member

Jul 8, 2011

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West Virginia

Sep 5, 2011

#29

• Sep 5, 2011

• #29

Any update on the installation of the VT's? I'm considering the same set up.

 

mhjo

Founding Member

Nov 9, 2000

490

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Oslo, Norway

Sep 6, 2011

#30

• Sep 6, 2011

• #30

Report - Dynomax VT

1. They are almost totally silent at cruising
2. They do not drone at any rpm
3. They scream like a cat when you rev up


Possible drawbacks:

1. You will start hearing all sorts of sounds from the mechanical devices in your car

2. You might fall asleep while driving



Note: They are more silent than the Super-Turbos I had previously, both in 2 and 3 muffler setups.

Note 2: I still have the rear resonators on

 

G

gjz30075

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Aug 30, 2004

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Roswell, Ga

Sep 6, 2011

#31

• Sep 6, 2011

• #31

Great to hear. I've been following this thread to hear the results of the VTs. Do you have any concerns about the internal mechanical stuff, spring, etc, wasting away over time and negating all what it is?

 

mhjo

Founding Member

Nov 9, 2000

490

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Oslo, Norway

Sep 6, 2011

#32

• Sep 6, 2011

• #32

Of course I do, and everyone is asking me the same question.

I guess the RD team at Dynomax did the same.

However, I read somewhere on the net that there was a guy who experienced rattle in the chamber, but that Dynomax offered return and compensation. Also, that there has been made improvents in the design since the first batches. Only time will tell weather the mechanism will last or not.

 

CochinoFilipino

Founding Member

Jan 14, 2002

171

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CA

Sep 6, 2011

#33

• Sep 6, 2011

• #33

Just a note: From what I understand, a cross-over needs to be properly placed to be beneficial. And not doing so may even hurt performance.

 

mhjo

Founding Member

Nov 9, 2000

490

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Oslo, Norway

Oct 8, 2011

#34

• Oct 8, 2011

• #34

My friend who owns a '67 289 convertible has just replaced his mufflers with the VT's. He is

 

2

2+2GT

10 Year Member

Apr 25, 2009

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Southeastern Pennsylvania

Oct 8, 2011

#35

• Oct 8, 2011

• #35

CochinoFilipino said:

Just a note: From what I understand, a cross-over needs to be properly placed to be beneficial. And not doing so may even hurt performance.

Click to expand...

I don't see how improper placement could hurt, but it's been established it needs to be as close to the engine as possible. Placed back by the mufflers, it'd be useless.

Fuel-Injected Corvettes have the crosstube wrapped around the engine.