TheSamba.com :: View topic - Getting that signature whistling muffler sound back?

Mon Aug 03, 2015 10:57 am

What part of the muffler makes that beautiful stock whistling sound?

I have a 72 Super and was assuming that the chrome tail pipes make that sound. Mine are rusted (of course) and I was going to replace them with stainless tail pipes. Do the stock tail pipes have a baffle in them that produce the whistling sound?

Thanks!
John

Mon Aug 03, 2015 11:09 am

The pea shooters, i.e. chrome tailpipe tips are indeed what makes the whistling sound.

Mon Aug 03, 2015 11:58 am

sjbartnik wrote: The pea shooters, i.e. chrome tailpipe tips are indeed what makes the whistling sound.

Very cool. Thanks!

Mon Aug 03, 2015 6:43 pm

...and it's known as FWEEM. :D

Mon Aug 03, 2015 7:14 pm

You also get the nice sound of the engine fan when using stock tailpipes. It tends to get drowned out by aftermarket headers or baffle-less tailpipes.

Mon Aug 03, 2015 7:32 pm

vamram wrote: You also get the nice sound of the engine fan when using stock tailpipes. It tends to get drowned out by aftermarket headers or baffle-less tailpipes.

So the stock tail pipes do have baffles in them no? Sorry, have not attempted to take the rusty ones off yet to look at them.

Mon Aug 03, 2015 7:37 pm

edelweiss wrote: vamram wrote: You also get the nice sound of the engine fan when using stock tailpipes. It tends to get drowned out by aftermarket headers or baffle-less tailpipes.

So the stock tail pipes do have baffles in them no? Sorry, have not attempted to take the rusty ones off yet to look at them.

Yep. Wolfsburg West and other vendors sell them.

http://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=113251163C

Probably lots of pics of them in the gallery.

Mon Aug 03, 2015 7:47 pm

vamram wrote: edelweiss wrote: vamram wrote: You also get the nice sound of the engine fan when using stock tailpipes. It tends to get drowned out by aftermarket headers or baffle-less tailpipes.

So the stock tail pipes do have baffles in them no? Sorry, have not attempted to take the rusty ones off yet to look at them.

Yep. Wolfsburg West and other vendors sell them.

http://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=113251163C

Probably lots of pics of them in the gallery.

Awesome! Thanks!

Tue Aug 04, 2015 6:45 am

It does not appear to be that simple. I have stock replacement tail-pipes and don't have the fweem. There are some instructions on how deep they should be insterted into the muffler. The muffler on mine may have some internal differences from stock since I could not insert the tail pipes as deep as suggested in the instructions before hitting in internal pipe.

Hopefully you will have better luck.

Tue Aug 04, 2015 6:55 am

bnam wrote: It does not appear to be that simple. I have stock replacement tail-pipes and don't have the fweem. There are some instructions on how deep they should be insterted into the muffler. The muffler on mine may have some internal differences from stock since I could not insert the tail pipes as deep as suggested in the instructions before hitting in internal pipe.
Sometimes the end of the heat riser tube that ends in the "muffler" is not centered in the exhaust opening. You may need to tweak it just a bit. That tube, which comes from the heat tube that runs below the intake manifold, should sit INSIDE the tail-pipes. This results in a vacuum that draws the exhaust through the heat riser and out the exhaust.

The adjustment for installing the tail-pipes does not specify how far they should seat into the "muffler". You bottom them out and then back them out a little (I can't recall how much you back them out??... maybe someone has their Bentley manual handy?).

BTW, I use "muffler" above to describe the resonator (what most call the muffler), but technically the tail pipes are actually the mufflers. They function the same as old glasspack mufflers.

Tue Aug 04, 2015 7:47 am

Adjust tail pipe length (from tip to muffler) to:

8 9/32 in. (210 mm) on 1961-1973 models

8 7/8 in. (226 mm) on 1974 models

Tail pipe length affects exhaust flow and engine back pressure.

Tue Aug 04, 2015 9:03 am

sjbartnik wrote: The pea shooters, i.e. chrome tailpipe tips are indeed what makes the whistling sound. . Parts place inc. in warren MI. Had original made in western Germany tail pipes, that's were I got mine. I still think they have them.........Quality chrome .

Tue Aug 04, 2015 10:32 am

Luft kühl wrote: Adjust tail pipe length (from tip to muffler) to:

8 9/32 in. (210 mm) on 1961-1973 models

8 7/8 in. (226 mm) on 1974 models

Tail pipe length affects exhaust flow and engine back pressure.

Only issue with this is the various lengths sold by the aftermarket. The tip to muffler measurement is only good if the entire tailpipe is stock length.

My blue Bentley says this:

On 66-67 cars the tail pipes should not enter muffler more than 1.8 inches. On 68-69 models 3.4 inches is the limit. Obtain these fittings by first measuring total length of pipe and then subtracting the length protruding after insertion.

Orange Bentley says:

Measure the tailpipes. 3 lengths are used. depending on model, these lengths are 276 MM, 249 MM and 226MM. The last length is on 73 and 74 cars only. (However, 74 pipes have an inside diameter of 23MM, not 20MM as in 73).

On 74 cars only, install the tailpipes so that they project 155 MM from the muffler

On 70-73 cars, insert the left tailpipe. Then insert a steel tape measure through the center of the pipe until it contacts the pre heating pipe inside the muffler.

Move the pipe in and out until its outer end aligns with the correct graduation on the pipe.

The correct graduations are 270MM for 276MM pipes, 243MM for 249MM pipes, and 220MM for 226 MM pipes.

Not sure it's worth the hassle for a whistle!

Tue Aug 04, 2015 7:18 pm

If you want that sound, use an NOS muffler and NOS tips. Be careful what you buy

Tue Aug 04, 2015 7:45 pm

In my experience, new tailpipes don't really fweem very much, but as they wear and the baffles start to get loose, that's when the fweem kicks in.

About NOS muffler and pipes:

For many years I ran taper tip tailpipes (the baffled style) mostly because I was sick of fweem. Then, several years back, I on an NOS Ernst muffler and NOS Ernst brand tail pipes, and I was very happy with them NOT fweeming when I put them on there (on my big-bore 40HP engine) Eventually they started to, but not too badly. Later, that muffler died but I moved the pipes to an NOS VW-made muffler and they still sounded fairly good to me. But, they do fweem a little now and I've been meaning to try some different pipes again.

-Andy

Wed Aug 05, 2015 12:15 am

Some years ago I wrote an article on the reason for the Bug's distinctive sound.

The beat part comes about through the flat 4 arrangement coupled with the muffler design. The rear two cylinders mount direct to the muffler (which is essentially just an open box) and the front two cylinders connect via the headers/heater boxes. But inside the muffler, the two rear cylinder connections each have an internal pipe across the muffler, so the headers for all 4 cylinders are the same length (two cylinders internal and two external). This results in the pulses coming out the tail pipes as left/left/right/right, rather than left/right/left/right, and our stereo hearing hears that as a distinctive beat. But because the muffler is in fact open inside and some of each pulse can leak across to the other tail pipe, it's really LEFTrightLEFTrightRIGHTleftRIGHTleft which you hear.

The whistle sound does indeed come from the peashooter tips. It's the inner perforated tube with fibreglass packing behind the perforated pipes which does it, and incidentally THESE are the true mufflers - put plain pipes in there and hear the difference! The narrow internal diameter of the perforated pipe, resulting in a high gas speed, plus the perforations, creates the whistle sound - a bit like blowing through a snake-light perforated tube.

Wed Aug 05, 2015 4:00 am

Aussiebug wrote: Some years ago I wrote an article on the reason for the Bug's distinctive sound.

The beat part comes about through the flat 4 arrangement coupled with the muffler design. The rear two cylinders mount direct to the muffler (which is essentially just an open box) and the front two cylinders connect via the headers/heater boxes. But inside the muffler, the two rear cylinder connections each have an internal pipe across the muffler, so the headers for all 4 cylinders are the same length (two cylinders internal and two external). This results in the pulses coming out the tail pipes as left/left/right/right, rather than left/right/left/right, and our stereo hearing hears that as a distinctive beat. But because the muffler is in fact open inside and some of each pulse can leak across to the other tail pipe, it's really LEFTrightLEFTrightRIGHTleftRIGHTleft which you hear.

The whistle sound does indeed come from the peashooter tips. It's the inner perforated tube with fibreglass packing behind the perforated pipes which does it, and incidentally THESE are the true mufflers - put plain pipes in there and hear the difference! The narrow internal diameter of the perforated pipe, resulting in a high gas speed, plus the perforations, creates the whistle sound - a bit like blowing through a snake-light perforated tube.

Thank you for sharing! Very interesting to read.

Wed Aug 05, 2015 4:47 am

pb_foots wrote:

[
Orange Bentley says:

Measure the tailpipes. 3 lengths are used. depending on model, these lengths are 276 MM, 249 MM and 226MM. The last length is on 73 and 74 cars only. (However, 74 pipes have an inside diameter of 23MM, not 20MM as in 73).

On 74 cars only, install the tailpipes so that they project 155 MM from the muffler

On 70-73 cars, insert the left tailpipe. Then insert a steel tape measure through the center of the pipe until it contacts the pre heating pipe inside the muffler.

Move the pipe in and out until its outer end aligns with the correct graduation on the pipe.

The correct graduations are 270MM for 276MM pipes, 243MM for 249MM pipes, and 220MM for 226 MM pipes.

Not sure it's worth the hassle for a whistle!

So...Reader's Digest version is: Jam pipe in all the way, back it out 6mm? Or are my reading skills that bad?

Wed Aug 05, 2015 6:08 am

I've never worried much about getting the correct fweem sound, although I'm thinking if you wanted to experiment with the correct placement of the tailpipes, why not just leave the clamps loose enough to move them in & out while the engine is running? Like tuning a pipe organ, right?

Wed Aug 05, 2015 10:26 am

My car had the fweem sound when I first got the car at 26,000 miles. But the muffler (or resonator) was rusting so very quickly it just got loud.

I had a new "muffler" :) installed and at first, the engine was nice and quiet, but I didn't have the fweem. Slowly as I drove it more and more, it came back. But now at 46,000 miles, it is going away again. I suppose due to wear in the tips.