72-74 Muffler Differences & Head Connection

[Jason0115]

Is there any difference in these two muffler styles in terms of performance, sound, functionality? The top muffler with the long tail pipe that connects to the middle of the muffler for a 69-72 bus and the later 72-74 muffler where the tail pipe comes out of the end. I will be putting one or the other on my 2.0L fuel injected type 4 motor with a 72-74 heater box conversion.

Also, can I use class 10.9 nuts on the heater box to head studs with copper anti-seize? I have to re-seal this connection AGAIN because there are small exhaust leaks at this connection after my rebuild. I didfollow ratwell's method of filing the flanges and annealing the rings, retorque, etc. but I must have not gotten the flanges perfectly flat or something along those lines. If anyone in NJ knows a machine shop or can get these flanges perfectly flat, let me know. If not I'll get a larger file and try again. Thx.

[Abscate]

69-71 Bus and 72-74 Bus are different engines in North America, and completely different mufflers.
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[Jason0115]

[busdaddy]

69-72 refers to 411/412 cars.

According to the guy who knows type 4's (ray) it's quieter, but runs hotter: https://www.thesamba.com/vw/forum/viewtopic.php?t=320407&highlight=tail+pipe
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[Jason0115]

[airkooledchris]

it's never worth additional heat.


that said, id also consider:
https://www.appletreeauto.com/exhaust-system-fits-type-2-and-type-4-72-74

The 2.0 bus setup like this style exhaust more when it comes to power and running cooler. It's EMPI, so yea, it won't last forever.

Id suggest just picking up the header and getting a local exhaust shop fit a nice free flowing muffler to it for you:https://www.appletreeauto.com/quiet-header-fits-type-2-and-type-4-72-74

I got sick of them going to crap and went with a Vintage Speed setup years ago. It's rock solid, but super pricey and my temps were better with the EMPI extractor/header. They have a SS version of it, but I don't know if I could justify that. The mufflers are the shite part, just grab the header and homebrew a muffler setup for best bang Vs buck in terms of heat and performance.

[Jason0115]

[raygreenwood]

Picture #1 and picture #3 are both for any type 4 engine except for US market 2.0 with late exhaust/catalyst/cross over pipe.

Yes, at BD noted..... it is correct that the mention of 1969 to 1972 on the 411 and 412 cars is where this muffler came from.

More correctly it's 1969 to 1974 for 411 and 412 for 1.7L and 1.8L.

The top picture with the center exit pipe is called a "damper" style. Its very quiet and smooth. Its a little bit more restrictive than the one in the 3rd picture/diagram with the end exit.

Whether that will make the twin carb 1.7L bus engine run warmer or the 1.8L bus engine run warmer....I don't know.

I kind of doubt it because they are tuned differently than the 411 and 412. Also, as long as you are aware of the issue, it was only an issue on the 411/412 in Hot climates. It was noticeably hotter exhaust and head temps in summer in Texas, Georgia and Oklahoma. Not tragic though as long as you are stock tuning.

The other issue with the center exit muffler...and again this may only be critical on 411 and 412.....that center exit pipe is a double walled resonator. It banks a lot of heat and radiates to anything above and close to it.

Unlike the Bay bus, the engine bay in 411 and 412 cars is fully sealed and the center exit muffler made for a lot more radiated heat into the engine bay.

The end exit muffler was slightly louder....mainly just different/deeper sound.

Both of these mufflers can work fine on 411/412 and bus 1.7 and 1.8L.

Both of these mufflers were available in both left and right side pipe exit.

Why were both largely available at the same time and through the same years? I purely speculate that its because the center exit was a more quiet muffler....so was spec'd for certain countries with noise variance regulations. I will look in my parts book and see if there are any M codes for the center exit. Ray

[Jason0115]

[airkooledchris]

[Clatter]

The best thing about the ‘72-74 heaters is you get to run the t-bird exhaust.

When you choke down exhaust flow heat stacks up in your motor.

Get exhaust flowing with a proper header and get heat OUT!
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