Aftermarket Exhaust Vs stock muffler

[Tbob]

In another thread, a poster was asking how to make his bus quieter, and he had an aftermarket exhaust. The answer given was to go stock, and the thread disintegrated into a "dialogue" about exhaust. In that thread, it appears that the stock exhaust seems to be the exhaust all the "cool" guys are now using. When one long term poster spoke of his success with an aftermarket exhaust, he was pretty much trounced by another long term poster who more than just liked stock exhaust.
So it got me thinking. In the bad old days, no one, I mean no one, at least in the area I grew up in, used a stock exhaust. It was "common" knowledge that a good 4 into 1 header with a quiet pack or a glasspack if you could stand the noise, would produce better power and pull heat off the heads, properly jetted, of course. In the days of the infantcy of the exhaust gas analyser, jet drills and jet guages(remember those?) were what you used.
My own experience has echoed that, as 4 to 1(extractor in VW aftermarket land) exhausts in a whole series of busses seemed to give better power. Non scientific tests such as driving up the famous Grapevine or the Conejo Grade showed later downshift points, and better performance overall. Low speed off road was better as well. Not a lot, but enough to make it worth it. A friend of mine was a research scientist who bought a 1969 bus the same as my deluxe did do a bunch of serious scientific tests on his aerospace employer's nickel, and he concluded that the claim of drawing heat off the heads was valid. I do not remember how he came to that conclusion testing wise, but that was his conclusion.
On my 1973, type 4 engine, the exhaust is fairly easy to change. 6 bolts, if installed with neverseize, come off easily , and a new different exhaust goes on easily. I have several exhausts, stock OEM, a non equal length header system, a 4 to 2 to 2 muffler system, and a 4 to 1 vintage thunderbird header. Hands down, the thunderbird makes better power. The other systems seem slightly better than stock, but not up to what the 4 to 1 does.
So, it now seems that the guys running these busses are all going back to stock, and the hot setup seems to be running dual exit a la bug exhausts with pipes going out to the sides. Yet all my experience shows more benefits, power wise, from a good header. P.S., we put tons of them on bugs, too, after taking off the dual exit factory exhausts. Better power on them, too.
Has there been a shift in knowledge that now the best way to go is the dual exit stock? Have we finally decided that it isn't worth the extra noise? Is what was once "common" knowledge been shown to not be correct? Did the popularity of the exhaust gas analyser teach us some things we didnt know back in the day?
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1969 Deluxe, owned since 1973
1973 Westfalia, owned since 1983
1980 Westfalia, watercooled conversion
1985 Westfalia, stock!
1986 Westfakia, Audi I-4 conversion
A couple of trucks and a couple of Jeeps

[Abscate]

Without a Dyno all the anecdata is just that, crap.

People justify the money spent on cool stuff on cars claiming all kinds of ridiculous improvements on power , handling, mpg

Fuel value of gas can easily vary By 5% so claims of 3 HP increases from glass packs are in the error bars.

Post dyno results or put in chit chat forum for wankers
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.ssS!

[raygreenwood]

Actually there has been testing. Jake Raby noted years ago that after extensive testing ....short of having a custom header made by either Tangerine or A-1.....that the basic T-bird header was the only off the shelf product that actually made improvement in hp/tq and head cooling on a few of his head combos.

This is not to say that the T-bird is actually great or excellent. We all know what kind of POS it is construction, fit and lifespan wise......but it made improvement....small....but useful improvement. I ran one on my 412 for a while back in the late 80s and installed on a few 914. While its not a bus.....it is type 4 and at least one of the 914 ran L-jet. It made tuning a little easier and it did run the heads noticably cooler in Texas heat.

Most people have gone or go back to the stock exhausts.....because most people at least in the bus world.....just want at least factory reliability and performance.....but are looking at fit, sound and longevity. Most people with campers take them on weekend trips.....and will not put up with excessive noise when they are out to enjoy themselves.

A t-bird header on a bus.....which is really a detuned engine designed for low gearing snd heavy weight.....will not really give you any real increase in hp. It can give slightly better....noticably.....throttle response and yes...decrease head temps......but its not drastic. Most would deem it hardly worth the noise and having to replace it every 2 years.

The factory mufflers are interesting. For all of their faults.....they were a decent piece of design. They are quiet....and fit in a very tight space. They are adequate. They last a long time if you get a good one.

That being said.....when you say factory muffler.....you need to say which factory muffler. The heat, sound, lifespan and mild differences in performance are noticably different between brands.

From the top of the heap down.....in my experience......Ernst, Leistritz, Wagner/Starla/Lange....Dansk.
The difference in Ernst and Dansk.....are significant.

The biggest problem the T-bird has.....actually two problems.....is build quality.....and the fact that the collector joint is lopsided. If they could reweld a t-bird header to have a REAL colle tor...even if short.....with each pipe coming in at the same angle.....and actually make them exact equal lengths (they are close....but not that close on some).....it would be notkcably better.
EMPI makes a stainless T-bird header.....have not had a chance to use or heard much about it yet.

Also.....there is a mistaken belief.....that some or certain engines REQUIRE back pressure. That is not true.

What they require is STABLE pressure.....without REVERSION. And.....in most cases....that is accomplished on the stock muffler.....with SOME back pressure. With its internal baffel design and zig zag gas path.....it "for the most part".....prevents a good amount of reversion.....but produces back pressure.....that at a lower level.....IS reversion.....but is not as drastic in effect as an actual pressure wave front reaching all the way to the exhaust valve pocket and causing inlet problems. This whole issue is also why the stock cams are built with a certain amount of overlap.

Ray

[SGKent]

having done extensive exhaust testing thru racing experience that led to lots of winning, and working for one of the most respected engine machine shops in the country at the time in the 1970's and early 80's I have tried to answer that question many times here but have been flamed for the answers many times. Many here, but not all, are more into myths and advertising than facts. That is not directed at any one person - just the general theme that runs here at the samba in the bay forum.

The answer is that anything you do to the engine that allows more air to flow thru it allows more fuel to be combined with it = more power. But VW engines are built with low cost and limited resources in mind. IN A BUS, more power means less miles of perfection running. In some changes significant loss of engine longevity can occur. It is not a cast iron water cooled engine with 5 heavy double bolt mains. It is a lightweight air cooled engine that does remarkably well for its size and weight.

In addition to more air flowing thru the engine, there is also the effect of oscillation. If you sit on a swing and time the putting of energy into the swing then you can make the swing go farther than it would with the energy of just one push. The same is true with the intake and exhaust. By adjusting the width and length of the intake and exhaust runners additional air flow can be added to each cycle at a given RPM. I believe that Ed Iskenderian was the first to take advantage of this with his racing engines and camshafts. Isky cams is the company he founded. Also laminar flow has to be considered. Once that happens the effective cross section of intake or exhaust is reduced so flow drops.

I can't speak for the mindset of VW engineers. But every time I increased the pwer with changes to my VW Type 1 motor in my 1971 bus the longevity of the perfect running engine fell. The more power I made, instead of getting 80,000 miles of perfection I got 40,000 miles before some tick started, or a head cracked, or a case pulled a stud etc. Unless fully loaded or on a grade we drove 70 mph +/- most everywhere we went unless on city streets. We payed music and talked with passengers, even in the back.

This doesn't answer your question directly. That is because you have to decide what is important to you before you choose a muffler. Do you want power? Do you want pre-heat for a carb on a very cold day? Do you want manifold heat? Do you want your bus heater to be a bit warmer in the cabin on a cold day? Are you going to run bigger cylinders that will need to exhaust even more than the 1500 & 1600 did? How loud are you willing to accept?

I eventually chose stock on a 1600 because the engine lasted the longest with perfection. If I wanted a better exhaust then a quiet pack type system flowed more exhaust, and it was also pretty quiet - but next were dual carbs, etc. That always led to loss of longevity.

Also, putting a little red high temp RTV on the donuts when installing them exhaust pretty much kept them quiet until the next time the exhaust was removed whether it was 10,000 miles or 80,000 miles. The 1971 was a daily driver for almost 500,000 miles. During that time it saw many different engine combinations. It went from factory to much more power then back to factory. I got tired of pulling it out every 40,000 miles because of some small thing that wore out due to being under engineered.

Also - how much you drive is a factor. If you put 2,000 miles a year on the bus you can make as much power as you want and drive 20 years before having an issue. If you drive 15,000 - 20,000 miles a year like I did, then you'll have it out every 2 - 3 years because of some weird issue or another if you make too much power and use it. Why make it if you won't use it.

So - stock has wonderful benefits that many people enjoy. A quiet pack also has the benefit of a small amount of more power but some of the benefits of a stock exhaust are lost. Add dual carbs and bigger cylinders to that and you won't be in 2nd gear climbing that grade. But you will work on the engine more often. The exhaust Gary made with dual tailpipes works better than a single tailpipe and resonator. It is also safer than dumping the exhaust directly behind the bus into the dead area.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[WhirledTraveller]

People spend endless hours analyzing and testing and in the end "peak power" is up maybe 5% with the best system and usable torque up maybe 3%. Your "butt dyno" can't tell the difference. Some systems just sound more powerful and that's probably most of the psychological effect. Look at modern cars. They make 300+HP easy and you can barely hear them run. The old thinking that loud = power is proven false.

Most "bus guys" these days don't give one whit about extra 3% performance and just want a reliable system that isn't too loud and won't rust out. And maybe keeps the head temps down as a bonus (again, reliability). On my '77 the original stock exhaust is a nightmare to keep leak and rust free, and some parts are simply no longer available. Hence I've gone to the '74 headers and stainless Vintage Speed exhaust. Which probably doesn't add much power, but it's stainless, trouble free, and I don't have to worry or think about it.
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[orwell84]

I don’t have the knowledge or experience (or the time) to tinker with performance modifications so I don’t deviate very much from stock. The cheap Empi 4 in one seems to give me a little more power. It’s also better suited for installing an oxygen sensor. Racing is a different world where engines get pulled apart often and longevity isn’t a huge concern. I noticed better throttle response when my neighbor set the timing by ear when we first installed my rebuilt engine. When I checked it, it turned out to be way advanced. It occurred to me why that would be good for performance but bad for longevity. I am happy with a plodder if it lasts a long time. For someone like me running a stock muffler vs a t-bird style header probably wouldn’t make much difference either way.

[Abscate]

I better eat some prunes before I post anymore. Everyone ran off my lawn this morning...
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.ssS!

[ccowx]

All of the below is true! Let's not forget that we are all getting older too, and quiet drives with grandchildren have long replaced taking the current girlfriend on a road trip, along with a case of beer and high hopes!

This is really a very subjective question anyway. There is no question that a stock muffler is quiet and does a great job with all of the pre-heat, etc things. There is also no question that a header will make more power, especially in a modified engine and at higher rpms. Anyone trying to tell you different is full of crap. After those facts are accepted, it really comes down to what tradeoffs work for you.

Myself, I am building a new engine for my 70 bus. This is based on 20+ years of daily driving, road trips and lots of advice from here and elsewhere. It should last a good long while, though not as long as stock. I also expect it to make about 50% additional hp. I am making use of mainly stock parts such as distributors, carb, and most of the externals. All of the pre-heat, manifold heat, filtration, chokes etc have been retained and even improved. I will put in a better cam and everything has been upgraded and recalibrated, but still basically a stock engine externally and in the function of it's various systems. Other than the header of course!

Chris

[raygreenwood]

SGKent gave a pretty good answer.

To add a little to it........expand a little.....his point about tube lengths is qlso associated with muffler chamber volume. When you vary either or both.....it changes where in the torque/rpm band benefits ....if any.....are gained.

Thats means you have to make choices because you cannot make an exhaust that adds improvement in the entire rpm range. And....everything comes into play.....fuel....heads...cam....gearing....tites..

You may design an exhaust system that is capable of giving a 5%....or even higher...improvememt in tbe "X" rpm range....but if that rpm range is out of sync with the gear8ng, tires or head flow.....you cant use it. Thats the biggest challange with a bus. Weight, drag and gearing. To work within those challanges.....there is not much.....affordable for most.....and that can even fit in the restricted space ......that is capable of giving any real improvement in the most common rpm range used.

You also....to use any improved exhaust....have to be able to re-tune the fuel and spark to be able to take real advantage of it. Not actually that easy on stock L-jet. A little easier on atock dual carbs.

As I alluded to....its a different world with a type 4 engine in a 411, 412, 914 or 912. Very different gears, less than half the weight and totallly different cam, compression, ignition and fuel tuning. A decent header can make a big difference. We have a different rpm band and driving range.
Ray

[Tbob]

Thanks, all for chiming in. I was really perplexed why an enthusiast organization such as this one that seems to thrive on any and every improvement to our busses, that this one change, which some other posters also noitice a difference in power, gets downplayed. And I do understand the necessity for quiet, as my hearing goes and the desire to communicate with my fellow travelers becomes more important.
But a couple of things. I have been on the Samba for over 10 years. I have heard it is not until you have been ridiculed that you are accepted. Now that I am a wanker, I am in. Thanks, Abscate! Actually, if you remember, in the early sheet metal age, we didn't have dynos. No one did, except maybe big companies. To determine improvements in power, you had to use other metrics. The early hot rodders used the drag strip and the dry lakes where I grew up. We used markers on hills and mountains, as far as when you needed to downshift and at what speeds, etc. You tried to do it as scientific and repeatable as possible(hit a marker at the bottom of the hill at 65 mph. go up the hill as fast as possible and see how far you could get before you were going only 35 and had to downshift into third. Carl Shipman wrote a book called " Tuning for Performance" in which he outlined, for motorcycles, how to best tell if you really did improve performance, and how to jet using controlled runs. Although we weren't going for overall performance(in a Bus?) we wanted our vehicles to run as well as we could make them.
An as many of you are also bringing up that there are more issues than power, such as fitment, heat production(how many hours did I spend in my life reforming heater tubes?) etc., etc., maybe stock makes sense. But I found that the extra power to be useful, and I absolutely agree with SGKent, that the more power you make the shorter the engine life. I have about 350,000 miles on my 1969, and I cannot remember how many engines, 4? 5? I get about 65,000 to 75,000 miles miles out of my engines before they become less than acceptable. I too, used my 1969 and my 1973 as daily drivers literally for decades. I no longer do, but I always valued the extra power of the 4 to one. Even if it was only 5% more, when you start with 57 horsepower, even a couple more helps.
Especially in the mountians. With a loaded Westy. Going uphill both ways. And Ray Greenwood, thank you for your thoughtful replies. I always learn when I read your responses. I wish I would have done whatever you have done in your life to collect so much knowledge. And thanks for taking the time to pass it on.
_________________
1969 Deluxe, owned since 1973
1973 Westfalia, owned since 1983
1980 Westfalia, watercooled conversion
1985 Westfalia, stock!
1986 Westfakia, Audi I-4 conversion
A couple of trucks and a couple of Jeeps

[raygreenwood]

If you want to get a good idea of what is inside of a GOOD factory muffler.....here is a disection of an Ernst I did about 3 years ago.

https://www.thesamba.com/vw/forum/viewtopic.php?t=653839

As I note in the thread....the overall design and for such a compact space....is really quite good. All it needs to be better performance wise (if for nothing else to be less restrictive and lower head temps) .......is a bit more internal volume in the chambers.....some tweaks to the perforation sizes.....and equal length tubes.

I have a design I have been working on using largely the stock internal configuration with some tweaks....that brings it to equal length primaries. The overall muffler would have to end up more square-ish and less oval....be about 1.5" deeper toward the ground and about 1" longer in each direction......and its a LOT of welding. Even with factory economy of scale.....if the facyory produced it the way I am redesigning it.....it would easily be 2 or 3X the cost.
Ray

[wcfvw69]

Wait, a thread where someone asked a question got side tracked in the Bay forums? Shut the front door!

Where the same people's resumes vomited out yet again and again and again?

I'll never know the exact RIGHT OR WRONG answer nor would I EVER tell someone you can or can't. However, I will share my experiences with this part or that part. It's the OP's job to filter through all the ego's, resumes, ego's again, BS again, resumes again and filter what information they want from the thread.

A stock muffler is perfectly fine for a basically stock engine, even with slightly larger pistons in it. Most of us bus owners only want to have a reliable VW that isn't loud, especially at freeway speeds and provides all the things the engineers designed in. A header/muffler isn't going to make any measurable difference and will only further damage our deteriorating hearing. Correct exhaust heat and flow through the heat risers to the carb manifold. Correct fresh air hook ups for the hot air to the cab being two big bonuses of running a stock muffler. The other key bonus is these stock muffler are pretty quiet mufflers.

As Ray noted, the best stock mufflers are the NOS ones by the brands he mentioned. They are still pretty abundant and priced close to the lowly Dansk mufflers sold today.
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[ccowx]

WCFV69,

I do have to laugh at the competing egos. Bluntly put, few of us here really know each other and therefore ALL resumes and egos need to be taken with a grain of salt.

I will only make one point to your comments below, and it is an important one. It applies to mufflers, carbs, thermostats and most everything else.

-Comparing broken or improperly installed modifications to properly functioning ones is valueless!!!

Case in point in my world is when I hear constantly how electronic ignition cured a million issues. Oh, and the points it replaced were 20 years old and out of tune, but that does not matter, it is all due to the electronic ignition! In this case, I will take issue with the statements about pre-heat, manifold heat, and all the other things. If you choose to install headers then you need to figure this out. There are a million threads here about how to modify your headers to do all that. Half of the work needed is done by the aftermarket header makers, simply needing a bit of work to make it functional. If you choose to install them without taking that time, then if they don't work that is on YOU. Blaming the aftermarket for not making it easy is not a valid excuse. This applies to many aspects of these engines and especially custom stuff. If you don't fully understand what you are doing and take the steps to make it work right, then the problem is YOU.

Because I live in a place that gets very cold and has many mountains, I have not only retained the stock systems, I have improved them. Now I should have the extra power and also the drivability and cold start benefits of the stock system. Noise wise, we shall see.......

As for the noise levels, that is a personal thing and fair enough. In my case, I am going to be improving the sound insulation in the bus while it is all apart. Hopefully that will be enough!

Chris

[wcfvw69]

[airschooled]

I'm going to be very honest; I don't have time to read this thread BUT I'd still like to respond to the original topic.

I think everyone who installed racing mufflers in their youth is suffering from tinnitus and hearing loss. Now they're growing up, and The Samba exists.

The five highest mileage buses in this forum all use stock mufflers, except for Rich who recently mentioned that he liked the volume reduction on a swap from a header (I think?) to a stock-style Vintage Speed. I think the amount of time spent behind the wheel (multiplied by time spent with passengers who deserve compelling conversation) is a LARGE motivating factor.

See you on the road,
Robbie
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[ccowx]

I probably do get some status for daily driving a bus too, with headers for the most part. I suspect something around 300,000 miles. Of course, I had my two young kids in it, so perhaps conversation was not a priority!

As for this comment, I assume it applies to you and I as well?

"Be highly suspicious of anyone who says you can or can't."

Thanks!

Chris

[wihr]

I am the original owner with 387,397.8 miles and all but about 50,000 with a
Bugpack "headers" system. It is only slightly louder than stock and allowed me to ascend the hill from candlestick north into the city (SF) without downshifting to third. It would seem to have given me more power. Has the mileage improved? Who knows? That was over 300,00 miles and over 45 years ago. How many engines? I would have to count.

I live in Portland now and when driving to Government Camp on Highway 26, I am only in third from just beyond Rhododendron to the top.

WW
_________________
WIHR

1970 Campmobile "Van Ordinaire"
2009 Lincoln Town Car "Behemoth"
1969 Lambretta 150 DL "Nina"
1962 Matchless G 12 CS 650cc

[airschooled]

[wihr]

Not soon, but the last time, several years ago, it was second and third all the way to the top.

I used to take lessons at Timberline but became a black diamond skier at Skibowl - had a hip replacement three years ago - couldn't find anyone to ski with last year and have only become excited again in the last few days with the base at over 70 in. The camper is the only way to go (that is with studs and beers)!

WW
_________________
WIHR

1970 Campmobile "Van Ordinaire"
2009 Lincoln Town Car "Behemoth"
1969 Lambretta 150 DL "Nina"
1962 Matchless G 12 CS 650cc

[Wildthings]

I will throw in that on top of not having as good of a manifold heat setup headers tend to hang down and get trashed by rocks and curbs and thus I have tended to avoid them.

For my T-181 Thing, I have bought but never installed a VW branded 4 into 1 header system. It uses smaller tubes than most aftermarket systems do and the price was certainly right. Don't know if they are still available or not.

I have wondered if part of the HP gain of using headers was just the lessened flow of exhaust gas for the manifold heat and thus a cooler more dense intake charge. I have toyed with the idea of installing a valve in the preheat pipe on my T-181 so I could lessen the amount of heat reaching the pipe in hotter weather.

FWIW, I have a stainless steel VW branded stock style exhaust on my '77 with an 1800 T-4 engine, not the best quality stainless as far as appearance, but it should be around a long long while.