Muffler and exhaust system for 1.9 NA DIESEL?

[johnnytod]

The time has come to replace my downpipe and muffler on my 1.9 NA Diesel.

My first basic question is:
Does the muffler has to be specifically designed for diesel or can I put any muffler that can fit (e.g. from a gas engine)? I am going to be using the FAS muffler hanger system

What other manufacturers / brands do you guys recommend as a replacement muffler?

I hear some people recommend spiral flow mufflers (instead of glass pack mufflers) but I am not sure what brands and models are those?

I also need to replace the S shaped down pipe as it is rusty and cracked. Do you know a cheaper source for that one? What diameter downpipe would you recommend for a NA diesel engine? Is the original diameter pipe too restrictive?

I read some people put also cats to make it less loud but would that restrict the flow and the power? Would I need to have a customer exhaust system if I wanted to mount a cat also or could I put it somewhere between the S-shaped down pipe?

I am not looking to spend more that $500 on this repair of downpipe and muffler but I would spend some money if I know that for instance a larger pipe size can substantially improve power output

I am pretty happy with my engine so far, I am getting upward of 30 mpg. I would enjoy a little more power in the uphills though.


Appreciate your recommendations.

[82westyrabbit]

Do not put a cat on a normally aspirated diesel it will plug up in short order with out other emission control devices to go with it. You can run pretty much any muffler you want with out having problems. I have the FAS muffler hanger system and it works for me. I would run the muffler FAS recommendeds but you will probably have to custom make your front pipe that is easily done if you can weld. If not you buy prebent angeles from a speed shop cut them so the pipe is the way you want then take it to someone to weld it. If this is above your ability it should not be to expensive to have some on do the hole job. I don’t think any thing you do to increase flow in your exhaust will help power much short of a turbo. John

[?Waldo?]

Moroso is the brand of spiral flow muffler that I have used. You can get them in either stainless or mild steel from places like Summitracing or Jegs. They are free-flowing and considerably better at reducing noise than a glasspack. The stock vanagon diesel muffler would be quieter on a non-turbo motor, though.

Don't add a cat to a non-turbo motor.

[johnnytod]

1. Are the mufflers for diesel designed with special characteristics that are specifically addressing the diesel engine and emissions?

Or can I put whatever muffler fit the dimensions and space?

2. What diameter downpipe would you recommend for 1.9 NA Diesel?
Is the original S-shaped diameter pipe too small - in other words would I increate the power with a little bigger diameter downpipe?
And if I increase the downpipe diameter would I have to increase also the in and out diameter of the muffler?

3. And why is the downpipe bent in this S-shape form? Does it need to be like that exactly or can it be straight (like on a TD) or maybe bent in a closer fashion but but not exactly the same shape? What difference would it make if it is not exactly bent in the same shape?

[?Waldo?]

1. No. (The stock muffler may be designed with specific baffles to mediate the specific 1.6 engine noises, but since you are already using a different engine the specific tuning of the stock exhaust is largely not relevant).

2. Just a guess, but 2" diameter pipe is probably plenty for a 1.9 non-turbo. The original pipe is quite small but I kinda doubt you'll gain enough power to notice any difference going bigger. Remove the pipe and drive it with earplugs in order to know the maximum power difference you will experience by attempting exhaust changes.

3. Again just conjecture, but I imagine the S-shape is both to reduce noise (bends reduce noise) and to create a small amount of spring into the pipe. A turbo dramatically reduces engine noise. You can certainly run a straight pipe but you may find it obnoxious (or those around you might).

The absolute biggest bang for buck power/efficiency improvement to a non-turbo diesel engine is to add a turbo.

[johnnytod]

Thank you Waldo! That is a great idea to test the van on a local hill with the pipes removed.
How much could it cost to put a Turbo? Granted, here is the SF Bay Area prices are double
My 1Y block says D/TD so I guess this is feasible

[?Waldo?]

Yes, a 1Y can be turbo-charged. It is a little different from the AAZ which was the stock 1.9 IDI turbo-diesel, but it would work fine. There is quite a bit to the turbo install - entire intake from filter to engine, entire exhaust including manifold, turbo, etc..., oil filter flange, turbo oil supply, turbo oil return, injection pump with boost fuel enrichment. None of that would be cheap especially if you are paying someone to do the work.

[johnnytod]

It sounds like I am better off just to leave it NA, if I am happy with it and if it does not make me any problems.

The other thing I have heard is that Turbo is more thirsty. More power, more fuel consumption. That is logical.

But are there any empirical data as to how much mpg would fall after installing a turbo? Anyone?

If I am doing 30mpg - 34 mpg currently with the 1.9 NA, will I get a 5 mpg decrease with a turbo (e.g. most people I have talked to with TDIs report ~ 25mpg)

I am asking because I am kind of fanatical about optimizing mpg, so this is THE biggest factor of all for me

[?Waldo?]

A turbo adds efficiency. It turns waste exhaust heat into useful work. This is an over-simplification, but all else equal, if a non-turbo and turbo-diesel engine are driven at the same speeds and acceleration rates, the turbo-diesel will consume less fuel. If you drive at faster speeds and greater acceleration rates, then you will get somewhat worse fuel economy. Most people drive their vehicles based on the available power and so take advantage of the dramatically increased performance that turbo-charging offers and those significantly higher acceleration rates/speeds result in lower fuel economy.

TDI engines are dramatically (~15%) more fuel efficient than IDI engines. That added efficiency is due primarily to the reduced heat loss to the cylinder head due to the greater surface area of the pre-combustion chamber (PCC) design (the TDI engines dump ~1/2 the waste heat into the coolant vs. the IDI engines). The IDI engines also suffer from additional pumping losses due to cramming the air into and out of the small opening of the PCC. All else equal TDI vehicles driven at the same speeds and acceleration rates as non-turbo IDI engines (like your 1Y) will easily get more than 10% better MPG and often more than 15% better.

[AndyBees]

I agree with Waldo's assessment.

Although my engine is an ALH TDI, I'll share this story. The first exhaust system was a disaster from every imaginable thought.

So, I ordered Stainless Steel components from Columbia River Mandrel Bending. From the Turbo out, each joint/connection, I transitioned to a slightly larger Inside Diameter. (2 1/4" exit and I forget the size at the Turbo).

In the pic below, you see a 180 turn coming off the Turbo joined by a spring loaded donut to a short Resonator. From the Resonator there is a 90 degree turn that connects to the OE CAT which is welded to a short non-reversed Glaspak that exits to the right similar to OE or the FAS. It is quiet.

This set-up resulted in just under 3/4 MPG better than the initial cobbled up mess on a very similar 12k plus road trip. And, the second trip we had two additional people on board including all their stuff.

Also, I pressure washed the CAT in both directions prior to the second trip. The pressure wash did not affect the CAT's performance.

From the exit at the Resonator, I used V-band welded quick connects. So, I can drop the exhaust in a matter of minutes. The donut allows good movement and works much better than a stiff flex connection.

So, to the OP, you can go back with an OE system or have a custom system built that will be as good or better.

_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

[11BC2]

[johnnytod]

Thanks for sharing this Waldo and friends! Another good learning experience.
I will be mounting the FAS muffler hanger system this weekend.
If anyone is interested in knowing how it will perform, I can report back.

[ndorian]

Andy has a sweet exhaust/van. +1 on turboing the motor, if you are looking for power gain. I wish I had a 1.9 base.

[AndyBees]

[?Waldo?]

I'm not a fan of any Vanagon exhaust system that hangs off the body.

[AndyBees]

[/quote] That is EXACTLY what I needed to see! What radius bend did you ues?
Thanks.[/quote]


Well, I'm not sure about the radius. It is 8 inches from outside to outside. The pipe is 2" OD and roughly 1.75" inside diameter ......... quite heavy. I'm thinking maybe 3" center-line radius. With 8 inches outside to outside, that would seem correct.

Seems I cannot find anything on Columbia River's website close to the thickness I used (about 11 gauge) with the 180.

http://www.mandrelbends.com/
_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

[ndorian]

[ndorian]

Maybe diesels vibrate too much for them?

[?Waldo?]

I have not used the FAS mount system and I doubt I ever will. It is fairly easy to build an exhaust that mounts entirely to the Vanagon engine. Bridging between the engine and chassis only adds vibration to the chassis and causes additional stress to the exhaust components without any upsides other than (arguably) convenience.

[AndyBees]

Well, my first exhaust system was a cobbled mess to say the least as I stated previously. It did make it on a 12k mile road trip with a number of makeshift repairs. It was mounted to the engine, although, that was part of the mess. I ended up buying some springs at a hardware store in downtown Saskatoon to support it from the body. I also used buggy cords.

So, when I built the SS system using the donut fitting at the down pipe, I hung it on the body in two locations. That was about 50k miles ago with no problems since. No rubbing, no thumping, no vibrations and no resonance or droning.

Below, somewhere south of Saskatoon, Saskatchewan in July, 2014.

_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.