Retrofitting old cars for cleaner exhaust
 

I've been pondering the idea of retrofitting late 70's early 80's vehicles (gas and diesel) such as the rabbit, chevette, omni, escorts, ect, with better/newer emissions components to make the car more ecofriendly. I realize some of these cars mainly the gas ones already had catalytic converts my main idea was cleaning up diesel emissions. I've already tried to research passive diesel particulate filters for older diesels and have only found things for large fleet vehicles. I've also looked for catalytic converters for diesels and found some for the rabbits but I've read that cats aren't very good for cleaning diesels. I've also looked for the selective catalyst reduction (urea fluid injection) kits for cars and haven't found any. I also know some of the cats had smog pumps because o2 sensors weren't installed along with computers so I was wondering if the pumps could be replaced with electronics. My question is, is this retrofitting plan a good idea or even practical? I know that the cats and filters can clog and that a lot of the vehicles didn't have sophisticated computers some had none at all. So that could be a problem

Are you thinking about this as a business? Is it legal to mess with the emissions controls on an old car? How many of these cars do you plan on modifying? I can envision lots of work and expense and no payoff.

Offhand, I would guess that most 70's and 80's autos would have much better emissions just by being converted to fuel injection. There are kits for that.

No. To what end?
You would be adding $2-3k to the price of a used car. Since you can only do a few cars and not the whole market, then no one would buy your cars because the were too expensive!
Where is the 'demand' for you service?
People don't want 'clean air' used cars, they want cheap used cars.

Today's market is not about retrofitting cars - If you want a car which is cleaner, more fuel efficient, etc., then you buy a new one.

You'd be better off swapping in a newer drivetrain.

I apologize I didn't mean to make it sound like I was doing this as a business which I am definitely not. I was looking into buying on old car for fuel mileage but I wanted to clean up the emissions a little better because I care about air quality. I'm doing it out of self interest. I know that the EPA grandfathers in these cars but I was wondering if I could make the one I purchase cleaner. I am prepared to spend some money but not all out and if it effects fuel economy significantly then I'm not going to do so.

i feel like these cars have engines to small to swap in a newer drivetrain because the current engine market is to large excluding something like a small gas engine I was talking more about a diesel. A rabbit with a 1.9 or 1.8 vw would be cool but idk if it would fit or be as efficient

The Smart ForTwo had an option with a 0.8 liter turbodiesel. I believe they were available in Canada.

Just for the halibut, How about just taking one of the cars that you like (70's or 80's) and adding a later model tranny with Overdrive and a lock-up converter. (Available in a Packard in 1955 or in a GM car in the mid 1980's.) Then convert the car to throttle body fuel injection (Holly) and you've brought an oldster into modern times.

Taking another tack, the GM small block has remained roughly the same size since 1955. And Ford's small block has remained roughly the same size since the mid 60's.

What particular vehicle do you plan on altering?

I'm looking at ford escort with the 2.0 diesel or a vw rabbit with a 1.6 diesel in particular. Do turbos lower emissions? I am open to suggestions both gas and diesel

Yes turbo chargers lower particulate emissions, increase fuel economy and may slightly increase NOx but who cares about NOx unless you are in a NOx pollution prone area.

In a diesel the exhaust scrubbers lower fuel economy by several MPG.
The only thing that should be done with diesel exhaust scrubbers is ripped out and taken to the scrap yard.

This may be your take on things.
 

But it is hardly the responsible thing to do environmentally and as time goes - legally.

It also shows a misunderstanding of how effective diesel particulate filters (DPF) can be. A properly sized and operating DPF will trap over 85% of particulate matter and reduce efficiency far less than your proposed "several miles per gallon". The problem has been the first applications have been less than stellar.

When the dpf is deleted people are typically claiming a +5MPG improvement on ford 6.4L and 6.7L Cummins guys are claiming a 2 to 4 mpg improvement. Even ford claims that a dpf regeneration cycle can use up to 17 liters of fuel.Q
Nothing I have found any where supports the claim that the dpf system does not hurt fuel economy.
The dpf system on a diesel is nothing like the catalyst system on a gasoline engine. I believe that the converter on a gas engine has little to no effect on fuel economy.

If you dont live some where smog is a problem then getting over all lower fuel economy and burning up to 17l of fuel to reduce NOx, make your diesel particulate smaller and more harmful is irresponsible.

Aren't they also the single component most prone to failure in new diesels?

They are failure prone and can be very expensive to repair as in labor hours and parts cost. EGR heat exchanges on ford are very well known for cracking then causing some exhaust and coolant to swap places.

One person I work with has a 2011 Cummins and is claiming that an egr and dpf delete, different injector timing and bigger straight pipe exhaust took him from 17mpg to 25mpg on his 35 mile drive to and from work every day.
There are also plenty of tails of 2007.5 trucks doubling fuel economy after an emission delete and reprogram.

I didn't say DPFs do not hurt economy.
 

You made that leap of logic. I am simply saying the systems in place at this point are 1st generation solutions to the problem. Much the same way the catalytic systems in gasoline powered cars back in the early 70s were 1st generation solutions. Those systems were horrible and difficult to keep working and they did harm economy. Note that I say systems. The same way early catalytic converters in gas cars were blamed for all problems, so it is with DPFs.

DPFs will improve just as Catalytic Converters did. But, along with that will be an improvement in the SYSTEM.

You gave the OP the impression that all diesel emissions systems are useless and harm economy greatly. These are simple first gen systems with much room for improvement. Yes, it is simple to throw them out when they fail, but that doesn't help the environment and that isn't much of a challenge. By design, a good DPF should only cause around 1 psi of back pressure. This in itself is not going to reduce your mileage by 4 - 6 MPG. However, as they load up with soot, the back pressure increase does start to effect economy. This isn't the whole story of lost mileage as you have pointed out, the fuel wasted to burn off this soot is a big part of the lost fuel efficiency. Also, another big gain is the result of removing the exhaust gas re-circulation (EGR) component. This is not directly related to the DPF but many attribute the greater power and economy to the removal of the DPF alone and not to the EGR delete.

This is a complex subject that is gaining technological momentum and with a little knowledge and thought someone determined could put together a retrofit system on their diesel vehicle that would outperform the 1st gen designs.

I can believe that a tune and EGR delete can achieve good numbers. Back when my parent's F350 7.3L (with dully fenders, front air deflector, and rain guards) was on the transmission it came to us with, it pulled 20 MPG with a slushbox. Turns out it had a chip it in that ran up the boost, when the transmission blew there was no option but to revert to stock to keep the transmission in warranty. Lost 5 MPG to going back to stock EPROM values.

On the topic of emissions:
It looks like volvo is messing with a system that goes engine-> DPF -> SCR that doesn't need active regen.

They are the single component most blamed.
 

Look at Oil Pan4's answer to your post. There is more to this than the DPF, but the DPF will be blamed if one is in the building.

If you are losing engine oil from a seal or ring, the DPF will load up and it will be blamed.

If you have coolant leaking into your exhaust causing solid deposits, the DPF will clog and be blamed.

If your EGR valve is stuck open and your soot production increases, the DPF will load up and be blamed.

If your injectors are worn and are imperfectly metering fuel, your DPF will load up and be blamed.

Get my drift.

It's a system, and it has room to improve.

And I do not agree with Oil Pan4's sentiment to rip out emission systems just because he lives in nice clean and free New Mexico. The emissions from diesels affect our elderly and growing kids the most. Do you want a school bus like the ones from just a few decades back transporting our kids? How about the retirement home shuttle moving seniors back and forth? How about sitting behind one of these coal rollers at a stop light?

Your exhaust is my air.

And yes, I have several diesels in my possession. Including a pair of Dodge Cummins diesels including the problematical 2008 model year with EGR and DPF. I have installed and tested several emissions systems of my design. I am going through reliability testing at this point. You can get economy and clean air all at the same time. The problem is the sensitivity to faults in the engine system. Gone are the days when I could run my mechanically injected Mercedes diesel with one cylinder passing oil past the rings and all the valve stem seals leaking oil and all the manner of crud accumulating on my injectors, and all I had to do was turn up the boost and the smoke went away.

See remove the DPF, EGR and EGR cooler, sell it to some sucker in NY or CA that has to have one and your problems go away.

New Mexico air isn't clean. Its full of dirt.
Mother nature is our main air polluter.
If you have ever smoked and live beyond the age of 65 here you are going to get COPD.

If there is a DPF doing its thing near you it is producing colorless odorless diesel particulate in the 1 to 2 micron range it defeats all your body's senses and defenses. And you unknowingly breath the particulate deeply into your lungs.
The DPF does eliminate most of the diesel particulate but what it does produce is exceptionally bad for you.

With a non emissions controlled diesel the particulate is big, from 20 to 250 micron is what I am hearing. You see it you smell it and react to it you don't breath it in, unless you really like the smell of burned diesel.

You want to know what the scarry thing is, when bad guys are trying to make dry powder type chemical or biological weapons they are trying to get the particulate in the 1 to 2 micron range, any smaller than that and you breath it in and right back out, any larger than 2 microns and your body stops most of it.

Again, you are talking about what is in the past.
 

DPFs eliminate the gross bulk pollution. You have to start there. And you are correct that they allow/create sub micron range particulates. But so do direct injection gas engines which are now coming under scrutiny. There are after treatment solutions to trap them. Diesel and gas engine controls will become more alike as time goes by.

Studying and understanding the combustion process to eliminate the particulate formation in the first place is intensifying.

The whole field of health vectors and population studies is well beyond the scope of this forum but bears the understanding that small particulates are all around us but do not negatively affect us. What is created in diesel and direct injection gas engines unfortunately are carcinogenic and/or biological mutagens. Much of this understanding came from tobacco health affects. As we all know, over a period of time small amounts of tobacco smoke can affect us negatively. Even minuscule amounts of second hand smoke. I think it is prudent to control the emissions of combustion particulates. The future health effects can only be extrapolated but look to be as massive a problem as the burden of tobacco.

This discussion is well past the OP. But it does make the point that an efficient diesel is a non-smoking diesel. That smoke represents lost fuel energy. For now we have to trap it and destroy that smoke. But, the real goal is to use that smoke in the engine cylinders.

As you said, one of the best ways to burn up smoke is install a turbo or turn up the boost slightly.
In my 6.5L diesels short life as a non-turbo it did smoke a little bit, then after I put the first turbo on that got rid of nearly all the smoke and improved fuel economy 2 to 2.5 mpg or by almost 10%.

To further reduce smoke production and engine oil consumption on my 6.5L I machined the heads so I could put actual seals on all the valve stems. The intake valves had something that barely resembled or functioned as a seal and the exhaust valves had nothing.
I didn't have to do it but I did.

So non-controlled diesels create only large particulates and controlled diesels only create small particulates?

Or...

Non-controlled diesels create all sizes of particulates, while controlled diesels filter out most of the large particulates?

If the latter, then do non-controlled diesels create less, more, or the same amount of the small particulates as controlled diesels?

Diesel and gas engines will become more alike as time goes by.

The DPF system stops up to 85% of particulate matter.
What gets through is too small to be seen at that quantity and too small to be smelled.
All the particulate made by emissions controlled diesels is covertly trying to get inside you.

From what I have been able to find non emissions controlled diesels do make particles of all sizes. But most of the particles are big. They are big enough to be captured by a standard paper air filter installed on the exhaust such as found on underground diesel powered mining equipment. If most of the diesel particulate was DPF sized, a lot of them would go right through a standard paper air filter.
If you have to breath the exhaust, in an underground mining environment diesels are preferred, they create very little CO compared to gas and their exhaust soot is easy to trap.

If you cant see or smell the particulate how are you going to avoid it?
When you choke on diesel smoke that is your body's way of telling you "this is bad for you".
With the 1 to 2 micron particles I guess ignorance truly is bliss, until it catches up with you a few decades later.

This is true.
 

But, remember we are talking about mass. A diesel with a DPF has 85% of the particulate mass removed from the exhaust. This leaves the sub micron particles to pass through. There have been studies that show that DPFs move some of the larger particulate mass into the sub micron range. However, the argument that it is better to have no DPF is utterly false as large particulates are cause for common lung, nose, throat and eye cancers. They cannot be ignored and removing them is the first step. Non DPF equipped diesels still produce a measure of sub micron particles. Studies on sub micron carbon emissions are still on going and inconclusive but I have no doubt the findings will see that long term exposure will result in various maladies and ailments.

There are various methodologies where we can trap and destroy these sub micron carbon particles, but it also behooves the manufacturers to work on the combustion technologies that will prevent these particulates from forming in the first place.

So all diesels produce sub-micron particulates, DPF-ed engines let out the same amount (or slightly more) as non-DPF-ed?

I read that the hotter your engine (or the hotter the exhaust) is running the less particulates it produces. Unsure whether the reduction is the same for all sizes, or whether only certain sizes are reduced. The price is more NOx.

You are correct.
 

All diesels produce sub-micron particulates (SMP). DPF use tend to result in more. Also, higher pressure injectors produce more SMPs by virtue of the much smaller droplet size they produce. To be exact, modern high pressure injection systems produce only about 20% by mass particulate mater that is larger than a micron. The rest is sub micron. Oxygenated fuel additives can also increase the amount of SMPs as larger droplets are broken up into smaller ones.

It is not so much that heat reduces particulates but more so that good combustion results in more heat and less fuel is turned into particulate mass. In other words, the particles are smaller and less massive though numerically the same. But, as you pointed out, this results in increased NOx.

When a fuel droplet enters a sufficiently hot combustion chamber it's surface starts evaporating and mixing with oxygen. Once the mix reaches the lower flammability limit, it starts burning. The middle of the droplet, not exposed to the oxygen depolymerizes and releases it's hydrogens resulting in a complex mix of carbon forms. This is referred to as nucleation. These particles can combine into larger particles. This is accumulation mode.

As Oil Pan4 pointed out, the deletion of EGR can reap huge performance gains. EGR and more specifically, cooled EGR causes the fuel droplet to enter a combustion chamber with reduced oxygen resulting in a lazy evaporation and combustion rate around the fuel droplet. The burnt exhaust gases also provide a buffering heat capacity sucking energy from the combustion reactions. This all reduces peak temperatures and the formation of NOx but has the adverse effect of increasing the mass of particles as the fuel droplet is not as well vaporized before it enters nucleation and solidifies. High pressure injection reduces the droplet size to begin with but it just means there are more particles produced, thus the bias to SMPs. If you could do away with the EGR, the greater availability of oxygen causes less massive (smaller ) particles and more power is available.

Note that a properly operating EGR system will reduce the flow of exhaust to the intake stream as engine load is increased as less oxygen becomes available to an increased mass of fuel. At lambda=0.8 what is generally regarded as the threshold for smoke to appear, the conditions are similar to those under EGR. The droplet finds less oxygen to combine with and burn and consequently, the particle mass increases. Thus the term "Rolling Coal" was coined as the smoke becomes very noticeable. It is not that there is an excess of fuel per se, but more correctly, the fuel is finding it difficult to pair up with an oxygen. Thus, it more readily nucleates and accumulates into the thick smoke we have all seen. The deletion of EGR really helps performance in the load ranges below lambda=0.8. This is where most driving is done and thus you can really feel the difference in added performance and fuel economy.

The above is a gross simplification of the process but it should give you a feel for what is happening in a diesel engine's combustion chamber.

RustyLugNut

Thanks for the above post. This makes it clearer for me now.

What are the Audi R10 TDI Le Mans Proto type LMP1 doing differently that the engine doesn't produce any smoke? I'm clueless when it comes to diesel technology.:o

I cannot say for sure.
 

But, as we have emphasized in this discussion, providing enough oxygen is paramount. Elevated boost is certainly in the formula. A friend who is a BMW/Audi tech thinks the Le Mans racers use elevated injections pressures well above the 2000 bar of road cars. This gives them more injection timing control and provides exceedingly small droplets to burn. They don't have to worry about extended reliability in the range of years. And remember, even though we don't see "smoke" there are still the SMPs which as Oil Pan4 pointed out, you can not see or smell.