K & N Air Filters on Diesel Engines

[jdalrymple]

The usefulness or performance of aftermarket products aside, the fact is vehicles produced in America, or produce in another country for sale or for use in America, achieve the poorest fuel economy in the world.

While vehicles sold here are some of the most technically advanced, government regulations on emissions require a waste of fuel to achieve the required levels. The on-board computers actually add fuel on the input side when the sensors see unburned products of combustion in the exhaust system. This additional fuel promotes higher temps in the catalytic converter, which re-burns the exhaust gasses, to assure the required emissions level.

An example is the European SmartCar. This vehicle achieves 50-60 mpg in the EU, but due to the emissions laws in the US, it is de-tuned to around 30 mpg. This is also witnessed by the fact that new engines, and improvements to current engines, are meant to meet emissions standards, and are less concerned about improving fuel economy.

One wonders if the outcome is truly a gain. Is burning more fuel now really better than the limited improvement of a slightly better emissions measurement.

Further, not all the automotive engineers work for the auto manufacturers. It seems that products not totally concerned with emissions limitations can make some improvements.

[Denis4x4]

Originally Posted by jdalrymple

The usefulness or performance of aftermarket products aside, the fact is vehicles produced in America, or produce in another country for sale or for use in America, achieve the poorest fuel economy in the world.

While vehicles sold here are some of the most technically advanced, government regulations on emissions require a waste of fuel to achieve the required levels. The on-board computers actually add fuel on the input side when the sensors see unburned products of combustion in the exhaust system. This additional fuel promotes higher temps in the catalytic converter, which re-burns the exhaust gasses, to assure the required emissions level.

An example is the European SmartCar. This vehicle achieves 50-60 mpg in the EU, but due to the emissions laws in the US, it is de-tuned to around 30 mpg. This is also witnessed by the fact that new engines, and improvements to current engines, are meant to meet emissions standards, and are less concerned about improving fuel economy.

One wonders if the outcome is truly a gain. Is burning more fuel now really better than the limited improvement of a slightly better emissions measurement.

Further, not all the automotive engineers work for the auto manufacturers. It seems that products not totally concerned with emissions limitations can make some improvements.

You hit the nail on the head! I participated in several tests using speed equipment installed on a SBC that not only increased HP, but improved economy both on the dyno and on the street. AND, was within the parameters of emission control requirements. What we didn't know at the time was the political forces that were at work to set standards that weren't always in the consumer's best interest. A good example was the "visual" test. I had two cars that had to be sold out of state (California) because they would not pass the visual test due to the installation of tube headers and an aluminum intake manifold with a low restriction air cleaner. Interestingly enough, both of these vehicles passed the smog check.

Emission controls need to be set by engineers, not congress pandering to environmentalists. That goes for state law makers too.

[canadianguy]

Originally Posted by jdalrymple

The usefulness or performance of aftermarket products aside, the fact is vehicles produced in America, or produce in another country for sale or for use in America, achieve the poorest fuel economy in the world.

We have the poorest average fuel economy in the world because we drive vehicles with the highest average weight, and designed for style and comfort rather than aerodynamics, and we drive them too fast. You can also blame highway safety requirements for increasing the weight of vehicles on our road.

Originally Posted by jdalrymple

While vehicles sold here are some of the most technically advanced, government regulations on emissions require a waste of fuel to achieve the required levels. The on-board computers actually add fuel on the input side when the sensors see unburned products of combustion in the exhaust system. This additional fuel promotes higher temps in the catalytic converter, which re-burns the exhaust gasses, to assure the required emissions level.

That's not true. The difference in efficiency between the air fuel ratio for optimum emission control, and the one for optimum efficiency is very small.

The catalytic converter works by absorbing nitrous oxides, carbon monoxide, and unburned hydrocarbons. Nitrous oxides are broken down by the catalyst to provide oxygen to consume the carbon monoxide and unburned hydrocarbons.

Until a few years ago the way the precise ratio was achieved was by running slightly rich to build up carbon monoxide and hydrocarbons on the catalyst for a second, then burn slightly lean to produce NOx and excess oxygen for a second. This was done because the oxygen sensors weren't accurate enough to stay on the exact ratio. The solution was to make sure the time average is the correct ratio. You can see the oscillation clearly on an oscilloscope.

About 5-6 years ago broad-band oxygen sensors came out that were capable of measuring the correct air fuel ratio came out. The improvement was fairly minor.

Originally Posted by jdalrymple

An example is the European SmartCar. This vehicle achieves 50-60 mpg in the EU, but due to the emissions laws in the US, it is de-tuned to around 30 mpg. This is also witnessed by the fact that new engines, and improvements to current engines, are meant to meet emissions standards, and are less concerned about improving fuel economy.

According to Smart's website the 2008 version uses 4.8 L/100km. By my calculation this is 46 MPG. This is for gasoline. Most of the European ones are diesel.

[HowieE]

Originally Posted by Jetstreamer

It's my understanding that a diesel engine has a fixed amount of airflow for all power settings. Only fuel is modulated as needed for performance. A clean stock filter should provide the proper airflow and superior filtering.

Diesels do not have a throttle plate, as a gasser does. The plumbing through the air flow is fixed in size but the volume of air that flows through it increases as RPMs increase. That is where K&N claims to have an advantage and yes they do but the amount of dirt that flows through the engine the rest of the time does not justify the increased air flow unless you are racing and intend to rebuild the engine anyway.

Bigger holes pass bigger pieces of dirt.

Been there did that and it is not worth it.

[Tom Nugler]

While this thread has strayed from the original post, canadianguy pretty much nailed it down. The range of fuel efficient sub compacts in Europe is quit broad and generally unavailable in the US. I’d love to see a Polo in this country. Sales says there’s not enough demand to bring in a US spec model. (time to rethink that position.) We got a Jetta in this Tuesday with the new "Clean Diesel" engine. 50 state certified and MPG numbers similar to Prius. This in a car with a real trunk and performance.
Recent polling data seems indicate that the general public is starting to re-examine the way, and what they drive. The data is born out in last months sales figures posted by the automakers.
I think for the non-technical readers it should be noted that gas and diesel engines have become nearly identical in the way fuel management and emissions are handled. The Duramax mentioned in the first post has electronically controlled fuel injectors, EGR, Catalysts and a full array of input and output sensors. Just like your family sedan. The Horsepower, Performance and Emissions balancing act have always been a difficult compromise.
Politics aside, even I have "Air Quality" issues with my county board. The opinion of some of my friends and colleagues here on the Forum is that air quality and economy be left in the hands of the engineers and not to the legislature. They might want to ask the people of some smog afflicted community how they feel about the problem. And how they voted. There’s no going back now.

OK, I'm done now,
Tom.

[yakman]

Originally Posted by HowieE

Diesels do not have a throttle plate, as a gasser does. The plumbing through the air flow is fixed in size but the volume of air that flows through it increases as RPMs increase. That is where K&N claims to have an advantage and yes they do but the amount of dirt that flows through the engine the rest of the time does not justify the increased air flow unless you are racing and intend to rebuild the engine anyway.

Bigger holes pass bigger pieces of dirt.

Been there did that and it is not worth it.

Ditto. I'm with you on this one. It's always been my understanding that K&N are designed for race applications. More airflow and less concern about what goes into the engine as it will be rebuilt soon anyhow. You have to be a master of the exact amount of oil to use on them etc. If you're not racing, don't bother with the K&N. Any gain will be offset by premature engine wear.

yakman

[DaveFL]

Originally Posted by Tom Nugler

The "tuners" mount the intake tube with a bare filter element mounted low behind the bumper. Works great a sucking puddles up into the engine on rainy days.

Tom.

When I bought this MH I figured I would sevice the K and N, read online how it is washed and oiled. On studying the installation I found the air intake was placed infront of radiator above bumper, the water diverter section was mounted 90 off, allowing any water pickup at the intake to be able to travel up to the motor instead of draining away. Somebody screwed up. My feeling is original installer as no bills were in the maintenance file, is K&N original equipment by AS? Chevy should have Delco?

[SSChanger]

Thanks to everyone for all of this info. My 2003 Silverado 2500HD with the 6.6L Duramax Diesel has the K&N filter, which I knew could be washed (I've done that) but didn't know was supposed to be oiled....

Yikes!

Got a Delco paper filter as a back-up. I'll be leaving the K&N in the garage.

Thanks!

[Mike Leary]

Originally Posted by SSChanger

the K&N filter, which I knew could be washed (I've done that) but didn't know was supposed to be oiled.... I'll be leaving the K&N in the garage.

It's a good system (we have one that is located in a canister and has a splash plate). Any NAPA parts outlet or such should have the K&N cleaning kit which comes with the oil and instructions. I clean ours every 30K or so.

[nti06]

Diesel engines are far different from gas engines. Almost all diesel engines have no throttle plate. So the engine is constantly flowing (lets say its a 7.3) the necessary CFM for a 7.3 liter engine.
A gas engine has a throttle plate, so it only flows enough air for the current rpm of the engine.
Think about how much air that K&N has to constantly filter on a diesel. Its going to filter the air but will quickly be filled with dust and dirt way faster than if it were on a gas engine.

[ROBERTSUNRUS]

Hi, according to a video from Ford Motor Company, [tests performed by Ford engineers] the use of after market [K&N Etc.] air filters allows for more dirt particles to enter the engine destroying the turbines in the intake side of the turbo-charger. Note the massive size and design on the Ford factory Diesel air filter elements. So much for the more horse power theory.

[rock60]

saw sometime back that k&n filters let to much fine grit in to air intake.

[Mike Leary]

Like many things in life, cleaning and oiling the K&N (original on our Izuzu) is a art/science. Note my mileage, problems zero with the turbo or the engine.

[HowieE]

The K&N filter is great for the drag strip where there is no sand but on the road they pass grit. I used them until I went west and encountered fine sand and grit. I checked the filter after about 1,000 miles of western travel and found sand in the air horn down stream of the filter.

None of us are pulling enough air into out engines to warrant they damage that will follow the use of a K&N filter. I have 2 diesels and both will maintain full boost pressure with stock filters. If the boost is there there is no shortage of air.

[Naper]

Originally Posted by jdalrymple

The usefulness or performance of aftermarket products aside, the fact is vehicles produced in America, or produce in another country for sale or for use in America, achieve the poorest fuel economy in the world.

While vehicles sold here are some of the most technically advanced, government regulations on emissions require a waste of fuel to achieve the required levels. The on-board computers actually add fuel on the input side when the sensors see unburned products of combustion in the exhaust system. This additional fuel promotes higher temps in the catalytic converter, which re-burns the exhaust gasses, to assure the required emissions level.

An example is the European SmartCar. This vehicle achieves 50-60 mpg in the EU, but due to the emissions laws in the US, it is de-tuned to around 30 mpg. This is also witnessed by the fact that new engines, and improvements to current engines, are meant to meet emissions standards, and are less concerned about improving fuel economy.

One wonders if the outcome is truly a gain. Is burning more fuel now really better than the limited improvement of a slightly better emissions measurement.

Further, not all the automotive engineers work for the auto manufacturers. It seems that products not totally concerned with emissions limitations can make some improvements.

In the EU they use an imperial gallon. Its about 5 US quarts versus the the US gallon at 4 quarts. This explains the difference.

[barts]

I would be very careful when comparing mileage between European models and US models, since the testing procedures vary significantly.
Remember also that the smallest European cars would be considered quite underpowered by most US drivers.

We'll see more fuel efficient cars here as gas prices continue to increase.

- Bart

[Dave Park]

The EU uses litres.

The EU former imperial gallons (1 gal = 4.564 litters.)
The US uses weird gallons (1 gal - 3.785 liters.)

Thus: a 45 mpg car in Europe is a 37 mpg car in the US. They are getting the same fuel economy.

As for the K&N filters, just strip down the engine and look at the valve seats after 1,000 miles with a K&N and you can see the difference - they're all clean and shiny and smooth. THis is a bad thing: as the valves close and bed into their seats, any fine dust particles gradually wear off the touching surfaces. After a hundred thousand miles or so, the valve seats become so worn either the valve cannot seat properly, and compression is lost, or the exhaust valve seat loses enough mass that it starts to overheat.

You can take the couple of hundred dollars worth of gas you saves and put it towards the repair bill, or more likely, the cost of a new car as you pass the old one down the road to be someone else's problem.

[slowmover]

K&N is a crapshoot. Oil analysis will show that they work fine, as intended. But proper seal, proper oil, no inadvertent tears, etc, make it hard to justify as these can slip by undetected.

The DONALDSON PowerCore Generation Two series is current state of the art for the diesels. Stock on Ford 6.0, and retrofit after market kits on others.

[JFScheck]

2011 Ford diesels - 400 hp with 800 lbs torque - I'll just keep mine stock when I get her...

[tjdonahoe]

No way...... I will buy stock from the dealer....that way we have no wRrenty problems...they spent millions on engineering........