EGR filtering?

[mitsuru]

Firstly sorry if posted in wrong area.

While trailing through forums I was poised with a thought after reading about the Sooty deposits that come trough the EGR combining with the deposits coming from the crank case breather that accumulate in the intake manifold.
Well everybody knows you can get a little filter for the crank cover.

But I remembered that on old cars that some used a wire mesh type for the air intake (can't remember what so don't ask!)
So I was wondering if something along those lines could be adapted for an in-line filter for the EGR?

A little research and I found that more modern cars actual come with EGR filters, which give better performance than just the straight through pipe.
This would help keep up fuel economy but give a bit more performance.
Has anyone actually retro fitted an EGR filter one to their Car?

[Chairchild]

EGR valves catgorically reduce economy! The burnt exhaust gasses, displace oxygen-rich air. This does two things:

1: reduces peak combustion pressure, thereby reducing NOx (noxious oxides) levels

2: reduces the thermal efficiency of the engine, by several percent



Perfect example is to drive an old-ish "bubble" shape Rover 200 (not newer than 1996). When cruising between 30mph-40mph, you can feel when the EGR valve cuts out, as you suddenly go a couple of mph faster. When it's opened again, you feel the car slowly reduce in speed again. Trying to keep at an exact speed with the EGR valve constantly varying your power levels, is bloody irritating!




End result:

EGR valves are good for reducing emmisions for the manufacturer - but as they're not measured in the MOT, disconnect the damned things, and leave them off!

[Jaffa]

Mitsu Delica's have a vacuum operated mechanical EGR valr valveve. They get clogged up with soot and stick either open or closed.

Solution

Remove egr valve, blank off ends, put valve in bin

[Renrut]

The EGR can improve economy in certain situations if the car is setup to use it, mostly at part throttle by displacing fresh air in the cylinder allowing less fuel to be used while keeping to the same emissions level. This allows the engine to suffer less throttling losses and can run leaner. A byproduct is they can speed up warmup of the engine as a lot of heat can be kept in the loop longer which again improves economy through not being in the 'choke' cycle for as long.

Obviously this is all theory and in practice they do clog up and become worse than useless, or in the case of the rover just plain setup wrong. Classic theory vs practice - blank it off

[majic79]

EGR valves catgorically reduce economy! The burnt exhaust gasses, displace oxygen-rich air. This does two things:

1: reduces peak combustion pressure, thereby reducing NOx (noxious oxides) levels

2: reduces the thermal efficiency of the engine, by several percent

Close, but no cigar

1) Reduces peak combustion TEMPERATURE, NOx is only produced when temps get excessively high, in combination with high pressures. Adding an ammount of inert (ie, pre-burnt) gases reduces the O2 content and hence reduces the combustion temperature.

2) Not really - EGR is only supposed to occur during steady state (ie cruising) and with the right ECU configuration, less fuel is required and so less is burnt. Thermal input (fuel) is reduced as the heat from the inert gas affects the input gas, which appears like a closing throttle (ie, less air), the overall efficiency remains about the same, but power drops slightly because the engine isn't sucking in quite as much air (it's only a small drop) or burning as much fuel. As thermal efficiency is a measure of input energy vs mechanical and wasted energy, both sides of the equation remain in balance and thermal efficiency remains unchanged. Admittedly the engine will run net leaner than previously, and the power produced will be down for a given throttle position, but it would be the same as if you leaned off the mixture and closed the throttle slightly.

Admittedly early systems were far from perfect, equally newer systems are quite good at making it seamless. I don't notice it at all on my polo (it rarely goes into steady state, the pedal is more often than not flat on the floor!) or the missus hyundai. Never noticed it on my Supra either when it was on the road. Lightweight cars with low inertia will be more sensitive to it, bigger cars with bigger engines (and bigger flywheels) will respond slower to the opening of EGR valves. If you hold the throttle at a given position and cruise, you might notice speed drop off slightly - that's the effect of EGR.

Sorry bud, I'm a control systems engineer for a gas turbine company and NOx reduction is one of the biggest things we sell the engines on (I think we actually get it down to less than 3ppm with DLE combustion)

Why remove it? disconnect the vac supply to the actuator, valve stays closed, no EGR - simples!

As for the filter, get some of the steel abrasive pads (like brillo, but without the pink powder!) and shove some into a container between the EGR ports on the exhaust and inlet, instant filter. Remember to de-coke it once in a while

[mitsuru]

So in layman's terms!
For a daily driver.
So if you live in a cold climate the egr system heats the car's engine quicker,
and with less fuel making it more efficient.
Especially helpful if doing loads of small trips where the car might take longer
in getting to proper running temp.
And when petrol/gas is at £1.34 per litre the less fuel the car uses the better!!

[Renrut]

So in layman's terms!
For a daily driver.
So if you live in a cold climate the egr system heats the car's engine quicker,
and with less fuel making it more efficient.
Especially helpful if doing loads of small trips where the car might take longer
in getting to proper running temp.
And when petrol/gas is at £1.34 per litre the less fuel the car uses the better!!

As I said that's the theory and probably the practice on a new car but I'd imagine after 20K or 30K miles it might be a very different story. As soon as it start clogging and jamming either open or closed you'll lose whatever benefit it gave you and reduce your power as Chairchild said.

Basically if you were only after power you would only ever be connecting exhaust and inlet together via a turbo!

Could really do with someone like Ralph to come and give his expert opinion as he is probably the most knowledgeable (on here) on these newfangled electronic emissions thingies. Also I'm not sure what effect it might have on one of those fancy new catalytic convertors as don't they need a very narrow band in the exhaust gas mixture?