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[Nick W]

The K&N's real advantage is that its performance doesn't deteriorate as it gets dirty. That's both airflow and filtering performance, which isn't true of a paper filter.

That's because a paper filter actually does what it says on the tin - it filters fine particles from the air before the air reaches the engine. As it filters the pores get blocked.

A K&N on the other hand is absolutely crap at filtering. There is some research online (that sadly I can't find quickly) which shows they allow particles in excess of 10 times the size of the paper filter to pass. If you think that's a good thing then you may as well just take ALL the filters out.

It's more efficient, so flows a lot more air for the same size which makes one really useful for applications that are short of space.

Thing is, the Omega doesn't need more air. If the paper filter can flow (say) 200L per second, and the K&N (say) 500L per second then yes the K&N flows more. But if the engine only needs (say) 100L per second then there is precicely zero benefit. 6000rpm * 3L 4 stroke = 150L/sec.

Which is mainly repeating all of my points: like all modifications, especially simple bolt-on ones, a performance filter changes the compromises made.


A paper filter is very good at filtering, but must be changed frequently if that is important. It needs a lot of surface area to meet an engine's breathing requirements. It also needs to be fitted in a rigid case. This tends to make them quiet. They're cheap, which is good because they're not reusable.


Oiled cotton doesn't filter quite as well to start with, but won't change much as it gets dirty. It will be much smaller for the same amount of airflow. It's self supporting too, which can be useful. They're much more expensive to buy, but are infinitely reusable. They don't reduce intake noise much, which is not a good thing for road cars.


I've used them before, and will probably do so again. But it will be for non-standard installations like fitting this 2.9 Granada engine in a Capri:





where there wasn't room for anything else.  Most of the hour(or so) I spent installing them was cutting the hole, making the box and welding it in. If I was doing this job today, I would mount the air flow meters and filters vertically, and with new hoses. But I wouldn't be doing the job on my daily driver over a weekend and need it for work on Monday. Even though the kit was the most expensive single part of the conversion at £110, it was still the best way of doing the job just like every other EFI conversion I've done.

[LC0112G]

Oiled cotton doesn't filter quite as well to start with, but won't change much as it gets dirty. It will be much smaller for the same amount of airflow. It's self supporting too, which can be useful. They're much more expensive to buy, but are infinitely reusable. They don't reduce intake noise much, which is not a good thing for road cars.

And the reason for that is that the pores don't get blocked, because it doesn't actually filter anything out.

[Eyal2002]

I noticed an immediate difference with panel K&N, I am on my second (the 1st one was replaced to paper panel by a machanic who didn't read the big K&N stickers...).
However, I am in the process of investigating force feeding of air, ie I cut the air inlet to the pipe end (in front of the AC fans) and attached a 90 degrees plastic piping "elbow" that starts bigger diameter thrn the stock pipe then it narrows down. By having the 90 deg. curve towards the direction of movement I expect the air pressure to increase down the pipe line into the box as the speed increases, plus expect the MAF to adjust on the fly. That done already, I plan to increase the entire pipe diameter all the way to the air box. Any thought on this at speed "supercharger"? it worked for the Mustangs in the '40s....

Also, I was wondering why the car maker didn't aim the pipe opening forward, and theorized it was to avoid water coming in? anyways didn't see water in my air system, though I do try not to have jets of water into the grill when I am washing the car (has a Catera sports grill).

Eyal

[Nick W]

What you suggest might work. Maybe. You will need to collect the air from a high pressure area. You'll have to make sure it can only be forced into the intake. The whole tract will need to be carefully tuned to work. How are you going to measure the changes - a seat of the pants dyno won't be accurate or repeatable enough.


The real question is just how much ram effect will you actually get at road speeds? Car manufacturers have lots of parameters for air filters; performance is only one. They're nearly all improved by fitting a bigger filter......

[Eyal2002]

We did see manufacturers fit air scoops on bonnets, these are facing forward. In the Omega there is a gap between from AC fans that has air pressure on it at speed. I would love to tell you I put the car on a dyno and inside a wind tunnel with 80mph, but I won't lie, I aim for economy (trip computer on known roads) from easier breathing and reduced drag, and if I get a bit of gain by adding a $2 plastic part......

[Doctor Gollum]

I don't know if this is a wind up or not

The idea exists, but as proposed won't achieve anything.

Basically anything other than a straight pass into the piston will be turbulent air. Air loses energy every time it changes direction and your 90° bends will do nothing to change the air pressure or speed.

Also the factory intake points forward behind the right hand headlight. The grill is only there for radiator airflow

[Doctor Gollum]

We did see manufacturers fit air scoops on bonnets, these are facing forward. In the Omega there is a gap between from AC fans that has air pressure on it at speed. I would love to tell you I put the car on a dyno and inside a wind tunnel with 80mph, but I won't lie, I aim for economy (trip computer on known roads) from easier breathing and reduced drag, and if I get a bit of gain by adding a $2 plastic part......

In which case fit a genuine GM filter, service it regularly and use decent fuel.

[Doctor Gollum]

And nothing costing $2 is going to make anything go faster, certainly not a 1,700kg Omega

[Nick W]

If you could duct straight to the throttle body from the outside, you might make a gain. But the airflow meter, multi rams and all the associated ducting is unlikely to give you anything.


All a straight through filter does in place of an adequately sized paper one is make more noise. It's the 'power increase' most people insist they can feel. That is OK on a rorty car but spoils a large saloon that is focused on comfort.

[Eyal2002]

And nothing costing $2 is going to make anything go faster, certainly not a 1,700kg Omega

The aim is efficiency not speed. Also, why did you write the factory inlet point forward? on my 2002 2.6L it behind the grill pointing up, that baffled me because as I appreciate the comment on turbulant air and the factory setup seems to seriously disrupt the air sucking by having movement airflow perpendicular to the pipe opening. I figured, if anything than the 90 deg. elbow will somewhat aid or better the flow.
Will upload a photo later on, comparing stock vs the elbow.
Appreciate all comments.

[Lizzie Zoom]

And nothing costing $2 is going to make anything go faster, certainly not a 1,700kg Omega

The aim is efficiency not speed. Also, why did you write the factory inlet point forward? on my 2002 2.6L it behind the grill pointing up, that baffled me because as I appreciate the comment on turbulant air and the factory setup seems to seriously disrupt the air sucking by having movement airflow perpendicular to the pipe opening. I figured, if anything than the 90 deg. elbow will somewhat aid or better the flow.
Will upload a photo later on, comparing stock vs the elbow.
Appreciate all comments.

I can only repeat my original comments back in April;  why are you bothering with this project on an old 2.6 car that cannot be improved on?

If you want efficiency not speed, then go for an up to date car that has been designed to be ultra efficient for the 21st century.   

[Doctor Gollum]

And nothing costing $2 is going to make anything go faster, certainly not a 1,700kg Omega

The aim is efficiency not speed. Also, why did you write the factory inlet point forward? on my 2002 2.6L it behind the grill pointing up, that baffled me because as I appreciate the comment on turbulant air and the factory setup seems to seriously disrupt the air sucking by having movement airflow perpendicular to the pipe opening. I figured, if anything than the 90 deg. elbow will somewhat aid or better the flow.
Will upload a photo later on, comparing stock vs the elbow.
Appreciate all comments.

My bad I forgot about the trumpet. 

But bypassing the front multiram isn't going to help any.

[Raeturbo]

The possible tiny gain you may get would be outweighed by the extra weight of the piping etc as you need to be travelling very fast to achieve a decent ram air effect

               https://i.stack.imgur.com/433lx.jpg

[Doctor Gollum]

And it only works if the air is travelling straight* into the intake.

*straight as in a true edge as opposed to directly via some turns and distortions.

Also too much intake speed or too much fuel and it won't ignition the mixture.

[Eyal2002]

Here's a pic for the first test:



Doctor Gollum - Nothing is bypassed, only the trumpet was replaced by a 90 degree and wider opening elbow. Next is to replace the pipe from this elbow to the air filter box, and use a larger diameter flex pipe with no hard turns.
With OOF members help perhaps I can quantify things, if you point me to measure the right parameter (MAF live data?) I was thinking to take a reading in parking running 3000 RPM and then cruising at 3000 RPM on level road. And compare if there is a gain in efficiency.

I am here to make things better with my car, my sole Omega.
I replaced an engine (Y26SE from a Vectra), repainted the car, added tons of modifications to form and function, so no, I do not consider the car "old". It has lots of life in it, it drives great and for its worth I will not find anything close to what it gives me.
I am a proud Omega owner, and any advice to switch to a newer car is, while legitimate, doesn't fit with the vibes I get from this forum. Nothing wrong with striving to achieve higher efficiency, performance or even car looks. When you take pride in something you invest in it, even if it not always the most economical or smartest.

Anyways, if someone can guide me re which parameters to check it will be much appreciated, definitely more than cheap criticism