K&N Air Filter Queries and Doubts

[abhiwltya]

Re: K&N Air Filter Queries and Doubts

Hello friends.
I own royal enfield C350 2014 model.
I am thinking about fitting my bike with pipercross or BMC air filter.
According to the specifications of AM air filter, performance AF intakes more quantity of pure air as compared to stock air filter.
So, engine will run on good combustion of fuel hence resulting in better power and maintaining the engine on better side.
But, as carburetor will suck more air, appropriate quantity of fuel is to be injected in the cylinder to maintain proper AF ratio.
To be more clear, if my engine is running on 15:1 AF ratio on stock airfilter, then that ratio is to be manipulated with the AM airfilter.
So the question which arises here is rejetting the carburetor will do the work or changing the carburetor settings?
Because both the settings is going to meter the quantity of fuel injected into the engine cylinder.
Please help me guys.
Also better combustion of fuel means better fuel economy, is this true?
I don't expect better FE, but it shouldn't at least alter the present FE.

I am running on k&n for a year now on my NS.Some personal observations and views-
Air carries fuel while travelling through the carb from small holes, now more air automatically mean that it will carry more fuel.But the increase in fuel <increase in air.Hence the need for stabilizing the af ratio.
What has helped me loads is to understand how your acclerator inputs feel.REMEMBER TO DIFFERENTIATE BETWEEN ACCELERATOR INPUTS AND ENGINE POWER, I AM TALKING ABOUT RESPONSIVENESS AND NOT SHEAR PULLING POWER.Learn how engine response feels on stock air filter, I.e. on opening throttle 10,20,40,50,70,100 percent etc..once you have paid enough attention to this on stock filter, change to AM and without any other changes, compare the throttle response.In my case I found the throttle response on higher rpms remains adequate/slightly better.So I tuned the afr screw (many advised rejetting but I was hell bent on understanding how all this worls) and rode it again trying to figure out the throttle responses.After 5-6 iterations I found that below 4k rpm the throttle responses have improved over the stock and on higher rpms I never felt that the response have dulled.So with this set up i have been riding for over a year, without rejetting and everything has gone as expected.No problems whatsoever with plugs etc.
The info Might help you.


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[dustom_99]

Re: K&amp;N Air Filter Queries and Doubts

A free flow filter's (FFF)job is to let more air pass through itself while filtering it well. That increases the power output of an engine provided the installer has fitted it right & adjusted the fuel-air ratio correctly. Most bad experiences related to FFFs can be traced back to improper installations, wrong or no jetting & improper cleaning of the filters. This forum intends to clear doubts and misconceptions about FFFs which are the most popular performance upgrades.

Filtering something is a relative term. Some would tie a Cotton rag over Intake and Think it is a Filter. well actually it is , It keeps out relatively larger particles , but permits much smaller ones.
On K&N - There was an independent research published , where in Lot of standard and FF Filters were tested for Performance and Filtering efficiency .
Most aftermarket free flow did better on Engine performance but failed Miserably on Filtering efficiency , letting in dust and particles into the engine which would have been captured by standard OEM filters. I remember K&N was second to bottom.

There is no Magic wand for letting more air into an Engine. Either increase surface area of filter used keeping filtering efficiency same , or lower the filteration itself , by having bigger openings than OEM filters.
Since aftermarket Fitlet companies do not have to deal with Engine warranty , they have no problem pushing their products in market.
Everyone loves more power from engines , Manufacturers too . If K&N or other cotton filters were as good as paper type ones , manufacturers would use them as OEM.

[sniper]

Re: K&amp;N Air Filter Queries and Doubts

Stock filters have an additional task besides that of filteration. Its reducing the intake noise caused by the movement of air rushing into the engine. This is achieved by making the intake pipes narrow and using extremely fine filtration material which literally chokes the engine from producing more power and giving better fuel efficiency for the sake of the Noise Pollution norms. If not for these norms, companies would have sold cars/ bikes with factory fitted FFFs. FFF manufacturers have their filteration test data on their websites just like the 'independent researchers' do, both are equally believable. Only difference is that there is more at stake for the manufacturers who can be sued for their claims. We just believe the one we WANT to believe in..

[dustom_99]

Re: K&amp;N Air Filter Queries and Doubts

Stock filters have an additional task besides that of filteration. Its reducing the intake noise caused by the movement of air rushing into the engine. This is achieved by making the intake pipes narrow and using extremely fine filtration material which literally chokes the engine from producing more power and giving better fuel efficiency for the sake of the Noise Pollution norms. If not for these norms, companies would have sold cars/ bikes with factory fitted FFFs. FFF manufacturers have their filteration test data on their websites just like the 'independent researchers' do, both are equally believable. Only difference is that there is more at stake for the manufacturers who can be sued for their claims. We just believe the one we WANT to believe in..

Hehe! Who gave you that theory? Reducing intake noise! Thats a first. You trying to tell me that intake noise is more than 80db limit for most automobiles. And which automobile will that be?
Most of the guys here would have driven around without filter at some point of time , they can decide for themselves if intake sound it loud enough to infringe with govt sound norms.
They(oem) provide extremely fine filtration , but they quote there power figure with same fine filter too and provide warranty aswell .
Fff manufacturers provide performance data but they never tell you how much they are not catching as compared to oem filter.
I would recommend fff to everyone if filter manufacturer can cover engine warranty or cost of repair along with performance.

[sniper]

My theories are based on facts which I have learnt from 15 years of being an automotive engineer, mechanic, performance tuner, etc. What is your field of expertise?

[dustom_99]

Re: K&amp;N Air Filter Queries and Doubts

My theories are based on facts which I have learnt from 15 years of being an automotive engineer, mechanic, performance tuner, etc. What is your field of expertise?

Mine is research manager ( vehicle engineering) for OEM car manufacturer.
15years of selling filters and you did not learn how much noise intake makes?
Since you have 15 yrs experience of tuning , why don't you launch a engine warranty program for the vehicles you send out with free flow ones.
By the way why did you care to mention your experience? I merely asked which automobile makes intake noise loud enough to infringe with sound pollution norms?

[sniper]

In your enthusiasm to prove your point, you didn't read my post right. The intake of any vehicle is designed in such a way so that it reduces intake noise. Thats why the intakes don't make noise. Take off the air filter cover, rev the engine a bit and you can measure and hear what intake noise is. In fact if you increase the diameter and straighten the path of the air intake upto the air filter, noise will increase. Thats a fact, try it, one doesn't need to be a 15 yr veteran or a research manager to figure that out, just some elbow grease. Regarding the warranty on my work, will a manufacturer give a warranty for his stock engine with the stock filter, if he knows, it will be used for racing around on the street or race track?

[dustom_99]

Re: K&amp;N Air Filter Queries and Doubts

In your enthusiasm to prove your point, you didn't read my post right. The intake of any vehicle is designed in such a way so that it reduces intake noise. Thats why the intakes don't make noise. In fact if you increase the diameter and straighten the path of the air intake upto the air filter, noise will increase. Thats a fact, try it, one doesn't need to be a 15 yr veteran or a research manager to figure that out, just some elbow grease. Regarding the warranty on my work, will a manufacturer give a warranty for his stock engine with the stock filter, if he knows, it will be used for racing around on the street or race track?

That what you have learned ?
Intake runner dia/ surface finish / length / material et all are designed to provide desired velocity & pressure to intake charge , so that air can rush into cylinder in very limited time available between valve opening and closing , not reduce noise.
Thats simple application of Bernoulli's theorem. Increase in speed of fluid will be accompanied by reduction of pressure and vice-versa.
It has absolutely nothing to do with intake noise.
Its has all to do with where the designers want there maximum cylinder fill efficiency. Using Bernoulli principle.. Ohh wait , no need to google it now or refer your college books to find out.



You should have learned that in automobile engg , didn't you?

Now that you say the intake is designed to reduce noise , isn't the path clear for oem to use FF filters. They would not have trouble with govt norms.
Or may be oem with million dollar facilities could not come up with an intake that uses K&n and not make noise enough to go against rules.( which they any way do not make , even without a filter anyway).

I don't have time to give you engineering tuition now. You can go back to selling your filters and i would take care of my work.

You still did not tell me which vehicle makes so loud that it doesn't qualify on sound pollution norms . that was the starting post i guess

[sniper]

Most of us learnt Bernoulli's theorem, pinching the pipe end while watering plants and washing our cars. I never disputed the fact that Mr. Bernoulli is responsible for better intakes among lots of other things. But, by using your infinite wisdom and bag full of theorems could you explain why a bike's engine (e.g. in a Yamaha R15) produces more power with a stock filter after removal of air box cover of the highly researched designer intake whose sole job is to actually improve airflow as per your research papers? You are taking it the wrong way. Don't let your ego cloud your judgement. I don't dispute the fact that modern intakes are purpose built to improve effciency. Its also a fact that compromises have to be made in the design to stay within pollution norms such as noise reducing design of intakes (not the intake section between the airbox and engine, obviously), muffled exhausts and EGRs to reduce NOX emmissions. Go back to school, u have a long way to go.

[sniper]

Re: K&amp;N Air Filter Queries and Doubts

This is me signing off from this discussion. All the best to you.

[Giftonsamuel]

Re: K&amp;N Air Filter Queries and Doubts

Errr...
Had two different theories now and me being a automobile engg student adds up to the confusion.

Am yet to experience anything but till now I know only this .
1.air intake is positioned in such a way that it does not get in contact to surface water/dust easily .
2. Suction is provided by vacuum created .


And what I have seen is
1. There is a roar if its a aftermarket filter .
2. No big gain in power but bike feels more rev friendly .
3.I think Fi engines can adjust itself with the new filter .
4. If the exhaust of a TVs 50 is removed it can easily compete with a RE FFE .
5. Primary source of noise will be after combustion so exhaust design plays vital in meeting earlier norms not sure what's now
6.on seeing a RC 390 video sound was different from Dukes and everyone was saying its because of Air intakes position .


IMHO Aftermarket filter are for the guys who have changed to FFE ,remapped the ecu and may be some other performance mods .Just a filter doesn't contribute much for its price .
Also for the dust part yeah there must be some small compromise even if its a stock replacement filter but then maintaining it regularly as with any mod stuff will keep it good conditions.


Please post more of your different views so that we inexperienced guys can learn and even its opposite to the other persons view in the end we get the pros & cons .(will definitely research on that Bernoulli part as I have fluid mech exam still bending )

[dustom_99]

Re: K&amp;amp;amp;N Air Filter Queries and Doubts

Errr...
Had two different theories now and me being a automobile engg student adds up to the confusion.

And what I have seen is
1. There is a roar if its a aftermarket filter .
2. No big gain in power but bike feels more rev friendly .
3.I think Fi engines can adjust itself with the new filter .
4. If the exhaust of a TVs 50 is removed it can easily compete with a RE FFE .
5. Primary source of noise will be after combustion so exhaust design plays vital in meeting earlier norms not sure what's now
6.on seeing a RC 390 video sound was different from Dukes and everyone was saying its because of Air intakes position .


)

I thought the whole point of debate was if K&N lets through more dirt into the engine or not. That was the starting point.
In the very first post I mentioned that lower restriction filters like K&N will allow engine to breath better / improve performance. But they do it by Virtue of larger size openings on their filtering surface Viz-a- Viz Oem Filters ( meaning they let through fine dust ).

People who have to sell there stuff will not give a Clean answer. Never.
They keep bringing in more and more parameters to the debate table , so that the whole thing becomes cluttered and debate takes a new direction instead of the Original question.
Here is a link that should be given some thought.
Lot of filters tested side by side and clearly K&N emerged as least restrictive but at the same time least efficient at actual filteration process.


K&N Air Filter Review - Debunking the Myths (and why OEM is better)

For racing they are fine , as the engine gets rebuilt very often anyway. but for average joe, K&N is a strict NO.

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See which filter passes How much dust into engine in an ISO 5011 standard test.

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.

http://www.knfilters.com/filter_facts.htm

On there Official website K&N filters accepts that theirFilters are somewhere 96-99% efficient at capturing dust. That is : they let through 3% dust all the time. How much do you think 3% of dust entering an engine is?
OEM paper filters filters like Delco / Purolator are 99.7% efficient on an average. while some filters going as much as 99.95% efficient.
When you compare % of dust let through over a sample running size ( like 1000km or 500hrs at 300CFM air flow) K&N will let through about 1500times more dust into engine.

Thats the reason OEM do not use them..all this sound theory is just a sham!

here is a Screen shot from K&N official site:

[vvk1987]

Re: K&amp;N Air Filter Queries and Doubts

My k&n experience:
Old version honda dio

I used to clean the air filter every 1500 kms due to dusty area. , As an experiment installed the k&n universal air filter & the experience was great .
No more chocking of carburetor jets, good inteval for cleaning it approximately 2000km ,i just loved it

Truly unbiased review.


Sent from my SGH-I337M

[Anuj_Gupta]

Re: K&amp;N Air Filter Queries and Doubts

There is a reason why this equipment is termed as filter .,pls don't use k&n unless you're rich and can afford another bike/engine.

[abhi7013]

Re: K&amp;N Air Filter Queries and Doubts

My k&n experience:
Old version honda dio

I used to clean the air filter every 1500 kms due to dusty area. , As an experiment installed the k&n universal air filter & the experience was great .
No more chocking of carburetor jets, good inteval for cleaning it approximately 2000km ,i just loved it

Truly unbiased review.


Sent from my SGH-I337M

Good interval for cleaning? And you say dusty area? How much does honda charge for replacing the engine? I guess you will need one soon.
You cannot have a look inside the engine can you? Cause if you could, you would throw the filter right away. Speaking out of experience. Not k&n but an even better brand.
You say cleaning interval is 2000kms? Why? Cause there's no dirt on the filter right. That my friend is no reason to be happy. Be scared instead. Cause the dust simply goes into the cylinder. If your filter filtered perfectly, your cleaning intervals would would be pretty short cause dirt would accumulate on the filter. Common sense..

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