K&N: worth it?

8305 Views 9 Replies 9 Participants Last post by Magilla, 17 d ago

Tomkat

Discussion Starter · Sep 4, 2018

As a mild power hop-up I'm considering swapping out the OE air filter for the K&N so-called "high flow" filter that sits in the standard airbox. Is it worth doing? Obvs would need to consider fuelling but I already have a PC5 so if necessary I can adjust.

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dubSolo

· #2 · Sep 4, 2018

Tomkat said:
As a mild power hop-up I'm considering swapping out the OE air filter for the K&N so-called "high flow" filter that sits in the standard airbox. Is it worth doing? Obvs would need to consider fuelling but I already have a PC5 so if necessary I can adjust.

No! not worth the $50 plus shipping for a oily gauze air filter that is still suffocated by the stock box design, Imo... but this is coming from a guy who would rather make his own intakes.

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Paultergeist

· #3 · Sep 4, 2018

Tomkat said:
As a mild power hop-up I'm considering swapping out the OE air filter for (a) so-called "high flow" filter.....

I have seen no convincing evidence that "opening up" the stock air-box or stock air-filter results in any significant increase in power or top speed, assuming a ~stock engine. Yes, I have seen many of the YouTube videos advocating air-box mods for "more power," but increased noise seems to be the only result I can observe.

I currently use a Koso "Hurricane" filter element and a Brock's velocity stack inside of my air-box. I get the same speed / power / feel as I did with the stock air-filter element. Your experience may be different, but that's my data point.

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WV_Grom

· #4 · Sep 4, 2018

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[email protected]

· #5 · Sep 4, 2018

I'd say no to the OP's question. You can do your own research but K&N's appear to allow more dirt to pass through them. I doubt even if it does flow more air there will be any benefit on a 9 hp stock motor.

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jonesn

· #6 · Oct 11, 2018

From my dyno data, ALL panel filters (BMC, K&N, KOSO, etc) perform the same as a stock filter with the mesh screen on the back removed. The only ones with a real benefit is the ones that are cleanable as the stock is not.

Stock grom with yoshimura rs2 exhaust. The blue and green are with the airbox lid off (koso vs stock), the red and purple are with the lid on. This is comparing the koso (thin foam) filter vs stock filter with mesh removed with and without the airbox lid.

Bone stock grom (over 1k miles, broken in)
Blue stock airbox lid on (no intake mod)
Red is still a stock airbox with the airbox lid removed (no intake mod)
Green is without the airbox lid with the intake mod (removed mesh behind filter, remove small tube at the back of the airbox)

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Tomkat

Discussion Starter · #7 · Oct 27, 2018

Thanks all, I think the decision is made.

Next step will be a Takegawa 181 kit with cam and dyno setup with PCV. I'll post up the printouts when it's done

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Wibbly

· #8 · Oct 27, 2018

think about this.... the grom makes 8 horsepower. it has an air filter about the same size as bikes that make 180 horsepower. do you honestly think that it's starving for air?

people have this idea that their engines are starved for air, but of course this isn't the case. the restrictions are NOT in the airbox.

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Grommit23

· #9 · 18 d ago

jonesn said:
From my dyno data, ALL panel filters (BMC, K&N, KOSO, etc) perform the same as a stock filter with the mesh screen on the back removed. The only ones with a real benefit is the ones that are cleanable as the stock is not.

Stock grom with yoshimura rs2 exhaust. The blue and green are with the airbox lid off (koso vs stock), the red and purple are with the lid on. This is comparing the koso (thin foam) filter vs stock filter with mesh removed with and without the airbox lid.
View attachment 76926
Bone stock grom (over 1k miles, broken in)
Blue stock airbox lid on (no intake mod)
Red is still a stock airbox with the airbox lid removed (no intake mod)
Green is without the airbox lid with the intake mod (removed mesh behind filter, remove small tube at the back of the airbox)
View attachment 76924

If I'm reading this correctly it looks like a slight difference with the lid off correct? It's hard for me to zoom into the colors. Thanks for the research and data BTW

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Magilla

· #10 · 17 d ago

The biggest restriction seems to be the inlet pipe connecting the airbox to TB. I have a new gen Monkey and that pipe doesn't have the removable protruding bellmouth. Instead, the pipe/bellmouth was redesigned with a channel molded into it which is supposed to help guide the air in more efficiently. Both ends of the inlet snorkel also have the same channel molded into them so it apparently helps in both directions. The new Grom uses the updated bellmouth too but they all still have a long, narrow path to travel before the TB.

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