Air filter experiment - Another K&N filter thread

[F.M.]

With all the talk of K&N air filters lately I decided to experiment for myself. I'm curious as to how much louder the actually are, and if there is any real world difference in rpm or performance.

I ordered a RU-1470 for the experiment because of price, if I decide to upgrade permanently I'll replace it with a flame arrestor version 59-2010 or 59-2015. I also ordered a push in k&n breather filter to put in the crankcase breather tube.

After removing the stock airbox and installing the new air and breather filters, I fired up the engines 1 at a time with the engine hatch open. Stock engine first, then the k&n filter engine, then back and forth a few times. To my untrained ears, there was a noticeably different tone between the two, but I don't believe the noise level changed much, if at all. I ran them at idle and did a slow increase in rpms up to 4000 rpms. I've got a buddy coming by on Friday with a decibel meter, if he can find it, so I'll know for sure..... fingers crossed.

I did notice that the engine with the k&n had a noticeable fluctuation in rpms (100 rpms or so, tach needle bouncing) versus being steady and smooth like the stock one.

Hopefully, weather permitting, I'll get it on the water Saturday to compare them side by side.

Anyone else notice an rpm fluctuation when ditching the stock airbox for a universal k&n or the power filter kit from Riva?

 

[F.M.]

Alright, I got it on the hose and ran the engines with a decibel meter. All tests were done with the engine hatch open, and about 20-30 seconds each.

Port engine at idle
-stock airbox - Riva filter - no snorkel


Srrbd engine at idle
- K&N clamp on filter and breather filter


Port engine at 4k RPM
-stock airbox - Riva filter - no snorkel


Srrbd engine at 4k RPM
- K&N clamp on filter and breather filter


It's actually quieter without the airbox.

 

[Weeb]

Good info thanks.

 

[jEt_jAk]

Interesting. I see my rpm move slightly also but not sure if it did that before to be honest.

 

[F.M.]

After running on the hose today, the rpm fluctuation didn't seem to be there anymore.

 

[F.M.]

Finally got the drop it in the water today.

Cons:
- No noticeable in noise difference at any rpm.
- No difference in top speed
- No noticeable difference in acceleration - the wife said that the midrange "might have a little more pep, but wasn't a WOW kind of difference"

Pros:
- To maintain a 30mph cruising speed, engine rpm was noticeably lower (@150 rpm less)
- They look cool when you open the engine hatch

Verdict:
If you have twin NA motors...... keep your airbox and the money in your wallet, unless you need some engine pics for Instagram.

 

[tdonoughue]

Now wait a minute. I thought the point of this board was to have us spend money. This post does not comply. I am going to report you to an Admin...

(a fun way of saying thanks for the good and useful report!)

 

[AZMark]

How is the engine tone different with the K&Ns? Do you consider it a better sound?

 

[F.M.]

How is the engine tone different with the K&Ns? Do you consider it a better sound?

It seemed a little deeper with the airbox on, but I like the tone now. Feels less droning.

 

[Crob83]

With all the talk of K&N air filters lately I decided to experiment for myself. I'm curious as to how much louder the actually are, and if there is any real world difference in rpm or performance.

I ordered a RU-1470 for the experiment because of price, if I decide to upgrade permanently I'll replace it with a flame arrestor version 59-2010 or 59-2015. I also ordered a push in k&n breather filter to put in the crankcase breather tube.

After removing the stock airbox and installing the new air and breather filters, I fired up the engines 1 at a time with the engine hatch open. Stock engine first, then the k&n filter engine, then back and forth a few times. To my untrained ears, there was a noticeably different tone between the two, but I don't believe the noise level changed much, if at all. I ran them at idle and did a slow increase in rpms up to 4000 rpms. I've got a buddy coming by on Friday with a decibel meter, if he can find it, so I'll know for sure..... fingers crossed.

I did notice that the engine with the k&n had a noticeable fluctuation in rpms (100 rpms or so, tach needle bouncing) versus being steady and smooth like the stock one.

Hopefully, weather permitting, I'll get it on the water Saturday to compare them side by side.

Anyone else notice an rpm fluctuation when ditching the stock airbox for a universal k&n or the power filter kit from Riva?

Did you end up going with the 59-2010 or the 2015? And what is the difference between the two?

 

[F.M.]

I haven't ordered either yet, still running the non flame arrestor.

The only difference in the 2010 & 2015 is the shape. The 2010 is straight, and the 2015 is a tapered filter.

 

[FSH 210 Sport]

After running on the hose today, the rpm fluctuation didn't seem to be there anymore.

The rpm’s fluctuating was probably the ECU re calibrating the MAP censor input into the map.

 

[the MfM]

K&N on a boat?!?

Didn’t realize that was a thing.

 

[Brody2012]

Interesting. I see my rpm move slightly also but not sure if it did that before to be honest.

Bro, I’m working on doing the k&n filter can you give me some insight. Is the filter all you need or is there more to it?

 

[jEt_jAk]

You need a bracket as well to connect the filter to the tube. Like this one.

HPS AJ400-300 6061 T6 Aluminum... Amazon.com: HPS AJ400-300 6061 T6 Aluminum Joiner Tubing with Bead Roll, 16 Gauge, 4" Length, 3" OD, 0.065" Wall Thickness: Industrial & Scientific

 

[Crob83]

You need a bracket as well to connect the filter to the tube. Like this one.

HPS AJ400-300 6061 T6 Aluminum... Amazon.com: HPS AJ400-300 6061 T6 Aluminum Joiner Tubing with Bead Roll, 16 Gauge, 4" Length, 3" OD, 0.065" Wall Thickness: Industrial & Scientific

I didn't use that piece, ran half the season like that and had no problems. But it would give me piece of mind...lol. Seems to stay on fine just with the hose clamp

 

[Overtime81]

The only cost effective performance mod for the N/A motors is the ribbon delete. Very noticeable difference on my 240

 

[Brody2012]

The only cost effective performance mod for the N/A motors is the ribbon delete. Very noticeable difference on my 240

I don’t think anyone does it for performance. I’m simply doing it to get rid of the stock air box.