RLoibl

Wow, my brain hurts after that!.....lol. great info. I will either get a K&N, or just replace with stock filter.

Cheers, Ron

On 2/22/2024 at 5:43 PM, BusyLittleShop said:

Understanding how an air box works and the reasons why a stock box is a safer bet...

 

If you have ever had the gas tank off your late-model sportbike, you
will notice that the front of the fuel tank doesn’t hold fuel; it
holds an airbox. In the old days, when you bought a new bike, it had
an air-filter case attached to feed the carburetors or the
fuel-injection intakes. All the sharp, young guys would immediately
rip off the filter case and replace it with four sock filters. Reduced
airflow resistance. Much better performance.

One day in the late 1980s, they began to rip off the airboxes of their
new bikes and their engines fell on their faces. They lost a bunch of
performance. “This can’t be happening! Putting on sock filters always
worked before.” But it turns out the industry found a way to boost
performance by making what is known as a resonant airbox.

We have all in an idle moment blown across the mouth of a beer bottle
and heard the "whoooo" of the bottle resonance. As air goes across the
mouth of the bottle, it creates a low pressure, which causes air to
flow up. That deflects the air away from the mouth of the bottle. Then
the air goes back in, the airflow from your mouth goes back across,
and the cycle repeats, rapidly fluttering and producing that deep
tone. The compressible air in the bottle is acting as a spring, and
the slug of air in the neck of the bottle is the mass that vibrates
against that spring.

This intake airbox from a fuel injected Honda is just a glorified beer
bottle. Instead of the engine blowing across the mouth of it, its four
throttle bodies are sucking from the box, pulling its pressure down.
Air rushes in through the ducts in the fairing to fill up that low
pressure. The next cylinder sucks the bottle pressure down and more
air rushes in and restores the pressure. If the volume of the box and
the mass of the air in the intake pipes are correctly chosen, the box
will hum like the beer bottle.

The trick is to get your engine to draw air from the box when the
pressure is up and then the box refills when the pressure is down. And
that is why ripping the airboxes off and putting on old-time sock
filters resulted in a reduction in performance. In a specific zone of
rpm, a resonant airbox can boost your engine’s torque by 10 percent.
That’s worth having!

My friend Stephen called long distance from England because he just
installed a $900.00 HRC air box on his RC45 and saw 120HP on the
dyno... mmmmm... together we wondered if the stock box be modified???

We found that stock RC45 throttle bodies are 46mm but the air box was
restricted to 40mm... no problem... I'll bore the air box out to 47mm
on the milling machine...

I drew up plans for 47mm bell mouth based on the stock 40mm bell
mouths and purchased a block of black Delrin...

I'm not happy doing repetitious work but I labored long hours to
machine 4 each bell mouths with my best accuracy...

Don't you love when a plan comes together especially if it turns out
perfect???

Now I had an unrestricted air box with my own 47mm bell mouths... it
was the best I could do to replicate HRC $900.00 air box... not to
mention I wanted to keep  my home made K&N filter...

Time to put the Mod to the test on the dyno... this is Dave at Chandelle
Motorsports...

No joy... I lost 1.8HP on the dyno... so bigger is not better in this
case... a whole week worth of work shot down in flames... it seems
Honda got the intake velocity right for a stock  pipe after all... air
boxes are like tuned instruments... alter the holes and the tune
just makes sour notes and power suffers...

Mr.RC45 fueling is not the problem... my air box will remain stock
because our air box works like a finely tuned instrument... any wild
ass guess mod disrupts this highly engineered resonant to where to
you're producing nothing but sour notes... The airbox inlet tubes, or
“horns”, are specifically designed to provide a resonance that can
increase the total airflow by up to 10-15%. Second guessing these can
cause the engine to loose power and increase the intake noise as in my
case...

RC45's stock intake horns are there for homologation purposes only and
do not directly feed into the airbox only the HRC intakes feed ram air
into the airbox...

 

Couldbnt find Big Airbox Mod anywhere

Hey sports fans, dont know if this topic has been discussed yet, or how I found out if it has....😖😖😖. Looking to buy a K&N air filter, is there any DIY mods to the air box that will improve airflow?

Thanks, Ron

I'm in Brighton, Ontario! My 2015 is put away for the winter. Let's hope spring comes quickly!

In my previous 2001 VFR800,  which had fuel injection,  just used any fuel stabilizer according to manufacturers directions. No issues. And on a side note, is it necessary to trickle charge the battery all winter?

I only use high test fuel, no ethanol. Thanks, Ron

Morning all, its been a long time since i put my 2001 vfr800 to sleep over the winter.  I have a 2015 now, and am getting ready to store it over the snowy months. Is it recommended to put oil down the cylinder for storage?

Ron

You'll love the vfr Billy. Purchased mine in May, Ontario Canada. Came with a Delkevic exhaust, sounds greaat. Enjoy

On 10/9/2023 at 7:02 PM, bmart said:

Seems like it. I sure hope so! 

 

Just in from the garage from finishing the PAIR delete job. It was interesting. I didn't have anything to plug the inside or outside of the airbox, so I put the short hose back on and had something to plug the hose. It seemed to run okay in the driveway. Testing tomorrow to get an inspection for registration renewal. It should also turn 30k on the ride. 

 

 

 

 

Can one of you explain what a PAIR is? Been out of the ride for some time, and bought a 8th gen in May......