Back in 2005 Stephen and I discussed, by long distance phone call, if the
stock RC45 air box could be modified for more power... he just installed a
$900.00 HRC air box on his RC45 and saw an increase to 120HP on the dyno...
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...
Repetitious hand Lathe work is not fun but I labored long hours to
machine 4 each bell mouths with accuracy...
We all 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 with the help of Dave at Chandelle
Motorsports...
Mercy... 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
suffers...
All in all 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...