ap1_tot

Hello all

I customized my intake arm and made a STRAIGHT 76mm (3 inch) aluminum intake pipe since the stock rubber hose don't fit my 68mm throttle body. I noticed that the stock rubber piping was already 3 inches in diameter going 4 inch in the bend/ near the intake filter and air box. My question now is, does the 4 inch tapering down to 3 inch design of the stock intake hose THAT important? Will my straight through 3 inch aluminum piping hurt performance in anyway? Im thinking of redoing it again but it would be kinda costly to do so over again. thank you all.

here is the pic:





P.S

I don't know if its that significant but i used SARD 80mm>75mm rubber pipe connectors.

D Loke

You have nothing to worry about. That arm you have wont expand or contract like the OEM rubber hose does. The end of it where it connects to the filter is actually only 3.5", not 4"... so your 3" is fine.

H22toF20

^what he said

Has anyone ever tried a 3.5" or 4" intake yet. I've read that some B18's and H22's gained some power with a 3.5" over a 3".

ap1_tot

Thanks sir. finally i can now sleep well at night. and oh yeah, i forgot to take into account that the 3 inch is actually the diameter including the walls of the rubber hose, which is i think around 2mm thick, and that part of the intake filter goes inside the 4 inch tube so yeah, 3.5 inch is good.


H22toF20:

Good question. would like to know a definite answer as well. Is a 3 inch pipe the best piping size for our intake side?

wadzii

for any honda making 225hp or more a long 3.5 or 4 inch intake will produce solid gains.

ap1_tot

225 or more?you mean at the crank right? and how long? like CAI long?

wadzii

take the power level with an ish...225ish

how long... as long as you can fit in the car... generally

Gernby

I believe the length is primarily going to just change the RPM range where the resonant hump occurs.

wadzii

it will change the "hump" but it will also increase top end power vs a short intake.

The last b-series car i dyno'd was making 230hp with a typical short ram 3inch intake. we extended it, it picked up 10hp from 7000 to 9000 and gained the typical cai hump in the midrange.

the length also tends to smooth the air out going into the tb... i think thats why it usually picks up a good amount of peak power as well

H22toF20

Here's some informative dyno's of a SRI vs a CAI on 2 different H22's and an H23 VTEC. Huge midrange gains are to be had.

http://bbmoto.net/wiki/index.php?VtecTuning