flapper valve - Honda Prelude Forum

92preludesi · 08-13-2002, 05:07 PM

has anyone opend thier flaper valve so that all 8 runners are open at the same time? does anyone have any dyno results on this? i ve been looking on the net and ive mostly seen negative things about this but that was on GSRs which is a totaly different motor, but what about our non vtec h23s?

92preludesi · 08-13-2002, 05:10 PM

this is what ive found on the net http://www.hondalife.com/articles/intakemanifold.htm

MidNKight-lude · 08-13-2002, 07:18 PM

i have done this mod. i am not using it right now to save gas. But wat i have notice is that it is such a simple mod u should just do it and see wat it feels like. ok on to my testing result, i have a h23. When i have all 8 runner open in manifold, the car actually bogs a lil under 3k, but it got a lil pep after that. My idle was also a lil freakie, it would slowly flux, nutn too insane, just a lil up and down. The only real reason i would do this is for the sound. the car has a nice throaty sound

4thGVtec · 08-13-2002, 07:27 PM

if you run a gsr ecu, then you need to open the runners cause the gsr ecu wont open them untill 6800 rpms of somthing.

Alstare · 08-13-2002, 07:29 PM

How do you do this mod on a 94 H22a? I believe I heard it was just unplugging a vacume line somewhere on the intake? Any help would be appreciated. Thanks

hypo-si · 08-13-2002, 07:49 PM

Ive done this before too. it felt better on the h22 then on the h23. on my friends 97 h22a it was rather nice feeling hitting vtec and having this surge of power, you could notice the difference

WHile on the h23 it wasnt as noticable, I have an auto so I dunno what the manual version would be like but the auto didnt feel to different, if it is auto you may want to leave the vacuum connected and keep the low end torque

Alstare · 08-13-2002, 08:10 PM

Pretty strange system so let me see I got this right? The vacume pressume on the line holds the flapper closed untill roughly 4K then the vacume would normally stop? and the flapper would open it self? I took the line off and noticed a signifcant difference, but I was just wondering the details to it's operation. Thanks any help would be appreciated.

WeedSpeed · 08-14-2002, 01:44 AM

In 4th gen the flaps open when engine speeds are above 4800 for H23 and 4600 for H22

wutangben · 08-14-2002, 12:48 PM

yeah, how do you do this mod? what line do you have to disconect on a 93 vtec? im interested in trying this.

peace

PreludeRacer023 · 08-16-2002, 12:20 AM

heres how the system works...theres a black box located underneath your intake manifold, this box is attached to the manifold, and builds up vacumn..it is also connected to the flapper that controls the secondaries runners...at a specific point the ecu sends a signal to this black box, it then releases the vacumn its holding thus opening the valves...by unplugging the vacumn line that goes to the flapper, your keeping your runners open constantly..im running mine always open, i have a chipped p28, so it wont open them at all...but mines perfectly fine this way..no lag or anything..peace

overdose · 08-16-2002, 11:36 AM

how about a better explanation of where these are and where to unplug the box?

picture?

SLICK96 · 08-16-2002, 11:49 PM

Why not just take the whole flapper valve out?