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View Full Version : removing secondary butterfly B18c


tekung89
23-06-2008, 01:52 AM
jus wondering if anyone has removed the secondary butterfly on a GSR or (SIR-R) b18C motor. any pro's and con's in doin this ?
EGB18CT
23-06-2008, 08:37 AM
havnt done this to mine as im swapping out the manifold for my turbo build, but aparently it will feel sluggish down low, but gain a bit up top..donno it its worth doing, you can definately hear the butterflies open up around 4k i think then vtec at 5.5ish, depends how you feel about it...
VTec1987
02-07-2008, 10:57 PM
havnt done this to mine as im swapping out the manifold for my turbo build, but aparently it will feel sluggish down low, but gain a bit up top..donno it its worth doing, you can definately hear the butterflies open up around 4k i think then vtec at 5.5ish, depends how you feel about it...

people still get it wrong, its the other way around, vtec comes in first then butterflies
B18cEG
03-07-2008, 03:43 PM
Yes it is the other way aroung on a B18c vtec then butterflies, covered many times.
90xsi
03-07-2008, 11:21 PM
it feels like crap
feels like driving a breeze
without the secondary butterfly
B18cEG
04-07-2008, 12:25 PM
it feels like crap
feels like driving a breeze
without the secondary butterfly

I disagree, It felt better along with a vtec crossover of 5200, but if the vtec crossover is left at stock it does feel a little weird,
dsp26
04-07-2008, 12:43 PM
I disagree, It felt better along with a vtec crossover of 5200, but if the vtec crossover is left at stock it does feel a little weird,

dyno of power curve with this setup?
CRXer
04-07-2008, 01:28 PM
dyno of power curve with this setup?

yeah x2
B18cEG
04-07-2008, 05:10 PM
dyno of power curve with this setup?

From me? i dont have one but before i took the engine out i used to play around with my field vtec a/f controller ALOT and found it much better with the secondaries removed with just a harder pull (mainly 1st and second) even against a mates car it was overall better, but never put it on the dyno, the secondaries are meant to keep a fairly linear torque curve but when the crossover point is changed that whole theory is out the window.
I will try find some dyno tests on it.
Thanks

Oh yeah, the engine was in my eg hatch so any little change in power was very apparent unlike a heavier dc2.