exhaust throttle 'butterfly' mod

Karapok11

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Jun 26, 2006
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Hi all,

recently did an exhaust pipe throttle body 'butterfly' valve to by pass exhaust gases from going to cat and muffler but instead expel out after the downpipe...

May I hear expert advise on whether doing so will richen or lean down the AFR during normal and wide open throttle?

Thanks in advance
 

polyxtroy

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Feb 18, 2004
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I think it will do absolutely nothing to ur afr. If u wan to see with ur eyes go on a dyno.
 

Karapok11

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Thanks for the advise... Cuz I'm rather concern with it due to my recent damage of all pistons and high chance I'm speculating is due to the butterfly mod which is done just about less than a month...
 

khoyos

2,000 RPM
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Nov 23, 2003
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Shah Alam
why dont u just install a 3inch inlet big muffler? something like tanabe G-power medallion. not loud yet not restrictive as it is straight flow.
 

pcdr

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erm wont that be loud?

from what i understand,u put a valve after the extractor during the long pipe section and the configuration should be open big while accelerating and close(not 100% close) for top speed.

this is bcuz bigger outlet gave more acceleration and smaller outlet creates more preasure(back preasure) thus giving more top speed to it(i think most of us know this)

well my bike have this valve,its called EXUP,and it does work well bcuz my bike is high revving bike,around 16k redline so in town the down low power is managable but after i tried my fwens bike,which he took out the valve,the power down low is worst but he dont mind cuz he dont do city riding wit it plus u can always slip the clutch to higher revs,well thats how my bike's valve work la,should be almost the same wit urs.

plus it can save ur petrol if its set to the right configuration

heres a picture of my fwens bike with exup,it has short pipe but valve is there to mimic long pipe preasure,well this is not exactly his bike picture but same model,so basicly u get the idea,and ill post my bikes exaust system.


well this is the rev,20k its tuned for high rpm running


well this is the short exaust if u can notice,theres a valve in the mid pipe to mimic longer exaust as i said


and this is the valve,the white circle is the motor to control the valve or named servo motor and the red circle is the valve actuator,and the way it move if im not mistaken is depending on the throttle,it will go adjacent wit the throttle twist im im not mistaken,this thing toooooo many electronic,even meter dun have cable,digital al the way,and if u put a transistor at the servo motor to make it open all the time to save money rather than buying rm12k fullsystem the meter will come out error code and ur meter will go crazy,so basicly do it properly or ur car will run like $hit



hope that will help,hopefully thanx,ciao
 

Karapok11

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khoyos said:
why dont u just install a 3inch inlet big muffler? something like tanabe G-power medallion. not loud yet not restrictive as it is straight flow.

Thats another alternative, but going back to the initial question, will the AFR be affected with the mod?
 

khoyos

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Nov 23, 2003
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if i'm not mistaken, the quantity of exhaust gas (volume out of turbine outlet) is affected, rather than the quality of it (AFR).

if anything might go wrong, it will be the blockage of exhaust flow, rather than leaning out at WOT.

well i'm just thinking using common sense, without any theories to back it up... might be wrong...
 

Karapok11

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khoyos said:
if i'm not mistaken, the quantity of exhaust gas (volume out of turbine outlet) is affected, rather than the quality of it (AFR).

if anything might go wrong, it will be the blockage of exhaust flow, rather than leaning out at WOT.

well i'm just thinking using common sense, without any theories to back it up... might be wrong...
Well, thats what I thought of too but made me more confused when I start to think deeper...

I agreed with exhaust gas quantity is affected (increase in this logic)... Resulting in faster spooling of the turbine and thus more air flow to the engine due to turbo compressor spinning faster...

Now thats what I'm concern...(Will that affect the AFR)?.....
 

egb18c

500 RPM
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Feb 8, 2006
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kuantan
dude,may i ask.where did u made the mod? doest it work
cuz m trying to the same mod.but failed misebably
 

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