Gains From Cut-out...
Thread Starter
TECH Fanatic
Joined: Sep 2003
Posts: 1,570
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From: San Diego, CA
Gains From Cut-out... well i tryed to do a comparisson when i dynoed on sat.
it was a dyno day so things were quick but i gained 5rwhp the entire curve.
well being that im funning FLP long tubes with no cats i thought a cut-out may actually kill power.....like 0 backpressure? but i gained!!!!!
to me the car feals stronger with it closed!
but i love it when its open!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!
it was a dyno day so things were quick but i gained 5rwhp the entire curve.
well being that im funning FLP long tubes with no cats i thought a cut-out may actually kill power.....like 0 backpressure? but i gained!!!!!
to me the car feals stronger with it closed!
but i love it when its open!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!
I just installed a cutout myself and just like you it FEELS faster closed, same basic exhaust setup Pacesetters and ORY/Hooker catback, I have a appointment with Allan Futral on the 26th of this month and am looking forward to seeing the difference. 
On The Tree
Joined: Feb 2002
Posts: 112
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From: Arlington, VA
Originally Posted by gomer
On my car the cutout is worth 15rwhp and 17rwtq all the way across the board over the B&B triflow. It really surprised me that my exhast was that restrictive.
Anyone know if the computer takes time to adjust when the cutouts opened/closed?
Thread Starter
TECH Fanatic
Joined: Sep 2003
Posts: 1,570
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From: San Diego, CA
good point JULIAN...i wonder if i would have gained more if my car would have had more time to adjust to the change....i only has about 30 sec. between pulls......next time ill drive with it open a while a dyno it open first! i bet the numbers will be better!
oh ya, QTP kick ***!!!!
oh ya, QTP kick ***!!!!
No dyno comparisons of my car, but I can definately feel it SOTP w/ the cut out open. The car screams in the upper RPMs vs. through my cat back. It does feel like it gives up a little down low, but in my mind - I think it's just my lack of gear & stock TC. I pick up a full MPH avg. at the track vs. closed up.
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!LS1 11 Second Club
Joined: Apr 2003
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From: Miami
For all the "it feels faster when closed" comments, your torque peak moves up in the rev range with the cutout open. Usually, you gain overall torque, it just higher in the powerband, thus the "feels sluggish" low end. Trust me, cutouts work.
This is my Dyno graph with current mods.....
I had installed a Car Chemistry 3" baffle inside my I pipe to reduce rasp and noise but it proved to be a huge restriction!!!!! After seeing these results it hit the trash can.
Redlines are with cutout closed with baffle in I pipe thru SLP DD Muffler
Bluelines are with 3" QTEC in I pipe Open.
I had installed a Car Chemistry 3" baffle inside my I pipe to reduce rasp and noise but it proved to be a huge restriction!!!!! After seeing these results it hit the trash can.
Redlines are with cutout closed with baffle in I pipe thru SLP DD Muffler
Bluelines are with 3" QTEC in I pipe Open.
I have dynoed over a hundred cars, most with cutouts. Never once has anyone lost torque at 3000 or above. Not once. Maybe twice, a car has lost a maximum of 5 ft lbs at some worthlessly low rpm (2000-2500) Perception is reality they say 
Seriously though, I think its just peoples perception due to the sound. Generally, when I uncap cars on the dyno its an across the board increase in power. Not like it gains just above 4500, but maybe 8 at 3000, and 11 at 6000 or something of the like
Intake restrictions seem to be more gain based on rpm. Like when I have cars not onpening to 100% throttle, youd think getting another 20% pedal rotation woudl be big gains, but its only a few percent of total power (maybe 4-7%, 10-25 hp) and gradually increasing as rpm goes up. The motor just isnt consuming all the air flowing through the TB until certain points
Seriously though, I think its just peoples perception due to the sound. Generally, when I uncap cars on the dyno its an across the board increase in power. Not like it gains just above 4500, but maybe 8 at 3000, and 11 at 6000 or something of the like
Intake restrictions seem to be more gain based on rpm. Like when I have cars not onpening to 100% throttle, youd think getting another 20% pedal rotation woudl be big gains, but its only a few percent of total power (maybe 4-7%, 10-25 hp) and gradually increasing as rpm goes up. The motor just isnt consuming all the air flowing through the TB until certain points
