When closed, would cutouts decrease power due to turbulence in exhaust flow?
02-27-2003, 11:51 AM
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When closed, would cutouts decrease power due to turbulence in exhaust flow? That's what I've heard.
Did anyone dyno his car with no cutouts & then dyno it with cutouts closed? If so, was there any difference?
Did anyone dyno his car with no cutouts & then dyno it with cutouts closed? If so, was there any difference?
02-27-2003, 05:19 PM
#2
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Re: When closed, would cutouts decrease power due to turbulence in exhaust flow? Closed cutout performance could suffer depending on how the cutout is mounted. However, a typical QTEC mounting as shown in this link
http://www.quicktimeperformance.com/qtec.htm
probably doesn't cause very much disturbance where the cutout pipe y's into the head pipe. It just packs with exhaust gas, and the flow hardly notices. Probably not a measurable hp loss on a chassis dyno.
My larger concern would be the less than optimum path with the cutout OPEN. Here the gas has to make a rather abrupt turn to find the path of least resistance. Lots of gas still goes thru the street portion of the system which is the straight shot.
If I were doing it, I'd place the cutouts where the head pipe turns 90 degrees so that when the cutout was open the exhaust had a straight out shot, and when it was closed it would go out the "Y-pipe". This would require QTEC's without their "Y's" and some fabrication. It there were room I'd probably put turndowns after the cutout also. Both my Chebbies have "true duals" and the Ultraflows (Impala) and Corsas (C5) flow well and sound good to me, so no cutouts.
My $.02
<small>[ February 27, 2003, 05:22 PM: Message edited by: Old SStroker ]</small>
http://www.quicktimeperformance.com/qtec.htm
probably doesn't cause very much disturbance where the cutout pipe y's into the head pipe. It just packs with exhaust gas, and the flow hardly notices. Probably not a measurable hp loss on a chassis dyno.
My larger concern would be the less than optimum path with the cutout OPEN. Here the gas has to make a rather abrupt turn to find the path of least resistance. Lots of gas still goes thru the street portion of the system which is the straight shot.
If I were doing it, I'd place the cutouts where the head pipe turns 90 degrees so that when the cutout was open the exhaust had a straight out shot, and when it was closed it would go out the "Y-pipe". This would require QTEC's without their "Y's" and some fabrication. It there were room I'd probably put turndowns after the cutout also. Both my Chebbies have "true duals" and the Ultraflows (Impala) and Corsas (C5) flow well and sound good to me, so no cutouts.
My $.02
<small>[ February 27, 2003, 05:22 PM: Message edited by: Old SStroker ]</small>
02-27-2003, 05:27 PM
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Re: When closed, would cutouts decrease power due to turbulence in exhaust flow? i gained 11 rwhp on the dyno through my cut out <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
02-27-2003, 07:44 PM
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Re: When closed, would cutouts decrease power due to turbulence in exhaust flow? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Old SStroker:
<strong> Closed cutout performance could suffer depending on how the cutout is mounted. However, a typical QTEC mounting as shown in this link
http://www.quicktimeperformance.com/qtec.htm
probably doesn't cause very much disturbance where the cutout pipe y's into the head pipe. It just packs with exhaust gas, and the flow hardly notices. Probably not a measurable hp loss on a chassis dyno.
My larger concern would be the less than optimum path with the cutout OPEN. Here the gas has to make a rather abrupt turn to find the path of least resistance. Lots of gas still goes thru the street portion of the system which is the straight shot.
If I were doing it, I'd place the cutouts where the head pipe turns 90 degrees so that when the cutout was open the exhaust had a straight out shot, and when it was closed it would go out the "Y-pipe". This would require QTEC's without their "Y's" and some fabrication. It there were room I'd probably put turndowns after the cutout also. Both my Chebbies have "true duals" and the Ultraflows (Impala) and Corsas (C5) flow well and sound good to me, so no cutouts.
My $.02 </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I agree, the way its tee-d off of the flowtech cutout it will create very little head loss. Probably be less than a smooth 45* mandrel bend would cause, definately nothing noticable at the track or dyno.
<strong> Closed cutout performance could suffer depending on how the cutout is mounted. However, a typical QTEC mounting as shown in this link
http://www.quicktimeperformance.com/qtec.htm
probably doesn't cause very much disturbance where the cutout pipe y's into the head pipe. It just packs with exhaust gas, and the flow hardly notices. Probably not a measurable hp loss on a chassis dyno.
My larger concern would be the less than optimum path with the cutout OPEN. Here the gas has to make a rather abrupt turn to find the path of least resistance. Lots of gas still goes thru the street portion of the system which is the straight shot.
If I were doing it, I'd place the cutouts where the head pipe turns 90 degrees so that when the cutout was open the exhaust had a straight out shot, and when it was closed it would go out the "Y-pipe". This would require QTEC's without their "Y's" and some fabrication. It there were room I'd probably put turndowns after the cutout also. Both my Chebbies have "true duals" and the Ultraflows (Impala) and Corsas (C5) flow well and sound good to me, so no cutouts.
My $.02 </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I agree, the way its tee-d off of the flowtech cutout it will create very little head loss. Probably be less than a smooth 45* mandrel bend would cause, definately nothing noticable at the track or dyno.
02-28-2003, 12:52 AM
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Re: When closed, would cutouts decrease power due to turbulence in exhaust flow? Theoretically yes, the exaust as it's leaving the vehicle wants to expand cause of heat and take the shortest path possible, when it reaches the cut-out the exaust will expand. and a portion of it will become trapped at the Y part.
Nothing significant but it would create a little more backpressure cause the cooler exaust would slow things down a little.
In a perfect world you would be able to compare the difference, but in our world I doubt you're gonna notice it.
<small>[ February 27, 2003, 12:54 PM: Message edited by: CamaroSS_2002 ]</small>
Nothing significant but it would create a little more backpressure cause the cooler exaust would slow things down a little.
In a perfect world you would be able to compare the difference, but in our world I doubt you're gonna notice it.
<small>[ February 27, 2003, 12:54 PM: Message edited by: CamaroSS_2002 ]</small>
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NewOrleansLT1 (12-24-2022)
03-22-2010, 11:40 AM
#16
I would say probably wouldnt bee more turbulant than making a sharp turn inside a muffler. I'm sure its more turbulant than a straight pipe, but the affects have to be minimal if any. I felt no difference before and after my cutout install with the cut out closed.
2000, c5, closed, cut, cutout, cutouts, decrease, electric, exhaust, horsepower, hp, installation, pipe, turbulance, turbulence
