Whats the deal with exhaust cutouts? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Bentley78 · 08-13-2008, 01:16 AM

Does anybody like these things, makes the car sound mean as hell but do they take away, remain the same or ad power?

This is something i will be interested in for sure on the SS. Cruise with the girlfriend, leave the cutouts closed, some fool wants to race, open the cutouts.....instant bad ass noise. You cant go wrong, this is so cooool.

*Mindz* · 08-13-2008, 01:22 AM

I would think you'd lose some back pressure and therefore some torque, but your engine breathes more and you can push more air/exhaust through the engine itself making it better for top end.

Just my speculation, and I have no idea if I'm even making sense, so don't quote me. Cut outs are awesome all around imo, the vette has them on the mufflers. Soon as you get past a certain throttle, they open up to really let the exhaust note out. That's why it idles and drives normally pretty quiet.

Bentley78 · 08-13-2008, 01:40 AM

Wow the vette has auto cutouts after a certain RPM!? That is really awesome, why didnt i know about this?!

Wouldnt mind having a system like that on the SS. Would it be possible?

The_Beast_ · 08-13-2008, 02:07 AM

I'm getting that for my LT. Now that will send little Beemers running.

headpunter · 08-13-2008, 02:23 AM

i have already talked to my local exhaust shop about getting electric cutouts installed when they do my full 3" exhaust and flowmaster mufflers with hiflow cats. i cant wait. living in rural washington state means i will never get smog checked

BowtieGuy · 08-13-2008, 03:09 AM

Just make sure you get electric cutouts so you can open them at high RPM.

*radz28* · 08-13-2008, 10:49 AM

The 'Vettes have a system where butterfly valves open after like ~ 3500 RPMs at WOT, or something along those lines. I think I remember reading the valves are vacuum operated, and many owners with this option remove the fuse for them, and run open all the time. I don't think, however, they completely bypass the mufflers. I know they sound better, and add a few more horses, but I don't think they are as beneficial as true cutouts. Obviously, this wouldn't pass sound certification testing, so their systems make complete sense given those circumstances.

There was a GMHTP buildup on an LS1 WS6 (that was eventually bored and stroked to 383 ci) wherein they swapped the OEM manifolds, SLP Y-pipe, and B&B catback with Dynatech LTs, QTP QTEC, and Borla CB. After tuning, they ran N20 runs with the cutout opened and closed and only gained ~ 8 RWHP, but something like ~ 30 RWTQ! That was around 430 RWHP though, so those gains will likely be higher than on a stock SS with manifolds.

I can tell you that I can't tell too big a difference in power with my QTEC. The sound is obviously different, but it feels like there is a little more torque on the bottom end with it closed, but I can't really tell what differences there are up top. I have a pretty loose converter (for a street car) so it soaks up a lot of feeling, but I know it can't hurt.

I'm sure I'll end up adding a pair, around the rear axle or something. I'm not a fan of drone, however, it's not like I'll be running around with them open all the time. I'm just going to have to see...

*radz28* · 08-13-2008, 07:29 PM

Another thing to consider is that the farther the restriction is from the exhaust port, the lesser effect it will have on power, so a cutout that is far downstream is not going to benefit power as much as it will make more noise.

BowtieGuy · 08-14-2008, 01:33 AM

Quote:

Originally Posted by radz282003

Another thing to consider is that the farther the restriction is from the exhaust port, the lesser effect it will have on power, so a cutout that is far downstream is not going to benefit power as much as it will make more noise.

Yea, thats why most people mount theirs rigt after the downpipes. Flip of a switch and open headers.

*radz28* · 08-14-2008, 10:35 AM

Quote:

Originally Posted by BowtieGuy

Yea, thats why most people mount theirs rigt after the downpipes. Flip of a switch and open headers.

The_Beast_ · 08-14-2008, 11:05 AM

But would having them right at the down pipe still provide the same sound as having them say at the rear axle?

Twitch · 08-14-2008, 01:10 PM

Quote:

Originally Posted by The_Beast_

But would having them right at the down pipe still provide the same sound as having them say at the rear axle?

no, it would be much deeper and louder, not cats, resenator or mufflers to go through, that is the whole point of cutouts any way

*radz28* · 08-14-2008, 01:11 PM

I think it would be louder and probably be more of a nuisance than anything inside the car itself. If you like you exhaust loud, have at it, but I think a lot of cutouts do leak a little... This may cause a problem with the 02s and tuning too if they are too close.

The_Beast_ · 08-14-2008, 03:30 PM

I'm Pretty sure I'll out mine just at the begining of the axle back, right befor the mufflers

08-13-2008, 01:22 AM	#2
Mindz E.B.A.H. Drives: you wild... Join Date: Mar 2007 Location: In the happy padded room wearing a jacket that makes me hug myself... Posts: 18,420	I would think you'd lose some back pressure and therefore some torque, but your engine breathes more and you can push more air/exhaust through the engine itself making it better for top end. Just my speculation, and I have no idea if I'm even making sense, so don't quote me. Cut outs are awesome all around imo, the vette has them on the mufflers. Soon as you get past a certain throttle, they open up to really let the exhaust note out. That's why it idles and drives normally pretty quiet. __________________ Blue Rush, 2010 SS [Car of the Week 3/22/2010] Traded in on...ZLZBUBB, 2013 ZL1

08-13-2008, 02:23 AM	#5
headpunter Not That sad..considering Drives: Man Join Date: Aug 2007 Location: the part of washington the capital forgot about. Posts: 3,745 View My Garage	i have already talked to my local exhaust shop about getting electric cutouts installed when they do my full 3" exhaust and flowmaster mufflers with hiflow cats. i cant wait. living in rural washington state means i will never get smog checked Last edited by headpunter; 08-13-2008 at 02:25 AM. Reason: v

08-13-2008, 10:49 AM	#7
radz28 Petro-sexual Drives: Ultra-Grin Join Date: Oct 2006 Location: Crazy Coast Posts: 15,795 View My Garage	The 'Vettes have a system where butterfly valves open after like ~ 3500 RPMs at WOT, or something along those lines. I think I remember reading the valves are vacuum operated, and many owners with this option remove the fuse for them, and run open all the time. I don't think, however, they completely bypass the mufflers. I know they sound better, and add a few more horses, but I don't think they are as beneficial as true cutouts. Obviously, this wouldn't pass sound certification testing, so their systems make complete sense given those circumstances. There was a GMHTP buildup on an LS1 WS6 (that was eventually bored and stroked to 383 ci) wherein they swapped the OEM manifolds, SLP Y-pipe, and B&B catback with Dynatech LTs, QTP QTEC, and Borla CB. After tuning, they ran N20 runs with the cutout opened and closed and only gained ~ 8 RWHP, but something like ~ 30 RWTQ! That was around 430 RWHP though, so those gains will likely be higher than on a stock SS with manifolds. I can tell you that I can't tell too big a difference in power with my QTEC. The sound is obviously different, but it feels like there is a little more torque on the bottom end with it closed, but I can't really tell what differences there are up top. I have a pretty loose converter (for a street car) so it soaks up a lot of feeling, but I know it can't hurt. I'm sure I'll end up adding a pair, around the rear axle or something. I'm not a fan of drone, however, it's not like I'll be running around with them open all the time. I'm just going to have to see... __________________ '20 ZL1 Black "Fury" A10, PDR, Exposed CF Extractor Magnuson Magnum DI TVS2650R // RFBG // Soler 103 // TooHighPSI Port Injection // THPSI Billet Lid // FF // Katech Drop-In // PLM Heat Exchanger // ZLE Cradle bushings // BMR Chassis-Suspension Stuff // aFe Bars // Diode Dynamics LEDs // ACS Composites Guards // CF Dash // Aeroforce // tint // other stuffs

08-13-2008, 07:29 PM	#8
radz28 Petro-sexual Drives: Ultra-Grin Join Date: Oct 2006 Location: Crazy Coast Posts: 15,795 View My Garage	Another thing to consider is that the farther the restriction is from the exhaust port, the lesser effect it will have on power, so a cutout that is far downstream is not going to benefit power as much as it will make more noise. __________________ '20 ZL1 Black "Fury" A10, PDR, Exposed CF Extractor Magnuson Magnum DI TVS2650R // RFBG // Soler 103 // TooHighPSI Port Injection // THPSI Billet Lid // FF // Katech Drop-In // PLM Heat Exchanger // ZLE Cradle bushings // BMR Chassis-Suspension Stuff // aFe Bars // Diode Dynamics LEDs // ACS Composites Guards // CF Dash // Aeroforce // tint // other stuffs

08-14-2008, 01:11 PM	#13
radz28 Petro-sexual Drives: Ultra-Grin Join Date: Oct 2006 Location: Crazy Coast Posts: 15,795 View My Garage	I think it would be louder and probably be more of a nuisance than anything inside the car itself. If you like you exhaust loud, have at it, but I think a lot of cutouts do leak a little... This may cause a problem with the 02s and tuning too if they are too close. __________________ '20 ZL1 Black "Fury" A10, PDR, Exposed CF Extractor Magnuson Magnum DI TVS2650R // RFBG // Soler 103 // TooHighPSI Port Injection // THPSI Billet Lid // FF // Katech Drop-In // PLM Heat Exchanger // ZLE Cradle bushings // BMR Chassis-Suspension Stuff // aFe Bars // Diode Dynamics LEDs // ACS Composites Guards // CF Dash // Aeroforce // tint // other stuffs

08-13-2008, 01:40 AM	#3
Bentley78 Rice Cooker Drives: Avalanche Z/71, 2010 Camaro2SS Join Date: Jun 2008 Location: Hawaii/Phoenix Posts: 590	Wow the vette has auto cutouts after a certain RPM!? That is really awesome, why didnt i know about this?! Wouldnt mind having a system like that on the SS. Would it be possible?

08-13-2008, 03:09 AM	#6
BowtieGuy Enlightened Drives: Nothing Currently Join Date: Jul 2008 Location: Oklahoma Posts: 1,285	Just make sure you get electric cutouts so you can open them at high RPM.

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