How much HP 2.5 exhaust? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Craig B · 08-19-2013, 07:06 PM

How much HP will 2.5 exhaust support in a N/A car?? Was wondering if it was worth it to go with a full 3in. system. Thanks.

LS3 SS · 08-19-2013, 08:24 PM

Quote:

Originally Posted by Criag B

How much HP will 2.5 exhaust support in a N/A car?? Was wondering if it was worth it to go with a full 3in. system. Thanks.

Zero. The factory exhaust is 2.5'', and flows pretty well. There is almost no gain to be had in 2.5'' exhaust. 3'' is overkill on an N/A motor unless you have some bigger cubes, high flowing heads and a beastly cam.

thahemp · 08-19-2013, 08:25 PM

Quote:

Originally Posted by LS3 SS

Zero. The factory exhaust is 2.5'', and flows pretty well. There is almost no gain to be had in 2.5'' exhaust. 3'' is overkill on an N/A motor unless you have some bigger cubes, high flowing heads and a beastly cam.

IIRC the stock system is good to ~600RWHP. Then the 3" is not just for sound anymore.

caverman · 08-19-2013, 08:27 PM

You won't get a true 3" system unless you buy one. I think KOOKS and LG are about the only ones that make a full header to exhaust tip in 3".

Most headers and cat-backs have a 2.5" connection point.

Unless you're making really big HP I wouldn't worry about going to a full 3" system. However, a 3" will give you a little bit of deeper tone when idling.

LS3 SS · 08-19-2013, 08:27 PM

Quote:

Originally Posted by thahemp

IIRC the stock system is good to ~600RWHP. Then the 3" is not just for sound anymore.

I stand corrected OP! You're gonna need a whole LOT of cubes then lol.

jcmG8 · 08-19-2013, 08:31 PM

the magic number is 2.2cfm /HP. Any more flow is a waste of money.

Here is a decent unbiased article with science behind exhaust system design

thahemp · 08-19-2013, 08:33 PM

Quote:

Originally Posted by caverman

You won't get a true 3" system unless you buy one. I think KOOKS and LG are about the only ones that make a full header to exhaust tip in 3".

Most headers and cat-backs have a 2.5" connection point.

Unless you're making really big HP I wouldn't worry about going to a full 3" system. However, a 3" will give you a little bit of deeper tone when idling.

Lots of companies make a full 3".

dekan513 · 08-19-2013, 09:07 PM

n/a i dont think the gains will be but like 1-2 hp if that. the weight of the extra pipe. will counter balance that tho lol

Craig B · 08-19-2013, 09:25 PM

Thanks for the replies. Looks like it's not worth changing to 3in.

thahemp · 08-19-2013, 09:34 PM

Sure it is. A 3" sounds like heaven on these cars.

Supercharged SS · 08-19-2013, 09:52 PM

JRE has an 800 rwhp on the 2.5" exhaust. Blower car though

I run the Kooks 3". It does sound evil at the track!

Baltimorejohn1 · 08-19-2013, 10:19 PM

Quote:

Originally Posted by jcmG8

the magic number is 2.2cfm /HP. Any more flow is a waste of money.

Here is a decent unbiased article with science behind exhaust system design

Great read

caverman · 08-20-2013, 11:07 AM

Quote:

Originally Posted by thahemp

Lots of companies make a full 3".

Not a true 3". I'm talking about 3" from the collector back.

Most 3" cat-backs have a 2.5" inlet so they can connect up to the stock mid pipes. KOOKS makes a 3" inlet cat-back as well as LG. I think ARH might have one setup that way as well.

thahemp · 08-20-2013, 01:32 PM

Quote:

Originally Posted by caverman

Not a true 3". I'm talking about 3" from the collector back.

Most 3" cat-backs have a 2.5" inlet so they can connect up to the stock mid pipes. KOOKS makes a 3" inlet cat-back as well as LG. I think ARH might have one setup that way as well.

And so does JBA. And so does SW. I know what you're talking about. I just know there are plenty of full 3" choices

.

08-19-2013, 07:06 PM	#1
Craig B Drives: 2013 1LE Join Date: May 2013 Location: NJ Posts: 685	How much HP 2.5 exhaust? How much HP will 2.5 exhaust support in a N/A car?? Was wondering if it was worth it to go with a full 3in. system. Thanks.

08-19-2013, 08:27 PM	#4
caverman Drives: '69 SS Convertible Join Date: May 2009 Location: DFW, TX Posts: 7,111	You won't get a true 3" system unless you buy one. I think KOOKS and LG are about the only ones that make a full header to exhaust tip in 3". Most headers and cat-backs have a 2.5" connection point. Unless you're making really big HP I wouldn't worry about going to a full 3" system. However, a 3" will give you a little bit of deeper tone when idling. __________________ *-2010 Camaro* 2SS \| M6 \| VR w/White Stripes \| 1 3/4" KOOKS - 3" Magnaflow \| LPE 3.91 gears \| ADM tuned \| Halltech w/ADM Scoop \| Spohn/BMR Trailing Arm/Toe Rod \| BC Coilovers\| Pedders FE4 ZL1 swaybars \| Cradle/Diff/Radius Rod bushings \| VMax TB \| Morimoto Projectors \| MGW shifter \| Red Calipers Build Journal

08-19-2013, 08:31 PM	#6
jcmG8 Drives: G8GT Join Date: Jan 2011 Location: Vermont Posts: 90	the magic number is 2.2cfm /HP. Any more flow is a waste of money. Here is a decent unbiased article with science behind exhaust system design __________________

08-19-2013, 09:07 PM	#8
dekan513 chevy pride Drives: 2ss/rs Join Date: Feb 2012 Location: pikeville ky Posts: 2,141 View My Garage	n/a i dont think the gains will be but like 1-2 hp if that. the weight of the extra pipe. will counter balance that tho lol __________________ check out ky speeds fb page https://www.facebook.com/kyspeed

08-19-2013, 09:34 PM	#10
thahemp Geek Drives: 2012 Black LS3 Join Date: Jan 2012 Location: Derby, KS Posts: 4,343 View My Garage	Sure it is. A 3" sounds like heaven on these cars. __________________ 01000111011011110110111101100100001000000110110001 11010101100011011010110010000001110111011010010111 01000110100000100000011101000110100001101001011100 110010000001101111011011100110010100100001 x = ac97968bd3df8f968c8cd3df998a9c94d3df9c8a918bd3df9c 909c94df8c8a9c949a8dd3df92908b979a8ddf998a9c949a8d d3df8b968b8cd1 x = ~x

08-19-2013, 09:25 PM	#9
Craig B Drives: 2013 1LE Join Date: May 2013 Location: NJ Posts: 685	Thanks for the replies. Looks like it's not worth changing to 3in.

08-19-2013, 09:52 PM	#11
Supercharged SS Account Suspended Drives: 2010 Camaro Join Date: Feb 2010 Location: Sandy Hook, CT Posts: 11,926	JRE has an 800 rwhp on the 2.5" exhaust. Blower car though I run the Kooks 3". It does sound evil at the track!