3" Exhaust Options
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Joined: Dec 2010
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From: Clearwater FL
3" Exhaust Options
Are there any ready to install 3" mandrel systems for the early C3s? I've seen the 2.5 systems but would like to go to 3" with my LS5 now at 468 CID.
Also, Flowmaster makes a 3" kit, with 16 in total, pre-bent pipes that are mandrel bent and supposed to have enough parts to match pipes up for a complete system minus the exhaust cans. Anyone with experience with making this kit a reality for install?
Also, Flowmaster makes a 3" kit, with 16 in total, pre-bent pipes that are mandrel bent and supposed to have enough parts to match pipes up for a complete system minus the exhaust cans. Anyone with experience with making this kit a reality for install?
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I have a three inch system. But what you have to do is think about a custom tranny cross member. You need a CM that has the exhaust pass under.
My ex come straight back from the header collectors
My ex come straight back from the header collectors
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Joined: Dec 2010
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From: Clearwater FL
I'm not completely sure I do need a 3 inch. Not sure what the flow difference is between the 2 1/2 and 3 and where the big advantage would be in the power band. It's a street driver weekend Vette but if I'm going to make the change I want to do it right the first time.
Drifting
Joined: Jan 2008
Posts: 1,518
Likes: 37
From: The Woodlands Texas
I think that Magnaflow makes a 2 1/2" stainless steel with x-pipe and mufflers. It might also come in a 3" version.
I was looking at this yesterday. Part numbers are 16840 or 16842. The price was about $800.
I was looking at this yesterday. Part numbers are 16840 or 16842. The price was about $800.
Safety Car
Joined: Mar 2005
Posts: 3,503
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From: Raleigh NC
I'm not completely sure I do need a 3 inch. Not sure what the flow difference is between the 2 1/2 and 3 and where the big advantage would be in the power band. It's a street driver weekend Vette but if I'm going to make the change I want to do it right the first time.
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Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I'm not completely sure I do need a 3 inch. Not sure what the flow difference is between the 2 1/2 and 3 and where the big advantage would be in the power band. It's a street driver weekend Vette but if I'm going to make the change I want to do it right the first time.
Then they installed an x-pipe on the 2.5 inch and the 400 rwhp gained some small %, but the 500 hp had a greater %.
Then they had a shop do a nice looking 3 inch system and again they both gained hp, but they made some statement that the 500 rwhp showed it was going lean on the O2 sensors. Then they went with the 3 inch and X-Pipe and rejetted each engine and lowered the total timing by 2 degrees. Each motor made the most HP with the big 3 inch and x-pipe.
The conclusion was that as HP went up so did the need for the least restrictive exhaust.
The 400 hp was some kind of a H-roller 383 and the 500 hp was an H-roller 427 SBC
Race Director
Joined: May 2003
Posts: 10,956
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From: California
my boys fabbed me up a 2 3/4" with X-pipe system..... 3" is to big imho do to dragging the pipes on every bump.... and i wanted an increase over 2.5"...... so I want 2.75" good fit without having to deal with 3"..... there are a lot of new cars being built with 2.75"... but no one makes a 2.75 for our cars.....
(BTW, about a 550hp engine, 383 pulling 6500-7000 RPM)
(BTW, about a 550hp engine, 383 pulling 6500-7000 RPM)
Last edited by pauldana; Oct 30, 2012 at 01:35 PM.
Safety Car
Joined: Oct 2004
Posts: 3,926
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From: Youngstown Ohio
If you have around 500 HP or more, you will benefit from 3" pipes.....more horsepower and torque throughout the power band. Just remember they will hang lower than the 2½". No one makes a ready made system for C3s. They are all custom made. I have a 3" system with Magnaflow mufflers, and yes they fit through the crossmember. Just be careful to route them around the trans pan for access (mine is an automatic)
Hear them.....
Hear them.....
Burning Brakes
Joined: Sep 2006
Posts: 1,242
Likes: 12
From: Kalispell MT
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I was going to install a rear end and manual tranny cooler. I just can't imagine wanting to run hot pipes so close to a tranny and the extra bends to shoot through little x-member holes.
Then for a tranny or exhaust removal you are dealing with pipes through the x-member. Or as the pictures show a highley complicated multipipe with lots of clamps for connections
Then for a tranny or exhaust removal you are dealing with pipes through the x-member. Or as the pictures show a highley complicated multipipe with lots of clamps for connections
Last edited by gkull; Oct 31, 2012 at 07:44 AM.
Thread Starter
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Joined: Dec 2010
Posts: 53
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From: Clearwater FL
my boys fabbed me up a 2 3/4" with X-pipe system..... 3" is to big imho do to dragging the pipes on every bump.... and i wanted an increase over 2.5"...... so I want 2.75" good fit without having to deal with 3"..... there are a lot of new cars being built with 2.75"... but no one makes a 2.75 for our cars.....
(BTW, about a 550hp engine, 383 pulling 6500-7000 RPM)
(BTW, about a 550hp engine, 383 pulling 6500-7000 RPM)
Did you go with 3" in and out mufflers?
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
I appreciate that option of doing a 2.75 vs. 3". Sounds like a perfect blend of flow and function. I've not seen any kits or option with that size and I want to stay with the mandrel bens because of the size reduction at the bending point. I have a 2.5 on mine now but at the bends it looks like a 2" not even close to 2.5.
Did you go with 3" in and out mufflers?
Did you go with 3" in and out mufflers?
) .... when they did the system, they were not here yet... so my sons put in the 2.5" Borlas back on...have not had time to finish...
Thread Starter
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Joined: Dec 2010
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From: Clearwater FL
System looks great for performance. Do you feel the X pipe is a critical part of the system? And did they custom fab that piece or can they be purchased ready to bolt up?
Melting Slicks
Joined: Mar 2008
Posts: 2,666
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From: Spring Park MN
I always look for the most economical way to do projects but still maintain quality and performance. When I built my 3" X pipe exhaust, after much research, I bought all the pieces to build it from Summit. I figured out what I needed for mandrel bends and bought their part number SUM-642130 X pipe kit. The inside of the X needs a little cleanup with a grinder, but it all fit together well and made a very nice setup. I used a BTO trans support/cross-member and it gives plenty of room to run the 3" under. The X is directly behind the tranny. The whole system is welded together front to back and will drop off the car in one piece. It only takes about 5 minutes to drop the whole exhaust.
I'll see if I can't get a photo of the system. It's off the car right now.
I'll see if I can't get a photo of the system. It's off the car right now.
Burning Brakes
Joined: Sep 2006
Posts: 1,242
Likes: 12
From: Kalispell MT
I definitely think the x-pipe improves the performance, and you are correct the mandrel bent pipe is the way to go in order to eliminate the restrictions at the bends. My X-pipe was from Magnaflow & is 3"x13 1/2" (#10782). Magnaflow mufflers #11229.