LS7 Exhaust question Help please!
Thread Starter
Teching In
Joined: Jan 2018
Posts: 46
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LS7 Exhaust question Help please! My project is an LS7 in a 1969 Corvette with factory side pipes.
The pipes I have are for a SB chevy vs the BB chevy exhaust and mufflers.
Can I use the small block pipes? I assume not given the 427 vs the 350 displacement. But I thought I'd ask the experts!
If I should move to the BB pipes, are there any issues I should know?
My thoughts are to get the BB factory stainless exhaust, add electric cutouts prior to the mufflers for you know, Those days . . . ..
and put on the car.
Before I **** away all my bucks, does anyone see serious fault with this?
Thanks in advance!
Scott
The pipes I have are for a SB chevy vs the BB chevy exhaust and mufflers.
Can I use the small block pipes? I assume not given the 427 vs the 350 displacement. But I thought I'd ask the experts!
If I should move to the BB pipes, are there any issues I should know?
My thoughts are to get the BB factory stainless exhaust, add electric cutouts prior to the mufflers for you know, Those days . . . ..
and put on the car.
Before I **** away all my bucks, does anyone see serious fault with this?
Thanks in advance!
Scott
TECH Senior Member
Joined: Jun 2016
Posts: 22,298
Likes: 3,619
From: Central Cal.
"Small block" pipes can be anywhere from 2" to 2-1/2". What size are they? An LS7 will not breathe thru 2", but be OK, not great thru 2-1/2". Look at what you are dealing with here. Ideally, the LS7 should be breathing thru 3" pipes.
I think the BB is a better start to building your own. A 2" OD header tube is the right size for a LS 427. The collector/exhaust tube should be at least 3".
Also, the BB is a symmetrical exhaust layout vs. the SB that has the center two paired so it should make fabrication easier.
Just get a good quality LSX exhaust flange and start connecting the two. Or be prepared to spend a decent amount and have a custom set made.
Also, the BB is a symmetrical exhaust layout vs. the SB that has the center two paired so it should make fabrication easier.
Just get a good quality LSX exhaust flange and start connecting the two. Or be prepared to spend a decent amount and have a custom set made.
TECH Senior Member
Joined: Jun 2016
Posts: 22,298
Likes: 3,619
From: Central Cal.
I think the BB is a better start to building your own. A 2" OD header tube is the right size for a LS 427. The collector/exhaust tube should be at least 3".
Also, the BB is a symmetrical exhaust layout vs. the SB that has the center two paired so it should make fabrication easier.
Just get a good quality LSX exhaust flange and start connecting the two.
Also, the BB is a symmetrical exhaust layout vs. the SB that has the center two paired so it should make fabrication easier.
Just get a good quality LSX exhaust flange and start connecting the two.
Thread Starter
Teching In
Joined: Jan 2018
Posts: 46
Likes: 13
Please note, this is a crate motor not pulled from an existing vehicle.The exhaust manifold and collector came with the crate engine so for now I will leave it as is.
I have a SB car with factory pipes.
I wish to keep the factory look as much as reasonably possible. For example, I want to keep the factory side exhaust.
The question is should I sell the factory SB side exhaust for factory style BB pipes.
I will also add electric cutouts for the one or two times I hit the 1/4 with family and friends. I will also use them to be intentionally loud at times.
Otherwise the car is a spirited street driver.
Research has me looking at Allen's exhaust and here are the choices:
- [SIZE=3px]1968-1980 Small Block 2 Inch Stock GM Sound[/SIZE]
- [SIZE=3px]1968-1980 Small Block 2 Inch w/ 2 Inch Inner (Little Quieter)[/SIZE]
- [SIZE=3px]1968-1980 Small Block 2 Inch w/ 2.25 Inch Inner (Loud)[/SIZE]
- [SIZE=3px]1968-1980 Big Block 2.5 Inch Stock GM Sound[/SIZE]
- [SIZE=3px]1968-1980 Big Block 2.5 Inch w/ 2 Inch Inner (Little Quieter)[/SIZE]
- [SIZE=3px]1968-1980 Big Block 2.5 Inch w/ 2.25 Inch Inner (Loud)[/SIZE]
Just looking for reasonable sound, not obnoxious. I can use cut outs for that.
Again, I appreciate input!
Please remember I have very limited experience here. Just looking to ensure she runs good on the street. Reliable and quick.
Scott
PS: I do not have the knowledge or tools to build my own.
