Another Exhaust Question
Thread Starter
Instructor
Joined: Feb 2001
Posts: 224
Likes: 41
From: Catawba, N.C. USA
Another Exhaust Question
Doing a "budget" body off resto of a 73 small block. Stroked the engine to 383 with Dart Heads, Performer intake, etc. Hope to be in the 350 hp range. TH 400 automatic has been rebuilt. Doing the build with mostly used and repurposed parts. Have a full used exhaust in good shape which appears to me to be a Corvette Central system with the 2 inch down pipe transitioning to 2 1/2. I want to stay with Ram horn style exhause manifolds and wondering if there is a big benefit to going with Speedway 2 1/2 smoothies and cutting off the 2 inch section of down pipe and replacing with a 2 1/2 inch section or sticking with standard 2 inch manifolds and bolting in as is. I have some decent welding skills so should be able to do the fab work if I go that route. Just wondering if the bigger size at the manifold is going to make a significant difference. Opinions wlelcomed. Thanks.
Melting Slicks
Joined: Feb 2018
Posts: 2,327
Likes: 721
From: Marietta GA
If you want to keep the rear chrome OEM looking exhaust tips, then the pipe will have to be 2 inch diameter. Also the OEM tips want the round mufflers, or you can by different tips (latter model) and use the oval shaped mufflers.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
You need at least a 2.5" out let manifold.......unless you put a stock L-48 cam in it.....it is going to make more than 350hp....more like 400hp with that cubic inch, those heads and intake.....
Headers are not a big deal if you use a graphite gasket, ARP stud or similar....make sure they are ceramic coated.....don't rule them out, they are beneficial to anything you bolt them to......and the stock exhaust outlet at the muffler is 2".......open that up too.....
An engine will run as good as it has potential when not choked off......the 2" manifolds are a cork....
Jebby
Headers are not a big deal if you use a graphite gasket, ARP stud or similar....make sure they are ceramic coated.....don't rule them out, they are beneficial to anything you bolt them to......and the stock exhaust outlet at the muffler is 2".......open that up too.....
An engine will run as good as it has potential when not choked off......the 2" manifolds are a cork....
Jebby
Thread Starter
Instructor
Joined: Feb 2001
Posts: 224
Likes: 41
From: Catawba, N.C. USA
Thanks for all the replies. I considered headers but read a lot of posts about melting plug wires etc. so figured the 2 1/2 manifold was a decent compromise. Cam and crank are new from Summit (that part wasn't so budget friendly). I will reconsider headers and definitely open the back end as well.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
But......if you tune the engine properly, and the tubes are quality ceramic coated.....no need for silly plug wire boots or wrap......
#1 cause of burnt plug wires is retarded timing......retarded timing elevates EGT's......so even if you put manfolds on it, you are leaving performance on the table.....proper ignition timing is crucial to power and efficiency......
Jebby
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