Exhaust system thoughts
Thread Starter
Instructor
Joined: Aug 2013
Posts: 159
Likes: 3
From: Swansea Illinois
Exhaust system thoughts
I am slowly going through my 1972 SB (base model) Corvette with automatic transmission (overdrive on the horizon) and slowly just cleaning, fixing and dreaming but looking at what I can do now that will also fit long term so the next project will probably be exhaust system, I like the magnaflow but they have part number 16840 listed for my car but it does not seem to exist or at least they don't sell it but a few places claim they do, not sure how that's possible. The other two they list are BB and SB that used to have sidepipes so has a turned down pipe on the muffler because of the filled in rear of the car, not what I need.
So keeping that in mind I also in a year or so would like to go from the base 350 to the ZZ4 (turnkey version) and would want the exhaust to still work, which is I read right it should except exhaust manifolds because of the D shape ports.
I am also thinking headers then or now if the same set would fit the exhaust system I get. Any thoughts on what might do both?
Side pipes are not something I am considering right now or chambered exhaust not sure I want it that loud, mainly a cruiser not a racer.
What are your thoughts on it? Any other products to consider, just like the sound of magnaflows but if they don't have them and no idea when they will which way do I go?
So keeping that in mind I also in a year or so would like to go from the base 350 to the ZZ4 (turnkey version) and would want the exhaust to still work, which is I read right it should except exhaust manifolds because of the D shape ports.
I am also thinking headers then or now if the same set would fit the exhaust system I get. Any thoughts on what might do both?
Side pipes are not something I am considering right now or chambered exhaust not sure I want it that loud, mainly a cruiser not a racer.
What are your thoughts on it? Any other products to consider, just like the sound of magnaflows but if they don't have them and no idea when they will which way do I go?
Burning Brakes
Joined: Sep 2009
Posts: 1,124
Likes: 140
From: Western New York
I also have a '72 smallblock, 4 speed, base engine. Some years back I decided to stop installing pipes and mufflers every few years. I put on Allen's stainless 2" pipes and a set of mufflers that I can't, right now, remember the brand. I have been very happy with the system. It sounds aggressive when you get on it, but you can cruise around all day and there is no rumble or noise that drones you to death in the car. When I get out to the garage, I'll look up in the rafters and get the make and numbers off the boxes. The mufflers were direct fit and all I did was bolt them on the pipes and put on my muffler tips.
Duane
Duane
Burning Brakes
Joined: Sep 2009
Posts: 1,124
Likes: 140
From: Western New York
Wife had me go out to the garage to get the Xmas tree out of the attic, so here's the info I promised. Mufflers are Dynomax Super Turbos. The numbers are R 17764 and R 17765. Hope that helps. I ordered them through Advance Auto Parts. They were around $75 a piece at the time, but that was a few years ago.
Duane
Duane
Thread Starter
Instructor
Joined: Aug 2013
Posts: 159
Likes: 3
From: Swansea Illinois
LT-1 fit?
I have the base 350 SB with 2 inch exhaust will the 2 1/2 from an LT-1 fit? Plan in a year or so is maybe go zZZ4 or rebuild and beef up the engine so would it hurt to get bigger exhaust now while I need it and do the engine later when I can afford it? Will it bolt right up (both were 350's...)
Thanks
Thanks
Burning Brakes
Joined: Sep 2009
Posts: 1,124
Likes: 140
From: Western New York
I have always been under the impression that the 2 1/2" exhaust starts out as a 2" pipe at the manifold and then becomes 2 1/2" a few inches after the pipe/manifold connection. If that is the case, I don't see any benefit in using the 2 1/2" pipes. Once there's a restriction in the system it's not going to matter if the pipes are larger past the restriction. Maybe someone will chime in on this and add some information. As far as the larger pipes fitting on your car, I don't think there'd be a problem.
Duane
Duane
Drifting
Joined: Jun 2012
Posts: 1,990
Likes: 183
From: Port St. Lucie Fl
the only way I know of to use headers on both engines is to get the 1 3/4 tubes because the port will be bigger than both of the head and will seal against the head, with a future plan to upgrade to a zz4 I would either find manifolds that dont reduce to 2 in or use headers and do 2 1/2 system with x pipe.
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Thread Starter
Instructor
Joined: Aug 2013
Posts: 159
Likes: 3
From: Swansea Illinois
I really like the x pipe idea kind of why I was looking at magna flow but they list a 350 set but it is not available but they have a 454 system that is 2 1/2 all the way and instead of connecting to manifold maybe straight to headers? just get new front pipe bent? Any other suggestions?
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
I have always been under the impression that the 2 1/2" exhaust starts out as a 2" pipe at the manifold and then becomes 2 1/2" a few inches after the pipe/manifold connection. If that is the case, I don't see any benefit in using the 2 1/2" pipes. Once there's a restriction in the system it's not going to matter if the pipes are larger past the restriction. Maybe someone will chime in on this and add some information. As far as the larger pipes fitting on your car, I don't think there'd be a problem.
Duane
Duane
The exhaust system handles gases, not solids. The ten inches of 2 inch tubing right at the manifold exit does not cause much restriction. All the engine "knows" is how easily the pipes flow; that is, how much backpressure the pipe/muffler system generates. The 2 1/2" systems do flow better- probably 30% better than a 2 " system. They are also somewhat heavier, stiffer, and a bit trickier to send through the crossmember than a 2" system. None of those are insurmountable problems.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
The size of the header tubes and the outlet of the manifold are the most important ones to enlarge. The hot gases coming out of the combustion chamber are expanded because of their high temperature. Once the gases get back to the muffler area, they have cooled and their volume has reduced. For an upgraded SB engine, you need 2-1/2 inch exhaust pipes from the header outlets [and back]. Putting a 2" manifold outlet on a set of 2-1/2" pipes makes absolutely no sense.
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
The size of the header tubes and the outlet of the manifold are the most important ones to enlarge. The hot gases coming out of the combustion chamber are expanded because of their high temperature. Once the gases get back to the muffler area, they have cooled and their volume has reduced. For an upgraded SB engine, you need 2-1/2 inch exhaust pipes from the header outlets [and back]. Putting a 2" manifold outlet on a set of 2-1/2" pipes makes absolutely no sense.
I have McJacks shorty headers with the 2 inch collector, not the 2.5 inch collector since they were hooking up to my OEM style 2.5 inch duals, which I all ready had when I bought the McJacks. I would do it differently today, buying the 2.5 inch collector Shorties, instead of the 2's but I will say even the McJacks that I have, they made a difference with power, especially mid to high RPM.
Thread Starter
Instructor
Joined: Aug 2013
Posts: 159
Likes: 3
From: Swansea Illinois
Had not heard of McJacks before so took a look, on the shorty style that replaces the manifold does the stock exhaust bolt to it or do you need to modify them? What about other shorty style headers?
for the ZZ4 for I think you need the D port, is that true or does any one know? Can I also use them on the stock engine so I would not have to change them out later?
Learning a lot, THANKS!!!
for the ZZ4 for I think you need the D port, is that true or does any one know? Can I also use them on the stock engine so I would not have to change them out later?
Learning a lot, THANKS!!!
Last edited by irelandr; Dec 5, 2013 at 05:38 PM. Reason: spelling
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Had not heard of McJacks before so took a look, on the shorty style that replaces the manifold does the stock exhaust bolt to it or do you need to modify them? What about other shorty style headers?
for the ZZ4 for I think you need the D port, is that true or does any one know? Can I also use them on the stock engine so I would not have to change them out later?
Learning a lot, THANKS!!!
for the ZZ4 for I think you need the D port, is that true or does any one know? Can I also use them on the stock engine so I would not have to change them out later?
Learning a lot, THANKS!!!