Well I think I read over a hundred posts last night and I still dont know what I should use. I have split my manifold and have 1 7/8 diameter tubing running down to the bottom of the bell housing. I know alot of guys like to run small diameter pipe for the rap. I really dont care about the loud rap I'm more concerned will performance. I was told that 1 7/8 is what should be run but I'm having a hard time finding it with out having it shipped. will 2" diameter hurt me on the performance side? I have looked at the exhaust calc formula and I **** at math but it looks like 2" might be to much? I read through my speed manuals and they make no mention of exhaust size. I need to get this finished today! Thankz
I had 2" on my 261 with a stock manifold, but i only had a single exhaut. Did not like the sound of bees chasing me every where. THe car ran fine, was even asked if it was a V-8.
I think that 2" might probably be too large for your application. Think of it like comparing it to header tube size, the larger the primary tubes are, the more your low end hp and torque suffer. I'm guessing most of your cruising rpm and speed is just that....cruising, so low speed throttle response and torque are going to be important factors for your choice. 1-7/8 tubing is the better choice for your driving needs, it might be a h***le to find, but I think you will be happier in the end. Plus, by splitting your manifolds, you are already gaining twice what you have to start with, but don't over do it! Hope this has been helpful to you....
I have Fenton headers dumping to 1 3/4" for about two feet, 1 1/2" for another couple of feet, finally dumping to 1 1/4" for the remainder, ending in 1 1/2" pencil tips out back. No mufflers... I like bees chasing me! -ns
Many years ago a guy who should know (he ran a blown SBC G***er) told me that exhaust pipe need not be larger than the diameter of the exhaust valve. He said anything bigger would be "superfluous." I dunno but I finally got to use the word "superfluous" just like my English teacher said in 1956.
Well I ended up getting 2" I should have it finished up in a few hours. Every place I went to including custom places looked at me like I was retarded when I asked for 1 7/8's. "why that small" "what kind of engine". I have read allot about exhaust systems needing to be matched properly with an engine. But all these exhaust places simple answer was run 2". I'm not made of money and I hate doing things twice but I will see how this 2" works and wait until my favorite s**** yard gets some 1 7/8's. steel tubbing seems to cost twice as much at an exhaust shop for the same stuff I get brand new at the s**** yard!
That's interesting you got weird looks for wanting small pipes... the ol' timer that welded up my exhaust was really excited about doing things "the way they did back in the day". Oh well, different strokes... are you runnin' gl***-packs or anything?
Well I have a new problem. After I had the exhaust all tacked in place. I realized I couldnt get the exhaust back out of the car to finish welding. I need someway to separate the pipe near the rear axle. What would be the best way to do this? I have seen exhaust sleeves before, how well do these work. I also looked at using a 1/8 thick flange (I dont have any heaver metal on hand) in the back but it seems like it might be a little tight.
One the advice of an old timer, I went 2" to the mufflers and 1 3/4" after that. Mufflers were 26" smitties, reversed and mounted as far forward as possible. My stovie never sounded so good - I'm still smiling
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