2" exhaust?

[Keith]

I'm putting some new HP manifolds in my barracuda next week (thanks PRO) and will need to redo the exhaust to match up with the manifolds. My current setup is dual exhaust, no X-over or H pipe, with 2" exhaust. Is this hurting me? Should I redo everything in 2.5"? Thanks,

Keith

[71 scamp]

More flow more go! What engine's in it?

[Keith]

The engine is a 340, Performer RPM intake, 9-9.5(?):1, stock heads (for now) and a MP .474" cam is underway. BTW, this is my first cam swap so you can expect to see more cries for help on here soon

Keith

[Jims451]

The easy answer is yes, the 2.5" dual exhaust will make more power. The hard question to answer is how much more?
I have ran 2.5" dual exhaust on a low buck, stock block 318 with stock cam (with MP lifters), cast iron 360 4-bbl intake, 600 cfm Holley, and headers. This cheap engine ran very good and even got better gas mialage.

The HP manifolds are the bottle neck that will create the most restriction. You should see some performance gain just by going to a 2-1/4" exhaust, but if you were changing from a 2-1/4" to 2-1/2" I'm not sure there would be as large a HP difference. The above is just my comment on the theory of the greatest restriction limiting the ultimate gain in exhaust flow.

The 2.5" will work good, and you will be set if you go to headers later.

[rumblefish360]

If you have a few extra bucks, go with a "X" or "H" over. Just a few hidden ponys there.

[jimm II]

Hi Rumblefish 360: Just a quick question regarding this thread ,the "X or the H " connection how far from the Header Flange should it be located back , or anyplace ahead of forward driveshaft U joint??? Hope this made sense... Jimm II

[Brian_wo]

Did the 340's come with 2" exhaust? I just putt TTI headers on my 1969 1/2 cuda and it also has 2",what a freaking joke

[rumblefish360]

To all and Jimm II;

"H" pipe;
1 publication from L Shep says 12-18 inches past the collector on headers. If exhaust manifolds are used, I would try to copy the factory on it. Most of the time there preety close to the front of the car, under the tranny.
"X" pipe;
I see "X" pipes done about mid car. I don't know if theres a optimun point for this pipeing. It makes more power than an "H" pipe, so says the boys at NASCAR. If it didn't, they wouldn't run it.

Brain_wo;

I'm not to sure, but I think the 340's came with 2 inch exhaust pipes. Heres a weird one that I can't explain. I have a '73 Cuda that came with a 340. (stock) According to some books, the pipe was 2 1/4 inch from the head pipe. At the tips in the valance, inlet size at the tip is 1 7/8. (??????????)
Now that you have tti headers, step up to a 2 1/4 inch pipe. 2 1/2 if your running with some power. 3 inch if your racing.