Dual Exhaust

[Orange Beezy]

On an exhaust system(dual) should there be a cross pipe somewhere between the manifolds and the mufflers?

[BobbyFord]

Yes, here's an article from CarCraft...
http://www.carcraft.com/techarticles/ex ... index.html

[hotrodfeguy]

What has me scratching my head is why not run 3" all the way? I saw the article but makes no sense, to step down to 2 1/2 then back to 3" Maybe they have found a new trick but sounds wierd to me.

[bb429power]

Well, you don't need to combine them at all. The only reason for that is to balance the exhaust flow which adds a little power. Narrowing it can add low end torque and its only a quick reduction and right back to normal size. You don't need to do either, it should be perfectly fine without doing so as it is just something "extra" to add to the power but not by much. They are called flow enhancers. This is the quick reduction that I was talking about.
http://www.summitracing.com/parts/CCI-PSBI350/

[DuckRyder]

I suspect that the smaller pipe up front keeps the velocity up, it is quite possible to have the exhaust too large.

If you have some room, you can paint the pipes and give it a good hard run (a dyno would be perfect) and where the paint stops burning off is a good spot for the X or H.

an X or H will also change the sound...

[hotrodfeguy]

Well I had always believed that size changes disrupt flow. But I guess not.

[cdeal28078]

It is said the X or H pipe add power or torque at certain speeds. I can't speak on the pipes getting smaller or whatever. I will say that on my 71 F100 I like have true duels. I like the sound mainly. Especially when you have a bit of a load on her and are just cruising, let her lug just a bit and you can hear that bump, bump, bump from each pipe. Hard to describe but I bet some of the older fellows know what I am talking about.
Too me with a cross over it almost sounds just like every other truck out there with Flow masters on them.
Also, check out the Hooker Aero-Chambers or some Magna-Flows before dropping money on Flows. Car craft did a muffler flow test years ago also. Don't have a link to it though
clint

[BobbyFord]

Flowmaster mufflers have been dyno-proven to decrease HP.

[Orange Beezy]

Ok thanks for all the info. I'll do some research from the articles you've suggested and go from there.

[TrikeKid]

What has me scratching my head is why not run 3" all the way? I saw the article but makes no sense, to step down to 2 1/2 then back to 3" Maybe they have found a new trick but sounds wierd to me.

From the CC article

We left the car at Magnaflow for about a week, and when we came back we found that after some preliminary testing, the guys had built a really trick system consisting of 2-½-inch tubing from the header collectors into the X-pipe, 3-inch out of the X flaring into 3½-inch tubing running for about 26 inches before necking back down into a pair of 3-inch mufflers with turn-downs. The theory behind this design is that it will keep the velocity of the exhaust gases moving quickly through the headers into the X-pipe to maximize the scavenging effect, while the larger-diameter tubing ahead of the mufflers prevents the gasses from stacking up as they pass through the mufflers to avoid excessive backpressure in the system.