True Duals vs Crossover

[ZombieWeinerDog]

what are the pro's and cons of each. wats the real difference?

[lax54650]

from my research here and other places an h or x crossover will provide more low end torque. the x pipe is a little harder to instal but provides a little better scavenging than the h pipe. basicly what is happening is you are combining both sides of the engine so when one cylinder is exhausting its pressure wave will be passing thru the x as another cylinder on the other bank is just starting to exhaust. pulling that cylinders exhaust along with it. thus creating "vacume" or suction in the overlap between exhaust and intake in the cylinder.

[ZombieWeinerDog]

Originally Posted by lax54650

from my research here and other places an h or x crossover will provide more low end torque. the x pipe is a little harder to instal but provides a little better scavenging than the h pipe. basicly what is happening is you are combining both sides of the engine so when one cylinder is exhausting its pressure wave will be passing thru the x as another cylinder on the other bank is just starting to exhaust. pulling that cylinders exhaust along with it. thus creating "vacume" or suction in the overlap between exhaust and intake in the cylinder.

thanks for the info

[Skirkpat]

On a 2800 pound drag car, a little. On your engine in your heavy truck, nothing but cost.

Do yourself a favor and put the cheapest, decent exaust you can on it. And bigger is not better. A small displacement, relatively mild engine needs backpressure to run efficiantly, Your airflow issues will originate in the heads, not the exaust. Now if you plan on stepping up to ported polished Edelbrocks, or Dart heads, with a high lift cam, heavy springs, stroker crank Blah,Blah,Blah, then you can worry about the exaust.

[fine69]

Originally Posted by Skirkpat

On a 2800 pound drag car, a little. On your engine in your heavy truck, nothing but cost.

Do yourself a favor and put the cheapest, decent exaust you can on it. And bigger is not better. A small displacement, relatively mild engine needs backpressure to run efficiantly, Your airflow issues will originate in the heads, not the exaust. Now if you plan on stepping up to ported polished Edelbrocks, or Dart heads, with a high lift cam, heavy springs, stroker crank Blah,Blah,Blah, then you can worry about the exaust.

^
what he said.

[lilred67]

the x or h pipe will help will noise( popping).makes a smoother melow sound. it can still be loud just not as much popping. that's why i run an h pipe on my trucks.

[big mike71]

Originally Posted by lilred67

the x or h pipe will help will noise( popping).makes a smoother melow sound. it can still be loud just not as much popping. that's why i run an h pipe on my trucks.

That's how I ran mine

[Hart_Rod]

Originally Posted by Skirkpat

On a 2800 pound drag car, a little. On your engine in your heavy truck, nothing but cost.

Do yourself a favor and put the cheapest, decent exaust you can on it. And bigger is not better. A small displacement, relatively mild engine needs backpressure to run efficiantly, Your airflow issues will originate in the heads, not the exaust. Now if you plan on stepping up to ported polished Edelbrocks, or Dart heads, with a high lift cam, heavy springs, stroker crank Blah,Blah,Blah, then you can worry about the exaust.

Does this apply to newer engines? I've got a 5.3 with a supercharger.

[Skirkpat]

Originally Posted by Hart_Rod

Does this apply to newer engines? I've got a 5.3 with a supercharger.

The newer LS heads flow MUCH better than the old SBC heads. Add some forced induction and you probably would gain power with a larger/modified exaust system, and low end torque with a croosover of some type. Alot of people believe that the bgger your exaust, the faster you get air out, this is true to a certain point,eventually you get to a point where you lose enough volocity that it starts to hurt performance.

I think of it like this, put a spitball ( small ball of paper soaked in spit )in a coffee stirrer, you cannot blow it out,just sticks in there.

now put it in a piece off one inch pipe, same thing the spitball sits there or barely moves as you blow,

Now get a softdrink straw, blow and watch it fly across th room and stick on the wall!!! You have an efficient way of moving it. Size is very important not too big , not to small.

[69 COPO]

I am restoring a 71 pickup and trying to keep it as original as possible. I think the 350 4-wheel drives came with single exhaust. Does anyone know if that is correct and if it would be a mistake to put single instead of duals on it? Thanks

[Hoffman65burb]

Originally Posted by Skirkpat

I think of it like this, put a spitball ( small ball of paper soaked in spit )in a coffee stirrer, you cannot blow it out,just sticks in there.

now put it in a piece off one inch pipe, same thing the spitball sits there or barely moves as you blow,

Now get a softdrink straw, blow and watch it fly across th room and stick on the wall!!! You have an efficient way of moving it. Size is very important not too big , not to small.

Thats an awsome way to explain it

[LuckyHenriksen]

I added the X to mine and the sound got so much better, not really more quiet just smoother

[ZombieWeinerDog]

here are my flowmasters:

YouTube - Most amazing 72 chevy ever. Flowmaster...

[special-K]

Originally Posted by 69 COPO

I am restoring a 71 pickup and trying to keep it as original as possible. I think the 350 4-wheel drives came with single exhaust. Does anyone know if that is correct and if it would be a mistake to put single instead of duals on it? Thanks

Yes,only big block trucks came with dual factory exhaust.But,I like duals exhaust with V-design motoes...just makes sense to me.One pipe per bank.

A system that runs one pipe from each cylinder back that run seperately to their exits,with or w/o a crossover,is a true dual system.What wouldn`t be a true dual system would be one that at some point runs into a single pipe and then back into two.Or on an inline,starting as a single then splitting into two.A true dual system on an inline would be a split header with 1/2 the ports into one pipe and the other 1/2 into the other.
I`ve never run crossovers and never knew I was missing anything.

[mrein3]

To further the discussion, you may want to consider leaving your factory exhaust manifolds on. Headers may hurt the scavenging effect of the exhaust flow. (Once again unless you plan on stepping up to ported polished Edelbrocks, or Dart heads, with a high lift cam, heavy springs, stroker crank Blah,Blah,Blah)

If you must run headers, wrap the heck out of them to keep the heat in there.

The Heartthrob Exhaust dual kit sold through LMC is a good bang for the buck, low cost system and it bolts right to your factory manifolds. Google Heartthrob Exhaust for more info. The LMC kit is drop shipped right from Heartthrob - at least it was when I bought my exhaust.

[Texasbigblock]

i just love the sound of a crossover compared to "true" duals. Not louder, just deeper and smoother...perfect

[Stocker]

Originally Posted by Skirkpat

Alot of people believe that the bgger your exaust, the faster you get air out, this is true to a certain point,eventually you get to a point where you lose enough volocity that it starts to hurt performance.

Size is very important not too big , not to small.

This pretty well sums it up -- and the reason size is important has to do with velocity, not backpressure. Engines don't require backpressure to run well (try breathing through that straw), but all components need to be designed to work together.

Exhaust gas velocity is the key, which is why size matters. And that's also why headers should be wrapped to retain heat -- a decrease in heat causes the gases to slow down.

[ZombieWeinerDog]

Originally Posted by Stocker

This pretty well sums it up -- and the reason size is important has to do with velocity, not backpressure. Engines don't require backpressure to run well (try breathing through that straw), but all components need to be designed to work together.

Exhaust gas velocity is the key, which is why size matters. And that's also why headers should be wrapped to retain heat -- a decrease in heat causes the gases to slow down.

Npt happening, its a show truck, looks bad

[Stocker]

Understood. In that case, don't even worry about what works best -- just go with whatever shows best!

[Ackattack]

Hot rod magazine did a story a few years ago comparing open headers vs "true" dual vs an H-pipe vs. an X-pipe.

Basically the open headers made the most power but lost a lot of low end torque.

The X-pipe setup had almost the same peak horsepower, but had a lot more low end torque.

I'm running an X-pipe on my truck.

[big mike71]

buy ceramic coated headers they don't put off much more heat than factory manifolds.

[ZombieWeinerDog]

Originally Posted by big mike71

buy ceramic coated headers they don't put off much more heat than factory manifolds.

right now im running corvette stock manifolds, ceramic headers are out of my budget. have about 6 bucks left.

[big mike71]

You can get a nice set of hedmens for less than $300.