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79C10 10-06-2007 10:10 PM

Dual or single exhaust???????
 
Hey guys---
I just finished dropping a new crate 350 into my 79 C20 work truck. I slapped an Edelbrock RPM manifold and a 600 cfm 4 bbl on it , otherwise , it is stock . ( chrome valve covers and dress up stuff , but nothin that'll add HP )
I was thinking about leaving the stock exhaust manifolds and running dual exhaust , or possibly just putting on a flomaster on the single pipe...... or switching out to headers and dual flomasters .
What do you think will work best for torque and why?

thanks for your tips and advice , , and keep America smokin'!

Lord_Hate 10-06-2007 11:46 PM

Dual exhaust is always best, less back pressure. The reason you want the least back pressure, is because gases like to move into the space with the least pressure. Hence why gas rushes out of cylinders when you open them.

curtis73 10-07-2007 04:27 AM

I would always suggest headers. Even though its not a really hot engine, stock manifolds suck.

I do have to slightly disagree with Lord_Hate, more is not better. Proper is better. Too much exhaust kills exhaust velocity which is what helps to fill the cylinders.

A dual 2.25" would be quite sufficient without killing the scavenging effect. A single 3" would do well also.

racer rick 10-07-2007 08:12 AM

i have to agree with curtis73. to much exh will kill engine performace in mileage .headers and duels are good.it depends onwhat your looking for .single exh will be queiter and smoother sounding.

Lord_Hate 10-07-2007 09:43 AM

Quote:

Originally Posted by curtis73
I would always suggest headers. Even though its not a really hot engine, stock manifolds suck.

I do have to slightly disagree with Lord_Hate, more is not better. Proper is better. Too much exhaust kills exhaust velocity which is what helps to fill the cylinders.

A dual 2.25" would be quite sufficient without killing the scavenging effect. A single 3" would do well also.

Your totally right, I didn't even address the exhaust diameter.
BTW for forced induction, bigger is better.

curtis73 10-07-2007 01:57 PM

Yeah... nothing like the sick sound of a turbo whistling at idle out of twin 3" pipes :evil:

Lord_Hate 10-07-2007 06:12 PM

Quote:

Originally Posted by curtis73
Yeah... nothing like the sick sound of a turbo whistling at idle out of twin 3" pipes :evil:

LOL reminds me of the city bus. When I'm on the bus, sometimes I'll listen for it.

oldbogie 10-08-2007 10:07 AM

Quote:

Originally Posted by 79C10
Hey guys---
I just finished dropping a new crate 350 into my 79 C20 work truck. I slapped an Edelbrock RPM manifold and a 600 cfm 4 bbl on it , otherwise , it is stock . ( chrome valve covers and dress up stuff , but nothin that'll add HP )
I was thinking about leaving the stock exhaust manifolds and running dual exhaust , or possibly just putting on a flomaster on the single pipe...... or switching out to headers and dual flomasters .
What do you think will work best for torque and why?

thanks for your tips and advice , , and keep America smokin'!

Ya know, every-time I run the Rocket Science to get numbers that justify putting duals on a mild V8, the numbers never say this is just something ya gotta do. Yet every-time I bolted on the hardware, even with OEM manifolds the engine responded with more available power and better fuel economy. So I guess doin' the arithmetic isn't the "end-all, be-all" of answers, just put some duals on it.

I haven't had the same success with 3 inch singles as with duals on mild street engines either. I think that space constraints tend to keep the head pipes too small with excessive turns and poor merging shapes especially where they form the common exit. There may be gains to be had with more streamline shapes where the pipes merge but available space generally prohibits getting the contours and distances needed to bring the head pipes elegantly together. Duals seem to easily get around this problem, which is probably their advantage in power and economy compared to even quite large single systems on a street driven vehicle.

Bogie


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