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18 vs 32 inch purple hornies

23K views 62 replies 9 participants last post by  454C10 
#1 ·
Ok i have a 350sbc with roughly 400hp give or take a few. i have hooker comp headers and im wandering which length to buy.

the 18inch or the 32 inch. BTW im looking at the ones that bolt up to the header i will not be putting pipes on after the muffler.
 
#53 ·
Let's say you have a big glup in your center consel and you don't feel like picking in up because is a about 1 gallon. So you get a long straw to suck out the life giving soda. If your lips were 15 inches away from the top level of the soda, it would take 15 inches of soda vacuum to get it into your mouth.

If you were in outer space (perfect vacuum) then your vacuum gage would read 29.9" hg or 407" of water. Since hg is much heavier than water it takes more vacuum to pull it a certain distance up a tube.

15" of water is about 1.1" of hg. Not much vacuum.
 
#55 ·
Vacuum is the absence of pressure. So yes, you can have vacuum without atmospheric pressure. However, if you live on a planet with no atmosphere then vacuum would be atmosphere pressure.

Yes, soda would shoot into your lungs but your lungs would explode not implode.

And since sound doesn't travel in a vacuum. Glasspacks would be very quiet in a vacuum.
 
#57 ·
You got it.

They make a consistent pressure differential across the muffler and measure the flow. The more air that goes through, the less restrictive the muffler is.

In this case, they are sucking air through the muffler. The vacuum pump speed is increased until a certain pressure differential is created across the muffler and then they measure the flow.
 
#58 ·
ok so they tested 2 1/4 inch louvered glass packs. how long where they???

also on that web page the test results for straight pipes...

2 1/2 inches 521 cfm
2 1/4 inches 365 cfm
2 inches 283 cfm

so from 2 inches to 2 1/2 inches it nearly doubled with just a 1/2 inch. so what might the flow be for 3 inch louvered glass packs??? it must be far better then the 2 1/4 inch ones.
 
#59 ·
Yes the 3 inch will flow better but the extra length (32 inch versus 18 inch) will cancel out a lot of the flow improvement gained from the extra diameter.

3" pipe has 180% more cross section than a 2-1/4 pipe but 32 inches just happens to be 180% longer than 18 inches. So there should be no flow difference between a 32 inch long, 3 inch diameter hornie and a 18 inch long, 2-1/4 diameter hornie.
 
#60 ·
15" of water refers to how they measure the vacuum. It's a vacuum that's strong enough to lift water 15" up a tube. Imagine putting a 6-foot clear rigid plastic tube on a vacuum cleaner and sticking the tube straight down into a bucket of water while the thing's running. If it sucks the water up 15" higher than the level of water in the bucket, that's the strength of vacuum they used. The "Hg refers to how far it'll suck mercury up a tube. The whole stinkin thing's kinda confusing, like measuring power in horsepower vs kilowatts.

Conversion: 1.5"Hg = 20.4"H2O = 0.74psi

But just in case anybody's curious, glasspacks actually are quite a bit quieter under water, with sort of a burbling sound. Can't say how they performed though, what with the wet tires and the resistance caused by water up to the stinkin doors, but the sound was kinda cool.
 
#61 ·
1970Chevy said:
Hey does anybody know what would happen if one were to only run resonators and no muffler. I know that on luxery cars there is a muffler Plus a resonator, thus a very muffled and quiet sound. I would think that the resonator doesnt do as much murdering of sound that a muffler does. I also take into consideration the tone of the sound produced, and Im assuming that depends on the volume of the resonator chamber.
slp has the loudmouth resanator exhaust system for camaros etc .....some resonators look like a perforated core glasspack(tips) but arent the resonators found in the exhaust system upstream of the exit just hollow like an expansion chamber ? ........I have an old set of "glasspacks" that appear to have 2 tubes in them :confused: ........that I'm going to cutapart and make resonators out of
Shane
 
#62 ·
I have used dynomax bullets as a resonators with great results. They also have perforated tube design and they don't cost much. They flow also like a straight pipe.

Recently I install dual 12" dynomax mufflers in a very ugly sounding exhaust that would resonate so badly you would think the exhaust was dumping in the cab. After the two little dynomax's, it sounded almost like stock exhaust with no flow penalty.
 
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