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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.
 
#27 ·
elcaminodragster said:
i wanted to get the bullets but after talking to my dad he didnt want to me be that loud so i got the next ones on my list. ive done a bit of researching and purple hornies dont flow all that bad yes there are far better mufflers. but im not going for super performance... not yet anyway. once the hornies start to blow out ill buy the bullets. its like my mom said "you gotta slowly warm up dad to the really loud exhaust" so its like a compromise really. i settled for something quieter. and once these are crap im buying the bullets.

my purple hornies will be here on monday!!! YAY!!! lol :p
after you run them and get them hot you can run water with a water hose up the pipes and crack the glass to make them loud or a lil atf smokes for a while but burns the glass out quicker
Shane
 
#28 ·
well i hooked up the hornies and on the passenger side it just barely clears the tranny cross member. well i gotta tell ya im not all that impressed at how they sound. they sound good an all but not what i was lookin for. and its not much louder then my 40s at all. not sure about performance yet coz i havent taking it on the road i still need to worm out my old pipes. ill have the sound clip up that i was talking about later today.
 
#30 ·
well after listen to them for a bit i started to really hear them. before is was more thinking of how to keep it from hitting the cross member so i didnt pay to much attention to the sound. but after listening to them they sound just like open headers only quieter not by much tho. im really loving the way they sound! and i have no clue where ppl are saying they dont flow well. there is very VERY little back pressure. i know this because when you have open headers your driven down the road and you let off the gas it starts to pop and crackle well the hornies are doing exactly that! plus if they flowed poorly how would i hear the sound of open headers??? so to all that say they flow poorly i dont believe it not one little bit! im not calling anyone liers but i just dont see nor hear them flowing poorly. i could not get a sound clip up yesterday but i am going to get a clip here in just a few min. and i gotta tell you the performance is awesome! nothing big but it is noticeable.
 
#32 ·
Just because a muffler sounds loud doesn't it mean it flows well. It can also mean it is a low quality muffler makes a bunch of back pressure and doesn't muffle sound very well. furthermore, a loud sounding engine can seem faster when it really isn't.

Did you look at the web site that I listed before?

For example:

2-1/4 glass pack flows 133 cfm and is loud as hell

2-1/4 stock OEM muffler flows at 149 cfm and is very very quiet.

2-1/2 dynomax super turbo flows 268 cfm and is also very quiet.

So which is the better muffler?

A loudass flowmaster doesn't even flow as much as a quiet dynomax super turbo.

So in theory, if you use dual 2-1/4 glasspacks for a total of 266 cfm, it would have enough flow for a 120 hp engine (2.2 cfm/hp for zero loss). That is, after 120hp, the dual glass packs start killing power. Twin dynomax's start losing power after 240hp.
 
#33 ·
454C10 said:
Just because a muffler sounds loud doesn't it mean it flows well. It can also mean it is a low quality muffler makes a bunch of back pressure and doesn't muffle sound very well. furthermore, a loud sounding engine can seem faster when it really isn't.

Did you look at the web site that I listed before?

For example:

2-1/4 glass pack flows 133 cfm and is loud as hell

2-1/4 stock OEM muffler flows at 149 cfm and is very very quiet.

2-1/2 dynomax super turbo flows 268 cfm and is also very quiet.

So which is the better muffler?

A loudass flowmaster doesn't even flow as much as a quiet dynomax super turbo.

So in theory, if you use dual 2-1/4 glasspacks for a total of 266 cfm, it would have enough flow for a 120 hp engine (2.2 cfm/hp for zero loss). That is, after 120hp, the dual glass packs start killing power. Twin dynomax's start losing power after 240hp.

what would the cfm be for a 3" louvered glass pack??? from that test to my hornies is a 3/4" difference that alone has to make a good increase. also how long are the glass packs they tested and what brand??? yes you lose hp with more back pressure but you gain torque. because back pressure creates torque correct??? and more torque on the street is a very good thing to have. but to be to restrictive is a bad thing and i understand that.

454C10 said:
furthermore, a loud sounding engine can seem faster when it really isn't.
i know that very well look at all of the rice burners!
 
#34 ·
i know for a fact that the ppl across the street from me arent happy about it at all the hated my flows but they never said anything. i bought a tubing kit from jegs. and it came for it to be set up that way but the tail pipes didnt work so i had a local shop weld some on for me. so what you saying is having the muffler right before the axle and then having it jump over the axle into tail pipes is bad for flow???
 
#35 ·
i know this doesnt have anything to do with the hornies, but ive run a lot of glasspacks and i go more for the sound than the flow, i just never really cared for a long time, but anyways, i got a chevy with a 350 and burn out glass packs that hook right up the header flanges with a turnout right after the cab and u get that real ratty rippin kinda sound, the best way i can explain it is like the opposite of a deep throaty kinda sound. I have the exact opposite with the dodge i got, i got 3 inch straight pipe coming off the headers that runs into 4 1/2 inch stacks (no mufflers) and thats just a sweet sound, the closest thing ive heard is late models running on a dirt track. its just a wide open, big horse power kinda sound. but it is hooked up to a lil 318 so thats kinda gay and gets funny looks, but hell. i just like to be as loud as possible, and its kinda funny to have the exhaust fumes thrown in the drive through window at mcdonalds. anyways, just throwing my 2 cents out there
 
#38 ·
ya im really starting to love the way they sound. this morning i went for a job interview at 730-800am something like that and when its really quiet out that early in the morning you really get to hear just how loud they are. the drive there i had to get on the freeway and its not a deep rumble but you hear in screaming in your head the whole drive :evil: :evil: :evil: :evil: ! i got home and my ears where ringing just enough that it put a smile to my face ear to ear :D . of course it will get quieter once i put carpet in with insulation but thats not gonna happen for a few more weeks. so until then if i gotta drive more then 10min im bringing ear plugs!

the last pic shows my interior a little bit
 

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#40 ·
Chevrolet4x4s said:
deffinately dont want ears ringing.....being able to hear your nice sounding slightly quiter hotrod is better than sonding good and loud but not being able to hear it........im not saying make it quiter just make sure you wear hearing protection.
Shane

the main reason i hear it so much inside the cab is because i dont have carpet or insulation. check out my photo album. i need to fab up the bracket for the passenger seat before i do the carpet.
 
#42 ·
Chevrolet4x4s said:
yeah i saw that i was just encouraging the ear plug usage the insulation will lower the incab dBs quite a bit

i havent even had them a full 2 days yet and im really wanting the insulation lol. i wanted loud and i got it. funny i wanted to hear it loud now i dont wanna hear it lol. i love it tho!!! boy do i LOVE IT :evil: :evil: :evil:
 
#43 ·
elcaminodragster said:
back pressure creates torque correct???
QUOTE]

Nope, that's just a fable. If more back pressure created more torque, bulldozers would exhale through soda straws. The only time more back pressure gives you more torque is when the fuel mixture is not calibrated correctly for the extra air flow that happened when you freed up the exhaust system.

Glasspacks with louvers (or other internal projections) are restrictive because the louvers not only decrease the diameter of the internal flow path, but they cause turbulence that effectively reduces flow even more. If you want a non-restrictive glasspack, look at the Thrush Magnum. No louvers, just smoothly punched holes, and an internal flow tube that's probably larger than the rest started with in the first place. Longer glasspacks will be generally quieter, but they'll still have that blat on deceleration that some folks are so fond of.
 
#44 ·
jimfulco said:
elcaminodragster said:
back pressure creates torque correct???
QUOTE]

Nope, that's just a fable. If more back pressure created more torque, bulldozers would exhale through soda straws. The only time more back pressure gives you more torque is when the fuel mixture is not calibrated correctly for the extra air flow that happened when you freed up the exhaust system.

Glasspacks with louvers (or other internal projections) are restrictive because the louvers not only decrease the diameter of the internal flow path, but they cause turbulence that effectively reduces flow even more. If you want a non-restrictive glasspack, look at the Thrush Magnum. No louvers, just smoothly punched holes, and an internal flow tube that's probably larger than the rest started with in the first place. Longer glasspacks will be generally quieter, but they'll still have that blat on deceleration that some folks are so fond of.

ok so the whole back pressure creating torque is a bs thing just like open full length headers warping valves. i got ya thanks for setting me straight :thumbup: . for the street tho the purples and good enough tho right??? im not going for serious performance. i think once these blow out im gonna go for the sleeper sound and performance.
 
#45 ·
Hmmm...

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.
 
#46 ·
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.

a resonator is just another name for muffler it helps newer cars be quieter. not sure about flow, power, or sound tho.
 
#47 ·
454C10 said:
Louvered glass packs flow very poorly. And Purple Hornie's are louvered.

A Dynomax Bullet would be a better choice. It is a perforated tube design and flows almost like a straight pipe.

http://www.broaderperformance.com/muffler_flow_tests.htm

i found out that the tests they did were under watter. so its not all that accurate really. for 1 the fiberglass would soak up water and 2 water clings to the metal just enough. poor water on your car and it will bead up. breath on your car it bounces off. im not trying to be a smart ***** here but those test to me dont seem all that accurate.
 
#48 · (Edited)
Did it say something like 15" of water or 20" or 28"? That's most likely a reference to how much pressure (or vacuum) was used to force the air through the muffler. More pressure will force more air through per unit of time. Vacuum is just negative pressure, and it's generally measured in inches of water ("H2O) or inches of mercury ("Hg), kinda like barometric pressure on the weather report.

You'll probably see different flow rates out there for the same muffler, and it's probably due to different pressures used. There's not really any standardization in the industry, and until there is, there's always going to be some confusion.

Same deal for carburetor flow rates. Fuel injection systems and 4-bbl carbs are rated at 1.5"Hg while 2-bbl carbs are rated at 3"Hg. To add to the confusion, doubling the pressure does NOT double the flow rate, it only increases it by a factor of 1.414, which is the square root of two. So a 500cfm 4-bbl will flow 1.414 times as much air as a 500cfm 2-bbl.

Walker, parent company of Dynomax & Thrush, uses something around 20"H2O, which is pretty close to the same as 1.5"Hg, for their advertised flow rates. Vizard's rule of thumb (2.2cfm/hp) for required exhaust flow was also developed at that pressure.
 
#49 ·
jimfulco said:
Did it say something like 15" of water or 20" or 28"? That's most likely a reference to how much pressure (or vacuum) was used to force the air through the muffler. More pressure will force more air through per unit of time. Vacuum is just negative pressure, and it's generally measured in inches of water ("H2O) or inches of mercury ("Hg), kinda like barometric pressure on the weather report is measured in millimeters of mercury (mmHg).

You'll probably see different flow rates out there for the same muffler, and it's probably due to different pressures used. There's not really any standardization in the industry, and until there is, there's always going to be some confusion.

Same deal for carburetor flow rates. Fuel injection systems and 4-bbl carbs are rated at 1.5"Hg while 2-bbl carbs are rated at 3"Hg. To add to the confusion, doubling the pressure does NOT double the flow rate, it only increases it by a factor of 1.414, which is the square root of two. So a 500cfm 4-bbl will flow 1.414 times as much air as a 500cfm 2-bbl.

Walker, parent company of Dynomax & Thrush, uses something around 20"H2O, which is pretty close to the same as 1.5"Hg, for their advertised flow rates. Vizard's rule of thumb (2.2cfm/hp) for required exhaust flow was also developed at that pressure.
i think it was 18" of water. i still dont understand why the hell they would test a car part under water especially a damn muffler! that makes absolutely no senses.
 
#50 ·
They are not testing under water!!!

and they used 15" of water as the vacuum.

Inches of mercury (hg) or inches of water (h20) is what they use to measure vacuum. They are sucking through the muffler at some vacuum level and measuring the flow.

Just like they use pound per square inch (psi) to measure flow rate on a fuel pump. And they aren't putting weights on the fuel pump to measure flow.
 
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