Supr_Vlln
Viper Owner
On April 5th, the SoCal Club had a Dyno Day at Stack Performance in Anaheim, CA. Ryan and his team were very gracious hosts and took good care of us and our cars...not to mention fed us some yummy burgers! A big thank you to them for supporting us! And of course, Dan and Cathy worked their usual magic "herding cats" to organize this event. Hats off and thanks to them!
In addition to just a Dyno Day, I wanted to add a bonus and shoot some video and measure sound levels to help answer some age old questions about exhaust systems. We’ve all seen the posts…”What kind of exhaust should I get?”, “Should I get headers?”, “What will it sound like?”, “How loud will it be?”
I hope that this video will help as an initial reference point for some of those questions. I kept it focused on just Gen 3 and 4 to make it easy on me. I wished there was more variety in the setups, but it just means we need more people in the club to MOD!
VIDEO Part 1 of 2
(exhaust video comes in right after the photo slide show at about 2:09 mins)
[media]http://www.youtube.com/watch?v=p6plghgsJcg[/media]
VIDEO Part 2 of 2
(we even had a non-Viper guest car at the end Its okay he's got a Gen 4 ACR too
)
[media]http://www.youtube.com/watch?v=PwRZEG9PVf4[/media]
Lets hope youtube doesn't screw with the videos because of the little bit of music at the beginning and end. Otherwise I'll have to re-post them somewhere else.
NUMBERS GAME
A little note about dyno numbers...don't get too hung up on the numbers. You cannot really go around comparing dyno numbers unless they were all taken on the same dyno. This is because every dyno is different as well as the conditions during which they are run. Even among the same brand, the readings can be different. This one will cook your noodle...at Stack Performance my car dyno'd 489 HP. A week later I dyno'd the car at DC Performance in West LA and it registered 472 HP. Both dynos were the same type- Dyno Jet. So did I suddenly lose 17 HP? Nope! Just proves my point…different dynos read differently.
Now don’t get me wrong, its always fun to see what your car will dyno at and since each dyno is different, it is sort of a guess every time…kinda like Keno, only not as fun. But at least you won’t be surrounded by blue haired, chain smoking, old ladies screaming “Keno!”
EXHAUST NOTES
The sound quality of an exhaust system is subjective and dependant on each individual’s tastes. But to help answer how loud will it be, the sound level meter helps quantify that into terms most everyone can relate to. In this case, the sound is measured in decibels and it is expressed as a unit of dB or dBA to show the “A” weighting which closely relates to human hearing. It is also important to note that decibel units are exponential as the numbers go up. For example, a sound that is 60 dBA is TWICE as loud as a sound that is 50 dBA.
A 1 dBA difference is practically imperceptible to human hearing. In other words, we can’t tell the difference between 70 dBA and 71 dBA. At about a 3 dBA difference, we start to notice a slight change in sound levels. A 5 dBA difference is definitely noticeable. A 10 dBA difference is perceived as twice as loud between two sounds.
To help better illustrate this and to provide a reference point here are some sound comparisons:
(The following list taken from a study by Marshall Chasin)
-A Quiet Library = 30 dB
-People talking in conversation (3’ to 5’ distance) = 60-70 dB
-Phone dial tone (held right up to your ear) = 80 dB
-City Traffic (inside car) = 85 dB
-Train Whistle at 500’ = 90 dB
-Snowmobile, Motorcycle = 100 dB
-Power Mower at 3’ = 107 dB
-Power Saw at 3’ = 110 dB
-Sandblasting or Loud Rock Concert = 115 dB
-Jet Engine at 100’ or a Gun Blast = 140 dB
Sustained exposure to sound levels of 90 to 95 dB without hearing protection can result in hearing loss.
As for our Vipers, I was able to baseline a stock Gen 3 and a stock Gen 4 and then a couple of different setups for each. I noted sound levels at cruising, high speed, and then the peak at wide open throttle. In some cases I had to take a weighted average of the sound. Here is what I found:
2004 Gen 3 that is totally stock
Cruising = 77 dBA
High Speed = 84 dBA
WOT = 107 dBA
The exhaust temp at the tips after the dyno run was 308 degrees.
05 and 06 Gen 3 with just 3” Corsa Track mufflers
Cruising = 78 dBA
High Speed = 86 dBA
WOT = 107 dBA
Exhaust tip temp after the dyno run was 369 degrees.
My theory as to why the cars with Corsas were hotter at the tip than the Stock one has to do with the long crossover tube in the stock system. The further the hot exhaust gases have to travel from the engine the more it cools down. This happens not only due to the length of travel, but also with more metal tubing present more of the heat is absorbed like a heat sink. Since the Corsas do away with the crossover tube, the exhaust gases go straight out the sides and stays hotter thereby also helping to maintain hot gas velocity. The stock system retains more of the heat and keeps us nice and toasty inside…if only we lived in Vermont.
Also interesting to note is that the Corsa had the same sound levels as the stock system during cruising and WOT. And they were just a little bit louder at high speed. Though one thing the sound level meter can’t really measure is tone. While the sound levels between the two were similar, the Corsa had a deeper tone than the stock system. The human ear may perceive this as louder even though it really isn’t.
06 Gen 3 with American Racing Headers (1-5/8” X 1-3/4” step design with Swain Tech thermal barrier coating) and Classic Chambered Exhaust’s 3” Cobrapacks 28” body length with packing.
Cruising = 83 dBA
High Speed = 88 dBA
WOT = 113 dBA
Yes, Virgina, headers do make the car louder and No there is no Santa Clause. I’ll be doing a separate write up of this exhaust system and how it came together at another time (soon, I promise!).
08 Gen 4 with stock exhaust
Cruising = 78 dBA
High Speed = 83 dBA
WOT = 107 dBA
Sound levels were pretty much the same as a Stock Gen 3.
08 Gen 4 with Belanger headers and exhaust
Cruising = 80 dBA
High Speed = 88 dBA
WOT = 112 dBA
At WOT and High Speed, definitely louder than stock and on par with the 06 header/exhaust Viper. However at cruising it was only a little louder than stock, but still quieter than the Gen 3 header/exhaust car. Damn VVT!
09 Gen 4 ACR with Belanger headers and stock mufflers
Cruising = 79 dBA
High Speed = 86 dBA
WOT = 112 dBA
This setup is a little quieter at high speed from the Gen 4 with full Belangers. But again the perception of tone plays in here. The Belanger with stock mufflers had a more mellow tone than the full Belanger header/exhaust package which had a deeper tone.
08 Gen 4 with Belanger headers and Corsa Exhaust
Cruising = 79 dBA
High Speed = 87 dBA
WOT = 114 dBA
Sound levels pretty much matched up with the other mod’ed Gen 4’s and just a little louder at WOT. Tone was a little more raspy.
Ford GT
Cruising = 83 dBA
High Speed = 90 dBA
WOT = 111 dBA
Not a Viper, but everybody is going to ask so might as well post the numbers. I don’t know what the setup of the car was. Made some mad power though! At cruising, sound level on par with the mod’ed 06 Gen 3. At high speed, louder than most all. But surprisingly, at WOT about the same as the mod’ed Gen 4s.
Overall it seems that headers have the most effect on the Viper’s loudness (especially at WOT). This does not include heads/cam or supercharger cars. Muffler changes with factory headers are more about heat reduction and changes in exhaust note/tone with little penalty in overall loudness, at least with the Corsas. Muffler changes on cars with headers seem to pay more dividends in terms of power. And between the Corsa, Belanger, Cobrapacks and Stock muffler, sound level loudness were close to the same.
In addition to just a Dyno Day, I wanted to add a bonus and shoot some video and measure sound levels to help answer some age old questions about exhaust systems. We’ve all seen the posts…”What kind of exhaust should I get?”, “Should I get headers?”, “What will it sound like?”, “How loud will it be?”
I hope that this video will help as an initial reference point for some of those questions. I kept it focused on just Gen 3 and 4 to make it easy on me. I wished there was more variety in the setups, but it just means we need more people in the club to MOD!
VIDEO Part 1 of 2
(exhaust video comes in right after the photo slide show at about 2:09 mins)
[media]http://www.youtube.com/watch?v=p6plghgsJcg[/media]
VIDEO Part 2 of 2
(we even had a non-Viper guest car at the end
Its okay he's got a Gen 4 ACR too) [media]http://www.youtube.com/watch?v=PwRZEG9PVf4[/media]
Lets hope youtube doesn't screw with the videos because of the little bit of music at the beginning and end. Otherwise I'll have to re-post them somewhere else.
NUMBERS GAME
A little note about dyno numbers...don't get too hung up on the numbers. You cannot really go around comparing dyno numbers unless they were all taken on the same dyno. This is because every dyno is different as well as the conditions during which they are run. Even among the same brand, the readings can be different. This one will cook your noodle...at Stack Performance my car dyno'd 489 HP. A week later I dyno'd the car at DC Performance in West LA and it registered 472 HP. Both dynos were the same type- Dyno Jet. So did I suddenly lose 17 HP? Nope! Just proves my point…different dynos read differently.
Now don’t get me wrong, its always fun to see what your car will dyno at and since each dyno is different, it is sort of a guess every time…kinda like Keno, only not as fun. But at least you won’t be surrounded by blue haired, chain smoking, old ladies screaming “Keno!”
EXHAUST NOTES
The sound quality of an exhaust system is subjective and dependant on each individual’s tastes. But to help answer how loud will it be, the sound level meter helps quantify that into terms most everyone can relate to. In this case, the sound is measured in decibels and it is expressed as a unit of dB or dBA to show the “A” weighting which closely relates to human hearing. It is also important to note that decibel units are exponential as the numbers go up. For example, a sound that is 60 dBA is TWICE as loud as a sound that is 50 dBA.
A 1 dBA difference is practically imperceptible to human hearing. In other words, we can’t tell the difference between 70 dBA and 71 dBA. At about a 3 dBA difference, we start to notice a slight change in sound levels. A 5 dBA difference is definitely noticeable. A 10 dBA difference is perceived as twice as loud between two sounds.
To help better illustrate this and to provide a reference point here are some sound comparisons:
(The following list taken from a study by Marshall Chasin)
-A Quiet Library = 30 dB
-People talking in conversation (3’ to 5’ distance) = 60-70 dB
-Phone dial tone (held right up to your ear) = 80 dB
-City Traffic (inside car) = 85 dB
-Train Whistle at 500’ = 90 dB
-Snowmobile, Motorcycle = 100 dB
-Power Mower at 3’ = 107 dB
-Power Saw at 3’ = 110 dB
-Sandblasting or Loud Rock Concert = 115 dB
-Jet Engine at 100’ or a Gun Blast = 140 dB
Sustained exposure to sound levels of 90 to 95 dB without hearing protection can result in hearing loss.
As for our Vipers, I was able to baseline a stock Gen 3 and a stock Gen 4 and then a couple of different setups for each. I noted sound levels at cruising, high speed, and then the peak at wide open throttle. In some cases I had to take a weighted average of the sound. Here is what I found:
2004 Gen 3 that is totally stock
Cruising = 77 dBA
High Speed = 84 dBA
WOT = 107 dBA
The exhaust temp at the tips after the dyno run was 308 degrees.
05 and 06 Gen 3 with just 3” Corsa Track mufflers
Cruising = 78 dBA
High Speed = 86 dBA
WOT = 107 dBA
Exhaust tip temp after the dyno run was 369 degrees.
My theory as to why the cars with Corsas were hotter at the tip than the Stock one has to do with the long crossover tube in the stock system. The further the hot exhaust gases have to travel from the engine the more it cools down. This happens not only due to the length of travel, but also with more metal tubing present more of the heat is absorbed like a heat sink. Since the Corsas do away with the crossover tube, the exhaust gases go straight out the sides and stays hotter thereby also helping to maintain hot gas velocity. The stock system retains more of the heat and keeps us nice and toasty inside…if only we lived in Vermont.
Also interesting to note is that the Corsa had the same sound levels as the stock system during cruising and WOT. And they were just a little bit louder at high speed. Though one thing the sound level meter can’t really measure is tone. While the sound levels between the two were similar, the Corsa had a deeper tone than the stock system. The human ear may perceive this as louder even though it really isn’t.
06 Gen 3 with American Racing Headers (1-5/8” X 1-3/4” step design with Swain Tech thermal barrier coating) and Classic Chambered Exhaust’s 3” Cobrapacks 28” body length with packing.
Cruising = 83 dBA
High Speed = 88 dBA
WOT = 113 dBA
Yes, Virgina, headers do make the car louder and No there is no Santa Clause. I’ll be doing a separate write up of this exhaust system and how it came together at another time (soon, I promise!).
08 Gen 4 with stock exhaust
Cruising = 78 dBA
High Speed = 83 dBA
WOT = 107 dBA
Sound levels were pretty much the same as a Stock Gen 3.
08 Gen 4 with Belanger headers and exhaust
Cruising = 80 dBA
High Speed = 88 dBA
WOT = 112 dBA
At WOT and High Speed, definitely louder than stock and on par with the 06 header/exhaust Viper. However at cruising it was only a little louder than stock, but still quieter than the Gen 3 header/exhaust car. Damn VVT!
09 Gen 4 ACR with Belanger headers and stock mufflers
Cruising = 79 dBA
High Speed = 86 dBA
WOT = 112 dBA
This setup is a little quieter at high speed from the Gen 4 with full Belangers. But again the perception of tone plays in here. The Belanger with stock mufflers had a more mellow tone than the full Belanger header/exhaust package which had a deeper tone.
08 Gen 4 with Belanger headers and Corsa Exhaust
Cruising = 79 dBA
High Speed = 87 dBA
WOT = 114 dBA
Sound levels pretty much matched up with the other mod’ed Gen 4’s and just a little louder at WOT. Tone was a little more raspy.
Ford GT
Cruising = 83 dBA
High Speed = 90 dBA
WOT = 111 dBA
Not a Viper, but everybody is going to ask so might as well post the numbers. I don’t know what the setup of the car was. Made some mad power though! At cruising, sound level on par with the mod’ed 06 Gen 3. At high speed, louder than most all. But surprisingly, at WOT about the same as the mod’ed Gen 4s.
Overall it seems that headers have the most effect on the Viper’s loudness (especially at WOT). This does not include heads/cam or supercharger cars. Muffler changes with factory headers are more about heat reduction and changes in exhaust note/tone with little penalty in overall loudness, at least with the Corsas. Muffler changes on cars with headers seem to pay more dividends in terms of power. And between the Corsa, Belanger, Cobrapacks and Stock muffler, sound level loudness were close to the same.
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