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Quad Exhaust Disc

Ok everyone, I'm sure there has been something posted about quad exhaust disc before. However, I tried something a little different and thought the group might like to hear about it. Instead of removing the plates and installing one plate with a 3/4 inch cutout. I decided to install two plates with 3/4 inch holes offset on the front/back side of the spacer plate. One plate has the hole on top side the other on the bottom side. I also made sure the plate with the hole up top had a small hole (3/16) on the lower side for water to pass through as I noticed some water buildup when I removed the stock plates. This has really improved the sound quality off throttle IMO. Sorry I didn't take any pictures before I installed the plates.

Chris
 
I'm not quite following you. Did you end up with more or less open area than just using one 3/4" disc? A friend of mine has 3/4 in his Boss and I have 7/8 and there's a noticeable difference in sound. I do not want my car any louder than it is driving around town, I also have GT500 mufflers, but will take out the discs for my next track day.
 
I understand what he did, I can MS paint it ;D Trying to stop the waves going back up to prevent the jake brake noise. Similar to the crooked tube idea I mentioned a while back but would cause more back pressure.
 
I'm eventually going to fab the crooked tube design and see if it works, though with TK it is not nearly as bad as it was before. If it allowed full engine braking I don't think it would be an issue at all anymore.
 
5 DOT 0 said:
I'm not quite following you. Did you end up with more or less open area than just using one 3/4" disc? A friend of mine has 3/4 in his Boss and I have 7/8 and there's a noticeable difference in sound. I do not want my car any louder than it is driving around town, I also have GT500 mufflers, but will take out the discs for my next track day.

The open area is the same as the factory spacer plate, which is about 1/2 thick separates the two plates. This just limits the jake brake noise as CaliMR stated. I wanted a smoother sound without changing the db level over just one plate. Just by ear, I would say to keep the same sound level you may need to increase the diameter by 1/8 inch or so over just one plate. Two plates reduce the sound level just a little. Enough that when I remove the plates for the track I am going to increase the size by 1/8 inch to 7/8. This will most likely increase backpressure, but not enough to matter as the factory exhaust system flows well IMO.
 
5 DOT 0 said:
I'm slow and missed the part on either side of the spacer. I got it now. So it sounds different than just one disc? I have a set of 3/4 and 7/8 so I could try it.

One of the key factors to my design is the offset holes. However, I'm thinking that a 7/8 followed by the 3/4 plate may produce similar effects and would be easy to try. If you decide to try it, let me know what you think. I'm always trying new things.
 
This is basically what we came up with, to minimize back pressure but still prevent the waves from coming back up. Eventually I will fab a set up but I have been lazy since it has been raining. It would in theory also allow a large opening so you could almost match the no-baffle sound level without the JB noise. I'm also not sure I want it that loud all the time.

baffle.jpg
 
CaliMR said:
This is basically what we came up with, to minimize back pressure but still prevent the waves from coming back up. Eventually I will fab a set up but I have been lazy since it has been raining. It would in theory also allow a large opening so you could almost match the no-baffle sound level without the JB noise. I'm also not sure I want it that loud all the time.

baffle.jpg

Dang it, something else to try! Looks like I may need to polish my welding skills for this one.
 
You can do the baffle on the other side so the tube goes through the spacer, if you don't make the tube too wide. I was going to measure how much straight section there is after the joint and try to figure out how big I can go and still have room for the tube to offset, but it has been raining. I think a 1 or 1 1/8" ID tube would be right about how I would want it, a little louder than the 7/8 I have now but not too much. Your solution is a lot easier to implement though, so I might go with that. Especially since it would be easier to keep cutting the holes bigger to get the right sound rather than cutting and welding new tubes. The key is having the upstream hole centered and the downstream hole as close to the edge as possible. My bro came up with the tube idea, and he is kind of an expert on sound wave manipulation and has a bunch of patents on tube based amplifiers and speaker coils.



I just talked to my bro, he says it should be like in the picture and not go through the spacer, since the tube has to be sticking 3 or 4 inches out into the pipe anyways as the overlap is what will prevent the waves from going back in.
 
113
0
I don't have my car yet, so this may sound like a stupid question. So you're saying that if I install restrictor plates with larger holes that I will get a jake brake sound on deceleration? I'm not liking that idea at all.
 

Justin

Save the dawn for your dishes!!!
JonW said:
I don't have my car yet, so this may sound like a stupid question. So you're saying that if I install restrictor plates with larger holes that I will get a jake brake sound on deceleration? I'm not liking that idea at all.
from what I have read only on holes bigger than 3/4" I have 3/4" on my boss and it doesnt J-brake for me. just a hint of pop pop pop on decel hard to describe its a crackle crackle crackle sound lol if your in va beach I will take you for a ride videos dont capture the sound right lol
 
Tflong24 said:
O M G!!!!!!!!!!!!

Tom, you should come over sometime a check out the sound quality. Its like a two block drive. The sound quality is much improved. BTW, Wray Ford installed TracKey Today. They are still looking into the clutch issue. I should get the Boss back Wednesday.

Chris
 
JonW said:
I don't have my car yet, so this may sound like a stupid question. So you're saying that if I install restrictor plates with larger holes that I will get a jake brake sound on deceleration? I'm not liking that idea at all.

The way I hear it the Jake Brake sound is not that bad until you reach the point of the engine braking working to slow the car and the RPM's are lower then the car's speed to help it slow. At that point I feel the sound is not desirable and as stated the 3/4 and below really cut that sound out, especially when using 1/2 and 5/8. The bigger discs like the 7/8 and 1 inch cut the Jake sound down but it is still there. It comes down to personal taste, some like the sound and it is not a bad thing, I happen to feel (like some others) that this sound just does not fit the Boss.

The Jake Brake sound is only one part of what the discs do. There is also tuning the sound because some do not like the car too loud or too quite, I personally like to hear the exhaust but without it drowning out the sweet music the engine makes when I power off a corner.

In the end hats off to the engineers for giving us all the ability to personalize the sound of out cars with such an easy mod. At the track this weekend there were three Bosses, open, 7/8 and 5/8 and each sounded like a different car.
 

Justin

Save the dawn for your dishes!!!
HackBoss302 said:
Tflong24 said:
O M G!!!!!!!!!!!!

Tom, you should come over sometime a check out the sound quality. Its like a two block drive. The sound quality is much improved. BTW, Wray Ford installed TracKey Today. They are still looking into the clutch issue. I should get the Boss back Wednesday.

Chris
is your clutch issue that it will get super stiff sometimes and returns to the top of the travel really slow? mine will do that randomly.
 
2012YellowBoss said:
The way I hear it the Jake Brake sound is not that bad until you reach the point of the engine braking working to slow the car and the RPM's are lower then the car's speed to help it slow. At that point I feel the sound is not desirable and as stated the 3/4 and below really cut that sound out, especially when using 1/2 and 5/8. The bigger discs like the 7/8 and 1 inch cut the Jake sound down but it is still there. It comes down to personal taste, some like the sound and it is not a bad thing, I happen to feel (like some others) that this sound just does not fit the Boss.
Are you saying the jake brake sound does or does not fit the Boss?
 
5 DOT 0 said:
2012YellowBoss said:
The way I hear it the Jake Brake sound is not that bad until you reach the point of the engine braking working to slow the car and the RPM's are lower then the car's speed to help it slow. At that point I feel the sound is not desirable and as stated the 3/4 and below really cut that sound out, especially when using 1/2 and 5/8. The bigger discs like the 7/8 and 1 inch cut the Jake sound down but it is still there. It comes down to personal taste, some like the sound and it is not a bad thing, I happen to feel (like some others) that this sound just does not fit the Boss.
Are you saying the jake brake sound does or does not fit the Boss?

Thanks, I fixed that by adding "not".
 
2012YellowBoss said:
JonW said:
I don't have my car yet, so this may sound like a stupid question. So you're saying that if I install restrictor plates with larger holes that I will get a jake brake sound on deceleration? I'm not liking that idea at all.

The way I hear it the Jake Brake sound is not that bad until you reach the point of the engine braking working to slow the car and the RPM's are lower then the car's speed to help it slow. At that point I feel the sound is not desirable and as stated the 3/4 and below really cut that sound out, especially when using 1/2 and 5/8. The bigger discs like the 7/8 and 1 inch cut the Jake sound down but it is still there. It comes down to personal taste, some like the sound and it is not a bad thing, I happen to feel (like some others) that this sound just does not fit the Boss.

The Jake Brake sound is only one part of what the discs do. There is also tuning the sound because some do not like the car too loud or too quite, I personally like to hear the exhaust but without it drowning out the sweet music the engine makes when I power off a corner.

In the end hats off to the engineers for giving us all the ability to personalize the sound of out cars with such an easy mod. At the track this weekend there were three Bosses, open, 7/8 and 5/8 and each sounded like a different car.

I got the opposite impression, it seems like the way they phase the cams to prevent engine braking is what causes the JB. Especially since it got less severe with TK installed which allows more engine braking, but either this car has the heaviest flywheel around or it is still limiting it quite a bit. The throttle hang, slow response and decreased engine braking are probably all from the tune, which even with the TK doesn't seem that aggressive.
 

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