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Meeting 90dB Noise with GT350/R

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Going to be dealing with this soon with my 2020 GT500 as Sonoma and Laguna Seca are my closest tracks.

Any additional feedback on one method be the other?

Sounds the like the AWE makes the exhaust mode independent of the drive mode?
 

Bugs

Jim. Avocation: Avoiding Blunt-Force Trauma.
34
63
Exp. Type
HPDE
Exp. Level
20+ Years
Eagle ID
I posted this GT350 noise-mitigation alternative on the Mustang6G site and thought it might be useful for some here as well:

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Here’s another noise management option for GT350 owners heading for Laguna Seca with the 90dB sound restriction.

I’d seen previous GT350 owners reporting that even with their exhausts locked into Quiet mode, they were right at the 90dB limit and occasionally got busted. I wanted some assurance that my 2019 GT350 would remain in compliance during my first visit. Here’s what I wound up doing:

* Removed the rear fascia from the GT350. 3 hr. labor.

* Purchased 2 GrimmSpeed (p/n 07004) Exhaust Valve Simulator plugs. Installed them in the GT350 after placing the exhausts in quiet mode. $30 ea.x 2 = $60

* Installed a 2” x 2.5” dia. straight extension on the outer tail pipes. This is needed for this configuration because the stock exhaust ends with a curve. Welding performed by a local muffler shop.

* Purchased 2 MagnaFlo (Summit Racing p/n MPE-14156) 6” round race mufflers. 2.5” straight-thru design to maximize flow. $143.87 ea. .x 2 = $287.74

* Modified the mufflers: $100 parts and labor at a local muffler shop
- Inlet: Added a 2” extension plus a 2” collar to fit over the tail pipes
- Outlet: Added a downturn
- Added (welded) an anchor ring to connect the retaining springs

* Reinstalled the rear fascia. 2 hr. labor

* Fabricated and installed an angle iron spring anchor to attach to the underside of the rear fascia. 1 hr. labor. Anchor is affixed to the fascia using an existing fascia bolt.

* Purchased 4 springs at a local hardware store: 2.25” springs with loops totaling 5” in length. $3

The mufflers are attached by slipping them over the new 2” exhaust pipe extension and securing them with spring tension from a pair of springs between the ring anchor and the fascia anchor.

The completed mufflers weigh 3 lbs. 15 oz. each. I tried to minimize the weight and the length/moment to minimize the stress on the stock exhaust supports.

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At Laguna Seca on January 31, weather conditions were clear, sunny and ~55⁰F. I arranged to do some solo passes in front of the sound booth between Turns 5 and 6 so that the noise reading from my car wouldn’t be affected by others. To facilitate this, my Run Group was held in the starting grid for 1 minute behind me and the track stewards arranged to have the sound booth look for me and record the readings. As I passed the sound booth, the GT350 was typically at max throttle, in third gear, 7500 RPM and 85MPH (as reported by my coach). The sound booth reported that my highest reading with this configuration was 86.1dB.

During our runs on the previous day, it was foggy in the morning. I didn’t get any sound readings at that time, but I never received a violation. I was told that the fog can cause the sound reading to be higher than on a clear day.

Total cost was ~$450 and 6 hr. labor. The mufflers can be installed and removed in seconds. The rotation of the muffler downturns can be adjusted a bit to direct the exhaust away from the booth - if the particular track allows this. This practice is allowed at Laguna Seca, but in this case, they were mostly pointing down at the track surface. The exhaust pipe extensions and the fascia spring anchor are the only visible changes with the mufflers removed.

I plan to replace the GrimmSpeed Exhaust Valve Simulator plugs with a switch in the cabin to defeat the exhaust solenoid as described in another Mustang6G thread. That will make it easier to use these in the future.

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1,246
1,243
In the V6L
I think they're a very clever solution to a complex problem. However, seeing how they're attached, they give me shivers. I wouldn't want to be on or near a race track when you're out there with them. A roll-over or even just a flat spin at 100+ mph and those four-pound weights will detach and fly away like those retainer springs aren't even there. They're capable of doing a lot of damage. I'm surprised you didn't fail tech inspection.

But, like I said, they're a good solution - they just need a more robust way to keep them attached if things go wrong. A short steel safety cable with all-metal fasteners would do it, hooked onto something on the chassis that can handle a couple of hundred pounds.
 

Bugs

Jim. Avocation: Avoiding Blunt-Force Trauma.
34
63
Exp. Type
HPDE
Exp. Level
20+ Years
Eagle ID
they just need a more robust way to keep them attached if things go wrong. A short steel safety cable with all-metal fasteners would do it, hooked onto something on the chassis that can handle a couple of hundred pounds.

A reasonable observation, JAJ. Good idea for an improved design.
 
I like the ingenuity. Going to make note of these to build a set for my 500.
I built Laguna pipes for my GT and what may be possible is to cut the factory tip and weld in v bands and then make the factory tip and a revised Laguna pipe interchangeable with a v hand clamp. Super solid and an easy switch from track to street with nothing that’s visible.

though the rear fascia with the GT350/500 may make that much more difficult taking a closer look at your photos.
 
1,040
1,088
Monaca Pa
I had just bought my car and first track night. I’m behind a Miata and all of a sudden something falls off his car. It bounced about 20’ in the air and almost hit my car o_O I found the guy with the Miata and he told me it was his Super Trap muffler. I was lucky that day. Here is what Dragster’s use to retain their collectors.E802C9C9-50E1-4E3A-B1A2-E8D5E304D64C.jpeg
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
Just my 2 cents worth on sound.... I was at 90.5 DB and our limit is 90Db... I was in danger of getting black flagged. The 90.5DB was with 2 exhaust bungs to reduce sound just in the sound booth (would take of the cheaters out before the race....). So then we decided to add a H pipe after the X pipe and guess what.... Sound went to 88DB with out having to cheat!

Mix those pulses!!!
 
51
48
Exp. Type
W2W Racing
Exp. Level
3-5 Years
Phoenix
I posted in the other thread but figured it would make sense here too. I like the AWE SwitchPath method better than the Grimmspeed modules because you don't have to keep plugging/unplugging anything. Just open and close at the press of a button. No CEL here either. It's more expensive but MUCH more convenient. This way you only need to keep them closed for a short amount of time every lap while you pass the sound booth. I didn't want anything that will keep them shut the entire session just in case there's a durability/tuning reason Ford forces the exhaust open at WOT. If there was a durability reason for it, it shouldn't hurt if you force them shut for a couple seconds every lap. Seems like a safer solution than forcing them shut the entire time.

Just called the guys at AWE, did you purchase the GT5.0L as they were unaware the GT350's were using it, let me know your thoughts?
I posted in the other thread but figured it would make sense here too. I like the AWE SwitchPath method better than the Grimmspeed modules because you don't have to keep plugging/unplugging anything. Just open and close at the press of a button. No CEL here either. It's more expensive but MUCH more convenient. This way you only need to keep them closed for a short amount of time every lap while you pass the sound booth. I didn't want anything that will keep them shut the entire session just in case there's a durability/tuning reason Ford forces the exhaust open at WOT. If there was a durability reason for it, it shouldn't hurt if you force them shut for a couple seconds every lap. Seems like a safer solution than forcing them shut the entire time.

 
Just called the guys at AWE, did you purchase the GT5.0L as they were unaware the GT350's were using it, let me know your thoughts?
Nope! The Mustang GT one is only good for 1 valve. Since ours have 2, you have to get the Focus RS version. It doesn't say it's compatible with the GT350 but it works 100%. Just make sure it says it's for the Focus RS and NOT the Mustang GT.
 
2
0
Exp. Type
HPDE
Exp. Level
Under 3 Years
Tracy, California
Going to be dealing with this soon with my 2020 GT500 as Sonoma and Laguna Seca are my closest tracks.

Any additional feedback on one method be the other?

Sounds the like the AWE makes the exhaust mode independent of the drive mode?
Hi, any luck with a solution for the 90db limit on 2020 GT500?

Thanks Eric
 
51
48
Exp. Type
W2W Racing
Exp. Level
3-5 Years
Phoenix
Hi, any luck with a solution for the 90db limit on 2020 GT500?

Thanks Eric
Yes, it worked great! Now what happened to me the second day was that the OEM exhaust actuators got tweaked and won't close all the way, probably from the back pressure. The course out here in AZ that I used it on is dead flat-open field, so I had to run the valves closed the entire day, that probably was more stress on the OEM actuator. That being said if there's just portions of the track that monitor sound you can simply blip the remote and it closes right up, or if there's terrain that masks the sound you should be OK. I also run aftermarket catless headers and with a flatplane crank= horrendously loud!

***I am selling my AWE that was used just the one day in the classifieds***
 
38
17
GA
Yes, it worked great! Now what happened to me the second day was that the OEM exhaust actuators got tweaked and won't close all the way, probably from the back pressure. The course out here in AZ that I used it on is dead flat-open field, so I had to run the valves closed the entire day, that probably was more stress on the OEM actuator. That being said if there's just portions of the track that monitor sound you can simply blip the remote and it closes right up, or if there's terrain that masks the sound you should be OK. I also run aftermarket catless headers and with a flatplane crank= horrendously loud!

***I am selling my AWE that was used just the one day in the classifieds***
Little survey, anyone else had similar issues?

Possibly broken actuator looks like this and if you remove the actuator it should look like this
1647882381937.png1647882454616.png

Working condition actuator in the closed position
1647882406228.png
 
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