Track car exhaust ideas
#18
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
The Y is stainless, so that's going to be left alone. The headers got dropped of at Performance Coatings yesterday, for their Chromex (looks a lot like Jet-Hot) coating. He said it would be a couple weeks, they are behind because the finish comes in barrels, and it actually froze at the suppliers in Oregon.
I've got two Borla's on the way. I wanted to use multi-core mufflers, but the round one was too big. The gap between the rear seat pans is 6", and the narrowest multi-core round is 6.25" . I went with the Sportsman model which is only 5" round and should fit nicely. For the mid muffler I went with the multi-core oval which measures 16" x 8". The heat shield will accommodate a 14" x 9", so I will need to cut the back off of it for the muffler to fit. It was either that or move down to the 12" model, which I didn't think was going to be big enough. Still waiting on info for the tail pipe.
I've got two Borla's on the way. I wanted to use multi-core mufflers, but the round one was too big. The gap between the rear seat pans is 6", and the narrowest multi-core round is 6.25" . I went with the Sportsman model which is only 5" round and should fit nicely. For the mid muffler I went with the multi-core oval which measures 16" x 8". The heat shield will accommodate a 14" x 9", so I will need to cut the back off of it for the muffler to fit. It was either that or move down to the 12" model, which I didn't think was going to be big enough. Still waiting on info for the tail pipe.
#20
Drifting
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Sounds like you got it sorted out about the Y. They are also pretty easy to make. I did the one on my car by splitting to 45* mandrel bends and seem welding them together.
![](http://farm4.staticflickr.com/3095/2609045108_7afa18466b_b.jpg)
Better pic of a t4 flange Y. Same idea.
![](http://farm4.staticflickr.com/3095/2609045108_7afa18466b_b.jpg)
Better pic of a t4 flange Y. Same idea.
![](http://farm6.staticflickr.com/5144/5597016110_70cb1423e0_b.jpg)
#21
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Wish I had your fab skills, you make it look so easy.
So this is the tail pipe I'm leaning towards, because it is a straight through and has a directional tip. Don't like the ricer look, might coat it. Question is, which way should it be mounted. I've heard downward can reflect sound off the Tarmac, and backward points to the mic. Any suggestions / recommendations ?
So this is the tail pipe I'm leaning towards, because it is a straight through and has a directional tip. Don't like the ricer look, might coat it. Question is, which way should it be mounted. I've heard downward can reflect sound off the Tarmac, and backward points to the mic. Any suggestions / recommendations ?
![](http://i710.photobucket.com/albums/ww110/atb928/5df5057fcc33405bb4738fb2914c0bcb_zps76c3de9b.jpg)
#23
Nordschleife Master
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Adam,
I'd like to also suggest before coating that you cut off those stupid 3 bolt flanges and add convert to v-band. Especially for a track car........
I'd like to also suggest before coating that you cut off those stupid 3 bolt flanges and add convert to v-band. Especially for a track car........
#25
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Those with welding skills (and equipment) take so much for granted.
.
Since the headers are steel, I'd need mild steel V-bands right? Can't use stainless V-bands on mild steel headers? I've got four right now, but they are stainless.
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
Since the headers are steel, I'd need mild steel V-bands right? Can't use stainless V-bands on mild steel headers? I've got four right now, but they are stainless.
#28
Addict
Rennlist Member
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
This combo is NOT going to meet 90dB. I have the Devek L2 headers, long Y to a 3.5" single. With two of the Borla XR-1s in line, I was hitting 94-95 dB at full throttle at the exit of Turn 6 at Laguna Seca. I had to add a Supertrapp w/ a 90° turn away from the sound booth just to achieve 92 dB.
90dB is quiet. Like stock exhaust quiet. Stock 997GT3's can't make that number at full throttle. You'll need something more serious/restrictive than the XR-1s to achieve this.
Sorry to be the bearer of bad news. The combo you're describing is an aural masterpiece but it's not quiet.
#29
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Thanks Dennis,
It's good to know the hard numbers. It sounds like I'm close, and may need to just swap in a different tail pipe muffler for tracks with serious sound restrictions. 94dB is pretty good for just the two borla's, I'm surprised by that. Do you know if they are multi-core or sportsmans?
It's good to know the hard numbers. It sounds like I'm close, and may need to just swap in a different tail pipe muffler for tracks with serious sound restrictions. 94dB is pretty good for just the two borla's, I'm surprised by that. Do you know if they are multi-core or sportsmans?
#30
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
So here's a test fit of the 16" Borla multicore oval. It's a tight fit, but if you modify the heat shield it does fit. You can't tell from this pic, but the heat shield does come down between the muffler and tranny.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0561_zpsgplwv0f8.jpg)
It will be mounted level when installed, but this gives an idea as to clearance at the rear cross member.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0561_zpsgplwv0f8.jpg)
It will be mounted level when installed, but this gives an idea as to clearance at the rear cross member.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0560_zpsm7moort0.jpg)