BS-Legal Exhaust Weights/HP Bonuses?
03-27-2008, 11:52 AM
#51
I didn't weight it before it was installed, but it was a lot lighter than the O.E. when I was on my back under the car.
I have described it as sounding like a sportbike, but thats close.
The sound is fantastic, especially with the windows down - like a big-bore superbike.
Last edited by alnielsen; 03-27-2008 at 11:57 AM.
03-27-2008, 09:11 PM
#52
it's only 9 lbs lighter than OE:
https://www.rx8club.com/showpost.php...3&postcount=32
I think a "new parts adrenaline rush" was kicking in when you were lifting it into place
https://www.rx8club.com/showpost.php...3&postcount=32
I think a "new parts adrenaline rush" was kicking in when you were lifting it into place
Last edited by TeamRX8; 03-27-2008 at 09:14 PM.
06-14-2008, 07:06 PM
#53
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Completed my light-weight catback exhaust...
Took a trip to my friend's place in WVa to put my B-stock exhaust together. The parts I used were as follows:
- Stock catback pipe
- 12" resonator (2.5")
- 45* mandrel bent 2.5" pipe
06-14-2008, 07:26 PM
#54
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There's almost 1.5" of clearance to the rear bumper all around the 2.5" tailpipe, and the bottom of the pipe sits 4.25" off the ground. Total weight came in at 8.130lbs on the digital scale in his shop.
Noise is deep and throaty and b/c the exhaust exits behind the car there's no resonance in the passenger cabin. We let the car idle for 20 minutes, I took her for a quick 2 mile spin (did a couple runs to redline & 2 launches) and then put her back up on the lift - the plastic rear bumper wasn't even warm.
My co-driver and I hope to put the car on the scales next weekend at the DC Pro.
Noise is deep and throaty and b/c the exhaust exits behind the car there's no resonance in the passenger cabin. We let the car idle for 20 minutes, I took her for a quick 2 mile spin (did a couple runs to redline & 2 launches) and then put her back up on the lift - the plastic rear bumper wasn't even warm.
My co-driver and I hope to put the car on the scales next weekend at the DC Pro.
06-14-2008, 10:19 PM
#57
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I built this to be a race-only exhaust - lightweight and no cabin vibrations/resonance were my goals which have been met. It's quiet enough to drive back-n-forth between an event site and a hotel, but it's definitely not intended to be a replacement for my daily driver exhaust. I bought a Mazdaspeed v2 catback for that purpose.
I hope to get a sound reading @ 50ft at one of my local SCCA events in June/July. Based on a loud SS Z06 that hit 95dB last season, mine is significantly quieter.
I hope to get a sound reading @ 50ft at one of my local SCCA events in June/July. Based on a loud SS Z06 that hit 95dB last season, mine is significantly quieter.
06-15-2008, 12:32 AM
#59
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I definitely feel confident that it will meet sound at the strictest sites as the exhaust has the resonator & is angled towards the ground.
LOL! I don't have the $$$ to compete with Team in that department! 
06-15-2008, 07:04 AM
#60
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Nice job.
I thought about doing a similar setup but putting the resonator in the first long straight section of stock pipe and then putting a turndown just after the differential. The reason I didn't do it was because of concerns about resonance in the cabin.
I like what you did because you increased the size of the resonator and eventual pipe. If you slash cut the turndown portion, you would probably gain an inch or two of clearance making it about level with the bottom of the bumper cover, but I guess it might impact sound output as well.
I thought about doing a similar setup but putting the resonator in the first long straight section of stock pipe and then putting a turndown just after the differential. The reason I didn't do it was because of concerns about resonance in the cabin.
I like what you did because you increased the size of the resonator and eventual pipe. If you slash cut the turndown portion, you would probably gain an inch or two of clearance making it about level with the bottom of the bumper cover, but I guess it might impact sound output as well.
06-15-2008, 07:30 AM
#61
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Nice job.
I thought about doing a similar setup but putting the resonator in the first long straight section of stock pipe and then putting a turndown just after the differential. The reason I didn't do it was because of concerns about resonance in the cabin.
I like what you did because you increased the size of the resonator and eventual pipe. If you slash cut the turndown portion, you would probably gain an inch or two of clearance making it about level with the bottom of the bumper cover, but I guess it might impact sound output as well.
I thought about doing a similar setup but putting the resonator in the first long straight section of stock pipe and then putting a turndown just after the differential. The reason I didn't do it was because of concerns about resonance in the cabin.
I like what you did because you increased the size of the resonator and eventual pipe. If you slash cut the turndown portion, you would probably gain an inch or two of clearance making it about level with the bottom of the bumper cover, but I guess it might impact sound output as well.
06-15-2008, 03:17 PM
#62
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I went the simple and light route. I can swap back to the factory exhaust in about 10 minutes. I left it on for the whole weekend of the Atlanta Tour and it wasn't too bad driving back and forth to the hotel.
06-15-2008, 03:37 PM
#63
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Has anyone done back to back dyno pulls with any of these exhausts? My pal just did some testing on his Porsche GT3 SS car and found that he was not only skewing the power band, but also losing power with a super low back pressure system. I don't know, but I wonder if the rotary requires a certain amount of reversion to evacuate gases efficiently...with the '8s power band and torque characteristics, it might be worth knowing...
06-15-2008, 08:46 PM
#64
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Has anyone done back to back dyno pulls with any of these exhausts? My pal just did some testing on his Porsche GT3 SS car and found that he was not only skewing the power band, but also losing power with a super low back pressure system. I don't know, but I wonder if the rotary requires a certain amount of reversion to evacuate gases efficiently...with the '8s power band and torque characteristics, it might be worth knowing...
I could see that happening on Porsches as they have extremely short and compact exhaust systems due to their rear engine layout.
I know racing beat dyno'd an RX-8 w/o a muffler and posted the results on their website:
Power Output
Utilizing our in-house dyno test facilities, the Racing Beat engineering staff has undertaken exhaust system extensive testing with the RX-8 Renesis engine. Our research has found that simply adding a large-diameter, "straight-through" muffler is very loud, and power gains are only modest. We focused our development efforts on optimizing the power output, while maintaining a moderate, but aggressive exhaust tone.
Based upon our initial test sessions, it appeared that the Mazda engineers did not leave much "untapped" horsepower behind in the stock exhaust system. Although it appears there might be modest power gains available from a "cat-back" exhaust system, be wary of big horsepower claims from any aftermarket exhaust system.
Our testing has provided the following results:
Stock production engine - with muffler removed +5 HP
Stock production engine - with RB muffler + 3.5 HP
Stock production engine - with aftermarket system "A" muffler + 3.5 HP
Stock production engine - with aftermarket system "B" muffler + -1.5 HP
Utilizing our in-house dyno test facilities, the Racing Beat engineering staff has undertaken exhaust system extensive testing with the RX-8 Renesis engine. Our research has found that simply adding a large-diameter, "straight-through" muffler is very loud, and power gains are only modest. We focused our development efforts on optimizing the power output, while maintaining a moderate, but aggressive exhaust tone.
Based upon our initial test sessions, it appeared that the Mazda engineers did not leave much "untapped" horsepower behind in the stock exhaust system. Although it appears there might be modest power gains available from a "cat-back" exhaust system, be wary of big horsepower claims from any aftermarket exhaust system.
Our testing has provided the following results:
Stock production engine - with muffler removed +5 HP
Stock production engine - with RB muffler + 3.5 HP
Stock production engine - with aftermarket system "A" muffler + 3.5 HP
Stock production engine - with aftermarket system "B" muffler + -1.5 HP
06-15-2008, 09:06 PM
#65
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How's the resonance/vibration in the car?
That was one idea I tossed around and even asked Sipe about his turn-down, but scratched the plan as I was concerned about the increase in interior noise. I also wasn't sure about it meeting sound at a strict site with a 92dB limit w/o a muffler or resonator being included.
06-15-2008, 10:16 PM
#66
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Mike,
I could see that happening on Porsches as they have extremely short and compact exhaust systems due to their rear engine layout.
I know racing beat dyno'd an RX-8 w/o a muffler and posted the results on their website:
http://www.racingbeat.com/FRmazda4.htm
I could see that happening on Porsches as they have extremely short and compact exhaust systems due to their rear engine layout.
I know racing beat dyno'd an RX-8 w/o a muffler and posted the results on their website:
http://www.racingbeat.com/FRmazda4.htm
06-15-2008, 10:39 PM
#67
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Thanks for the info. I understand that the Porsche was not the best example, because of the exhaust layout, but it would be interesting to see actual dyno plots of the RX8 with stock muffler, no muffler and the typical single exit autocross system. I'd like to see if the power band changes and how...
06-15-2008, 10:58 PM
#68
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06-17-2008, 07:32 AM
#69
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Miles,
How's the resonance/vibration in the car?
That was one idea I tossed around and even asked Sipe about his turn-down, but scratched the plan as I was concerned about the increase in interior noise. I also wasn't sure about it meeting sound at a strict site with a 92dB limit w/o a muffler or resonator being included.
How's the resonance/vibration in the car?
That was one idea I tossed around and even asked Sipe about his turn-down, but scratched the plan as I was concerned about the increase in interior noise. I also wasn't sure about it meeting sound at a strict site with a 92dB limit w/o a muffler or resonator being included.
It is acceptable for driving to and from the event site for a weekend but other than that it would be punishing. As far as outside the car, it was nowhere near the loudest car at the Atl Tour. I have not had the dB measured or anything but I don't see it being a problem.
I do have a backup plan though. For really strict sites I plan on bringing an "extension" that I know is fairly quiet.
06-17-2008, 08:52 AM
#70
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I would not drive the car daily with this setup. It is pretty loud in the car at any speed unless you have the clutch in. At idle and coasting clutch-in it's not too loud It is acceptable for driving to and from the event site for a weekend but other than that it would be punishing.
As far as outside the car, it was nowhere near the loudest car at the Atl Tour. I have not had the dB measured or anything but I don't see it being a problem.
I do have a backup plan though. For really strict sites I plan on bringing an "extension" that I know is fairly quiet.
It is acceptable for driving to and from the event site for a weekend but other than that it would be punishing. As far as outside the car, it was nowhere near the loudest car at the Atl Tour. I have not had the dB measured or anything but I don't see it being a problem.
I do have a backup plan though. For really strict sites I plan on bringing an "extension" that I know is fairly quiet.
One reason I chose a resonator over a muffler was weight - most light mufflers were in the 4-5lbs range, while my stainless resonator came in at 2.5lbs.
06-17-2008, 03:55 PM
#71
the only thing a a Porsche boxer engine and a Renesis rotary have in common is that they power a chassis ... 
the similar TeamRX8 V1 exhaust using 20 ga tube and a single ultralite muffler weighed 9 lbs, so I'm doubtful that this one is 8.5 lbs catback pipe and all ....
https://www.rx8club.com/showpost.php...3&postcount=47
.
the similar TeamRX8 V1 exhaust using 20 ga tube and a single ultralite muffler weighed 9 lbs, so I'm doubtful that this one is 8.5 lbs catback pipe and all ....
https://www.rx8club.com/showpost.php...3&postcount=47
.
Last edited by TeamRX8; 06-17-2008 at 04:00 PM.
06-17-2008, 04:04 PM
#72
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I drove a car once that had a turn-down and the vibrations inside were so strong I couldn't concentrate on course. Your back-up exhaust looks great. How much does the entire catback weigh in that configuration (i.e. catback pipe + the additional piece you put together)?
One reason I chose a resonator over a muffler was weight - most light mufflers were in the 4-5lbs range, while my stainless resonator came in at 2.5lbs.
One reason I chose a resonator over a muffler was weight - most light mufflers were in the 4-5lbs range, while my stainless resonator came in at 2.5lbs.
I initially planned on using the complete "extension" as a modular exhaust system. I made sure that I could use any 20" long muffler in case the Magnaflow was too loud. When we started the car on the lift with no muffler or turn-down it wasn't as loud as we thought it was going to be. Next we put the Magnaflow on and it was way quieter than expected. All hooked up it sounds awesome and I have thought about running the complete system daily but so far I have stuck with the OE muffler for daily use.
A 2.5lb resonator sounds interesting though......
Last edited by MilesJ; 06-17-2008 at 04:07 PM.
06-17-2008, 05:02 PM
#73
06-17-2008, 06:11 PM
#74
a 2.5" ID model will weigh 3 lbs with stainless packing and enough volume to muffle noise below 95 dB
what you hear in the interior and what the sound meter reads are not directly connected
I've run a cat back straight pipe, it won't pass most sound regs and if you spend any time driving it that way you'll end up with the ringing ears from hell syndrome, assuming you have any hearing to start with ...
The OE cat back pipe without OE muffler weighs about 6 lbs by itself, if you use a std gauge muffler elbow that will weigh several pounds plus the weight of the muffler/resonator, plus anything extra
Last edited by TeamRX8; 06-17-2008 at 06:18 PM.
06-17-2008, 06:46 PM
#75
Has anyone done back to back dyno pulls with any of these exhausts? My pal just did some testing on his Porsche GT3 SS car and found that he was not only skewing the power band, but also losing power with a super low back pressure system. I don't know, but I wonder if the rotary requires a certain amount of reversion to evacuate gases efficiently...with the '8s power band and torque characteristics, it might be worth knowing...
With larger pipe, the weight was 12#, but with the Burns Muffler, the sound at WOT is unreal-throaty and smooth. The Horsepower increased by 7 and the torque by 5.4 ft lbs.
This is now on my '07 which was pictured in the article that Jason wrote in SportsCar last month on PDX and Time Trials. While I was instructing in another vehicle during the PDX portion of the day, my son was circling in the 8 and passed us two times.
The sound at full throttle rivals that of the Speedsource 3-rotor, just not quite as deep! It is a little loud, but passes sound at events-better than most M3's.